Add fields order (#550)

PR approved by mistake.

.github/dependabot.yml

@@ -0,0 +1,10 @@
+version: 2
+updates:
+  - package-ecosystem: github-actions
+    directory: /
+    schedule:
+      interval: weekly
+  - package-ecosystem: gomod
+    directory: /
+    schedule:
+      interval: weekly

.github/workflows/test.yml

@@ -0,0 +1,36 @@
+on: [push, pull_request]
+name: Test
+jobs:
+  test:
+    strategy:
+      matrix:
+        go-version: [1.18.x, 1.21.x]
+        os: [ubuntu-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
+    steps:
+    - name: Install Go
+      uses: actions/setup-go@v5
+      with:
+        go-version: ${{ matrix.go-version }}
+    - name: Checkout code
+      uses: actions/checkout@v4
+    - uses: actions/cache@v4
+      with:
+        path: ~/go/pkg/mod
+        key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
+        restore-keys: |
+          ${{ runner.os }}-go-
+    - name: Test
+      run: go test -race -bench . -benchmem ./...
+    - name: Test CBOR
+      run: go test -tags binary_log ./...
+  coverage:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Update coverage report
+      uses: ncruces/go-coverage-report@main
+      with:
+        report: 'true'
+        chart: 'true'
+        amend: 'true'
+      continue-on-error: true

.gitignore

@@ -6,6 +6,7 @@
 # Folders
 _obj
 _test
+tmp
 
 # Architecture specific extensions/prefixes
 *.[568vq]

.travis.yml

@@ -1,10 +0,0 @@
-language: go
-go:
-- 1.7
-- 1.8
-- tip
-matrix:
-  allow_failures:
-      - go: tip
-script:
-  go test -v -race -cpu=1,2,4 -bench . -benchmem ./...

CNAME

@@ -0,0 +1 @@
+zerolog.io

README.md

@@ -1,74 +1,314 @@
 # Zero Allocation JSON Logger
 
-[![godoc](http://img.shields.io/badge/godoc-reference-blue.svg?style=flat)](https://godoc.org/github.com/rs/zerolog) [![license](http://img.shields.io/badge/license-MIT-red.svg?style=flat)](https://raw.githubusercontent.com/rs/zerolog/master/LICENSE) [![Build Status](https://travis-ci.org/rs/zerolog.svg?branch=master)](https://travis-ci.org/rs/zerolog) [![Coverage](http://gocover.io/_badge/github.com/rs/zerolog)](http://gocover.io/github.com/rs/zerolog)
+[![godoc](http://img.shields.io/badge/godoc-reference-blue.svg?style=flat)](https://godoc.org/github.com/rs/zerolog) [![license](http://img.shields.io/badge/license-MIT-red.svg?style=flat)](https://raw.githubusercontent.com/rs/zerolog/master/LICENSE) [![Build Status](https://github.com/rs/zerolog/actions/workflows/test.yml/badge.svg)](https://github.com/rs/zerolog/actions/workflows/test.yml) [![Go Coverage](https://github.com/rs/zerolog/wiki/coverage.svg)](https://raw.githack.com/wiki/rs/zerolog/coverage.html)
 
 The zerolog package provides a fast and simple logger dedicated to JSON output.
 
-Zerolog's API is designed to provide both a great developer experience and stunning [performance](#performance). Its unique chaining API allows zerolog to write JSON log events by avoiding allocations and reflection.
+Zerolog's API is designed to provide both a great developer experience and stunning [performance](#benchmarks). Its unique chaining API allows zerolog to write JSON (or CBOR) log events by avoiding allocations and reflection.
 
-The uber's [zap](https://godoc.org/go.uber.org/zap) library pioneered this approach. Zerolog is taking this concept to the next level with simpler to use API and even better performance.
+Uber's [zap](https://godoc.org/go.uber.org/zap) library pioneered this approach. Zerolog is taking this concept to the next level with a simpler to use API and even better performance.
 
-To keep the code base and the API simple, zerolog focuses on JSON logging only. Pretty logging on the console is made possible using the provided (but inefficient) `zerolog.ConsoleWriter`.
+To keep the code base and the API simple, zerolog focuses on efficient structured logging only. Pretty logging on the console is made possible using the provided (but inefficient) [`zerolog.ConsoleWriter`](#pretty-logging).
 
-![](pretty.png)
+![Pretty Logging Image](pretty.png)
+
+## Who uses zerolog
+
+Find out [who uses zerolog](https://github.com/rs/zerolog/wiki/Who-uses-zerolog) and add your company / project to the list.
 
 ## Features
 
-* Blazing fast
-* Low to zero allocation
-* Level logging
-* Sampling
-* Contextual fields
-* `context.Context` integration
-* `net/http` helpers
-* Pretty logging for development
+* [Blazing fast](#benchmarks)
+* [Low to zero allocation](#benchmarks)
+* [Leveled logging](#leveled-logging)
+* [Sampling](#log-sampling)
+* [Hooks](#hooks)
+* [Contextual fields](#contextual-logging)
+* [`context.Context` integration](#contextcontext-integration)
+* [Integration with `net/http`](#integration-with-nethttp)
+* [JSON and CBOR encoding formats](#binary-encoding)
+* [Pretty logging for development](#pretty-logging)
+* [Error Logging (with optional Stacktrace)](#error-logging)
 
-## Usage
+## Installation
 
-```go
-import "github.com/rs/zerolog/log"
+```bash
+go get -u github.com/rs/zerolog/log
 ```
 
-### A global logger can be use for simple logging
+## Getting Started
+
+### Simple Logging Example
+
+For simple logging, import the global logger package **github.com/rs/zerolog/log**
 
 ```go
-log.Print("hello world")
+package main
 
-// Output: {"level":"debug","time":1494567715,"message":"hello world"}
+import (
+    "github.com/rs/zerolog"
+    "github.com/rs/zerolog/log"
+)
+
+func main() {
+    // UNIX Time is faster and smaller than most timestamps
+    zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
+
+    log.Print("hello world")
+}
+
+// Output: {"time":1516134303,"level":"debug","message":"hello world"}
 ```
+> Note: By default log writes to `os.Stderr`
+> Note: The default log level for `log.Print` is *trace*
 
+### Contextual Logging
+
+**zerolog** allows data to be added to log messages in the form of key:value pairs. The data added to the message adds "context" about the log event that can be critical for debugging as well as myriad other purposes. An example of this is below:
 
 ```go
-log.Info().Msg("hello world")
+package main
 
-// Output: {"level":"info","time":1494567715,"message":"hello world"}
+import (
+    "github.com/rs/zerolog"
+    "github.com/rs/zerolog/log"
+)
+
+func main() {
+    zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
+
+    log.Debug().
+        Str("Scale", "833 cents").
+        Float64("Interval", 833.09).
+        Msg("Fibonacci is everywhere")
+    
+    log.Debug().
+        Str("Name", "Tom").
+        Send()
+}
+
+// Output: {"level":"debug","Scale":"833 cents","Interval":833.09,"time":1562212768,"message":"Fibonacci is everywhere"}
+// Output: {"level":"debug","Name":"Tom","time":1562212768}
 ```
 
-NOTE: To import the global logger, import the `log` subpackage `github.com/rs/zerolog/log`.
+> You'll note in the above example that when adding contextual fields, the fields are strongly typed. You can find the full list of supported fields [here](#standard-types)
+
+### Leveled Logging
+
+#### Simple Leveled Logging Example
 
 ```go
-log.Fatal().
-    Err(err).
-    Str("service", service).
-    Msgf("Cannot start %s", service)
+package main
 
-// Output: {"level":"fatal","time":1494567715,"message":"Cannot start myservice","error":"some error","service":"myservice"}
-// Exit 1
+import (
+    "github.com/rs/zerolog"
+    "github.com/rs/zerolog/log"
+)
+
+func main() {
+    zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
+
+    log.Info().Msg("hello world")
+}
+
+// Output: {"time":1516134303,"level":"info","message":"hello world"}
 ```
 
-NOTE: Using `Msgf` generates one allocation even when the logger is disabled.
+> It is very important to note that when using the **zerolog** chaining API, as shown above (`log.Info().Msg("hello world"`), the chain must have either the `Msg` or `Msgf` method call. If you forget to add either of these, the log will not occur and there is no compile time error to alert you of this.
 
-### Fields can be added to log messages
+**zerolog** allows for logging at the following levels (from highest to lowest):
+
+* panic (`zerolog.PanicLevel`, 5)
+* fatal (`zerolog.FatalLevel`, 4)
+* error (`zerolog.ErrorLevel`, 3)
+* warn (`zerolog.WarnLevel`, 2)
+* info (`zerolog.InfoLevel`, 1)
+* debug (`zerolog.DebugLevel`, 0)
+* trace (`zerolog.TraceLevel`, -1)
+
+You can set the Global logging level to any of these options using the `SetGlobalLevel` function in the zerolog package, passing in one of the given constants above, e.g. `zerolog.InfoLevel` would be the "info" level.  Whichever level is chosen, all logs with a level greater than or equal to that level will be written. To turn off logging entirely, pass the `zerolog.Disabled` constant.
+
+#### Setting Global Log Level
+
+This example uses command-line flags to demonstrate various outputs depending on the chosen log level.
 
 ```go
-log.Info().
-    Str("foo", "bar").
-    Int("n", 123).
-    Msg("hello world")
+package main
 
-// Output: {"level":"info","time":1494567715,"foo":"bar","n":123,"message":"hello world"}
+import (
+    "flag"
+
+    "github.com/rs/zerolog"
+    "github.com/rs/zerolog/log"
+)
+
+func main() {
+    zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
+    debug := flag.Bool("debug", false, "sets log level to debug")
+
+    flag.Parse()
+
+    // Default level for this example is info, unless debug flag is present
+    zerolog.SetGlobalLevel(zerolog.InfoLevel)
+    if *debug {
+        zerolog.SetGlobalLevel(zerolog.DebugLevel)
+    }
+
+    log.Debug().Msg("This message appears only when log level set to Debug")
+    log.Info().Msg("This message appears when log level set to Debug or Info")
+
+    if e := log.Debug(); e.Enabled() {
+        // Compute log output only if enabled.
+        value := "bar"
+        e.Str("foo", value).Msg("some debug message")
+    }
+}
 ```
 
+Info Output (no flag)
+
+```bash
+$ ./logLevelExample
+{"time":1516387492,"level":"info","message":"This message appears when log level set to Debug or Info"}
+```
+
+Debug Output (debug flag set)
+
+```bash
+$ ./logLevelExample -debug
+{"time":1516387573,"level":"debug","message":"This message appears only when log level set to Debug"}
+{"time":1516387573,"level":"info","message":"This message appears when log level set to Debug or Info"}
+{"time":1516387573,"level":"debug","foo":"bar","message":"some debug message"}
+```
+
+#### Logging without Level or Message
+
+You may choose to log without a specific level by using the `Log` method. You may also write without a message by setting an empty string in the `msg string` parameter of the `Msg` method. Both are demonstrated in the example below.
+
+```go
+package main
+
+import (
+    "github.com/rs/zerolog"
+    "github.com/rs/zerolog/log"
+)
+
+func main() {
+    zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
+
+    log.Log().
+        Str("foo", "bar").
+        Msg("")
+}
+
+// Output: {"time":1494567715,"foo":"bar"}
+```
+
+### Error Logging
+
+You can log errors using the `Err` method
+
+```go
+package main
+
+import (
+	"errors"
+
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/log"
+)
+
+func main() {
+	zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
+
+	err := errors.New("seems we have an error here")
+	log.Error().Err(err).Msg("")
+}
+
+// Output: {"level":"error","error":"seems we have an error here","time":1609085256}
+```
+
+> The default field name for errors is `error`, you can change this by setting `zerolog.ErrorFieldName` to meet your needs.
+
+#### Error Logging with Stacktrace
+
+Using `github.com/pkg/errors`, you can add a formatted stacktrace to your errors. 
+
+```go
+package main
+
+import (
+	"github.com/pkg/errors"
+	"github.com/rs/zerolog/pkgerrors"
+
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/log"
+)
+
+func main() {
+	zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
+	zerolog.ErrorStackMarshaler = pkgerrors.MarshalStack
+
+	err := outer()
+	log.Error().Stack().Err(err).Msg("")
+}
+
+func inner() error {
+	return errors.New("seems we have an error here")
+}
+
+func middle() error {
+	err := inner()
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func outer() error {
+	err := middle()
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+// Output: {"level":"error","stack":[{"func":"inner","line":"20","source":"errors.go"},{"func":"middle","line":"24","source":"errors.go"},{"func":"outer","line":"32","source":"errors.go"},{"func":"main","line":"15","source":"errors.go"},{"func":"main","line":"204","source":"proc.go"},{"func":"goexit","line":"1374","source":"asm_amd64.s"}],"error":"seems we have an error here","time":1609086683}
+```
+
+> zerolog.ErrorStackMarshaler must be set in order for the stack to output anything.
+
+#### Logging Fatal Messages
+
+```go
+package main
+
+import (
+    "errors"
+
+    "github.com/rs/zerolog"
+    "github.com/rs/zerolog/log"
+)
+
+func main() {
+    err := errors.New("A repo man spends his life getting into tense situations")
+    service := "myservice"
+
+    zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
+
+    log.Fatal().
+        Err(err).
+        Str("service", service).
+        Msgf("Cannot start %s", service)
+}
+
+// Output: {"time":1516133263,"level":"fatal","error":"A repo man spends his life getting into tense situations","service":"myservice","message":"Cannot start myservice"}
+//         exit status 1
+```
+
+> NOTE: Using `Msgf` generates one allocation even when the logger is disabled.
+
+
 ### Create logger instance to manage different outputs
 
 ```go
@@ -83,40 +323,47 @@ logger.Info().Str("foo", "bar").Msg("hello world")
 
 ```go
 sublogger := log.With().
-                 Str("component": "foo").
+                 Str("component", "foo").
                  Logger()
 sublogger.Info().Msg("hello world")
 
 // Output: {"level":"info","time":1494567715,"message":"hello world","component":"foo"}
 ```
 
-### Level logging
-
-```go
-zerolog.SetGlobalLevel(zerolog.InfoLevel)
-
-log.Debug().Msg("filtered out message")
-log.Info().Msg("routed message")
-
-if e := log.Debug(); e.Enabled() {
-    // Compute log output only if enabled.
-    value := compute()
-    e.Str("foo": value).Msg("some debug message")
-}
-
-// Output: {"level":"info","time":1494567715,"message":"routed message"}
-```
-
 ### Pretty logging
 
+To log a human-friendly, colorized output, use `zerolog.ConsoleWriter`:
+
 ```go
-if isConsole {
-    log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr})
-}
+log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr})
 
 log.Info().Str("foo", "bar").Msg("Hello world")
 
-// Output: 1494567715 |INFO| Hello world foo=bar
+// Output: 3:04PM INF Hello World foo=bar
+```
+
+To customize the configuration and formatting:
+
+```go
+output := zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: time.RFC3339}
+output.FormatLevel = func(i interface{}) string {
+    return strings.ToUpper(fmt.Sprintf("| %-6s|", i))
+}
+output.FormatMessage = func(i interface{}) string {
+    return fmt.Sprintf("***%s****", i)
+}
+output.FormatFieldName = func(i interface{}) string {
+    return fmt.Sprintf("%s:", i)
+}
+output.FormatFieldValue = func(i interface{}) string {
+    return strings.ToUpper(fmt.Sprintf("%s", i))
+}
+
+log := zerolog.New(output).With().Timestamp().Logger()
+
+log.Info().Str("foo", "bar").Msg("Hello World")
+
+// Output: 2006-01-02T15:04:05Z07:00 | INFO  | ***Hello World**** foo:BAR
 ```
 
 ### Sub dictionary
@@ -126,7 +373,7 @@ log.Info().
     Str("foo", "bar").
     Dict("dict", zerolog.Dict().
         Str("bar", "baz").
-        Int("n", 1)
+        Int("n", 1),
     ).Msg("hello world")
 
 // Output: {"level":"info","time":1494567715,"foo":"bar","dict":{"bar":"baz","n":1},"message":"hello world"}
@@ -144,20 +391,49 @@ log.Info().Msg("hello world")
 // Output: {"l":"info","t":1494567715,"m":"hello world"}
 ```
 
-### Log with no level nor message
-
-```go
-log.Log().Str("foo","bar").Msg("")
-
-// Output: {"time":1494567715,"foo":"bar"}
-```
-
 ### Add contextual fields to the global logger
 
 ```go
 log.Logger = log.With().Str("foo", "bar").Logger()
 ```
 
+### Add file and line number to log
+
+Equivalent of `Llongfile`:
+
+```go
+log.Logger = log.With().Caller().Logger()
+log.Info().Msg("hello world")
+
+// Output: {"level": "info", "message": "hello world", "caller": "/go/src/your_project/some_file:21"}
+```
+
+Equivalent of `Lshortfile`:
+
+```go
+zerolog.CallerMarshalFunc = func(pc uintptr, file string, line int) string {
+    return filepath.Base(file) + ":" + strconv.Itoa(line)
+}
+log.Logger = log.With().Caller().Logger()
+log.Info().Msg("hello world")
+
+// Output: {"level": "info", "message": "hello world", "caller": "some_file:21"}
+```
+
+### Thread-safe, lock-free, non-blocking writer
+
+If your writer might be slow or not thread-safe and you need your log producers to never get slowed down by a slow writer, you can use a `diode.Writer` as follows:
+
+```go
+wr := diode.NewWriter(os.Stdout, 1000, 10*time.Millisecond, func(missed int) {
+		fmt.Printf("Logger Dropped %d messages", missed)
+	})
+log := zerolog.New(wr)
+log.Print("test")
+```
+
+You will need to install `code.cloudfoundry.org/go-diodes` to use this feature.
+
 ### Log Sampling
 
 ```go
@@ -185,11 +461,27 @@ sampled.Debug().Msg("hello world")
 // Output: {"time":1494567715,"level":"debug","message":"hello world"}
 ```
 
+### Hooks
+
+```go
+type SeverityHook struct{}
+
+func (h SeverityHook) Run(e *zerolog.Event, level zerolog.Level, msg string) {
+    if level != zerolog.NoLevel {
+        e.Str("severity", level.String())
+    }
+}
+
+hooked := log.Hook(SeverityHook{})
+hooked.Warn().Msg("")
+
+// Output: {"level":"warn","severity":"warn"}
+```
 
 ### Pass a sub-logger by context
 
 ```go
-ctx := log.With("component", "module").Logger().WithContext(ctx)
+ctx := log.With().Str("component", "module").Logger().WithContext(ctx)
 
 log.Ctx(ctx).Info().Msg("hello world")
 
@@ -211,6 +503,58 @@ stdlog.Print("hello world")
 // Output: {"foo":"bar","message":"hello world"}
 ```
 
+### context.Context integration
+
+Go contexts are commonly passed throughout Go code, and this can help you pass
+your Logger into places it might otherwise be hard to inject.  The `Logger`
+instance may be attached to Go context (`context.Context`) using
+`Logger.WithContext(ctx)` and extracted from it using `zerolog.Ctx(ctx)`.
+For example:
+
+```go
+func f() {
+    logger := zerolog.New(os.Stdout)
+    ctx := context.Background()
+
+    // Attach the Logger to the context.Context
+    ctx = logger.WithContext(ctx)
+    someFunc(ctx)
+}
+
+func someFunc(ctx context.Context) {
+    // Get Logger from the go Context. if it's nil, then
+    // `zerolog.DefaultContextLogger` is returned, if
+    // `DefaultContextLogger` is nil, then a disabled logger is returned.
+    logger := zerolog.Ctx(ctx)
+    logger.Info().Msg("Hello")
+}
+```
+
+A second form of `context.Context` integration allows you to pass the current
+context.Context into the logged event, and retrieve it from hooks.  This can be
+useful to log trace and span IDs or other information stored in the go context,
+and facilitates the unification of logging and tracing in some systems:
+
+```go
+type TracingHook struct{}
+
+func (h TracingHook) Run(e *zerolog.Event, level zerolog.Level, msg string) {
+    ctx := e.GetCtx()
+    spanId := getSpanIdFromContext(ctx) // as per your tracing framework
+    e.Str("span-id", spanId)
+}
+
+func f() {
+    // Setup the logger
+    logger := zerolog.New(os.Stdout)
+    logger = logger.Hook(TracingHook{})
+
+    ctx := context.Background()
+    // Use the Ctx function to make the context available to the hook
+    logger.Info().Ctx(ctx).Msg("Hello")
+}
+```
+
 ### Integration with `net/http`
 
 The `github.com/rs/zerolog/hlog` package provides some helpers to integrate zerolog with `http.Handler`.
@@ -230,11 +574,11 @@ c := alice.New()
 c = c.Append(hlog.NewHandler(log))
 
 // Install some provided extra handler to set some request's context fields.
-// Thanks to those handler, all our logs will come with some pre-populated fields.
+// Thanks to that handler, all our logs will come with some prepopulated fields.
 c = c.Append(hlog.AccessHandler(func(r *http.Request, status, size int, duration time.Duration) {
     hlog.FromRequest(r).Info().
         Str("method", r.Method).
-        Str("url", r.URL.String()).
+        Stringer("url", r.URL).
         Int("status", status).
         Int("size", size).
         Dur("duration", duration).
@@ -264,22 +608,44 @@ if err := http.ListenAndServe(":8080", nil); err != nil {
 }
 ```
 
+## Multiple Log Output
+`zerolog.MultiLevelWriter` may be used to send the log message to multiple outputs. 
+In this example, we send the log message to both `os.Stdout` and the in-built ConsoleWriter.
+```go
+func main() {
+	consoleWriter := zerolog.ConsoleWriter{Out: os.Stdout}
+
+	multi := zerolog.MultiLevelWriter(consoleWriter, os.Stdout)
+
+	logger := zerolog.New(multi).With().Timestamp().Logger()
+
+	logger.Info().Msg("Hello World!")
+}
+
+// Output (Line 1: Console; Line 2: Stdout)
+// 12:36PM INF Hello World!
+// {"level":"info","time":"2019-11-07T12:36:38+03:00","message":"Hello World!"}
+```
+
 ## Global Settings
 
-Some settings can be changed and will by applied to all loggers:
+Some settings can be changed and will be applied to all loggers:
 
 * `log.Logger`: You can set this value to customize the global logger (the one used by package level methods).
-* `zerolog.SetGlobalLevel`: Can raise the minimum level of all loggers. Set this to `zerolog.Disable` to disable logging altogether (quiet mode).
+* `zerolog.SetGlobalLevel`: Can raise the minimum level of all loggers. Call this with `zerolog.Disabled` to disable logging altogether (quiet mode).
 * `zerolog.DisableSampling`: If argument is `true`, all sampled loggers will stop sampling and issue 100% of their log events.
 * `zerolog.TimestampFieldName`: Can be set to customize `Timestamp` field name.
 * `zerolog.LevelFieldName`: Can be set to customize level field name.
 * `zerolog.MessageFieldName`: Can be set to customize message field name.
 * `zerolog.ErrorFieldName`: Can be set to customize `Err` field name.
-* `zerolog.TimeFieldFormat`: Can be set to customize `Time` field value formatting. If set with an empty string, times are formated as UNIX timestamp.
-	// DurationFieldUnit defines the unit for time.Duration type fields added
-	// using the Dur method.
-* `DurationFieldUnit`: Sets the unit of the fields added by `Dur` (default: `time.Millisecond`).
-* `DurationFieldInteger`: If set to true, `Dur` fields are formatted as integers instead of floats.
+* `zerolog.TimeFieldFormat`: Can be set to customize `Time` field value formatting. If set with `zerolog.TimeFormatUnix`, `zerolog.TimeFormatUnixMs` or `zerolog.TimeFormatUnixMicro`, times are formatted as UNIX timestamp.
+* `zerolog.DurationFieldUnit`: Can be set to customize the unit for time.Duration type fields added by `Dur` (default: `time.Millisecond`).
+* `zerolog.DurationFieldInteger`: If set to `true`, `Dur` fields are formatted as integers instead of floats (default: `false`). 
+* `zerolog.ErrorHandler`: Called whenever zerolog fails to write an event on its output. If not set, an error is printed on the stderr. This handler must be thread safe and non-blocking.
+* `zerolog.FloatingPointPrecision`: If set to a value other than -1, controls the number
+of digits when formatting float numbers in JSON. See
+[strconv.FormatFloat](https://pkg.go.dev/strconv#FormatFloat)
+for more details.
 
 ## Field Types
 
@@ -293,29 +659,53 @@ Some settings can be changed and will by applied to all loggers:
 
 ### Advanced Fields
 
-* `Err`: Takes an `error` and render it as a string using the `zerolog.ErrorFieldName` field name.
-* `Timestamp`: Insert a timestamp field with `zerolog.TimestampFieldName` field name and formatted using `zerolog.TimeFieldFormat`.
-* `Time`: Adds a field with the time formated with the `zerolog.TimeFieldFormat`.
-* `Dur`: Adds a field with a `time.Duration`.
+* `Err`: Takes an `error` and renders it as a string using the `zerolog.ErrorFieldName` field name.
+* `Func`: Run a `func` only if the level is enabled.
+* `Timestamp`: Inserts a timestamp field with `zerolog.TimestampFieldName` field name, formatted using `zerolog.TimeFieldFormat`.
+* `Time`: Adds a field with time formatted with `zerolog.TimeFieldFormat`.
+* `Dur`: Adds a field with `time.Duration`.
 * `Dict`: Adds a sub-key/value as a field of the event.
+* `RawJSON`: Adds a field with an already encoded JSON (`[]byte`)
+* `Hex`: Adds a field with value formatted as a hexadecimal string (`[]byte`)
 * `Interface`: Uses reflection to marshal the type.
 
+Most fields are also available in the slice format (`Strs` for `[]string`, `Errs` for `[]error` etc.)
+
+## Binary Encoding
+
+In addition to the default JSON encoding, `zerolog` can produce binary logs using [CBOR](https://cbor.io) encoding. The choice of encoding can be decided at compile time using the build tag `binary_log` as follows:
+
+```bash
+go build -tags binary_log .
+```
+
+To Decode binary encoded log files you can use any CBOR decoder. One has been tested to work
+with zerolog library is [CSD](https://github.com/toravir/csd/).
+
+## Related Projects
+
+* [grpc-zerolog](https://github.com/cheapRoc/grpc-zerolog): Implementation of `grpclog.LoggerV2` interface using `zerolog`
+* [overlog](https://github.com/Trendyol/overlog): Implementation of `Mapped Diagnostic Context` interface using `zerolog`
+* [zerologr](https://github.com/go-logr/zerologr): Implementation of `logr.LogSink` interface using `zerolog`
+
 ## Benchmarks
 
+See [logbench](http://bench.zerolog.io/) for more comprehensive and up-to-date benchmarks.
+
 All operations are allocation free (those numbers *include* JSON encoding):
 
-```
-BenchmarkLogEmpty-8        100000000    19.1 ns/op	   0 B/op       0 allocs/op
-BenchmarkDisabled-8        500000000     4.07 ns/op	   0 B/op       0 allocs/op
-BenchmarkInfo-8            30000000	    42.5 ns/op	   0 B/op       0 allocs/op
-BenchmarkContextFields-8   30000000	    44.9 ns/op	   0 B/op       0 allocs/op
-BenchmarkLogFields-8       10000000	   184 ns/op	   0 B/op       0 allocs/op
+```text
+BenchmarkLogEmpty-8        100000000    19.1 ns/op     0 B/op       0 allocs/op
+BenchmarkDisabled-8        500000000    4.07 ns/op     0 B/op       0 allocs/op
+BenchmarkInfo-8            30000000     42.5 ns/op     0 B/op       0 allocs/op
+BenchmarkContextFields-8   30000000     44.9 ns/op     0 B/op       0 allocs/op
+BenchmarkLogFields-8       10000000     184 ns/op      0 B/op       0 allocs/op
 ```
 
 There are a few Go logging benchmarks and comparisons that include zerolog.
 
-- [imkira/go-loggers-bench](https://github.com/imkira/go-loggers-bench)
-- [uber-common/zap](https://github.com/uber-go/zap#performance)
+* [imkira/go-loggers-bench](https://github.com/imkira/go-loggers-bench)
+* [uber-common/zap](https://github.com/uber-go/zap#performance)
 
 Using Uber's zap comparison benchmark:
 
@@ -359,3 +749,34 @@ Log a static string, without any context or `printf`-style templating:
 | apex/log | 2751 ns/op | 584 B/op | 11 allocs/op |
 | log15 | 5181 ns/op | 1592 B/op | 26 allocs/op |
 
+## Caveats
+
+### Field duplication
+
+Note that zerolog does no de-duplication of fields. Using the same key multiple times creates multiple keys in final JSON:
+
+```go
+logger := zerolog.New(os.Stderr).With().Timestamp().Logger()
+logger.Info().
+       Timestamp().
+       Msg("dup")
+// Output: {"level":"info","time":1494567715,"time":1494567715,"message":"dup"}
+```
+
+In this case, many consumers will take the last value, but this is not guaranteed; check yours if in doubt.
+
+### Concurrency safety
+
+Be careful when calling UpdateContext. It is not concurrency safe. Use the With method to create a child logger:
+
+```go
+func handler(w http.ResponseWriter, r *http.Request) {
+    // Create a child logger for concurrency safety
+    logger := log.Logger.With().Logger()
+
+    // Add context fields, for example User-Agent from HTTP headers
+    logger.UpdateContext(func(c zerolog.Context) zerolog.Context {
+        ...
+    })
+}
+```

_config.yml

@@ -0,0 +1 @@
+remote_theme: rs/gh-readme

array.go

@@ -1,10 +1,9 @@
 package zerolog
 
 import (
+	"net"
 	"sync"
 	"time"
-
-	"github.com/rs/zerolog/internal/json"
 )
 
 var arrayPool = &sync.Pool{
@@ -15,10 +14,26 @@ var arrayPool = &sync.Pool{
 	},
 }
 
+// Array is used to prepopulate an array of items
+// which can be re-used to add to log messages.
 type Array struct {
 	buf []byte
 }
 
+func putArray(a *Array) {
+	// Proper usage of a sync.Pool requires each entry to have approximately
+	// the same memory cost. To obtain this property when the stored type
+	// contains a variably-sized buffer, we add a hard limit on the maximum buffer
+	// to place back in the pool.
+	//
+	// See https://golang.org/issue/23199
+	const maxSize = 1 << 16 // 64KiB
+	if cap(a.buf) > maxSize {
+		return
+	}
+	arrayPool.Put(a)
+}
+
 // Arr creates an array to be added to an Event or Context.
 func Arr() *Array {
 	a := arrayPool.Get().(*Array)
@@ -26,144 +41,200 @@ func Arr() *Array {
 	return a
 }
 
+// MarshalZerologArray method here is no-op - since data is
+// already in the needed format.
 func (*Array) MarshalZerologArray(*Array) {
 }
 
 func (a *Array) write(dst []byte) []byte {
-	if len(a.buf) == 0 {
-		dst = append(dst, `[]`...)
-	} else {
-		a.buf[0] = '['
-		dst = append(append(dst, a.buf...), ']')
+	dst = enc.AppendArrayStart(dst)
+	if len(a.buf) > 0 {
+		dst = append(dst, a.buf...)
 	}
-	arrayPool.Put(a)
+	dst = enc.AppendArrayEnd(dst)
+	putArray(a)
 	return dst
 }
 
 // Object marshals an object that implement the LogObjectMarshaler
-// interface and append it to the array.
+// interface and appends it to the array.
 func (a *Array) Object(obj LogObjectMarshaler) *Array {
-	a.buf = append(a.buf, ',')
 	e := Dict()
 	obj.MarshalZerologObject(e)
-	e.buf = append(e.buf, '}')
-	a.buf = append(a.buf, e.buf...)
+	e.buf = enc.AppendEndMarker(e.buf)
+	a.buf = append(enc.AppendArrayDelim(a.buf), e.buf...)
+	putEvent(e)
 	return a
 }
 
-// Str append the val as a string to the array.
+// Str appends the val as a string to the array.
 func (a *Array) Str(val string) *Array {
-	a.buf = json.AppendString(append(a.buf, ','), val)
+	a.buf = enc.AppendString(enc.AppendArrayDelim(a.buf), val)
 	return a
 }
 
-// Bytes append the val as a string to the array.
+// Bytes appends the val as a string to the array.
 func (a *Array) Bytes(val []byte) *Array {
-	a.buf = json.AppendBytes(append(a.buf, ','), val)
+	a.buf = enc.AppendBytes(enc.AppendArrayDelim(a.buf), val)
 	return a
 }
 
-// Err append the err as a string to the array.
+// Hex appends the val as a hex string to the array.
+func (a *Array) Hex(val []byte) *Array {
+	a.buf = enc.AppendHex(enc.AppendArrayDelim(a.buf), val)
+	return a
+}
+
+// RawJSON adds already encoded JSON to the array.
+func (a *Array) RawJSON(val []byte) *Array {
+	a.buf = appendJSON(enc.AppendArrayDelim(a.buf), val)
+	return a
+}
+
+// Err serializes and appends the err to the array.
 func (a *Array) Err(err error) *Array {
-	a.buf = json.AppendError(append(a.buf, ','), err)
+	switch m := ErrorMarshalFunc(err).(type) {
+	case LogObjectMarshaler:
+		e := newEvent(nil, 0)
+		e.buf = e.buf[:0]
+		e.appendObject(m)
+		a.buf = append(enc.AppendArrayDelim(a.buf), e.buf...)
+		putEvent(e)
+	case error:
+		if m == nil || isNilValue(m) {
+			a.buf = enc.AppendNil(enc.AppendArrayDelim(a.buf))
+		} else {
+			a.buf = enc.AppendString(enc.AppendArrayDelim(a.buf), m.Error())
+		}
+	case string:
+		a.buf = enc.AppendString(enc.AppendArrayDelim(a.buf), m)
+	default:
+		a.buf = enc.AppendInterface(enc.AppendArrayDelim(a.buf), m)
+	}
+
 	return a
 }
 
-// Bool append the val as a bool to the array.
+// Bool appends the val as a bool to the array.
 func (a *Array) Bool(b bool) *Array {
-	a.buf = json.AppendBool(append(a.buf, ','), b)
+	a.buf = enc.AppendBool(enc.AppendArrayDelim(a.buf), b)
 	return a
 }
 
-// Int append i as a int to the array.
+// Int appends i as a int to the array.
 func (a *Array) Int(i int) *Array {
-	a.buf = json.AppendInt(append(a.buf, ','), i)
+	a.buf = enc.AppendInt(enc.AppendArrayDelim(a.buf), i)
 	return a
 }
 
-// Int8 append i as a int8 to the array.
+// Int8 appends i as a int8 to the array.
 func (a *Array) Int8(i int8) *Array {
-	a.buf = json.AppendInt8(append(a.buf, ','), i)
+	a.buf = enc.AppendInt8(enc.AppendArrayDelim(a.buf), i)
 	return a
 }
 
-// Int16 append i as a int16 to the array.
+// Int16 appends i as a int16 to the array.
 func (a *Array) Int16(i int16) *Array {
-	a.buf = json.AppendInt16(append(a.buf, ','), i)
+	a.buf = enc.AppendInt16(enc.AppendArrayDelim(a.buf), i)
 	return a
 }
 
-// Int32 append i as a int32 to the array.
+// Int32 appends i as a int32 to the array.
 func (a *Array) Int32(i int32) *Array {
-	a.buf = json.AppendInt32(append(a.buf, ','), i)
+	a.buf = enc.AppendInt32(enc.AppendArrayDelim(a.buf), i)
 	return a
 }
 
-// Int64 append i as a int64 to the array.
+// Int64 appends i as a int64 to the array.
 func (a *Array) Int64(i int64) *Array {
-	a.buf = json.AppendInt64(append(a.buf, ','), i)
+	a.buf = enc.AppendInt64(enc.AppendArrayDelim(a.buf), i)
 	return a
 }
 
-// Uint append i as a uint to the array.
+// Uint appends i as a uint to the array.
 func (a *Array) Uint(i uint) *Array {
-	a.buf = json.AppendUint(append(a.buf, ','), i)
+	a.buf = enc.AppendUint(enc.AppendArrayDelim(a.buf), i)
 	return a
 }
 
-// Uint8 append i as a uint8 to the array.
+// Uint8 appends i as a uint8 to the array.
 func (a *Array) Uint8(i uint8) *Array {
-	a.buf = json.AppendUint8(append(a.buf, ','), i)
+	a.buf = enc.AppendUint8(enc.AppendArrayDelim(a.buf), i)
 	return a
 }
 
-// Uint16 append i as a uint16 to the array.
+// Uint16 appends i as a uint16 to the array.
 func (a *Array) Uint16(i uint16) *Array {
-	a.buf = json.AppendUint16(append(a.buf, ','), i)
+	a.buf = enc.AppendUint16(enc.AppendArrayDelim(a.buf), i)
 	return a
 }
 
-// Uint32 append i as a uint32 to the array.
+// Uint32 appends i as a uint32 to the array.
 func (a *Array) Uint32(i uint32) *Array {
-	a.buf = json.AppendUint32(append(a.buf, ','), i)
+	a.buf = enc.AppendUint32(enc.AppendArrayDelim(a.buf), i)
 	return a
 }
 
-// Uint64 append i as a uint64 to the array.
+// Uint64 appends i as a uint64 to the array.
 func (a *Array) Uint64(i uint64) *Array {
-	a.buf = json.AppendUint64(append(a.buf, ','), i)
+	a.buf = enc.AppendUint64(enc.AppendArrayDelim(a.buf), i)
 	return a
 }
 
-// Float32 append f as a float32 to the array.
+// Float32 appends f as a float32 to the array.
 func (a *Array) Float32(f float32) *Array {
-	a.buf = json.AppendFloat32(append(a.buf, ','), f)
+	a.buf = enc.AppendFloat32(enc.AppendArrayDelim(a.buf), f, FloatingPointPrecision)
 	return a
 }
 
-// Float64 append f as a float64 to the array.
+// Float64 appends f as a float64 to the array.
 func (a *Array) Float64(f float64) *Array {
-	a.buf = json.AppendFloat64(append(a.buf, ','), f)
+	a.buf = enc.AppendFloat64(enc.AppendArrayDelim(a.buf), f, FloatingPointPrecision)
 	return a
 }
 
-// Time append t formated as string using zerolog.TimeFieldFormat.
+// Time appends t formatted as string using zerolog.TimeFieldFormat.
 func (a *Array) Time(t time.Time) *Array {
-	a.buf = json.AppendTime(append(a.buf, ','), t, TimeFieldFormat)
+	a.buf = enc.AppendTime(enc.AppendArrayDelim(a.buf), t, TimeFieldFormat)
 	return a
 }
 
-// Dur append d to the array.
+// Dur appends d to the array.
 func (a *Array) Dur(d time.Duration) *Array {
-	a.buf = json.AppendDuration(append(a.buf, ','), d, DurationFieldUnit, DurationFieldInteger)
+	a.buf = enc.AppendDuration(enc.AppendArrayDelim(a.buf), d, DurationFieldUnit, DurationFieldInteger, FloatingPointPrecision)
 	return a
 }
 
-// Interface append i marshaled using reflection.
+// Interface appends i marshaled using reflection.
 func (a *Array) Interface(i interface{}) *Array {
 	if obj, ok := i.(LogObjectMarshaler); ok {
 		return a.Object(obj)
 	}
-	a.buf = json.AppendInterface(append(a.buf, ','), i)
+	a.buf = enc.AppendInterface(enc.AppendArrayDelim(a.buf), i)
+	return a
+}
+
+// IPAddr adds IPv4 or IPv6 address to the array
+func (a *Array) IPAddr(ip net.IP) *Array {
+	a.buf = enc.AppendIPAddr(enc.AppendArrayDelim(a.buf), ip)
+	return a
+}
+
+// IPPrefix adds IPv4 or IPv6 Prefix (IP + mask) to the array
+func (a *Array) IPPrefix(pfx net.IPNet) *Array {
+	a.buf = enc.AppendIPPrefix(enc.AppendArrayDelim(a.buf), pfx)
+	return a
+}
+
+// MACAddr adds a MAC (Ethernet) address to the array
+func (a *Array) MACAddr(ha net.HardwareAddr) *Array {
+	a.buf = enc.AppendMACAddr(enc.AppendArrayDelim(a.buf), ha)
+	return a
+}
+
+// Dict adds the dict Event to the array
+func (a *Array) Dict(dict *Event) *Array {
+	dict.buf = enc.AppendEndMarker(dict.buf)
+	a.buf = append(enc.AppendArrayDelim(a.buf), dict.buf...)
 	return a
 }

array_test.go

@@ -1,6 +1,7 @@
 package zerolog
 
 import (
+	"net"
 	"testing"
 	"time"
 )
@@ -18,13 +19,21 @@ func TestArray(t *testing.T) {
 		Uint16(8).
 		Uint32(9).
 		Uint64(10).
-		Float32(11).
-		Float64(12).
+		Float32(11.98122).
+		Float64(12.987654321).
 		Str("a").
+		Bytes([]byte("b")).
+		Hex([]byte{0x1f}).
+		RawJSON([]byte(`{"some":"json"}`)).
 		Time(time.Time{}).
-		Dur(0)
-	want := `[true,1,2,3,4,5,6,7,8,9,10,11,12,"a","0001-01-01T00:00:00Z",0]`
-	if got := string(a.write([]byte{})); got != want {
+		IPAddr(net.IP{192, 168, 0, 10}).
+		Dur(0).
+		Dict(Dict().
+			Str("bar", "baz").
+			Int("n", 1),
+		)
+	want := `[true,1,2,3,4,5,6,7,8,9,10,11.98122,12.987654321,"a","b","1f",{"some":"json"},"0001-01-01T00:00:00Z","192.168.0.10",0,{"bar":"baz","n":1}]`
+	if got := decodeObjectToStr(a.write([]byte{})); got != want {
 		t.Errorf("Array.write()\ngot:  %s\nwant: %s", got, want)
 	}
 }

benchmark_test.go

@@ -1,8 +1,10 @@
 package zerolog
 
 import (
+	"context"
 	"errors"
-	"io/ioutil"
+	"io"
+	"net"
 	"testing"
 	"time"
 )
@@ -13,7 +15,7 @@ var (
 )
 
 func BenchmarkLogEmpty(b *testing.B) {
-	logger := New(ioutil.Discard)
+	logger := New(io.Discard)
 	b.ResetTimer()
 	b.RunParallel(func(pb *testing.PB) {
 		for pb.Next() {
@@ -23,7 +25,7 @@ func BenchmarkLogEmpty(b *testing.B) {
 }
 
 func BenchmarkDisabled(b *testing.B) {
-	logger := New(ioutil.Discard).Level(Disabled)
+	logger := New(io.Discard).Level(Disabled)
 	b.ResetTimer()
 	b.RunParallel(func(pb *testing.PB) {
 		for pb.Next() {
@@ -33,7 +35,7 @@ func BenchmarkDisabled(b *testing.B) {
 }
 
 func BenchmarkInfo(b *testing.B) {
-	logger := New(ioutil.Discard)
+	logger := New(io.Discard)
 	b.ResetTimer()
 	b.RunParallel(func(pb *testing.PB) {
 		for pb.Next() {
@@ -43,7 +45,7 @@ func BenchmarkInfo(b *testing.B) {
 }
 
 func BenchmarkContextFields(b *testing.B) {
-	logger := New(ioutil.Discard).With().
+	logger := New(io.Discard).With().
 		Str("string", "four!").
 		Time("time", time.Time{}).
 		Int("int", 123).
@@ -58,7 +60,7 @@ func BenchmarkContextFields(b *testing.B) {
 }
 
 func BenchmarkContextAppend(b *testing.B) {
-	logger := New(ioutil.Discard).With().
+	logger := New(io.Discard).With().
 		Str("foo", "bar").
 		Logger()
 	b.ResetTimer()
@@ -70,7 +72,7 @@ func BenchmarkContextAppend(b *testing.B) {
 }
 
 func BenchmarkLogFields(b *testing.B) {
-	logger := New(ioutil.Discard)
+	logger := New(io.Discard)
 	b.ResetTimer()
 	b.RunParallel(func(pb *testing.PB) {
 		for pb.Next() {
@@ -96,6 +98,22 @@ func (o obj) MarshalZerologObject(e *Event) {
 		Int("priv", o.priv)
 }
 
+func BenchmarkLogArrayObject(b *testing.B) {
+	obj1 := obj{"a", "b", 2}
+	obj2 := obj{"c", "d", 3}
+	obj3 := obj{"e", "f", 4}
+	logger := New(io.Discard)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		arr := Arr()
+		arr.Object(&obj1)
+		arr.Object(&obj2)
+		arr.Object(&obj3)
+		logger.Info().Array("objects", arr).Msg("test")
+	}
+}
+
 func BenchmarkLogFieldType(b *testing.B) {
 	bools := []bool{true, false, true, false, true, false, true, false, true, false}
 	ints := []int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
@@ -131,18 +149,19 @@ func BenchmarkLogFieldType(b *testing.B) {
 		{"a", "a", 0},
 	}
 	objects := []obj{
-		obj{"a", "a", 0},
-		obj{"a", "a", 0},
-		obj{"a", "a", 0},
-		obj{"a", "a", 0},
-		obj{"a", "a", 0},
-		obj{"a", "a", 0},
-		obj{"a", "a", 0},
-		obj{"a", "a", 0},
-		obj{"a", "a", 0},
-		obj{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
 	}
 	errs := []error{errors.New("a"), errors.New("b"), errors.New("c"), errors.New("d"), errors.New("e")}
+	ctx := context.Background()
 	types := map[string]func(e *Event) *Event{
 		"Bool": func(e *Event) *Event {
 			return e.Bool("k", bools[0])
@@ -174,6 +193,9 @@ func BenchmarkLogFieldType(b *testing.B) {
 		"Errs": func(e *Event) *Event {
 			return e.Errs("k", errs)
 		},
+		"Ctx": func(e *Event) *Event {
+			return e.Ctx(ctx)
+		},
 		"Time": func(e *Event) *Event {
 			return e.Time("k", times[0])
 		},
@@ -202,7 +224,7 @@ func BenchmarkLogFieldType(b *testing.B) {
 			return e.Object("k", objects[0])
 		},
 	}
-	logger := New(ioutil.Discard)
+	logger := New(io.Discard)
 	b.ResetTimer()
 	for name := range types {
 		f := types[name]
@@ -215,3 +237,138 @@ func BenchmarkLogFieldType(b *testing.B) {
 		})
 	}
 }
+
+func BenchmarkContextFieldType(b *testing.B) {
+	oldFormat := TimeFieldFormat
+	TimeFieldFormat = TimeFormatUnix
+	defer func() { TimeFieldFormat = oldFormat }()
+	bools := []bool{true, false, true, false, true, false, true, false, true, false}
+	ints := []int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
+	floats := []float64{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
+	strings := []string{"a", "b", "c", "d", "e", "f", "g", "h", "i", "j"}
+	stringer := net.IP{127, 0, 0, 1}
+	durations := []time.Duration{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
+	times := []time.Time{
+		time.Unix(0, 0),
+		time.Unix(1, 0),
+		time.Unix(2, 0),
+		time.Unix(3, 0),
+		time.Unix(4, 0),
+		time.Unix(5, 0),
+		time.Unix(6, 0),
+		time.Unix(7, 0),
+		time.Unix(8, 0),
+		time.Unix(9, 0),
+	}
+	interfaces := []struct {
+		Pub  string
+		Tag  string `json:"tag"`
+		priv int
+	}{
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+	}
+	objects := []obj{
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+	}
+	errs := []error{errors.New("a"), errors.New("b"), errors.New("c"), errors.New("d"), errors.New("e")}
+	ctx := context.Background()
+	types := map[string]func(c Context) Context{
+		"Bool": func(c Context) Context {
+			return c.Bool("k", bools[0])
+		},
+		"Bools": func(c Context) Context {
+			return c.Bools("k", bools)
+		},
+		"Int": func(c Context) Context {
+			return c.Int("k", ints[0])
+		},
+		"Ints": func(c Context) Context {
+			return c.Ints("k", ints)
+		},
+		"Float": func(c Context) Context {
+			return c.Float64("k", floats[0])
+		},
+		"Floats": func(c Context) Context {
+			return c.Floats64("k", floats)
+		},
+		"Str": func(c Context) Context {
+			return c.Str("k", strings[0])
+		},
+		"Strs": func(c Context) Context {
+			return c.Strs("k", strings)
+		},
+		"Stringer": func(c Context) Context {
+			return c.Stringer("k", stringer)
+		},
+		"Err": func(c Context) Context {
+			return c.Err(errs[0])
+		},
+		"Errs": func(c Context) Context {
+			return c.Errs("k", errs)
+		},
+		"Ctx": func(c Context) Context {
+			return c.Ctx(ctx)
+		},
+		"Time": func(c Context) Context {
+			return c.Time("k", times[0])
+		},
+		"Times": func(c Context) Context {
+			return c.Times("k", times)
+		},
+		"Dur": func(c Context) Context {
+			return c.Dur("k", durations[0])
+		},
+		"Durs": func(c Context) Context {
+			return c.Durs("k", durations)
+		},
+		"Interface": func(c Context) Context {
+			return c.Interface("k", interfaces[0])
+		},
+		"Interfaces": func(c Context) Context {
+			return c.Interface("k", interfaces)
+		},
+		"Interface(Object)": func(c Context) Context {
+			return c.Interface("k", objects[0])
+		},
+		"Interface(Objects)": func(c Context) Context {
+			return c.Interface("k", objects)
+		},
+		"Object": func(c Context) Context {
+			return c.Object("k", objects[0])
+		},
+		"Timestamp": func(c Context) Context {
+			return c.Timestamp()
+		},
+	}
+	logger := New(io.Discard)
+	b.ResetTimer()
+	for name := range types {
+		f := types[name]
+		b.Run(name, func(b *testing.B) {
+			b.RunParallel(func(pb *testing.PB) {
+				for pb.Next() {
+					l := f(logger.With()).Logger()
+					l.Info().Msg("")
+				}
+			})
+		})
+	}
+}

binary_test.go

@@ -0,0 +1,583 @@
+// +build binary_log
+
+package zerolog
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+
+	stdlog "log"
+	"time"
+)
+
+func ExampleBinaryNew() {
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	log.Info().Msg("hello world")
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"level":"info","message":"hello world"}
+}
+
+func ExampleLogger_With() {
+	dst := bytes.Buffer{}
+	log := New(&dst).
+		With().
+		Str("foo", "bar").
+		Logger()
+
+	log.Info().Msg("hello world")
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+
+	// Output: {"level":"info","foo":"bar","message":"hello world"}
+}
+
+func ExampleLogger_Level() {
+	dst := bytes.Buffer{}
+	log := New(&dst).Level(WarnLevel)
+
+	log.Info().Msg("filtered out message")
+	log.Error().Msg("kept message")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"level":"error","message":"kept message"}
+}
+
+func ExampleLogger_Sample() {
+	dst := bytes.Buffer{}
+	log := New(&dst).Sample(&BasicSampler{N: 2})
+
+	log.Info().Msg("message 1")
+	log.Info().Msg("message 2")
+	log.Info().Msg("message 3")
+	log.Info().Msg("message 4")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"level":"info","message":"message 1"}
+	// {"level":"info","message":"message 3"}
+}
+
+type LevelNameHook1 struct{}
+
+func (h LevelNameHook1) Run(e *Event, l Level, msg string) {
+	if l != NoLevel {
+		e.Str("level_name", l.String())
+	} else {
+		e.Str("level_name", "NoLevel")
+	}
+}
+
+type MessageHook string
+
+func (h MessageHook) Run(e *Event, l Level, msg string) {
+	e.Str("the_message", msg)
+}
+
+func ExampleLogger_Hook() {
+	var levelNameHook LevelNameHook1
+	var messageHook MessageHook = "The message"
+
+	dst := bytes.Buffer{}
+	log := New(&dst).Hook(levelNameHook).Hook(messageHook)
+
+	log.Info().Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"level":"info","level_name":"info","the_message":"hello world","message":"hello world"}
+}
+
+func ExampleLogger_Print() {
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	log.Print("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"level":"debug","message":"hello world"}
+}
+
+func ExampleLogger_Printf() {
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	log.Printf("hello %s", "world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"level":"debug","message":"hello world"}
+}
+
+func ExampleLogger_Trace() {
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	log.Trace().
+		Str("foo", "bar").
+		Int("n", 123).
+		Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"level":"trace","foo":"bar","n":123,"message":"hello world"}
+}
+
+func ExampleLogger_Debug() {
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	log.Debug().
+		Str("foo", "bar").
+		Int("n", 123).
+		Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"level":"debug","foo":"bar","n":123,"message":"hello world"}
+}
+
+func ExampleLogger_Info() {
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	log.Info().
+		Str("foo", "bar").
+		Int("n", 123).
+		Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"level":"info","foo":"bar","n":123,"message":"hello world"}
+}
+
+func ExampleLogger_Warn() {
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	log.Warn().
+		Str("foo", "bar").
+		Msg("a warning message")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"level":"warn","foo":"bar","message":"a warning message"}
+}
+
+func ExampleLogger_Error() {
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	log.Error().
+		Err(errors.New("some error")).
+		Msg("error doing something")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"level":"error","error":"some error","message":"error doing something"}
+}
+
+func ExampleLogger_WithLevel() {
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	log.WithLevel(InfoLevel).
+		Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"level":"info","message":"hello world"}
+}
+
+func ExampleLogger_Write() {
+	dst := bytes.Buffer{}
+	log := New(&dst).With().
+		Str("foo", "bar").
+		Logger()
+
+	stdlog.SetFlags(0)
+	stdlog.SetOutput(log)
+
+	stdlog.Print("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","message":"hello world"}
+}
+
+func ExampleLogger_Log() {
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	log.Log().
+		Str("foo", "bar").
+		Str("bar", "baz").
+		Msg("")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","bar":"baz"}
+}
+
+func ExampleEvent_Dict() {
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	log.Log().
+		Str("foo", "bar").
+		Dict("dict", Dict().
+			Str("bar", "baz").
+			Int("n", 1),
+		).
+		Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","dict":{"bar":"baz","n":1},"message":"hello world"}
+}
+
+type User struct {
+	Name    string
+	Age     int
+	Created time.Time
+}
+
+func (u User) MarshalZerologObject(e *Event) {
+	e.Str("name", u.Name).
+		Int("age", u.Age).
+		Time("created", u.Created)
+}
+
+type Users []User
+
+func (uu Users) MarshalZerologArray(a *Array) {
+	for _, u := range uu {
+		a.Object(u)
+	}
+}
+
+func ExampleEvent_Array() {
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	log.Log().
+		Str("foo", "bar").
+		Array("array", Arr().
+			Str("baz").
+			Int(1),
+		).
+		Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","array":["baz",1],"message":"hello world"}
+}
+
+func ExampleEvent_Array_object() {
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	// Users implements LogArrayMarshaler
+	u := Users{
+		User{"John", 35, time.Time{}},
+		User{"Bob", 55, time.Time{}},
+	}
+
+	log.Log().
+		Str("foo", "bar").
+		Array("users", u).
+		Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","users":[{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},{"name":"Bob","age":55,"created":"0001-01-01T00:00:00Z"}],"message":"hello world"}
+}
+
+func ExampleEvent_Object() {
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	// User implements LogObjectMarshaler
+	u := User{"John", 35, time.Time{}}
+
+	log.Log().
+		Str("foo", "bar").
+		Object("user", u).
+		Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","user":{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},"message":"hello world"}
+}
+
+func ExampleEvent_EmbedObject() {
+	price := Price{val: 6449, prec: 2, unit: "$"}
+
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	log.Log().
+		Str("foo", "bar").
+		EmbedObject(price).
+		Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","price":"$64.49","message":"hello world"}
+}
+
+func ExampleEvent_Interface() {
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	obj := struct {
+		Name string `json:"name"`
+	}{
+		Name: "john",
+	}
+
+	log.Log().
+		Str("foo", "bar").
+		Interface("obj", obj).
+		Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","obj":{"name":"john"},"message":"hello world"}
+}
+
+func ExampleEvent_Dur() {
+	d := time.Duration(10 * time.Second)
+
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	log.Log().
+		Str("foo", "bar").
+		Dur("dur", d).
+		Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","dur":10000,"message":"hello world"}
+}
+
+func ExampleEvent_Durs() {
+	d := []time.Duration{
+		time.Duration(10 * time.Second),
+		time.Duration(20 * time.Second),
+	}
+
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	log.Log().
+		Str("foo", "bar").
+		Durs("durs", d).
+		Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","durs":[10000,20000],"message":"hello world"}
+}
+
+func ExampleEvent_Fields_map() {
+	fields := map[string]interface{}{
+		"bar": "baz",
+		"n":   1,
+	}
+
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	log.Log().
+		Str("foo", "bar").
+		Fields(fields).
+		Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","bar":"baz","n":1,"message":"hello world"}
+}
+
+func ExampleEvent_Fields_slice() {
+	fields := []interface{}{
+		"bar", "baz",
+		"n", 1,
+	}
+
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	log.Log().
+		Str("foo", "bar").
+		Fields(fields).
+		Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","bar":"baz","n":1,"message":"hello world"}
+}
+
+func ExampleContext_Dict() {
+	dst := bytes.Buffer{}
+	log := New(&dst).With().
+		Str("foo", "bar").
+		Dict("dict", Dict().
+			Str("bar", "baz").
+			Int("n", 1),
+		).Logger()
+
+	log.Log().Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","dict":{"bar":"baz","n":1},"message":"hello world"}
+}
+
+func ExampleContext_Array() {
+	dst := bytes.Buffer{}
+	log := New(&dst).With().
+		Str("foo", "bar").
+		Array("array", Arr().
+			Str("baz").
+			Int(1),
+		).Logger()
+
+	log.Log().Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","array":["baz",1],"message":"hello world"}
+}
+
+func ExampleContext_Array_object() {
+	// Users implements LogArrayMarshaler
+	u := Users{
+		User{"John", 35, time.Time{}},
+		User{"Bob", 55, time.Time{}},
+	}
+
+	dst := bytes.Buffer{}
+	log := New(&dst).With().
+		Str("foo", "bar").
+		Array("users", u).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","users":[{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},{"name":"Bob","age":55,"created":"0001-01-01T00:00:00Z"}],"message":"hello world"}
+}
+
+type Price struct {
+	val  uint64
+	prec int
+	unit string
+}
+
+func (p Price) MarshalZerologObject(e *Event) {
+	denom := uint64(1)
+	for i := 0; i < p.prec; i++ {
+		denom *= 10
+	}
+	result := []byte(p.unit)
+	result = append(result, fmt.Sprintf("%d.%d", p.val/denom, p.val%denom)...)
+	e.Str("price", string(result))
+}
+
+func ExampleContext_EmbedObject() {
+	price := Price{val: 6449, prec: 2, unit: "$"}
+
+	dst := bytes.Buffer{}
+	log := New(&dst).With().
+		Str("foo", "bar").
+		EmbedObject(price).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","price":"$64.49","message":"hello world"}
+}
+func ExampleContext_Object() {
+	// User implements LogObjectMarshaler
+	u := User{"John", 35, time.Time{}}
+
+	dst := bytes.Buffer{}
+	log := New(&dst).With().
+		Str("foo", "bar").
+		Object("user", u).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","user":{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},"message":"hello world"}
+}
+
+func ExampleContext_Interface() {
+	obj := struct {
+		Name string `json:"name"`
+	}{
+		Name: "john",
+	}
+
+	dst := bytes.Buffer{}
+	log := New(&dst).With().
+		Str("foo", "bar").
+		Interface("obj", obj).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","obj":{"name":"john"},"message":"hello world"}
+}
+
+func ExampleContext_Dur() {
+	d := time.Duration(10 * time.Second)
+
+	dst := bytes.Buffer{}
+	log := New(&dst).With().
+		Str("foo", "bar").
+		Dur("dur", d).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","dur":10000,"message":"hello world"}
+}
+
+func ExampleContext_Durs() {
+	d := []time.Duration{
+		time.Duration(10 * time.Second),
+		time.Duration(20 * time.Second),
+	}
+
+	dst := bytes.Buffer{}
+	log := New(&dst).With().
+		Str("foo", "bar").
+		Durs("durs", d).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","durs":[10000,20000],"message":"hello world"}
+}
+
+func ExampleContext_Fields_map() {
+	fields := map[string]interface{}{
+		"bar": "baz",
+		"n":   1,
+	}
+
+	dst := bytes.Buffer{}
+	log := New(&dst).With().
+		Str("foo", "bar").
+		Fields(fields).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","bar":"baz","n":1,"message":"hello world"}
+}
+
+func ExampleContext_Fields_slice() {
+	fields := []interface{}{
+		"bar", "baz",
+		"n", 1,
+	}
+
+	dst := bytes.Buffer{}
+	log := New(&dst).With().
+		Str("foo", "bar").
+		Fields(fields).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","bar":"baz","n":1,"message":"hello world"}
+}

cmd/lint/README.md

@@ -0,0 +1,39 @@
+# Zerolog Lint
+
+**DEPRECATED: In favor of https://github.com/ykadowak/zerologlint which is integrated with `go vet` and [golangci-lint](https://golangci-lint.run/).**
+
+This is a basic linter that checks for missing log event finishers. Finds errors like: `log.Error().Int64("userID": 5)` - missing the `Msg`/`Msgf` finishers.
+
+## Problem
+
+When using zerolog it's easy to forget to finish the log event chain by calling a finisher - the `Msg` or `Msgf` function that will schedule the event for writing. The problem with this is that it doesn't warn/panic during compilation and it's not easily found by grep or other general tools. It's even prominently mentioned in the project's readme, that:
+
+> It is very important to note that when using the **zerolog** chaining API, as shown above (`log.Info().Msg("hello world"`), the chain must have either the `Msg` or `Msgf` method call. If you forget to add either of these, the log will not occur and there is no compile time error to alert you of this.
+
+## Solution
+
+A basic linter like this one here that looks for method invocations on `zerolog.Event` can examine the last call in a method call chain and check if it is a finisher, thus pointing out these errors.
+
+## Usage
+
+Just compile this and then run it. Or just run it via `go run` command via something like `go run cmd/lint/lint.go`.
+
+The command accepts only one argument - the package to be inspected - and 4 optional flags, all of which can occur multiple times. The standard synopsis of the command is:
+
+`lint [-finisher value] [-ignoreFile value] [-ignorePkg value] [-ignorePkgRecursively value] package`
+
+#### Flags
+
+- finisher
+    - specify which finishers to accept, defaults to `Msg` and `Msgf`
+- ignoreFile
+    - which files to ignore, either by full path or by go path (package/file.go)
+- ignorePkg
+    - do not inspect the specified package if found in the dependency tree
+- ignorePkgRecursively
+    - do not inspect the specified package or its subpackages if found in the dependency tree
+
+## Drawbacks
+
+As it is, linter can generate a false positives in a specific case. These false positives come from the fact that if you have a method that returns a `zerolog.Event` the linter will flag it because you are obviously not finishing the event. This will be solved in later release.
+

cmd/lint/go.mod

@@ -0,0 +1,5 @@
+module github.com/rs/zerolog/cmd/lint
+
+go 1.15
+
+require golang.org/x/tools v0.1.8

cmd/lint/go.sum

@@ -0,0 +1,28 @@
+github.com/yuin/goldmark v1.4.1/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/mod v0.5.1 h1:OJxoQ/rynoF0dcCdI7cLPktw/hR2cueqYfjm43oqK38=
+golang.org/x/mod v0.5.1/go.mod h1:5OXOZSfqPIIbmVBIIKWRFfZjPR0E5r58TLhUjH0a2Ro=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20211015210444-4f30a5c0130f/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20211019181941-9d821ace8654 h1:id054HUawV2/6IGm2IV8KZQjqtwAOo2CYlOToYqa0d0=
+golang.org/x/sys v0.0.0-20211019181941-9d821ace8654/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.1.8 h1:P1HhGGuLW4aAclzjtmJdf0mJOjVUZUzOTqkAkWL+l6w=
+golang.org/x/tools v0.1.8/go.mod h1:nABZi5QlRsZVlzPpHl034qft6wpY4eDcsTt5AaioBiU=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
+golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

cmd/lint/lint.go

@@ -0,0 +1,175 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"go/ast"
+	"go/token"
+	"go/types"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"golang.org/x/tools/go/loader"
+)
+
+var (
+	recursivelyIgnoredPkgs arrayFlag
+	ignoredPkgs            arrayFlag
+	ignoredFiles           arrayFlag
+	allowedFinishers       arrayFlag = []string{"Msg", "Msgf"}
+	rootPkg                string
+)
+
+// parse input flags and args
+func init() {
+	flag.Var(&recursivelyIgnoredPkgs, "ignorePkgRecursively", "ignore the specified package and all subpackages recursively")
+	flag.Var(&ignoredPkgs, "ignorePkg", "ignore the specified package")
+	flag.Var(&ignoredFiles, "ignoreFile", "ignore the specified file by its path and/or go path (package/file.go)")
+	flag.Var(&allowedFinishers, "finisher", "allowed finisher for the event chain")
+	flag.Parse()
+
+	// add zerolog to recursively ignored packages
+	recursivelyIgnoredPkgs = append(recursivelyIgnoredPkgs, "github.com/rs/zerolog")
+	args := flag.Args()
+	if len(args) != 1 {
+		fmt.Fprintln(os.Stderr, "you must provide exactly one package path")
+		os.Exit(1)
+	}
+	rootPkg = args[0]
+}
+
+func main() {
+	// load the package and all its dependencies
+	conf := loader.Config{}
+	conf.Import(rootPkg)
+	p, err := conf.Load()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error: unable to load the root package. %s\n", err.Error())
+		os.Exit(1)
+	}
+
+	// get the github.com/rs/zerolog.Event type
+	event := getEvent(p)
+	if event == nil {
+		fmt.Fprintln(os.Stderr, "Error: github.com/rs/zerolog.Event declaration not found, maybe zerolog is not imported in the scanned package?")
+		os.Exit(1)
+	}
+
+	// get all selections (function calls) with the github.com/rs/zerolog.Event (or pointer) receiver
+	selections := getSelectionsWithReceiverType(p, event)
+
+	// print the violations (if any)
+	hasViolations := false
+	for _, s := range selections {
+		if hasBadFinisher(p, s) {
+			hasViolations = true
+			fmt.Printf("Error: missing or bad finisher for log chain, last call: %q at: %s:%v\n", s.fn.Name(), p.Fset.File(s.Pos()).Name(), p.Fset.Position(s.Pos()).Line)
+		}
+	}
+
+	// if no violations detected, return normally
+	if !hasViolations {
+		fmt.Println("No violations found")
+		return
+	}
+
+	// if violations were detected, return error code
+	os.Exit(1)
+}
+
+func getEvent(p *loader.Program) types.Type {
+	for _, pkg := range p.AllPackages {
+		if strings.HasSuffix(pkg.Pkg.Path(), "github.com/rs/zerolog") {
+			for _, d := range pkg.Defs {
+				if d != nil && d.Name() == "Event" {
+					return d.Type()
+				}
+			}
+		}
+	}
+
+	return nil
+}
+
+func getSelectionsWithReceiverType(p *loader.Program, targetType types.Type) map[token.Pos]selection {
+	selections := map[token.Pos]selection{}
+
+	for _, z := range p.AllPackages {
+		for i, t := range z.Selections {
+			switch o := t.Obj().(type) {
+			case *types.Func:
+				// this is not a bug, o.Type() is always *types.Signature, see docs
+				if vt := o.Type().(*types.Signature).Recv(); vt != nil {
+					typ := vt.Type()
+					if pointer, ok := typ.(*types.Pointer); ok {
+						typ = pointer.Elem()
+					}
+
+					if typ == targetType {
+						if s, ok := selections[i.Pos()]; !ok || i.End() > s.End() {
+							selections[i.Pos()] = selection{i, o, z.Pkg}
+						}
+					}
+				}
+			default:
+				// skip
+			}
+		}
+	}
+
+	return selections
+}
+
+func hasBadFinisher(p *loader.Program, s selection) bool {
+	pkgPath := strings.TrimPrefix(s.pkg.Path(), rootPkg+"/vendor/")
+	absoluteFilePath := strings.TrimPrefix(p.Fset.File(s.Pos()).Name(), rootPkg+"/vendor/")
+	goFilePath := pkgPath + "/" + filepath.Base(p.Fset.Position(s.Pos()).Filename)
+
+	for _, f := range allowedFinishers {
+		if f == s.fn.Name() {
+			return false
+		}
+	}
+
+	for _, ignoredPkg := range recursivelyIgnoredPkgs {
+		if strings.HasPrefix(pkgPath, ignoredPkg) {
+			return false
+		}
+	}
+
+	for _, ignoredPkg := range ignoredPkgs {
+		if pkgPath == ignoredPkg {
+			return false
+		}
+	}
+
+	for _, ignoredFile := range ignoredFiles {
+		if absoluteFilePath == ignoredFile {
+			return false
+		}
+
+		if goFilePath == ignoredFile {
+			return false
+		}
+	}
+
+	return true
+}
+
+type arrayFlag []string
+
+func (i *arrayFlag) String() string {
+	return fmt.Sprintf("%v", []string(*i))
+}
+
+func (i *arrayFlag) Set(value string) error {
+	*i = append(*i, value)
+	return nil
+}
+
+type selection struct {
+	*ast.SelectorExpr
+	fn  *types.Func
+	pkg *types.Package
+}

cmd/prettylog/README.md

@@ -0,0 +1,40 @@
+# Zerolog PrettyLog
+
+This is a basic CLI utility that will colorize and pretty print your structured JSON logs.
+
+## Usage
+
+You can compile it or run it directly. The only issue is that by default Zerolog does not output to `stdout`
+but rather to `stderr` so we must pipe `stderr` stream to this CLI tool.
+
+### Linux
+
+These commands will redirect `stderr` to our `prettylog` tool and `stdout` will remain unaffected.
+
+1. Compiled version
+
+```shell
+some_program_with_zerolog 2> >(prettylog)
+```
+
+2. Run it directly with `go run`
+
+```shell
+some_program_with_zerolog 2> >(go run cmd/prettylog/prettylog.go)
+```
+
+### Windows
+
+These commands will redirect `stderr` to `stdout` and then pipe it to our `prettylog` tool.
+
+1. Compiled version
+
+```shell
+some_program_with_zerolog 2>&1 | prettylog
+```
+
+2. Run it directly with `go run`
+
+```shell
+some_program_with_zerolog 2>&1 | go run cmd/prettylog/prettylog.go
+```

cmd/prettylog/prettylog.go

@@ -0,0 +1,82 @@
+package main
+
+import (
+	"bufio"
+	"errors"
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"time"
+
+	"github.com/rs/zerolog"
+)
+
+func isInputFromPipe() bool {
+	fileInfo, _ := os.Stdin.Stat()
+	return fileInfo.Mode()&os.ModeCharDevice == 0
+}
+
+func processInput(reader io.Reader, writer io.Writer) error {
+	scanner := bufio.NewScanner(reader)
+	for scanner.Scan() {
+		bytesToWrite := scanner.Bytes()
+		_, err := writer.Write(bytesToWrite)
+		if err != nil {
+			if errors.Is(err, io.EOF) {
+				break
+			}
+
+			fmt.Printf("%s\n", bytesToWrite)
+		}
+	}
+
+	return scanner.Err()
+}
+
+func main() {
+	timeFormats := map[string]string{
+		"default": time.Kitchen,
+		"full":    time.RFC1123,
+	}
+
+	timeFormatFlag := flag.String(
+		"time-format",
+		"default",
+		"Time format, either 'default' or 'full'",
+	)
+
+	flag.Parse()
+
+	timeFormat, ok := timeFormats[*timeFormatFlag]
+	if !ok {
+		panic("Invalid time-format provided")
+	}
+
+	writer := zerolog.NewConsoleWriter()
+	writer.TimeFormat = timeFormat
+
+	if isInputFromPipe() {
+		_ = processInput(os.Stdin, writer)
+	} else if flag.NArg() >= 1 {
+		for _, filename := range flag.Args() {
+			// Scan each line from filename and write it into writer
+			reader, err := os.Open(filename)
+			if err != nil {
+				fmt.Printf("%s open: %v", filename, err)
+				os.Exit(1)
+			}
+
+			if err := processInput(reader, writer); err != nil {
+				fmt.Printf("%s scan: %v", filename, err)
+				os.Exit(1)
+			}
+		}
+	} else {
+		fmt.Println("Usage:")
+		fmt.Println("  app_with_zerolog | 2> >(prettylog)")
+		fmt.Println("  prettylog zerolog_output.jsonl")
+		os.Exit(1)
+		return
+	}
+}

console.go

@@ -5,108 +5,362 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"os"
+	"path/filepath"
 	"sort"
 	"strconv"
 	"strings"
 	"sync"
+	"time"
+
+	"github.com/mattn/go-colorable"
 )
 
 const (
-	cReset    = 0
-	cBold     = 1
-	cRed      = 31
-	cGreen    = 32
-	cYellow   = 33
-	cBlue     = 34
-	cMagenta  = 35
-	cCyan     = 36
-	cGray     = 37
-	cDarkGray = 90
+	colorBlack = iota + 30
+	colorRed
+	colorGreen
+	colorYellow
+	colorBlue
+	colorMagenta
+	colorCyan
+	colorWhite
+
+	colorBold     = 1
+	colorDarkGray = 90
+
+	unknownLevel = "???"
 )
 
-var consoleBufPool = sync.Pool{
-	New: func() interface{} {
-		return bytes.NewBuffer(make([]byte, 0, 100))
-	},
-}
+var (
+	consoleBufPool = sync.Pool{
+		New: func() interface{} {
+			return bytes.NewBuffer(make([]byte, 0, 100))
+		},
+	}
+)
 
-// ConsoleWriter reads a JSON object per write operation and output an
-// optionally colored human readable version on the Out writer.
+const (
+	consoleDefaultTimeFormat = time.Kitchen
+)
+
+// Formatter transforms the input into a formatted string.
+type Formatter func(interface{}) string
+
+// ConsoleWriter parses the JSON input and writes it in an
+// (optionally) colorized, human-friendly format to Out.
 type ConsoleWriter struct {
-	Out     io.Writer
+	// Out is the output destination.
+	Out io.Writer
+
+	// NoColor disables the colorized output.
 	NoColor bool
+
+	// TimeFormat specifies the format for timestamp in output.
+	TimeFormat string
+
+	// TimeLocation tells ConsoleWriter’s default FormatTimestamp
+	// how to localize the time.
+	TimeLocation *time.Location
+
+	// PartsOrder defines the order of parts in output.
+	PartsOrder []string
+
+	// PartsExclude defines parts to not display in output.
+	PartsExclude []string
+
+	// FieldsOrder defines the order of contextual fields in output.
+	FieldsOrder []string
+
+	fieldIsOrdered map[string]int
+
+	// FieldsExclude defines contextual fields to not display in output.
+	FieldsExclude []string
+
+	FormatTimestamp     Formatter
+	FormatLevel         Formatter
+	FormatCaller        Formatter
+	FormatMessage       Formatter
+	FormatFieldName     Formatter
+	FormatFieldValue    Formatter
+	FormatErrFieldName  Formatter
+	FormatErrFieldValue Formatter
+
+	FormatExtra func(map[string]interface{}, *bytes.Buffer) error
+
+	FormatPrepare func(map[string]interface{}) error
 }
 
+// NewConsoleWriter creates and initializes a new ConsoleWriter.
+func NewConsoleWriter(options ...func(w *ConsoleWriter)) ConsoleWriter {
+	w := ConsoleWriter{
+		Out:          os.Stdout,
+		TimeFormat:   consoleDefaultTimeFormat,
+		PartsOrder:   consoleDefaultPartsOrder(),
+	}
+
+	for _, opt := range options {
+		opt(&w)
+	}
+
+	// Fix color on Windows
+	if w.Out == os.Stdout || w.Out == os.Stderr {
+		w.Out = colorable.NewColorable(w.Out.(*os.File))
+	}
+
+	return w
+}
+
+// Write transforms the JSON input with formatters and appends to w.Out.
 func (w ConsoleWriter) Write(p []byte) (n int, err error) {
-	var event map[string]interface{}
-	err = json.Unmarshal(p, &event)
+	// Fix color on Windows
+	if w.Out == os.Stdout || w.Out == os.Stderr {
+		w.Out = colorable.NewColorable(w.Out.(*os.File))
+	}
+
+	if w.PartsOrder == nil {
+		w.PartsOrder = consoleDefaultPartsOrder()
+	}
+
+	var buf = consoleBufPool.Get().(*bytes.Buffer)
+	defer func() {
+		buf.Reset()
+		consoleBufPool.Put(buf)
+	}()
+
+	var evt map[string]interface{}
+	p = decodeIfBinaryToBytes(p)
+	d := json.NewDecoder(bytes.NewReader(p))
+	d.UseNumber()
+	err = d.Decode(&evt)
 	if err != nil {
-		return
+		return n, fmt.Errorf("cannot decode event: %s", err)
 	}
-	buf := consoleBufPool.Get().(*bytes.Buffer)
-	defer consoleBufPool.Put(buf)
-	lvlColor := cReset
-	level := "????"
-	if l, ok := event[LevelFieldName].(string); ok {
-		if !w.NoColor {
-			lvlColor = levelColor(l)
+
+	if w.FormatPrepare != nil {
+		err = w.FormatPrepare(evt)
+		if err != nil {
+			return n, err
 		}
-		level = strings.ToUpper(l)[0:4]
 	}
-	fmt.Fprintf(buf, "%s |%s| %s",
-		colorize(event[TimestampFieldName], cDarkGray, !w.NoColor),
-		colorize(level, lvlColor, !w.NoColor),
-		colorize(event[MessageFieldName], cReset, !w.NoColor))
-	fields := make([]string, 0, len(event))
-	for field := range event {
+
+	for _, p := range w.PartsOrder {
+		w.writePart(buf, evt, p)
+	}
+
+	w.writeFields(evt, buf)
+
+	if w.FormatExtra != nil {
+		err = w.FormatExtra(evt, buf)
+		if err != nil {
+			return n, err
+		}
+	}
+
+	err = buf.WriteByte('\n')
+	if err != nil {
+		return n, err
+	}
+
+	_, err = buf.WriteTo(w.Out)
+	return len(p), err
+}
+
+// Call the underlying writer's Close method if it is an io.Closer. Otherwise
+// does nothing.
+func (w ConsoleWriter) Close() error {
+	if closer, ok := w.Out.(io.Closer); ok {
+		return closer.Close()
+	}
+	return nil
+}
+
+// writeFields appends formatted key-value pairs to buf.
+func (w ConsoleWriter) writeFields(evt map[string]interface{}, buf *bytes.Buffer) {
+	var fields = make([]string, 0, len(evt))
+	for field := range evt {
+		var isExcluded bool
+		for _, excluded := range w.FieldsExclude {
+			if field == excluded {
+				isExcluded = true
+				break
+			}
+		}
+		if isExcluded {
+			continue
+		}
+
 		switch field {
-		case LevelFieldName, TimestampFieldName, MessageFieldName:
+		case LevelFieldName, TimestampFieldName, MessageFieldName, CallerFieldName:
 			continue
 		}
 		fields = append(fields, field)
 	}
-	sort.Strings(fields)
-	for _, field := range fields {
-		fmt.Fprintf(buf, " %s=", colorize(field, cCyan, !w.NoColor))
-		switch value := event[field].(type) {
-		case string:
-			if needsQuote(value) {
-				buf.WriteString(strconv.Quote(value))
-			} else {
-				buf.WriteString(value)
+
+	if len(w.FieldsOrder) > 0 {
+		w.orderFields(fields)
+	} else {
+		sort.Strings(fields)
+	}
+
+	// Write space only if something has already been written to the buffer, and if there are fields.
+	if buf.Len() > 0 && len(fields) > 0 {
+		buf.WriteByte(' ')
+	}
+
+	// Move the "error" field to the front
+	ei := sort.Search(len(fields), func(i int) bool { return fields[i] >= ErrorFieldName })
+	if ei < len(fields) && fields[ei] == ErrorFieldName {
+		fields[ei] = ""
+		fields = append([]string{ErrorFieldName}, fields...)
+		var xfields = make([]string, 0, len(fields))
+		for _, field := range fields {
+			if field == "" { // Skip empty fields
+				continue
 			}
+			xfields = append(xfields, field)
+		}
+		fields = xfields
+	}
+
+	for i, field := range fields {
+		var fn Formatter
+		var fv Formatter
+
+		if field == ErrorFieldName {
+			if w.FormatErrFieldName == nil {
+				fn = consoleDefaultFormatErrFieldName(w.NoColor)
+			} else {
+				fn = w.FormatErrFieldName
+			}
+
+			if w.FormatErrFieldValue == nil {
+				fv = consoleDefaultFormatErrFieldValue(w.NoColor)
+			} else {
+				fv = w.FormatErrFieldValue
+			}
+		} else {
+			if w.FormatFieldName == nil {
+				fn = consoleDefaultFormatFieldName(w.NoColor)
+			} else {
+				fn = w.FormatFieldName
+			}
+
+			if w.FormatFieldValue == nil {
+				fv = consoleDefaultFormatFieldValue
+			} else {
+				fv = w.FormatFieldValue
+			}
+		}
+
+		buf.WriteString(fn(field))
+
+		switch fValue := evt[field].(type) {
+		case string:
+			if needsQuote(fValue) {
+				buf.WriteString(fv(strconv.Quote(fValue)))
+			} else {
+				buf.WriteString(fv(fValue))
+			}
+		case json.Number:
+			buf.WriteString(fv(fValue))
 		default:
-			fmt.Fprint(buf, value)
+			b, err := InterfaceMarshalFunc(fValue)
+			if err != nil {
+				fmt.Fprintf(buf, colorize("[error: %v]", colorRed, w.NoColor), err)
+			} else {
+				fmt.Fprint(buf, fv(b))
+			}
+		}
+
+		if i < len(fields)-1 { // Skip space for last field
+			buf.WriteByte(' ')
 		}
 	}
-	buf.WriteByte('\n')
-	buf.WriteTo(w.Out)
-	n = len(p)
-	return
 }
 
-func colorize(s interface{}, color int, enabled bool) string {
-	if !enabled {
-		return fmt.Sprintf("%v", s)
+// writePart appends a formatted part to buf.
+func (w ConsoleWriter) writePart(buf *bytes.Buffer, evt map[string]interface{}, p string) {
+	var f Formatter
+
+	if w.PartsExclude != nil && len(w.PartsExclude) > 0 {
+		for _, exclude := range w.PartsExclude {
+			if exclude == p {
+				return
+			}
+		}
 	}
-	return fmt.Sprintf("\x1b[%dm%v\x1b[0m", color, s)
-}
 
-func levelColor(level string) int {
-	switch level {
-	case "debug":
-		return cMagenta
-	case "info":
-		return cGreen
-	case "warn":
-		return cYellow
-	case "error", "fatal", "panic":
-		return cRed
+	switch p {
+	case LevelFieldName:
+		if w.FormatLevel == nil {
+			f = consoleDefaultFormatLevel(w.NoColor)
+		} else {
+			f = w.FormatLevel
+		}
+	case TimestampFieldName:
+		if w.FormatTimestamp == nil {
+			f = consoleDefaultFormatTimestamp(w.TimeFormat, w.TimeLocation, w.NoColor)
+		} else {
+			f = w.FormatTimestamp
+		}
+	case MessageFieldName:
+		if w.FormatMessage == nil {
+			f = consoleDefaultFormatMessage(w.NoColor, evt[LevelFieldName])
+		} else {
+			f = w.FormatMessage
+		}
+	case CallerFieldName:
+		if w.FormatCaller == nil {
+			f = consoleDefaultFormatCaller(w.NoColor)
+		} else {
+			f = w.FormatCaller
+		}
 	default:
-		return cReset
+		if w.FormatFieldValue == nil {
+			f = consoleDefaultFormatFieldValue
+		} else {
+			f = w.FormatFieldValue
+		}
+	}
+
+	var s = f(evt[p])
+
+	if len(s) > 0 {
+		if buf.Len() > 0 {
+			buf.WriteByte(' ') // Write space only if not the first part
+		}
+		buf.WriteString(s)
 	}
 }
 
+// orderFields takes an array of field names and an array representing field order
+// and returns an array with any ordered fields at the beginning, in order,
+// and the remaining fields after in their original order.
+func (w ConsoleWriter) orderFields(fields []string) {
+	if w.fieldIsOrdered == nil {
+		w.fieldIsOrdered = make(map[string]int)
+		for i, fieldName := range w.FieldsOrder {
+			w.fieldIsOrdered[fieldName] = i
+		}
+	}
+	sort.Slice(fields, func(i, j int) bool {
+		ii, iOrdered := w.fieldIsOrdered[fields[i]]
+		jj, jOrdered := w.fieldIsOrdered[fields[j]]
+		if iOrdered && jOrdered {
+			return ii < jj
+		}
+		if iOrdered {
+			return true
+		}
+		if jOrdered {
+			return false
+		}
+		return fields[i] < fields[j]
+	})
+}
+
+// needsQuote returns true when the string s should be quoted in output.
 func needsQuote(s string) bool {
 	for i := range s {
 		if s[i] < 0x20 || s[i] > 0x7e || s[i] == ' ' || s[i] == '\\' || s[i] == '"' {
@@ -115,3 +369,152 @@ func needsQuote(s string) bool {
 	}
 	return false
 }
+
+// colorize returns the string s wrapped in ANSI code c, unless disabled is true or c is 0.
+func colorize(s interface{}, c int, disabled bool) string {
+	e := os.Getenv("NO_COLOR")
+	if e != "" || c == 0 {
+		disabled = true
+	}
+
+	if disabled {
+		return fmt.Sprintf("%s", s)
+	}
+	return fmt.Sprintf("\x1b[%dm%v\x1b[0m", c, s)
+}
+
+// ----- DEFAULT FORMATTERS ---------------------------------------------------
+
+func consoleDefaultPartsOrder() []string {
+	return []string{
+		TimestampFieldName,
+		LevelFieldName,
+		CallerFieldName,
+		MessageFieldName,
+	}
+}
+
+func consoleDefaultFormatTimestamp(timeFormat string, location *time.Location, noColor bool) Formatter {
+	if timeFormat == "" {
+		timeFormat = consoleDefaultTimeFormat
+	}
+	if location == nil {
+		location = time.Local
+	}
+
+	return func(i interface{}) string {
+		t := "<nil>"
+		switch tt := i.(type) {
+		case string:
+			ts, err := time.ParseInLocation(TimeFieldFormat, tt, location)
+			if err != nil {
+				t = tt
+			} else {
+				t = ts.In(location).Format(timeFormat)
+			}
+		case json.Number:
+			i, err := tt.Int64()
+			if err != nil {
+				t = tt.String()
+			} else {
+				var sec, nsec int64
+
+				switch TimeFieldFormat {
+				case TimeFormatUnixNano:
+					sec, nsec = 0, i
+				case TimeFormatUnixMicro:
+					sec, nsec = 0, int64(time.Duration(i)*time.Microsecond)
+				case TimeFormatUnixMs:
+					sec, nsec = 0, int64(time.Duration(i)*time.Millisecond)
+				default:
+					sec, nsec = i, 0
+				}
+
+				ts := time.Unix(sec, nsec)
+				t = ts.In(location).Format(timeFormat)
+			}
+		}
+		return colorize(t, colorDarkGray, noColor)
+	}
+}
+
+func stripLevel(ll string) string {
+	if len(ll) == 0 {
+		return unknownLevel
+	}
+	if len(ll) > 3 {
+		ll = ll[:3]
+	}
+	return strings.ToUpper(ll)
+}
+
+func consoleDefaultFormatLevel(noColor bool) Formatter {
+	return func(i interface{}) string {
+		if ll, ok := i.(string); ok {
+			level, _ := ParseLevel(ll)
+			fl, ok := FormattedLevels[level]
+			if ok {
+				return colorize(fl, LevelColors[level], noColor)
+			}
+			return stripLevel(ll)
+		}
+		if i == nil {
+			return unknownLevel
+		}
+		return stripLevel(fmt.Sprintf("%s", i))
+	}
+}
+
+func consoleDefaultFormatCaller(noColor bool) Formatter {
+	return func(i interface{}) string {
+		var c string
+		if cc, ok := i.(string); ok {
+			c = cc
+		}
+		if len(c) > 0 {
+			if cwd, err := os.Getwd(); err == nil {
+				if rel, err := filepath.Rel(cwd, c); err == nil {
+					c = rel
+				}
+			}
+			c = colorize(c, colorBold, noColor) + colorize(" >", colorCyan, noColor)
+		}
+		return c
+	}
+}
+
+func consoleDefaultFormatMessage(noColor bool, level interface{}) Formatter {
+	return func(i interface{}) string {
+		if i == nil || i == "" {
+			return ""
+		}
+		switch level {
+		case LevelInfoValue, LevelWarnValue, LevelErrorValue, LevelFatalValue, LevelPanicValue:
+			return colorize(fmt.Sprintf("%s", i), colorBold, noColor)
+		default:
+			return fmt.Sprintf("%s", i)
+		}
+	}
+}
+
+func consoleDefaultFormatFieldName(noColor bool) Formatter {
+	return func(i interface{}) string {
+		return colorize(fmt.Sprintf("%s=", i), colorCyan, noColor)
+	}
+}
+
+func consoleDefaultFormatFieldValue(i interface{}) string {
+	return fmt.Sprintf("%s", i)
+}
+
+func consoleDefaultFormatErrFieldName(noColor bool) Formatter {
+	return func(i interface{}) string {
+		return colorize(fmt.Sprintf("%s=", i), colorCyan, noColor)
+	}
+}
+
+func consoleDefaultFormatErrFieldValue(noColor bool) Formatter {
+	return func(i interface{}) string {
+		return colorize(colorize(fmt.Sprintf("%s", i), colorBold, noColor), colorRed, noColor)
+	}
+}

console_test.go

@@ -0,0 +1,607 @@
+package zerolog_test
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/rs/zerolog"
+)
+
+func ExampleConsoleWriter() {
+	log := zerolog.New(zerolog.ConsoleWriter{Out: os.Stdout, NoColor: true})
+
+	log.Info().Str("foo", "bar").Msg("Hello World")
+	// Output: <nil> INF Hello World foo=bar
+}
+
+func ExampleConsoleWriter_customFormatters() {
+	out := zerolog.ConsoleWriter{Out: os.Stdout, NoColor: true}
+	out.FormatLevel = func(i interface{}) string { return strings.ToUpper(fmt.Sprintf("%-6s|", i)) }
+	out.FormatFieldName = func(i interface{}) string { return fmt.Sprintf("%s:", i) }
+	out.FormatFieldValue = func(i interface{}) string { return strings.ToUpper(fmt.Sprintf("%s", i)) }
+	log := zerolog.New(out)
+
+	log.Info().Str("foo", "bar").Msg("Hello World")
+	// Output: <nil> INFO  | Hello World foo:BAR
+}
+
+func ExampleNewConsoleWriter() {
+	out := zerolog.NewConsoleWriter()
+	out.NoColor = true // For testing purposes only
+	log := zerolog.New(out)
+
+	log.Debug().Str("foo", "bar").Msg("Hello World")
+	// Output: <nil> DBG Hello World foo=bar
+}
+
+func ExampleNewConsoleWriter_customFormatters() {
+	out := zerolog.NewConsoleWriter(
+		func(w *zerolog.ConsoleWriter) {
+			// Customize time format
+			w.TimeFormat = time.RFC822
+			// Customize level formatting
+			w.FormatLevel = func(i interface{}) string { return strings.ToUpper(fmt.Sprintf("[%-5s]", i)) }
+		},
+	)
+	out.NoColor = true // For testing purposes only
+
+	log := zerolog.New(out)
+
+	log.Info().Str("foo", "bar").Msg("Hello World")
+	// Output: <nil> [INFO ] Hello World foo=bar
+}
+
+func TestConsoleLogger(t *testing.T) {
+	t.Run("Numbers", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		log := zerolog.New(zerolog.ConsoleWriter{Out: buf, NoColor: true})
+		log.Info().
+			Float64("float", 1.23).
+			Uint64("small", 123).
+			Uint64("big", 1152921504606846976).
+			Msg("msg")
+		if got, want := strings.TrimSpace(buf.String()), "<nil> INF msg big=1152921504606846976 float=1.23 small=123"; got != want {
+			t.Errorf("\ngot:\n%s\nwant:\n%s", got, want)
+		}
+	})
+}
+
+func TestConsoleWriter(t *testing.T) {
+	t.Run("Default field formatter", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, NoColor: true, PartsOrder: []string{"foo"}}
+
+		_, err := w.Write([]byte(`{"foo": "DEFAULT"}`))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := "DEFAULT foo=DEFAULT\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("Write colorized", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, NoColor: false}
+
+		_, err := w.Write([]byte(`{"level": "warn", "message": "Foobar"}`))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := "\x1b[90m<nil>\x1b[0m \x1b[33mWRN\x1b[0m \x1b[1mFoobar\x1b[0m\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("NO_COLOR = true", func(t *testing.T) {
+		os.Setenv("NO_COLOR", "anything")
+
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf}
+
+		_, err := w.Write([]byte(`{"level": "warn", "message": "Foobar"}`))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := "<nil> WRN Foobar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+		os.Unsetenv("NO_COLOR")
+	})
+
+	t.Run("Write fields", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, NoColor: true}
+
+		ts := time.Unix(0, 0)
+		d := ts.UTC().Format(time.RFC3339)
+		_, err := w.Write([]byte(`{"time": "` + d + `", "level": "debug", "message": "Foobar", "foo": "bar"}`))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := ts.Format(time.Kitchen) + " DBG Foobar foo=bar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("Unix timestamp input format", func(t *testing.T) {
+		of := zerolog.TimeFieldFormat
+		defer func() {
+			zerolog.TimeFieldFormat = of
+		}()
+		zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
+
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, TimeFormat: time.StampMilli, NoColor: true}
+
+		_, err := w.Write([]byte(`{"time": 1234, "level": "debug", "message": "Foobar", "foo": "bar"}`))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := time.Unix(1234, 0).Format(time.StampMilli) + " DBG Foobar foo=bar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("Unix timestamp ms input format", func(t *testing.T) {
+		of := zerolog.TimeFieldFormat
+		defer func() {
+			zerolog.TimeFieldFormat = of
+		}()
+		zerolog.TimeFieldFormat = zerolog.TimeFormatUnixMs
+
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, TimeFormat: time.StampMilli, NoColor: true}
+
+		_, err := w.Write([]byte(`{"time": 1234567, "level": "debug", "message": "Foobar", "foo": "bar"}`))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := time.Unix(1234, 567000000).Format(time.StampMilli) + " DBG Foobar foo=bar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("Unix timestamp us input format", func(t *testing.T) {
+		of := zerolog.TimeFieldFormat
+		defer func() {
+			zerolog.TimeFieldFormat = of
+		}()
+		zerolog.TimeFieldFormat = zerolog.TimeFormatUnixMicro
+
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, TimeFormat: time.StampMicro, NoColor: true}
+
+		_, err := w.Write([]byte(`{"time": 1234567891, "level": "debug", "message": "Foobar", "foo": "bar"}`))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := time.Unix(1234, 567891000).Format(time.StampMicro) + " DBG Foobar foo=bar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("No message field", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, NoColor: true}
+
+		_, err := w.Write([]byte(`{"level": "debug", "foo": "bar"}`))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := "<nil> DBG foo=bar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("No level field", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, NoColor: true}
+
+		_, err := w.Write([]byte(`{"message": "Foobar", "foo": "bar"}`))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := "<nil> ??? Foobar foo=bar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("Write colorized fields", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, NoColor: false}
+
+		_, err := w.Write([]byte(`{"level": "warn", "message": "Foobar", "foo": "bar"}`))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := "\x1b[90m<nil>\x1b[0m \x1b[33mWRN\x1b[0m \x1b[1mFoobar\x1b[0m \x1b[36mfoo=\x1b[0mbar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("Write error field", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, NoColor: true}
+
+		ts := time.Unix(0, 0)
+		d := ts.UTC().Format(time.RFC3339)
+		evt := `{"time": "` + d + `", "level": "error", "message": "Foobar", "aaa": "bbb", "error": "Error"}`
+		// t.Log(evt)
+
+		_, err := w.Write([]byte(evt))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := ts.Format(time.Kitchen) + " ERR Foobar error=Error aaa=bbb\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("Write caller field", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, NoColor: true}
+
+		cwd, err := os.Getwd()
+		if err != nil {
+			t.Fatalf("Cannot get working directory: %s", err)
+		}
+
+		ts := time.Unix(0, 0)
+		d := ts.UTC().Format(time.RFC3339)
+		evt := `{"time": "` + d + `", "level": "debug", "message": "Foobar", "foo": "bar", "caller": "` + cwd + `/foo/bar.go"}`
+		// t.Log(evt)
+
+		_, err = w.Write([]byte(evt))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := ts.Format(time.Kitchen) + " DBG foo/bar.go > Foobar foo=bar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("Write JSON field", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, NoColor: true}
+
+		evt := `{"level": "debug", "message": "Foobar", "foo": [1, 2, 3], "bar": true}`
+		// t.Log(evt)
+
+		_, err := w.Write([]byte(evt))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := "<nil> DBG Foobar bar=true foo=[1,2,3]\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("With an extra 'level' field", func(t *testing.T) {
+		t.Run("malformed string", func(t *testing.T) {
+			cases := []struct {
+				field  string
+				output string
+			}{
+				{"", "<nil> ??? Hello World foo=bar\n"},
+				{"-", "<nil> - Hello World foo=bar\n"},
+				{"1", "<nil> " + zerolog.FormattedLevels[1] + " Hello World foo=bar\n"},
+				{"a", "<nil> A Hello World foo=bar\n"},
+				{"12", "<nil> 12 Hello World foo=bar\n"},
+				{"a2", "<nil> A2 Hello World foo=bar\n"},
+				{"2a", "<nil> 2A Hello World foo=bar\n"},
+				{"ab", "<nil> AB Hello World foo=bar\n"},
+				{"12a", "<nil> 12A Hello World foo=bar\n"},
+				{"a12", "<nil> A12 Hello World foo=bar\n"},
+				{"abc", "<nil> ABC Hello World foo=bar\n"},
+				{"123", "<nil> 123 Hello World foo=bar\n"},
+				{"abcd", "<nil> ABC Hello World foo=bar\n"},
+				{"1234", "<nil> 123 Hello World foo=bar\n"},
+				{"123d", "<nil> 123 Hello World foo=bar\n"},
+				{"01", "<nil> " + zerolog.FormattedLevels[1] + " Hello World foo=bar\n"},
+				{"001", "<nil> " + zerolog.FormattedLevels[1] + " Hello World foo=bar\n"},
+				{"0001", "<nil> " + zerolog.FormattedLevels[1] + " Hello World foo=bar\n"},
+			}
+			for i, c := range cases {
+				c := c
+				t.Run(fmt.Sprintf("case %d", i), func(t *testing.T) {
+					buf := &bytes.Buffer{}
+					out := zerolog.NewConsoleWriter()
+					out.NoColor = true
+					out.Out = buf
+					log := zerolog.New(out)
+
+					log.Debug().Str("level", c.field).Str("foo", "bar").Msg("Hello World")
+
+					actualOutput := buf.String()
+					if actualOutput != c.output {
+						t.Errorf("Unexpected output %q, want: %q", actualOutput, c.output)
+					}
+				})
+			}
+		})
+
+		t.Run("weird value", func(t *testing.T) {
+			cases := []struct {
+				field  interface{}
+				output string
+			}{
+				{0, "<nil> 0 Hello World foo=bar\n"},
+				{1, "<nil> 1 Hello World foo=bar\n"},
+				{-1, "<nil> -1 Hello World foo=bar\n"},
+				{-3, "<nil> -3 Hello World foo=bar\n"},
+				{-32, "<nil> -32 Hello World foo=bar\n"},
+				{-321, "<nil> -32 Hello World foo=bar\n"},
+				{12, "<nil> 12 Hello World foo=bar\n"},
+				{123, "<nil> 123 Hello World foo=bar\n"},
+				{1234, "<nil> 123 Hello World foo=bar\n"},
+			}
+			for i, c := range cases {
+				c := c
+				t.Run(fmt.Sprintf("case %d", i), func(t *testing.T) {
+					buf := &bytes.Buffer{}
+					out := zerolog.NewConsoleWriter()
+					out.NoColor = true
+					out.Out = buf
+					log := zerolog.New(out)
+
+					log.Debug().Interface("level", c.field).Str("foo", "bar").Msg("Hello World")
+
+					actualOutput := buf.String()
+					if actualOutput != c.output {
+						t.Errorf("Unexpected output %q, want: %q", actualOutput, c.output)
+					}
+				})
+			}
+		})
+	})
+}
+
+func TestConsoleWriterConfiguration(t *testing.T) {
+	t.Run("Sets TimeFormat", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, NoColor: true, TimeFormat: time.RFC3339}
+
+		ts := time.Unix(0, 0)
+		d := ts.UTC().Format(time.RFC3339)
+		evt := `{"time": "` + d + `", "level": "info", "message": "Foobar"}`
+
+		_, err := w.Write([]byte(evt))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := ts.Format(time.RFC3339) + " INF Foobar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("Sets TimeFormat and TimeLocation", func(t *testing.T) {
+		locs := []*time.Location{ time.Local, time.UTC }
+
+		for _, location := range locs {
+			buf := &bytes.Buffer{}
+			w := zerolog.ConsoleWriter{
+				Out: buf,
+				NoColor: true,
+				TimeFormat: time.RFC3339,
+				TimeLocation: location,
+			}
+
+			ts := time.Unix(0, 0)
+			d := ts.UTC().Format(time.RFC3339)
+			evt := `{"time": "` + d + `", "level": "info", "message": "Foobar"}`
+
+			_, err := w.Write([]byte(evt))
+			if err != nil {
+				t.Errorf("Unexpected error when writing output: %s", err)
+			}
+
+			expectedOutput := ts.In(location).Format(time.RFC3339) + " INF Foobar\n"
+			actualOutput := buf.String()
+			if actualOutput != expectedOutput {
+				t.Errorf("Unexpected output %q, want: %q (location=%s)", actualOutput, expectedOutput, location)
+			}
+		}
+	})
+
+	t.Run("Sets PartsOrder", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, NoColor: true, PartsOrder: []string{"message", "level"}}
+
+		evt := `{"level": "info", "message": "Foobar"}`
+		_, err := w.Write([]byte(evt))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := "Foobar INF\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("Sets PartsExclude", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, NoColor: true, PartsExclude: []string{"time"}}
+
+		d := time.Unix(0, 0).UTC().Format(time.RFC3339)
+		evt := `{"time": "` + d + `", "level": "info", "message": "Foobar"}`
+		_, err := w.Write([]byte(evt))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := "INF Foobar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("Sets FieldsOrder", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, NoColor: true, FieldsOrder: []string{"zebra", "aardvark"}}
+
+		evt := `{"level": "info", "message": "Zoo", "aardvark": "Able", "mussel": "Mountain", "zebra": "Zulu"}`
+		_, err := w.Write([]byte(evt))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := "<nil> INF Zoo zebra=Zulu aardvark=Able mussel=Mountain\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("Sets FieldsExclude", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, NoColor: true, FieldsExclude: []string{"foo"}}
+
+		evt := `{"level": "info", "message": "Foobar", "foo":"bar", "baz":"quux"}`
+		_, err := w.Write([]byte(evt))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := "<nil> INF Foobar baz=quux\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("Sets FormatExtra", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{
+			Out: buf, NoColor: true, PartsOrder: []string{"level", "message"},
+			FormatExtra: func(evt map[string]interface{}, buf *bytes.Buffer) error {
+				buf.WriteString("\nAdditional stacktrace")
+				return nil
+			},
+		}
+
+		evt := `{"level": "info", "message": "Foobar"}`
+		_, err := w.Write([]byte(evt))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := "INF Foobar\nAdditional stacktrace\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("Sets FormatPrepare", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{
+			Out: buf, NoColor: true, PartsOrder: []string{"level", "message"},
+			FormatPrepare: func(evt map[string]interface{}) error {
+				evt["message"] = fmt.Sprintf("msg=%s", evt["message"])
+				return nil
+			},
+		}
+
+		evt := `{"level": "info", "message": "Foobar"}`
+		_, err := w.Write([]byte(evt))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := "INF msg=Foobar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("Uses local time for console writer without time zone", func(t *testing.T) {
+		// Regression test for issue #483 (check there for more details)
+
+		timeFormat := "2006-01-02 15:04:05"
+		expectedOutput := "2022-10-20 20:24:50 INF Foobar\n"
+		evt := `{"time": "2022-10-20 20:24:50", "level": "info", "message": "Foobar"}`
+
+		of := zerolog.TimeFieldFormat
+		defer func() {
+			zerolog.TimeFieldFormat = of
+		}()
+		zerolog.TimeFieldFormat = timeFormat
+
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, NoColor: true, TimeFormat: timeFormat}
+		_, err := w.Write([]byte(evt))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+}
+
+func BenchmarkConsoleWriter(b *testing.B) {
+	b.ResetTimer()
+	b.ReportAllocs()
+
+	var msg = []byte(`{"level": "info", "foo": "bar", "message": "HELLO", "time": "1990-01-01"}`)
+
+	w := zerolog.ConsoleWriter{Out: io.Discard, NoColor: false}
+
+	for i := 0; i < b.N; i++ {
+		w.Write(msg)
+	}
+}

context.go

@@ -1,10 +1,12 @@
 package zerolog
 
 import (
-	"io/ioutil"
+	"context"
+	"fmt"
+	"io"
+	"math"
+	"net"
 	"time"
-
-	"github.com/rs/zerolog/internal/json"
 )
 
 // Context configures a new sub-logger with contextual fields.
@@ -17,17 +19,19 @@ func (c Context) Logger() Logger {
 	return c.l
 }
 
-// Fields is a helper function to use a map to set fields using type assertion.
-func (c Context) Fields(fields map[string]interface{}) Context {
-	c.l.context = appendFields(c.l.context, fields)
+// Fields is a helper function to use a map or slice to set fields using type assertion.
+// Only map[string]interface{} and []interface{} are accepted. []interface{} must
+// alternate string keys and arbitrary values, and extraneous ones are ignored.
+func (c Context) Fields(fields interface{}) Context {
+	c.l.context = appendFields(c.l.context, fields, c.l.stack)
 	return c
 }
 
 // Dict adds the field key with the dict to the logger context.
 func (c Context) Dict(key string, dict *Event) Context {
-	dict.buf = append(dict.buf, '}')
-	c.l.context = append(json.AppendKey(c.l.context, key), dict.buf...)
-	eventPool.Put(dict)
+	dict.buf = enc.AppendEndMarker(dict.buf)
+	c.l.context = append(enc.AppendKey(c.l.context, key), dict.buf...)
+	putEvent(dict)
 	return c
 }
 
@@ -35,7 +39,7 @@ func (c Context) Dict(key string, dict *Event) Context {
 // Use zerolog.Arr() to create the array or pass a type that
 // implement the LogArrayMarshaler interface.
 func (c Context) Array(key string, arr LogArrayMarshaler) Context {
-	c.l.context = json.AppendKey(c.l.context, key)
+	c.l.context = enc.AppendKey(c.l.context, key)
 	if arr, ok := arr.(*Array); ok {
 		c.l.context = arr.write(c.l.context)
 		return c
@@ -53,248 +57,424 @@ func (c Context) Array(key string, arr LogArrayMarshaler) Context {
 
 // Object marshals an object that implement the LogObjectMarshaler interface.
 func (c Context) Object(key string, obj LogObjectMarshaler) Context {
-	e := newEvent(levelWriterAdapter{ioutil.Discard}, 0, true)
+	e := newEvent(LevelWriterAdapter{io.Discard}, 0)
 	e.Object(key, obj)
-	e.buf[0] = ',' // A new event starts as an object, we want to embed it.
-	c.l.context = append(c.l.context, e.buf...)
-	eventPool.Put(e)
+	c.l.context = enc.AppendObjectData(c.l.context, e.buf)
+	putEvent(e)
+	return c
+}
+
+// EmbedObject marshals and Embeds an object that implement the LogObjectMarshaler interface.
+func (c Context) EmbedObject(obj LogObjectMarshaler) Context {
+	e := newEvent(LevelWriterAdapter{io.Discard}, 0)
+	e.EmbedObject(obj)
+	c.l.context = enc.AppendObjectData(c.l.context, e.buf)
+	putEvent(e)
 	return c
 }
 
 // Str adds the field key with val as a string to the logger context.
 func (c Context) Str(key, val string) Context {
-	c.l.context = json.AppendString(json.AppendKey(c.l.context, key), val)
+	c.l.context = enc.AppendString(enc.AppendKey(c.l.context, key), val)
 	return c
 }
 
 // Strs adds the field key with val as a string to the logger context.
 func (c Context) Strs(key string, vals []string) Context {
-	c.l.context = json.AppendStrings(json.AppendKey(c.l.context, key), vals)
+	c.l.context = enc.AppendStrings(enc.AppendKey(c.l.context, key), vals)
+	return c
+}
+
+// Stringer adds the field key with val.String() (or null if val is nil) to the logger context.
+func (c Context) Stringer(key string, val fmt.Stringer) Context {
+	if val != nil {
+		c.l.context = enc.AppendString(enc.AppendKey(c.l.context, key), val.String())
+		return c
+	}
+
+	c.l.context = enc.AppendInterface(enc.AppendKey(c.l.context, key), nil)
 	return c
 }
 
 // Bytes adds the field key with val as a []byte to the logger context.
 func (c Context) Bytes(key string, val []byte) Context {
-	c.l.context = json.AppendBytes(json.AppendKey(c.l.context, key), val)
+	c.l.context = enc.AppendBytes(enc.AppendKey(c.l.context, key), val)
 	return c
 }
 
-// AnErr adds the field key with err as a string to the logger context.
+// Hex adds the field key with val as a hex string to the logger context.
+func (c Context) Hex(key string, val []byte) Context {
+	c.l.context = enc.AppendHex(enc.AppendKey(c.l.context, key), val)
+	return c
+}
+
+// RawJSON adds already encoded JSON to context.
+//
+// No sanity check is performed on b; it must not contain carriage returns and
+// be valid JSON.
+func (c Context) RawJSON(key string, b []byte) Context {
+	c.l.context = appendJSON(enc.AppendKey(c.l.context, key), b)
+	return c
+}
+
+// AnErr adds the field key with serialized err to the logger context.
 func (c Context) AnErr(key string, err error) Context {
-	if err != nil {
-		c.l.context = json.AppendError(json.AppendKey(c.l.context, key), err)
+	switch m := ErrorMarshalFunc(err).(type) {
+	case nil:
+		return c
+	case LogObjectMarshaler:
+		return c.Object(key, m)
+	case error:
+		if m == nil || isNilValue(m) {
+			return c
+		} else {
+			return c.Str(key, m.Error())
+		}
+	case string:
+		return c.Str(key, m)
+	default:
+		return c.Interface(key, m)
 	}
-	return c
 }
 
-// Errs adds the field key with errs as an array of strings to the logger context.
+// Errs adds the field key with errs as an array of serialized errors to the
+// logger context.
 func (c Context) Errs(key string, errs []error) Context {
-	c.l.context = json.AppendErrors(json.AppendKey(c.l.context, key), errs)
-	return c
+	arr := Arr()
+	for _, err := range errs {
+		switch m := ErrorMarshalFunc(err).(type) {
+		case LogObjectMarshaler:
+			arr = arr.Object(m)
+		case error:
+			if m == nil || isNilValue(m) {
+				arr = arr.Interface(nil)
+			} else {
+				arr = arr.Str(m.Error())
+			}
+		case string:
+			arr = arr.Str(m)
+		default:
+			arr = arr.Interface(m)
+		}
+	}
+
+	return c.Array(key, arr)
 }
 
-// Err adds the field "error" with err as a string to the logger context.
-// To customize the key name, change zerolog.ErrorFieldName.
+// Err adds the field "error" with serialized err to the logger context.
 func (c Context) Err(err error) Context {
-	if err != nil {
-		c.l.context = json.AppendError(json.AppendKey(c.l.context, ErrorFieldName), err)
+	if c.l.stack && ErrorStackMarshaler != nil {
+		switch m := ErrorStackMarshaler(err).(type) {
+		case nil:
+		case LogObjectMarshaler:
+			c = c.Object(ErrorStackFieldName, m)
+		case error:
+			if m != nil && !isNilValue(m) {
+				c = c.Str(ErrorStackFieldName, m.Error())
+			}
+		case string:
+			c = c.Str(ErrorStackFieldName, m)
+		default:
+			c = c.Interface(ErrorStackFieldName, m)
+		}
 	}
+
+	return c.AnErr(ErrorFieldName, err)
+}
+
+// Ctx adds the context.Context to the logger context. The context.Context is
+// not rendered in the error message, but is made available for hooks to use.
+// A typical use case is to extract tracing information from the
+// context.Context.
+func (c Context) Ctx(ctx context.Context) Context {
+	c.l.ctx = ctx
 	return c
 }
 
 // Bool adds the field key with val as a bool to the logger context.
 func (c Context) Bool(key string, b bool) Context {
-	c.l.context = json.AppendBool(json.AppendKey(c.l.context, key), b)
+	c.l.context = enc.AppendBool(enc.AppendKey(c.l.context, key), b)
 	return c
 }
 
 // Bools adds the field key with val as a []bool to the logger context.
 func (c Context) Bools(key string, b []bool) Context {
-	c.l.context = json.AppendBools(json.AppendKey(c.l.context, key), b)
+	c.l.context = enc.AppendBools(enc.AppendKey(c.l.context, key), b)
 	return c
 }
 
 // Int adds the field key with i as a int to the logger context.
 func (c Context) Int(key string, i int) Context {
-	c.l.context = json.AppendInt(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInt(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Ints adds the field key with i as a []int to the logger context.
 func (c Context) Ints(key string, i []int) Context {
-	c.l.context = json.AppendInts(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInts(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Int8 adds the field key with i as a int8 to the logger context.
 func (c Context) Int8(key string, i int8) Context {
-	c.l.context = json.AppendInt8(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInt8(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Ints8 adds the field key with i as a []int8 to the logger context.
 func (c Context) Ints8(key string, i []int8) Context {
-	c.l.context = json.AppendInts8(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInts8(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Int16 adds the field key with i as a int16 to the logger context.
 func (c Context) Int16(key string, i int16) Context {
-	c.l.context = json.AppendInt16(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInt16(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Ints16 adds the field key with i as a []int16 to the logger context.
 func (c Context) Ints16(key string, i []int16) Context {
-	c.l.context = json.AppendInts16(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInts16(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Int32 adds the field key with i as a int32 to the logger context.
 func (c Context) Int32(key string, i int32) Context {
-	c.l.context = json.AppendInt32(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInt32(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Ints32 adds the field key with i as a []int32 to the logger context.
 func (c Context) Ints32(key string, i []int32) Context {
-	c.l.context = json.AppendInts32(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInts32(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Int64 adds the field key with i as a int64 to the logger context.
 func (c Context) Int64(key string, i int64) Context {
-	c.l.context = json.AppendInt64(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInt64(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Ints64 adds the field key with i as a []int64 to the logger context.
 func (c Context) Ints64(key string, i []int64) Context {
-	c.l.context = json.AppendInts64(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInts64(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Uint adds the field key with i as a uint to the logger context.
 func (c Context) Uint(key string, i uint) Context {
-	c.l.context = json.AppendUint(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendUint(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Uints adds the field key with i as a []uint to the logger context.
 func (c Context) Uints(key string, i []uint) Context {
-	c.l.context = json.AppendUints(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendUints(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Uint8 adds the field key with i as a uint8 to the logger context.
 func (c Context) Uint8(key string, i uint8) Context {
-	c.l.context = json.AppendUint8(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendUint8(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Uints8 adds the field key with i as a []uint8 to the logger context.
 func (c Context) Uints8(key string, i []uint8) Context {
-	c.l.context = json.AppendUints8(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendUints8(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Uint16 adds the field key with i as a uint16 to the logger context.
 func (c Context) Uint16(key string, i uint16) Context {
-	c.l.context = json.AppendUint16(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendUint16(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Uints16 adds the field key with i as a []uint16 to the logger context.
 func (c Context) Uints16(key string, i []uint16) Context {
-	c.l.context = json.AppendUints16(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendUints16(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Uint32 adds the field key with i as a uint32 to the logger context.
 func (c Context) Uint32(key string, i uint32) Context {
-	c.l.context = json.AppendUint32(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendUint32(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Uints32 adds the field key with i as a []uint32 to the logger context.
 func (c Context) Uints32(key string, i []uint32) Context {
-	c.l.context = json.AppendUints32(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendUints32(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Uint64 adds the field key with i as a uint64 to the logger context.
 func (c Context) Uint64(key string, i uint64) Context {
-	c.l.context = json.AppendUint64(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendUint64(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Uints64 adds the field key with i as a []uint64 to the logger context.
 func (c Context) Uints64(key string, i []uint64) Context {
-	c.l.context = json.AppendUints64(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendUints64(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Float32 adds the field key with f as a float32 to the logger context.
 func (c Context) Float32(key string, f float32) Context {
-	c.l.context = json.AppendFloat32(json.AppendKey(c.l.context, key), f)
+	c.l.context = enc.AppendFloat32(enc.AppendKey(c.l.context, key), f, FloatingPointPrecision)
 	return c
 }
 
 // Floats32 adds the field key with f as a []float32 to the logger context.
 func (c Context) Floats32(key string, f []float32) Context {
-	c.l.context = json.AppendFloats32(json.AppendKey(c.l.context, key), f)
+	c.l.context = enc.AppendFloats32(enc.AppendKey(c.l.context, key), f, FloatingPointPrecision)
 	return c
 }
 
 // Float64 adds the field key with f as a float64 to the logger context.
 func (c Context) Float64(key string, f float64) Context {
-	c.l.context = json.AppendFloat64(json.AppendKey(c.l.context, key), f)
+	c.l.context = enc.AppendFloat64(enc.AppendKey(c.l.context, key), f, FloatingPointPrecision)
 	return c
 }
 
 // Floats64 adds the field key with f as a []float64 to the logger context.
 func (c Context) Floats64(key string, f []float64) Context {
-	c.l.context = json.AppendFloats64(json.AppendKey(c.l.context, key), f)
+	c.l.context = enc.AppendFloats64(enc.AppendKey(c.l.context, key), f, FloatingPointPrecision)
 	return c
 }
 
-// Timestamp adds the current local time as UNIX timestamp to the logger context with the "time" key.
+type timestampHook struct{}
+
+func (ts timestampHook) Run(e *Event, level Level, msg string) {
+	e.Timestamp()
+}
+
+var th = timestampHook{}
+
+// Timestamp adds the current local time to the logger context with the "time" key, formatted using zerolog.TimeFieldFormat.
 // To customize the key name, change zerolog.TimestampFieldName.
+// To customize the time format, change zerolog.TimeFieldFormat.
+//
+// NOTE: It won't dedupe the "time" key if the *Context has one already.
 func (c Context) Timestamp() Context {
-	if len(c.l.context) > 0 {
-		c.l.context[0] = 1
-	} else {
-		c.l.context = append(c.l.context, 1)
-	}
+	c.l = c.l.Hook(th)
 	return c
 }
 
-// Time adds the field key with t formated as string using zerolog.TimeFieldFormat.
+// Time adds the field key with t formatted as string using zerolog.TimeFieldFormat.
 func (c Context) Time(key string, t time.Time) Context {
-	c.l.context = json.AppendTime(json.AppendKey(c.l.context, key), t, TimeFieldFormat)
+	c.l.context = enc.AppendTime(enc.AppendKey(c.l.context, key), t, TimeFieldFormat)
 	return c
 }
 
-// Times adds the field key with t formated as string using zerolog.TimeFieldFormat.
+// Times adds the field key with t formatted as string using zerolog.TimeFieldFormat.
 func (c Context) Times(key string, t []time.Time) Context {
-	c.l.context = json.AppendTimes(json.AppendKey(c.l.context, key), t, TimeFieldFormat)
+	c.l.context = enc.AppendTimes(enc.AppendKey(c.l.context, key), t, TimeFieldFormat)
 	return c
 }
 
 // Dur adds the fields key with d divided by unit and stored as a float.
 func (c Context) Dur(key string, d time.Duration) Context {
-	c.l.context = json.AppendDuration(json.AppendKey(c.l.context, key), d, DurationFieldUnit, DurationFieldInteger)
+	c.l.context = enc.AppendDuration(enc.AppendKey(c.l.context, key), d, DurationFieldUnit, DurationFieldInteger, FloatingPointPrecision)
 	return c
 }
 
 // Durs adds the fields key with d divided by unit and stored as a float.
 func (c Context) Durs(key string, d []time.Duration) Context {
-	c.l.context = json.AppendDurations(json.AppendKey(c.l.context, key), d, DurationFieldUnit, DurationFieldInteger)
+	c.l.context = enc.AppendDurations(enc.AppendKey(c.l.context, key), d, DurationFieldUnit, DurationFieldInteger, FloatingPointPrecision)
 	return c
 }
 
 // Interface adds the field key with obj marshaled using reflection.
 func (c Context) Interface(key string, i interface{}) Context {
-	c.l.context = json.AppendInterface(json.AppendKey(c.l.context, key), i)
+	if obj, ok := i.(LogObjectMarshaler); ok {
+		return c.Object(key, obj)
+	}
+	c.l.context = enc.AppendInterface(enc.AppendKey(c.l.context, key), i)
+	return c
+}
+
+// Type adds the field key with val's type using reflection.
+func (c Context) Type(key string, val interface{}) Context {
+	c.l.context = enc.AppendType(enc.AppendKey(c.l.context, key), val)
+	return c
+}
+
+// Any is a wrapper around Context.Interface.
+func (c Context) Any(key string, i interface{}) Context {
+	return c.Interface(key, i)
+}
+
+// Reset removes all the context fields.
+func (c Context) Reset() Context {
+	c.l.context = enc.AppendBeginMarker(make([]byte, 0, 500))
+	return c
+}
+
+type callerHook struct {
+	callerSkipFrameCount int
+}
+
+func newCallerHook(skipFrameCount int) callerHook {
+	return callerHook{callerSkipFrameCount: skipFrameCount}
+}
+
+func (ch callerHook) Run(e *Event, level Level, msg string) {
+	switch ch.callerSkipFrameCount {
+	case useGlobalSkipFrameCount:
+		// Extra frames to skip (added by hook infra).
+		e.caller(CallerSkipFrameCount + contextCallerSkipFrameCount)
+	default:
+		// Extra frames to skip (added by hook infra).
+		e.caller(ch.callerSkipFrameCount + contextCallerSkipFrameCount)
+	}
+}
+
+// useGlobalSkipFrameCount acts as a flag to informat callerHook.Run
+// to use the global CallerSkipFrameCount.
+const useGlobalSkipFrameCount = math.MinInt32
+
+// ch is the default caller hook using the global CallerSkipFrameCount.
+var ch = newCallerHook(useGlobalSkipFrameCount)
+
+// Caller adds the file:line of the caller with the zerolog.CallerFieldName key.
+func (c Context) Caller() Context {
+	c.l = c.l.Hook(ch)
+	return c
+}
+
+// CallerWithSkipFrameCount adds the file:line of the caller with the zerolog.CallerFieldName key.
+// The specified skipFrameCount int will override the global CallerSkipFrameCount for this context's respective logger.
+// If set to -1 the global CallerSkipFrameCount will be used.
+func (c Context) CallerWithSkipFrameCount(skipFrameCount int) Context {
+	c.l = c.l.Hook(newCallerHook(skipFrameCount))
+	return c
+}
+
+// Stack enables stack trace printing for the error passed to Err().
+func (c Context) Stack() Context {
+	c.l.stack = true
+	return c
+}
+
+// IPAddr adds IPv4 or IPv6 Address to the context
+func (c Context) IPAddr(key string, ip net.IP) Context {
+	c.l.context = enc.AppendIPAddr(enc.AppendKey(c.l.context, key), ip)
+	return c
+}
+
+// IPPrefix adds IPv4 or IPv6 Prefix (address and mask) to the context
+func (c Context) IPPrefix(key string, pfx net.IPNet) Context {
+	c.l.context = enc.AppendIPPrefix(enc.AppendKey(c.l.context, key), pfx)
+	return c
+}
+
+// MACAddr adds MAC address to the context
+func (c Context) MACAddr(key string, ha net.HardwareAddr) Context {
+	c.l.context = enc.AppendMACAddr(enc.AppendKey(c.l.context, key), ha)
 	return c
 }

ctx.go

@@ -2,34 +2,37 @@ package zerolog
 
 import (
 	"context"
-	"io/ioutil"
 )
 
 var disabledLogger *Logger
 
 func init() {
-	l := New(ioutil.Discard).Level(Disabled)
+	SetGlobalLevel(TraceLevel)
+	l := Nop()
 	disabledLogger = &l
 }
 
 type ctxKey struct{}
 
-// WithContext returns a copy of ctx with l associated. If an instance of Logger
-// is already in the context, the pointer to this logger is updated with l.
+// WithContext returns a copy of ctx with the receiver attached. The Logger
+// attached to the provided Context (if any) will not be effected.  If the
+// receiver's log level is Disabled it will only be attached to the returned
+// Context if the provided Context has a previously attached Logger. If the
+// provided Context has no attached Logger, a Disabled Logger will not be
+// attached.
 //
-// For instance, to add a field to an existing logger in the context, use this
+// Note: to modify the existing Logger attached to a Context (instead of
+// replacing it in a new Context), use UpdateContext with the following
 // notation:
 //
 //     ctx := r.Context()
 //     l := zerolog.Ctx(ctx)
-//     ctx = l.With().Str("foo", "bar").WithContext(ctx)
+//     l.UpdateContext(func(c Context) Context {
+//         return c.Str("bar", "baz")
+//     })
+//
 func (l Logger) WithContext(ctx context.Context) context.Context {
-	if lp, ok := ctx.Value(ctxKey{}).(*Logger); ok {
-		// Update existing pointer.
-		*lp = l
-		return ctx
-	}
-	if l.level == Disabled {
+	if _, ok := ctx.Value(ctxKey{}).(*Logger); !ok && l.level == Disabled {
 		// Do not store disabled logger.
 		return ctx
 	}
@@ -37,10 +40,13 @@ func (l Logger) WithContext(ctx context.Context) context.Context {
 }
 
 // Ctx returns the Logger associated with the ctx. If no logger
-// is associated, a disabled logger is returned.
+// is associated, DefaultContextLogger is returned, unless DefaultContextLogger
+// is nil, in which case a disabled logger is returned.
 func Ctx(ctx context.Context) *Logger {
 	if l, ok := ctx.Value(ctxKey{}).(*Logger); ok {
 		return l
+	} else if l = DefaultContextLogger; l != nil {
+		return l
 	}
 	return disabledLogger
 }

ctx_test.go

@@ -1,14 +1,17 @@
 package zerolog
 
 import (
+	"bytes"
 	"context"
-	"io/ioutil"
+	"io"
 	"reflect"
 	"testing"
+
+	"github.com/rs/zerolog/internal/cbor"
 )
 
 func TestCtx(t *testing.T) {
-	log := New(ioutil.Discard)
+	log := New(io.Discard)
 	ctx := log.WithContext(context.Background())
 	log2 := Ctx(ctx)
 	if !reflect.DeepEqual(log, *log2) {
@@ -27,21 +30,72 @@ func TestCtx(t *testing.T) {
 	if log2 != disabledLogger {
 		t.Error("Ctx did not return the expected logger")
 	}
+
+	DefaultContextLogger = &log
+	t.Cleanup(func() { DefaultContextLogger = nil })
+	log2 = Ctx(context.Background())
+	if log2 != &log {
+		t.Error("Ctx did not return the expected logger")
+	}
 }
 
 func TestCtxDisabled(t *testing.T) {
-	ctx := disabledLogger.WithContext(context.Background())
+	dl := New(io.Discard).Level(Disabled)
+	ctx := dl.WithContext(context.Background())
 	if ctx != context.Background() {
 		t.Error("WithContext stored a disabled logger")
 	}
 
-	ctx = New(ioutil.Discard).WithContext(ctx)
-	if reflect.DeepEqual(Ctx(ctx), disabledLogger) {
+	l := New(io.Discard).With().Str("foo", "bar").Logger()
+	ctx = l.WithContext(ctx)
+	if !reflect.DeepEqual(Ctx(ctx), &l) {
 		t.Error("WithContext did not store logger")
 	}
 
-	ctx = disabledLogger.WithContext(ctx)
-	if !reflect.DeepEqual(Ctx(ctx), disabledLogger) {
-		t.Error("WithContext did not update logger pointer with disabled logger")
+	l.UpdateContext(func(c Context) Context {
+		return c.Str("bar", "baz")
+	})
+	ctx = l.WithContext(ctx)
+	if !reflect.DeepEqual(Ctx(ctx), &l) {
+		t.Error("WithContext did not store updated logger")
+	}
+
+	l = l.Level(DebugLevel)
+	ctx = l.WithContext(ctx)
+	if !reflect.DeepEqual(Ctx(ctx), &l) {
+		t.Error("WithContext did not store copied logger")
+	}
+
+	ctx = dl.WithContext(ctx)
+	if !reflect.DeepEqual(Ctx(ctx), &dl) {
+		t.Error("WithContext did not override logger with a disabled logger")
+	}
+}
+
+type logObjectMarshalerImpl struct {
+	name string
+	age  int
+}
+
+func (t logObjectMarshalerImpl) MarshalZerologObject(e *Event) {
+	e.Str("name", "custom_value").Int("age", t.age)
+}
+
+func Test_InterfaceLogObjectMarshaler(t *testing.T) {
+	var buf bytes.Buffer
+	log := New(&buf)
+	ctx := log.WithContext(context.Background())
+
+	log2 := Ctx(ctx)
+
+	withLog := log2.With().Interface("obj", &logObjectMarshalerImpl{
+		name: "foo",
+		age:  29,
+	}).Logger()
+
+	withLog.Info().Msg("test")
+
+	if got, want := cbor.DecodeIfBinaryToString(buf.Bytes()), `{"level":"info","obj":{"name":"custom_value","age":29},"message":"test"}`+"\n"; got != want {
+		t.Errorf("got %q, want %q", got, want)
 	}
 }

diode/diode.go

@@ -0,0 +1,114 @@
+// Package diode provides a thread-safe, lock-free, non-blocking io.Writer
+// wrapper.
+package diode
+
+import (
+	"context"
+	"io"
+	"sync"
+	"time"
+
+	"github.com/rs/zerolog/diode/internal/diodes"
+)
+
+var bufPool = &sync.Pool{
+	New: func() interface{} {
+		return make([]byte, 0, 500)
+	},
+}
+
+type Alerter func(missed int)
+
+type diodeFetcher interface {
+	diodes.Diode
+	Next() diodes.GenericDataType
+}
+
+// Writer is a io.Writer wrapper that uses a diode to make Write lock-free,
+// non-blocking and thread safe.
+type Writer struct {
+	w    io.Writer
+	d    diodeFetcher
+	c    context.CancelFunc
+	done chan struct{}
+}
+
+// NewWriter creates a writer wrapping w with a many-to-one diode in order to
+// never block log producers and drop events if the writer can't keep up with
+// the flow of data.
+//
+// Use a diode.Writer when
+//
+//     wr := diode.NewWriter(w, 1000, 0, func(missed int) {
+//         log.Printf("Dropped %d messages", missed)
+//     })
+//     log := zerolog.New(wr)
+//
+// If pollInterval is greater than 0, a poller is used otherwise a waiter is
+// used.
+//
+// See code.cloudfoundry.org/go-diodes for more info on diode.
+func NewWriter(w io.Writer, size int, pollInterval time.Duration, f Alerter) Writer {
+	ctx, cancel := context.WithCancel(context.Background())
+	dw := Writer{
+		w:    w,
+		c:    cancel,
+		done: make(chan struct{}),
+	}
+	if f == nil {
+		f = func(int) {}
+	}
+	d := diodes.NewManyToOne(size, diodes.AlertFunc(f))
+	if pollInterval > 0 {
+		dw.d = diodes.NewPoller(d,
+			diodes.WithPollingInterval(pollInterval),
+			diodes.WithPollingContext(ctx))
+	} else {
+		dw.d = diodes.NewWaiter(d,
+			diodes.WithWaiterContext(ctx))
+	}
+	go dw.poll()
+	return dw
+}
+
+func (dw Writer) Write(p []byte) (n int, err error) {
+	// p is pooled in zerolog so we can't hold it passed this call, hence the
+	// copy.
+	p = append(bufPool.Get().([]byte), p...)
+	dw.d.Set(diodes.GenericDataType(&p))
+	return len(p), nil
+}
+
+// Close releases the diode poller and call Close on the wrapped writer if
+// io.Closer is implemented.
+func (dw Writer) Close() error {
+	dw.c()
+	<-dw.done
+	if w, ok := dw.w.(io.Closer); ok {
+		return w.Close()
+	}
+	return nil
+}
+
+func (dw Writer) poll() {
+	defer close(dw.done)
+	for {
+		d := dw.d.Next()
+		if d == nil {
+			return
+		}
+		p := *(*[]byte)(d)
+		dw.w.Write(p)
+
+		// Proper usage of a sync.Pool requires each entry to have approximately
+		// the same memory cost. To obtain this property when the stored type
+		// contains a variably-sized buffer, we add a hard limit on the maximum buffer
+		// to place back in the pool.
+		//
+		// See https://golang.org/issue/23199
+		const maxSize = 1 << 16 // 64KiB
+		if cap(p) <= maxSize {
+			bufPool.Put(p[:0])
+		}
+	}
+}

diode/diode_example_test.go

@@ -0,0 +1,23 @@
+// +build !binary_log
+
+package diode_test
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/diode"
+)
+
+func ExampleNewWriter() {
+	w := diode.NewWriter(os.Stdout, 1000, 0, func(missed int) {
+		fmt.Printf("Dropped %d messages\n", missed)
+	})
+	log := zerolog.New(w)
+	log.Print("test")
+
+	w.Close()
+
+	// Output: {"level":"debug","message":"test"}
+}

diode/diode_test.go

@@ -0,0 +1,100 @@
+package diode_test
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"os/exec"
+	"testing"
+	"time"
+
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/diode"
+	"github.com/rs/zerolog/internal/cbor"
+)
+
+func TestNewWriter(t *testing.T) {
+	buf := bytes.Buffer{}
+	w := diode.NewWriter(&buf, 1000, 0, func(missed int) {
+		fmt.Printf("Dropped %d messages\n", missed)
+	})
+	log := zerolog.New(w)
+	log.Print("test")
+
+	w.Close()
+	want := "{\"level\":\"debug\",\"message\":\"test\"}\n"
+	got := cbor.DecodeIfBinaryToString(buf.Bytes())
+	if got != want {
+		t.Errorf("Diode New Writer Test failed. got:%s, want:%s!", got, want)
+	}
+}
+
+func TestClose(t *testing.T) {
+	buf := bytes.Buffer{}
+	w := diode.NewWriter(&buf, 1000, 0, func(missed int) {})
+	log := zerolog.New(w)
+	log.Print("test")
+	w.Close()
+}
+
+func TestFatal(t *testing.T) {
+	if os.Getenv("TEST_FATAL") == "1" {
+		w := diode.NewWriter(os.Stderr, 1000, 0, func(missed int) {
+			fmt.Printf("Dropped %d messages\n", missed)
+		})
+		defer w.Close()
+		log := zerolog.New(w)
+		log.Fatal().Msg("test")
+		return
+	}
+
+	cmd := exec.Command(os.Args[0], "-test.run=TestFatal")
+	cmd.Env = append(os.Environ(), "TEST_FATAL=1")
+	stderr, err := cmd.StderrPipe()
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = cmd.Start()
+	if err != nil {
+		t.Fatal(err)
+	}
+	slurp, err := io.ReadAll(stderr)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = cmd.Wait()
+	if err == nil {
+		t.Error("Expected log.Fatal to exit with non-zero status")
+	}
+
+	want := "{\"level\":\"fatal\",\"message\":\"test\"}\n"
+	got := cbor.DecodeIfBinaryToString(slurp)
+	if got != want {
+		t.Errorf("Diode Fatal Test failed. got:%s, want:%s!", got, want)
+	}
+}
+
+func Benchmark(b *testing.B) {
+	log.SetOutput(io.Discard)
+	defer log.SetOutput(os.Stderr)
+	benchs := map[string]time.Duration{
+		"Waiter": 0,
+		"Pooler": 10 * time.Millisecond,
+	}
+	for name, interval := range benchs {
+		b.Run(name, func(b *testing.B) {
+			w := diode.NewWriter(io.Discard, 100000, interval, nil)
+			log := zerolog.New(w)
+			defer w.Close()
+
+			b.SetParallelism(1000)
+			b.RunParallel(func(pb *testing.PB) {
+				for pb.Next() {
+					log.Print("test")
+				}
+			})
+		})
+	}
+}

diode/internal/diodes/README

@@ -0,0 +1 @@
+Copied from https://github.com/cloudfoundry/go-diodes to avoid test dependencies.

diode/internal/diodes/many_to_one.go

@@ -0,0 +1,130 @@
+package diodes
+
+import (
+	"log"
+	"sync/atomic"
+	"unsafe"
+)
+
+// ManyToOne diode is optimal for many writers (go-routines B-n) and a single
+// reader (go-routine A). It is not thread safe for multiple readers.
+type ManyToOne struct {
+	writeIndex uint64
+	readIndex  uint64
+	buffer     []unsafe.Pointer
+	alerter    Alerter
+}
+
+// NewManyToOne creates a new diode (ring buffer). The ManyToOne diode
+// is optimized for many writers (on go-routines B-n) and a single reader
+// (on go-routine A). The alerter is invoked on the read's go-routine. It is
+// called when it notices that the writer go-routine has passed it and wrote
+// over data. A nil can be used to ignore alerts.
+func NewManyToOne(size int, alerter Alerter) *ManyToOne {
+	if alerter == nil {
+		alerter = AlertFunc(func(int) {})
+	}
+
+	d := &ManyToOne{
+		buffer:  make([]unsafe.Pointer, size),
+		alerter: alerter,
+	}
+
+	// Start write index at the value before 0
+	// to allow the first write to use AddUint64
+	// and still have a beginning index of 0
+	d.writeIndex = ^d.writeIndex
+	return d
+}
+
+// Set sets the data in the next slot of the ring buffer.
+func (d *ManyToOne) Set(data GenericDataType) {
+	for {
+		writeIndex := atomic.AddUint64(&d.writeIndex, 1)
+		idx := writeIndex % uint64(len(d.buffer))
+		old := atomic.LoadPointer(&d.buffer[idx])
+
+		if old != nil &&
+			(*bucket)(old) != nil &&
+			(*bucket)(old).seq > writeIndex-uint64(len(d.buffer)) {
+			log.Println("Diode set collision: consider using a larger diode")
+			continue
+		}
+
+		newBucket := &bucket{
+			data: data,
+			seq:  writeIndex,
+		}
+
+		if !atomic.CompareAndSwapPointer(&d.buffer[idx], old, unsafe.Pointer(newBucket)) {
+			log.Println("Diode set collision: consider using a larger diode")
+			continue
+		}
+
+		return
+	}
+}
+
+// TryNext will attempt to read from the next slot of the ring buffer.
+// If there is no data available, it will return (nil, false).
+func (d *ManyToOne) TryNext() (data GenericDataType, ok bool) {
+	// Read a value from the ring buffer based on the readIndex.
+	idx := d.readIndex % uint64(len(d.buffer))
+	result := (*bucket)(atomic.SwapPointer(&d.buffer[idx], nil))
+
+	// When the result is nil that means the writer has not had the
+	// opportunity to write a value into the diode. This value must be ignored
+	// and the read head must not increment.
+	if result == nil {
+		return nil, false
+	}
+
+	// When the seq value is less than the current read index that means a
+	// value was read from idx that was previously written but since has
+	// been dropped. This value must be ignored and the read head must not
+	// increment.
+	//
+	// The simulation for this scenario assumes the fast forward occurred as
+	// detailed below.
+	//
+	// 5. The reader reads again getting seq 5. It then reads again expecting
+	//    seq 6 but gets seq 2. This is a read of a stale value that was
+	//    effectively "dropped" so the read fails and the read head stays put.
+	//    `| 4 | 5 | 2 | 3 |` r: 7, w: 6
+	//
+	if result.seq < d.readIndex {
+		return nil, false
+	}
+
+	// When the seq value is greater than the current read index that means a
+	// value was read from idx that overwrote the value that was expected to
+	// be at this idx. This happens when the writer has lapped the reader. The
+	// reader needs to catch up to the writer so it moves its write head to
+	// the new seq, effectively dropping the messages that were not read in
+	// between the two values.
+	//
+	// Here is a simulation of this scenario:
+	//
+	// 1. Both the read and write heads start at 0.
+	//    `| nil | nil | nil | nil |` r: 0, w: 0
+	// 2. The writer fills the buffer.
+	//    `| 0 | 1 | 2 | 3 |` r: 0, w: 4
+	// 3. The writer laps the read head.
+	//    `| 4 | 5 | 2 | 3 |` r: 0, w: 6
+	// 4. The reader reads the first value, expecting a seq of 0 but reads 4,
+	//    this forces the reader to fast forward to 5.
+	//    `| 4 | 5 | 2 | 3 |` r: 5, w: 6
+	//
+	if result.seq > d.readIndex {
+		dropped := result.seq - d.readIndex
+		d.readIndex = result.seq
+		d.alerter.Alert(int(dropped))
+	}
+
+	// Only increment read index if a regular read occurred (where seq was
+	// equal to readIndex) or a value was read that caused a fast forward
+	// (where seq was greater than readIndex).
+	//
+	d.readIndex++
+	return result.data, true
+}

diode/internal/diodes/one_to_one.go

@@ -0,0 +1,129 @@
+package diodes
+
+import (
+	"sync/atomic"
+	"unsafe"
+)
+
+// GenericDataType is the data type the diodes operate on.
+type GenericDataType unsafe.Pointer
+
+// Alerter is used to report how many values were overwritten since the
+// last write.
+type Alerter interface {
+	Alert(missed int)
+}
+
+// AlertFunc type is an adapter to allow the use of ordinary functions as
+// Alert handlers.
+type AlertFunc func(missed int)
+
+// Alert calls f(missed)
+func (f AlertFunc) Alert(missed int) {
+	f(missed)
+}
+
+type bucket struct {
+	data GenericDataType
+	seq  uint64 // seq is the recorded write index at the time of writing
+}
+
+// OneToOne diode is meant to be used by a single reader and a single writer.
+// It is not thread safe if used otherwise.
+type OneToOne struct {
+	writeIndex uint64
+	readIndex  uint64
+	buffer     []unsafe.Pointer
+	alerter    Alerter
+}
+
+// NewOneToOne creates a new diode is meant to be used by a single reader and
+// a single writer. The alerter is invoked on the read's go-routine. It is
+// called when it notices that the writer go-routine has passed it and wrote
+// over data. A nil can be used to ignore alerts.
+func NewOneToOne(size int, alerter Alerter) *OneToOne {
+	if alerter == nil {
+		alerter = AlertFunc(func(int) {})
+	}
+
+	return &OneToOne{
+		buffer:  make([]unsafe.Pointer, size),
+		alerter: alerter,
+	}
+}
+
+// Set sets the data in the next slot of the ring buffer.
+func (d *OneToOne) Set(data GenericDataType) {
+	idx := d.writeIndex % uint64(len(d.buffer))
+
+	newBucket := &bucket{
+		data: data,
+		seq:  d.writeIndex,
+	}
+	d.writeIndex++
+
+	atomic.StorePointer(&d.buffer[idx], unsafe.Pointer(newBucket))
+}
+
+// TryNext will attempt to read from the next slot of the ring buffer.
+// If there is no data available, it will return (nil, false).
+func (d *OneToOne) TryNext() (data GenericDataType, ok bool) {
+	// Read a value from the ring buffer based on the readIndex.
+	idx := d.readIndex % uint64(len(d.buffer))
+	result := (*bucket)(atomic.SwapPointer(&d.buffer[idx], nil))
+
+	// When the result is nil that means the writer has not had the
+	// opportunity to write a value into the diode. This value must be ignored
+	// and the read head must not increment.
+	if result == nil {
+		return nil, false
+	}
+
+	// When the seq value is less than the current read index that means a
+	// value was read from idx that was previously written but since has
+	// been dropped. This value must be ignored and the read head must not
+	// increment.
+	//
+	// The simulation for this scenario assumes the fast forward occurred as
+	// detailed below.
+	//
+	// 5. The reader reads again getting seq 5. It then reads again expecting
+	//    seq 6 but gets seq 2. This is a read of a stale value that was
+	//    effectively "dropped" so the read fails and the read head stays put.
+	//    `| 4 | 5 | 2 | 3 |` r: 7, w: 6
+	//
+	if result.seq < d.readIndex {
+		return nil, false
+	}
+
+	// When the seq value is greater than the current read index that means a
+	// value was read from idx that overwrote the value that was expected to
+	// be at this idx. This happens when the writer has lapped the reader. The
+	// reader needs to catch up to the writer so it moves its write head to
+	// the new seq, effectively dropping the messages that were not read in
+	// between the two values.
+	//
+	// Here is a simulation of this scenario:
+	//
+	// 1. Both the read and write heads start at 0.
+	//    `| nil | nil | nil | nil |` r: 0, w: 0
+	// 2. The writer fills the buffer.
+	//    `| 0 | 1 | 2 | 3 |` r: 0, w: 4
+	// 3. The writer laps the read head.
+	//    `| 4 | 5 | 2 | 3 |` r: 0, w: 6
+	// 4. The reader reads the first value, expecting a seq of 0 but reads 4,
+	//    this forces the reader to fast forward to 5.
+	//    `| 4 | 5 | 2 | 3 |` r: 5, w: 6
+	//
+	if result.seq > d.readIndex {
+		dropped := result.seq - d.readIndex
+		d.readIndex = result.seq
+		d.alerter.Alert(int(dropped))
+	}
+
+	// Only increment read index if a regular read occurred (where seq was
+	// equal to readIndex) or a value was read that caused a fast forward
+	// (where seq was greater than readIndex).
+	d.readIndex++
+	return result.data, true
+}

diode/internal/diodes/poller.go

@@ -0,0 +1,80 @@
+package diodes
+
+import (
+	"context"
+	"time"
+)
+
+// Diode is any implementation of a diode.
+type Diode interface {
+	Set(GenericDataType)
+	TryNext() (GenericDataType, bool)
+}
+
+// Poller will poll a diode until a value is available.
+type Poller struct {
+	Diode
+	interval time.Duration
+	ctx      context.Context
+}
+
+// PollerConfigOption can be used to setup the poller.
+type PollerConfigOption func(*Poller)
+
+// WithPollingInterval sets the interval at which the diode is queried
+// for new data. The default is 10ms.
+func WithPollingInterval(interval time.Duration) PollerConfigOption {
+	return func(c *Poller) {
+		c.interval = interval
+	}
+}
+
+// WithPollingContext sets the context to cancel any retrieval (Next()). It
+// will not change any results for adding data (Set()). Default is
+// context.Background().
+func WithPollingContext(ctx context.Context) PollerConfigOption {
+	return func(c *Poller) {
+		c.ctx = ctx
+	}
+}
+
+// NewPoller returns a new Poller that wraps the given diode.
+func NewPoller(d Diode, opts ...PollerConfigOption) *Poller {
+	p := &Poller{
+		Diode:    d,
+		interval: 10 * time.Millisecond,
+		ctx:      context.Background(),
+	}
+
+	for _, o := range opts {
+		o(p)
+	}
+
+	return p
+}
+
+// Next polls the diode until data is available or until the context is done.
+// If the context is done, then nil will be returned.
+func (p *Poller) Next() GenericDataType {
+	for {
+		data, ok := p.Diode.TryNext()
+		if !ok {
+			if p.isDone() {
+				return nil
+			}
+
+			time.Sleep(p.interval)
+			continue
+		}
+		return data
+	}
+}
+
+func (p *Poller) isDone() bool {
+	select {
+	case <-p.ctx.Done():
+		return true
+	default:
+		return false
+	}
+}

diode/internal/diodes/waiter.go

@@ -0,0 +1,88 @@
+package diodes
+
+import (
+	"context"
+	"sync"
+)
+
+// Waiter will use a conditional mutex to alert the reader to when data is
+// available.
+type Waiter struct {
+	Diode
+	mu  sync.Mutex
+	c   *sync.Cond
+	ctx context.Context
+}
+
+// WaiterConfigOption can be used to setup the waiter.
+type WaiterConfigOption func(*Waiter)
+
+// WithWaiterContext sets the context to cancel any retrieval (Next()). It
+// will not change any results for adding data (Set()). Default is
+// context.Background().
+func WithWaiterContext(ctx context.Context) WaiterConfigOption {
+	return func(c *Waiter) {
+		c.ctx = ctx
+	}
+}
+
+// NewWaiter returns a new Waiter that wraps the given diode.
+func NewWaiter(d Diode, opts ...WaiterConfigOption) *Waiter {
+	w := new(Waiter)
+	w.Diode = d
+	w.c = sync.NewCond(&w.mu)
+	w.ctx = context.Background()
+
+	for _, opt := range opts {
+		opt(w)
+	}
+
+	go func() {
+		<-w.ctx.Done()
+
+		// Mutex is strictly necessary here to avoid a race in Next() (between
+		// w.isDone() and w.c.Wait()) and w.c.Broadcast() here.
+		w.mu.Lock()
+		w.c.Broadcast()
+		w.mu.Unlock()
+	}()
+
+	return w
+}
+
+// Set invokes the wrapped diode's Set with the given data and uses Broadcast
+// to wake up any readers.
+func (w *Waiter) Set(data GenericDataType) {
+	w.Diode.Set(data)
+	w.c.Broadcast()
+}
+
+// Next returns the next data point on the wrapped diode. If there is not any
+// new data, it will Wait for set to be called or the context to be done.
+// If the context is done, then nil will be returned.
+func (w *Waiter) Next() GenericDataType {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+
+	for {
+		data, ok := w.Diode.TryNext()
+		if !ok {
+			if w.isDone() {
+				return nil
+			}
+
+			w.c.Wait()
+			continue
+		}
+		return data
+	}
+}
+
+func (w *Waiter) isDone() bool {
+	select {
+	case <-w.ctx.Done():
+		return true
+	default:
+		return false
+	}
+}

encoder.go

@@ -0,0 +1,56 @@
+package zerolog
+
+import (
+	"net"
+	"time"
+)
+
+type encoder interface {
+	AppendArrayDelim(dst []byte) []byte
+	AppendArrayEnd(dst []byte) []byte
+	AppendArrayStart(dst []byte) []byte
+	AppendBeginMarker(dst []byte) []byte
+	AppendBool(dst []byte, val bool) []byte
+	AppendBools(dst []byte, vals []bool) []byte
+	AppendBytes(dst, s []byte) []byte
+	AppendDuration(dst []byte, d time.Duration, unit time.Duration, useInt bool, precision int) []byte
+	AppendDurations(dst []byte, vals []time.Duration, unit time.Duration, useInt bool, precision int) []byte
+	AppendEndMarker(dst []byte) []byte
+	AppendFloat32(dst []byte, val float32, precision int) []byte
+	AppendFloat64(dst []byte, val float64, precision int) []byte
+	AppendFloats32(dst []byte, vals []float32, precision int) []byte
+	AppendFloats64(dst []byte, vals []float64, precision int) []byte
+	AppendHex(dst, s []byte) []byte
+	AppendIPAddr(dst []byte, ip net.IP) []byte
+	AppendIPPrefix(dst []byte, pfx net.IPNet) []byte
+	AppendInt(dst []byte, val int) []byte
+	AppendInt16(dst []byte, val int16) []byte
+	AppendInt32(dst []byte, val int32) []byte
+	AppendInt64(dst []byte, val int64) []byte
+	AppendInt8(dst []byte, val int8) []byte
+	AppendInterface(dst []byte, i interface{}) []byte
+	AppendInts(dst []byte, vals []int) []byte
+	AppendInts16(dst []byte, vals []int16) []byte
+	AppendInts32(dst []byte, vals []int32) []byte
+	AppendInts64(dst []byte, vals []int64) []byte
+	AppendInts8(dst []byte, vals []int8) []byte
+	AppendKey(dst []byte, key string) []byte
+	AppendLineBreak(dst []byte) []byte
+	AppendMACAddr(dst []byte, ha net.HardwareAddr) []byte
+	AppendNil(dst []byte) []byte
+	AppendObjectData(dst []byte, o []byte) []byte
+	AppendString(dst []byte, s string) []byte
+	AppendStrings(dst []byte, vals []string) []byte
+	AppendTime(dst []byte, t time.Time, format string) []byte
+	AppendTimes(dst []byte, vals []time.Time, format string) []byte
+	AppendUint(dst []byte, val uint) []byte
+	AppendUint16(dst []byte, val uint16) []byte
+	AppendUint32(dst []byte, val uint32) []byte
+	AppendUint64(dst []byte, val uint64) []byte
+	AppendUint8(dst []byte, val uint8) []byte
+	AppendUints(dst []byte, vals []uint) []byte
+	AppendUints16(dst []byte, vals []uint16) []byte
+	AppendUints32(dst []byte, vals []uint32) []byte
+	AppendUints64(dst []byte, vals []uint64) []byte
+	AppendUints8(dst []byte, vals []uint8) []byte
+}

encoder_cbor.go

@@ -0,0 +1,45 @@
+// +build binary_log
+
+package zerolog
+
+// This file contains bindings to do binary encoding.
+
+import (
+	"github.com/rs/zerolog/internal/cbor"
+)
+
+var (
+	_ encoder = (*cbor.Encoder)(nil)
+
+	enc = cbor.Encoder{}
+)
+
+func init() {
+	// using closure to reflect the changes at runtime.
+	cbor.JSONMarshalFunc = func(v interface{}) ([]byte, error) {
+		return InterfaceMarshalFunc(v)
+	}
+}
+
+func appendJSON(dst []byte, j []byte) []byte {
+	return cbor.AppendEmbeddedJSON(dst, j)
+}
+func appendCBOR(dst []byte, c []byte) []byte {
+	return cbor.AppendEmbeddedCBOR(dst, c)
+}
+
+// decodeIfBinaryToString - converts a binary formatted log msg to a
+// JSON formatted String Log message.
+func decodeIfBinaryToString(in []byte) string {
+	return cbor.DecodeIfBinaryToString(in)
+}
+
+func decodeObjectToStr(in []byte) string {
+	return cbor.DecodeObjectToStr(in)
+}
+
+// decodeIfBinaryToBytes - converts a binary formatted log msg to a
+// JSON formatted Bytes Log message.
+func decodeIfBinaryToBytes(in []byte) []byte {
+	return cbor.DecodeIfBinaryToBytes(in)
+}

encoder_json.go

@@ -0,0 +1,51 @@
+// +build !binary_log
+
+package zerolog
+
+// encoder_json.go file contains bindings to generate
+// JSON encoded byte stream.
+
+import (
+	"encoding/base64"
+	"github.com/rs/zerolog/internal/json"
+)
+
+var (
+	_ encoder = (*json.Encoder)(nil)
+
+	enc = json.Encoder{}
+)
+
+func init() {
+	// using closure to reflect the changes at runtime.
+	json.JSONMarshalFunc = func(v interface{}) ([]byte, error) {
+		return InterfaceMarshalFunc(v)
+	}
+}
+
+func appendJSON(dst []byte, j []byte) []byte {
+	return append(dst, j...)
+}
+func appendCBOR(dst []byte, cbor []byte) []byte {
+	dst = append(dst, []byte("\"data:application/cbor;base64,")...)
+	l := len(dst)
+	enc := base64.StdEncoding
+	n := enc.EncodedLen(len(cbor))
+	for i := 0; i < n; i++ {
+		dst = append(dst, '.')
+	}
+	enc.Encode(dst[l:], cbor)
+	return append(dst, '"')
+}
+
+func decodeIfBinaryToString(in []byte) string {
+	return string(in)
+}
+
+func decodeObjectToStr(in []byte) string {
+	return string(in)
+}
+
+func decodeIfBinaryToBytes(in []byte) []byte {
+	return in
+}

event.go

@@ -1,13 +1,13 @@
 package zerolog
 
 import (
+	"context"
 	"fmt"
-	"io/ioutil"
+	"net"
 	"os"
+	"runtime"
 	"sync"
 	"time"
-
-	"github.com/rs/zerolog/internal/json"
 )
 
 var eventPool = &sync.Pool{
@@ -21,11 +21,28 @@ var eventPool = &sync.Pool{
 // Event represents a log event. It is instanced by one of the level method of
 // Logger and finalized by the Msg or Msgf method.
 type Event struct {
-	buf     []byte
-	w       LevelWriter
-	level   Level
-	enabled bool
-	done    func(msg string)
+	buf       []byte
+	w         LevelWriter
+	level     Level
+	done      func(msg string)
+	stack     bool            // enable error stack trace
+	ch        []Hook          // hooks from context
+	skipFrame int             // The number of additional frames to skip when printing the caller.
+	ctx       context.Context // Optional Go context for event
+}
+
+func putEvent(e *Event) {
+	// Proper usage of a sync.Pool requires each entry to have approximately
+	// the same memory cost. To obtain this property when the stored type
+	// contains a variably-sized buffer, we add a hard limit on the maximum buffer
+	// to place back in the pool.
+	//
+	// See https://golang.org/issue/23199
+	const maxSize = 1 << 16 // 64KiB
+	if cap(e.buf) > maxSize {
+		return
+	}
+	eventPool.Put(e)
 }
 
 // LogObjectMarshaler provides a strongly-typed and encoding-agnostic interface
@@ -40,33 +57,46 @@ type LogArrayMarshaler interface {
 	MarshalZerologArray(a *Array)
 }
 
-func newEvent(w LevelWriter, level Level, enabled bool) *Event {
-	if !enabled {
-		return &Event{}
-	}
+func newEvent(w LevelWriter, level Level) *Event {
 	e := eventPool.Get().(*Event)
-	e.buf = e.buf[:1]
-	e.buf[0] = '{'
+	e.buf = e.buf[:0]
+	e.ch = nil
+	e.buf = enc.AppendBeginMarker(e.buf)
 	e.w = w
 	e.level = level
-	e.enabled = true
+	e.stack = false
+	e.skipFrame = 0
 	return e
 }
 
 func (e *Event) write() (err error) {
-	if !e.enabled {
+	if e == nil {
 		return nil
 	}
-	e.buf = append(e.buf, '}', '\n')
-	_, err = e.w.WriteLevel(e.level, e.buf)
-	eventPool.Put(e)
+	if e.level != Disabled {
+		e.buf = enc.AppendEndMarker(e.buf)
+		e.buf = enc.AppendLineBreak(e.buf)
+		if e.w != nil {
+			_, err = e.w.WriteLevel(e.level, e.buf)
+		}
+	}
+	putEvent(e)
 	return
 }
 
 // Enabled return false if the *Event is going to be filtered out by
 // log level or sampling.
 func (e *Event) Enabled() bool {
-	return e.enabled
+	return e != nil && e.level != Disabled
+}
+
+// Discard disables the event so Msg(f) won't print it.
+func (e *Event) Discard() *Event {
+	if e == nil {
+		return e
+	}
+	e.level = Disabled
+	return nil
 }
 
 // Msg sends the *Event with msg added as the message field if not empty.
@@ -74,57 +104,79 @@ func (e *Event) Enabled() bool {
 // NOTICE: once this method is called, the *Event should be disposed.
 // Calling Msg twice can have unexpected result.
 func (e *Event) Msg(msg string) {
-	if !e.enabled {
+	if e == nil {
 		return
 	}
-	if msg != "" {
-		e.buf = json.AppendString(json.AppendKey(e.buf, MessageFieldName), msg)
-	}
-	if e.done != nil {
-		defer e.done(msg)
-	}
-	if err := e.write(); err != nil {
-		fmt.Fprintf(os.Stderr, "zerolog: could not write event: %v", err)
-	}
+	e.msg(msg)
 }
 
-// Msgf sends the event with formated msg added as the message field if not empty.
+// Send is equivalent to calling Msg("").
 //
-// NOTICE: once this methid is called, the *Event should be disposed.
-// Calling Msg twice can have unexpected result.
-func (e *Event) Msgf(format string, v ...interface{}) {
-	if !e.enabled {
+// NOTICE: once this method is called, the *Event should be disposed.
+func (e *Event) Send() {
+	if e == nil {
 		return
 	}
-	msg := fmt.Sprintf(format, v...)
+	e.msg("")
+}
+
+// Msgf sends the event with formatted msg added as the message field if not empty.
+//
+// NOTICE: once this method is called, the *Event should be disposed.
+// Calling Msgf twice can have unexpected result.
+func (e *Event) Msgf(format string, v ...interface{}) {
+	if e == nil {
+		return
+	}
+	e.msg(fmt.Sprintf(format, v...))
+}
+
+func (e *Event) MsgFunc(createMsg func() string) {
+	if e == nil {
+		return
+	}
+	e.msg(createMsg())
+}
+
+func (e *Event) msg(msg string) {
+	for _, hook := range e.ch {
+		hook.Run(e, e.level, msg)
+	}
 	if msg != "" {
-		e.buf = json.AppendString(json.AppendKey(e.buf, MessageFieldName), msg)
+		e.buf = enc.AppendString(enc.AppendKey(e.buf, MessageFieldName), msg)
 	}
 	if e.done != nil {
 		defer e.done(msg)
 	}
 	if err := e.write(); err != nil {
-		fmt.Fprintf(os.Stderr, "zerolog: could not write event: %v", err)
+		if ErrorHandler != nil {
+			ErrorHandler(err)
+		} else {
+			fmt.Fprintf(os.Stderr, "zerolog: could not write event: %v\n", err)
+		}
 	}
 }
 
-// Fields is a helper function to use a map to set fields using type assertion.
-func (e *Event) Fields(fields map[string]interface{}) *Event {
-	if !e.enabled {
+// Fields is a helper function to use a map or slice to set fields using type assertion.
+// Only map[string]interface{} and []interface{} are accepted. []interface{} must
+// alternate string keys and arbitrary values, and extraneous ones are ignored.
+func (e *Event) Fields(fields interface{}) *Event {
+	if e == nil {
 		return e
 	}
-	e.buf = appendFields(e.buf, fields)
+	e.buf = appendFields(e.buf, fields, e.stack)
 	return e
 }
 
 // Dict adds the field key with a dict to the event context.
 // Use zerolog.Dict() to create the dictionary.
 func (e *Event) Dict(key string, dict *Event) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = append(append(json.AppendKey(e.buf, key), dict.buf...), '}')
-	eventPool.Put(dict)
+	dict.buf = enc.AppendEndMarker(dict.buf)
+	e.buf = append(enc.AppendKey(e.buf, key), dict.buf...)
+	putEvent(dict)
 	return e
 }
 
@@ -132,17 +184,17 @@ func (e *Event) Dict(key string, dict *Event) *Event {
 // Call usual field methods like Str, Int etc to add fields to this
 // event and give it as argument the *Event.Dict method.
 func Dict() *Event {
-	return newEvent(levelWriterAdapter{ioutil.Discard}, 0, true)
+	return newEvent(nil, 0)
 }
 
 // Array adds the field key with an array to the event context.
 // Use zerolog.Arr() to create the array or pass a type that
 // implement the LogArrayMarshaler interface.
 func (e *Event) Array(key string, arr LogArrayMarshaler) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendKey(e.buf, key)
+	e.buf = enc.AppendKey(e.buf, key)
 	var a *Array
 	if aa, ok := arr.(*Array); ok {
 		a = aa
@@ -155,44 +207,83 @@ func (e *Event) Array(key string, arr LogArrayMarshaler) *Event {
 }
 
 func (e *Event) appendObject(obj LogObjectMarshaler) {
-	pos := len(e.buf)
+	e.buf = enc.AppendBeginMarker(e.buf)
 	obj.MarshalZerologObject(e)
-	if pos < len(e.buf) {
-		// As MarshalZerologObject will use event API, the first field will be
-		// preceded by a comma. If at least one field has been added (buf grew),
-		// we replace this coma by the opening bracket.
-		e.buf[pos] = '{'
-	} else {
-		e.buf = append(e.buf, '{')
-	}
-	e.buf = append(e.buf, '}')
+	e.buf = enc.AppendEndMarker(e.buf)
 }
 
 // Object marshals an object that implement the LogObjectMarshaler interface.
 func (e *Event) Object(key string, obj LogObjectMarshaler) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendKey(e.buf, key)
+	e.buf = enc.AppendKey(e.buf, key)
+	if obj == nil {
+		e.buf = enc.AppendNil(e.buf)
+
+		return e
+	}
+
 	e.appendObject(obj)
 	return e
 }
 
+// Func allows an anonymous func to run only if the event is enabled.
+func (e *Event) Func(f func(e *Event)) *Event {
+	if e != nil && e.Enabled() {
+		f(e)
+	}
+	return e
+}
+
+// EmbedObject marshals an object that implement the LogObjectMarshaler interface.
+func (e *Event) EmbedObject(obj LogObjectMarshaler) *Event {
+	if e == nil {
+		return e
+	}
+	if obj == nil {
+		return e
+	}
+	obj.MarshalZerologObject(e)
+	return e
+}
+
 // Str adds the field key with val as a string to the *Event context.
 func (e *Event) Str(key, val string) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendString(json.AppendKey(e.buf, key), val)
+	e.buf = enc.AppendString(enc.AppendKey(e.buf, key), val)
 	return e
 }
 
 // Strs adds the field key with vals as a []string to the *Event context.
 func (e *Event) Strs(key string, vals []string) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendStrings(json.AppendKey(e.buf, key), vals)
+	e.buf = enc.AppendStrings(enc.AppendKey(e.buf, key), vals)
+	return e
+}
+
+// Stringer adds the field key with val.String() (or null if val is nil)
+// to the *Event context.
+func (e *Event) Stringer(key string, val fmt.Stringer) *Event {
+	if e == nil {
+		return e
+	}
+	e.buf = enc.AppendStringer(enc.AppendKey(e.buf, key), val)
+	return e
+}
+
+// Stringers adds the field key with vals where each individual val
+// is used as val.String() (or null if val is empty) to the *Event
+// context.
+func (e *Event) Stringers(key string, vals []fmt.Stringer) *Event {
+	if e == nil {
+		return e
+	}
+	e.buf = enc.AppendStringers(enc.AppendKey(e.buf, key), vals)
 	return e
 }
 
@@ -201,307 +292,417 @@ func (e *Event) Strs(key string, vals []string) *Event {
 // Runes outside of normal ASCII ranges will be hex-encoded in the resulting
 // JSON.
 func (e *Event) Bytes(key string, val []byte) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendBytes(json.AppendKey(e.buf, key), val)
+	e.buf = enc.AppendBytes(enc.AppendKey(e.buf, key), val)
 	return e
 }
 
-// AnErr adds the field key with err as a string to the *Event context.
+// Hex adds the field key with val as a hex string to the *Event context.
+func (e *Event) Hex(key string, val []byte) *Event {
+	if e == nil {
+		return e
+	}
+	e.buf = enc.AppendHex(enc.AppendKey(e.buf, key), val)
+	return e
+}
+
+// RawJSON adds already encoded JSON to the log line under key.
+//
+// No sanity check is performed on b; it must not contain carriage returns and
+// be valid JSON.
+func (e *Event) RawJSON(key string, b []byte) *Event {
+	if e == nil {
+		return e
+	}
+	e.buf = appendJSON(enc.AppendKey(e.buf, key), b)
+	return e
+}
+
+// RawCBOR adds already encoded CBOR to the log line under key.
+//
+// No sanity check is performed on b
+// Note: The full featureset of CBOR is supported as data will not be mapped to json but stored as data-url
+func (e *Event) RawCBOR(key string, b []byte) *Event {
+	if e == nil {
+		return e
+	}
+	e.buf = appendCBOR(enc.AppendKey(e.buf, key), b)
+	return e
+}
+
+// AnErr adds the field key with serialized err to the *Event context.
 // If err is nil, no field is added.
 func (e *Event) AnErr(key string, err error) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	if err != nil {
-		e.buf = json.AppendError(json.AppendKey(e.buf, key), err)
+	switch m := ErrorMarshalFunc(err).(type) {
+	case nil:
+		return e
+	case LogObjectMarshaler:
+		return e.Object(key, m)
+	case error:
+		if m == nil || isNilValue(m) {
+			return e
+		} else {
+			return e.Str(key, m.Error())
+		}
+	case string:
+		return e.Str(key, m)
+	default:
+		return e.Interface(key, m)
 	}
-	return e
 }
 
-// Errs adds the field key with errs as an array of strings to the *Event context.
-// If err is nil, no field is added.
+// Errs adds the field key with errs as an array of serialized errors to the
+// *Event context.
 func (e *Event) Errs(key string, errs []error) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendErrors(json.AppendKey(e.buf, key), errs)
+	arr := Arr()
+	for _, err := range errs {
+		switch m := ErrorMarshalFunc(err).(type) {
+		case LogObjectMarshaler:
+			arr = arr.Object(m)
+		case error:
+			arr = arr.Err(m)
+		case string:
+			arr = arr.Str(m)
+		default:
+			arr = arr.Interface(m)
+		}
+	}
+
+	return e.Array(key, arr)
+}
+
+// Err adds the field "error" with serialized err to the *Event context.
+// If err is nil, no field is added.
+//
+// To customize the key name, change zerolog.ErrorFieldName.
+//
+// If Stack() has been called before and zerolog.ErrorStackMarshaler is defined,
+// the err is passed to ErrorStackMarshaler and the result is appended to the
+// zerolog.ErrorStackFieldName.
+func (e *Event) Err(err error) *Event {
+	if e == nil {
+		return e
+	}
+	if e.stack && ErrorStackMarshaler != nil {
+		switch m := ErrorStackMarshaler(err).(type) {
+		case nil:
+		case LogObjectMarshaler:
+			e.Object(ErrorStackFieldName, m)
+		case error:
+			if m != nil && !isNilValue(m) {
+				e.Str(ErrorStackFieldName, m.Error())
+			}
+		case string:
+			e.Str(ErrorStackFieldName, m)
+		default:
+			e.Interface(ErrorStackFieldName, m)
+		}
+	}
+	return e.AnErr(ErrorFieldName, err)
+}
+
+// Stack enables stack trace printing for the error passed to Err().
+//
+// ErrorStackMarshaler must be set for this method to do something.
+func (e *Event) Stack() *Event {
+	if e != nil {
+		e.stack = true
+	}
 	return e
 }
 
-// Err adds the field "error" with err as a string to the *Event context.
-// If err is nil, no field is added.
-// To customize the key name, change zerolog.ErrorFieldName.
-func (e *Event) Err(err error) *Event {
-	if !e.enabled {
-		return e
-	}
-	if err != nil {
-		e.buf = json.AppendError(json.AppendKey(e.buf, ErrorFieldName), err)
+// Ctx adds the Go Context to the *Event context.  The context is not rendered
+// in the output message, but is available to hooks and to Func() calls via the
+// GetCtx() accessor. A typical use case is to extract tracing information from
+// the Go Ctx.
+func (e *Event) Ctx(ctx context.Context) *Event {
+	if e != nil {
+		e.ctx = ctx
 	}
 	return e
 }
 
+// GetCtx retrieves the Go context.Context which is optionally stored in the
+// Event.  This allows Hooks and functions passed to Func() to retrieve values
+// which are stored in the context.Context.  This can be useful in tracing,
+// where span information is commonly propagated in the context.Context.
+func (e *Event) GetCtx() context.Context {
+	if e == nil || e.ctx == nil {
+		return context.Background()
+	}
+	return e.ctx
+}
+
 // Bool adds the field key with val as a bool to the *Event context.
 func (e *Event) Bool(key string, b bool) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendBool(json.AppendKey(e.buf, key), b)
+	e.buf = enc.AppendBool(enc.AppendKey(e.buf, key), b)
 	return e
 }
 
 // Bools adds the field key with val as a []bool to the *Event context.
 func (e *Event) Bools(key string, b []bool) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendBools(json.AppendKey(e.buf, key), b)
+	e.buf = enc.AppendBools(enc.AppendKey(e.buf, key), b)
 	return e
 }
 
 // Int adds the field key with i as a int to the *Event context.
 func (e *Event) Int(key string, i int) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendInt(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInt(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Ints adds the field key with i as a []int to the *Event context.
 func (e *Event) Ints(key string, i []int) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendInts(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInts(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Int8 adds the field key with i as a int8 to the *Event context.
 func (e *Event) Int8(key string, i int8) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendInt8(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInt8(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Ints8 adds the field key with i as a []int8 to the *Event context.
 func (e *Event) Ints8(key string, i []int8) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendInts8(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInts8(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Int16 adds the field key with i as a int16 to the *Event context.
 func (e *Event) Int16(key string, i int16) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendInt16(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInt16(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Ints16 adds the field key with i as a []int16 to the *Event context.
 func (e *Event) Ints16(key string, i []int16) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendInts16(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInts16(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Int32 adds the field key with i as a int32 to the *Event context.
 func (e *Event) Int32(key string, i int32) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendInt32(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInt32(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Ints32 adds the field key with i as a []int32 to the *Event context.
 func (e *Event) Ints32(key string, i []int32) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendInts32(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInts32(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Int64 adds the field key with i as a int64 to the *Event context.
 func (e *Event) Int64(key string, i int64) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendInt64(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInt64(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Ints64 adds the field key with i as a []int64 to the *Event context.
 func (e *Event) Ints64(key string, i []int64) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendInts64(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInts64(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Uint adds the field key with i as a uint to the *Event context.
 func (e *Event) Uint(key string, i uint) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendUint(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendUint(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Uints adds the field key with i as a []int to the *Event context.
 func (e *Event) Uints(key string, i []uint) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendUints(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendUints(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Uint8 adds the field key with i as a uint8 to the *Event context.
 func (e *Event) Uint8(key string, i uint8) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendUint8(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendUint8(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Uints8 adds the field key with i as a []int8 to the *Event context.
 func (e *Event) Uints8(key string, i []uint8) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendUints8(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendUints8(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Uint16 adds the field key with i as a uint16 to the *Event context.
 func (e *Event) Uint16(key string, i uint16) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendUint16(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendUint16(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Uints16 adds the field key with i as a []int16 to the *Event context.
 func (e *Event) Uints16(key string, i []uint16) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendUints16(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendUints16(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Uint32 adds the field key with i as a uint32 to the *Event context.
 func (e *Event) Uint32(key string, i uint32) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendUint32(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendUint32(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Uints32 adds the field key with i as a []int32 to the *Event context.
 func (e *Event) Uints32(key string, i []uint32) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendUints32(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendUints32(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Uint64 adds the field key with i as a uint64 to the *Event context.
 func (e *Event) Uint64(key string, i uint64) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendUint64(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendUint64(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Uints64 adds the field key with i as a []int64 to the *Event context.
 func (e *Event) Uints64(key string, i []uint64) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendUints64(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendUints64(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Float32 adds the field key with f as a float32 to the *Event context.
 func (e *Event) Float32(key string, f float32) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendFloat32(json.AppendKey(e.buf, key), f)
+	e.buf = enc.AppendFloat32(enc.AppendKey(e.buf, key), f, FloatingPointPrecision)
 	return e
 }
 
 // Floats32 adds the field key with f as a []float32 to the *Event context.
 func (e *Event) Floats32(key string, f []float32) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendFloats32(json.AppendKey(e.buf, key), f)
+	e.buf = enc.AppendFloats32(enc.AppendKey(e.buf, key), f, FloatingPointPrecision)
 	return e
 }
 
 // Float64 adds the field key with f as a float64 to the *Event context.
 func (e *Event) Float64(key string, f float64) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendFloat64(json.AppendKey(e.buf, key), f)
+	e.buf = enc.AppendFloat64(enc.AppendKey(e.buf, key), f, FloatingPointPrecision)
 	return e
 }
 
 // Floats64 adds the field key with f as a []float64 to the *Event context.
 func (e *Event) Floats64(key string, f []float64) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendFloats64(json.AppendKey(e.buf, key), f)
+	e.buf = enc.AppendFloats64(enc.AppendKey(e.buf, key), f, FloatingPointPrecision)
 	return e
 }
 
 // Timestamp adds the current local time as UNIX timestamp to the *Event context with the "time" key.
 // To customize the key name, change zerolog.TimestampFieldName.
+//
+// NOTE: It won't dedupe the "time" key if the *Event (or *Context) has one
+// already.
 func (e *Event) Timestamp() *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendTime(json.AppendKey(e.buf, TimestampFieldName), TimestampFunc(), TimeFieldFormat)
+	e.buf = enc.AppendTime(enc.AppendKey(e.buf, TimestampFieldName), TimestampFunc(), TimeFieldFormat)
 	return e
 }
 
-// Time adds the field key with t formated as string using zerolog.TimeFieldFormat.
+// Time adds the field key with t formatted as string using zerolog.TimeFieldFormat.
 func (e *Event) Time(key string, t time.Time) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendTime(json.AppendKey(e.buf, key), t, TimeFieldFormat)
+	e.buf = enc.AppendTime(enc.AppendKey(e.buf, key), t, TimeFieldFormat)
 	return e
 }
 
-// Times adds the field key with t formated as string using zerolog.TimeFieldFormat.
+// Times adds the field key with t formatted as string using zerolog.TimeFieldFormat.
 func (e *Event) Times(key string, t []time.Time) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendTimes(json.AppendKey(e.buf, key), t, TimeFieldFormat)
+	e.buf = enc.AppendTimes(enc.AppendKey(e.buf, key), t, TimeFieldFormat)
 	return e
 }
 
@@ -509,10 +710,10 @@ func (e *Event) Times(key string, t []time.Time) *Event {
 // If zerolog.DurationFieldInteger is true, durations are rendered as integer
 // instead of float.
 func (e *Event) Dur(key string, d time.Duration) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendDuration(json.AppendKey(e.buf, key), d, DurationFieldUnit, DurationFieldInteger)
+	e.buf = enc.AppendDuration(enc.AppendKey(e.buf, key), d, DurationFieldUnit, DurationFieldInteger, FloatingPointPrecision)
 	return e
 }
 
@@ -520,10 +721,10 @@ func (e *Event) Dur(key string, d time.Duration) *Event {
 // If zerolog.DurationFieldInteger is true, durations are rendered as integer
 // instead of float.
 func (e *Event) Durs(key string, d []time.Duration) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendDurations(json.AppendKey(e.buf, key), d, DurationFieldUnit, DurationFieldInteger)
+	e.buf = enc.AppendDurations(enc.AppendKey(e.buf, key), d, DurationFieldUnit, DurationFieldInteger, FloatingPointPrecision)
 	return e
 }
 
@@ -531,25 +732,99 @@ func (e *Event) Durs(key string, d []time.Duration) *Event {
 // If time t is not greater than start, duration will be 0.
 // Duration format follows the same principle as Dur().
 func (e *Event) TimeDiff(key string, t time.Time, start time.Time) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
 	var d time.Duration
 	if t.After(start) {
 		d = t.Sub(start)
 	}
-	e.buf = json.AppendDuration(json.AppendKey(e.buf, key), d, DurationFieldUnit, DurationFieldInteger)
+	e.buf = enc.AppendDuration(enc.AppendKey(e.buf, key), d, DurationFieldUnit, DurationFieldInteger, FloatingPointPrecision)
 	return e
 }
 
+// Any is a wrapper around Event.Interface.
+func (e *Event) Any(key string, i interface{}) *Event {
+	return e.Interface(key, i)
+}
+
 // Interface adds the field key with i marshaled using reflection.
 func (e *Event) Interface(key string, i interface{}) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
 	if obj, ok := i.(LogObjectMarshaler); ok {
 		return e.Object(key, obj)
 	}
-	e.buf = json.AppendInterface(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInterface(enc.AppendKey(e.buf, key), i)
+	return e
+}
+
+// Type adds the field key with val's type using reflection.
+func (e *Event) Type(key string, val interface{}) *Event {
+	if e == nil {
+		return e
+	}
+	e.buf = enc.AppendType(enc.AppendKey(e.buf, key), val)
+	return e
+}
+
+// CallerSkipFrame instructs any future Caller calls to skip the specified number of frames.
+// This includes those added via hooks from the context.
+func (e *Event) CallerSkipFrame(skip int) *Event {
+	if e == nil {
+		return e
+	}
+	e.skipFrame += skip
+	return e
+}
+
+// Caller adds the file:line of the caller with the zerolog.CallerFieldName key.
+// The argument skip is the number of stack frames to ascend
+// Skip If not passed, use the global variable CallerSkipFrameCount
+func (e *Event) Caller(skip ...int) *Event {
+	sk := CallerSkipFrameCount
+	if len(skip) > 0 {
+		sk = skip[0] + CallerSkipFrameCount
+	}
+	return e.caller(sk)
+}
+
+func (e *Event) caller(skip int) *Event {
+	if e == nil {
+		return e
+	}
+	pc, file, line, ok := runtime.Caller(skip + e.skipFrame)
+	if !ok {
+		return e
+	}
+	e.buf = enc.AppendString(enc.AppendKey(e.buf, CallerFieldName), CallerMarshalFunc(pc, file, line))
+	return e
+}
+
+// IPAddr adds IPv4 or IPv6 Address to the event
+func (e *Event) IPAddr(key string, ip net.IP) *Event {
+	if e == nil {
+		return e
+	}
+	e.buf = enc.AppendIPAddr(enc.AppendKey(e.buf, key), ip)
+	return e
+}
+
+// IPPrefix adds IPv4 or IPv6 Prefix (address and mask) to the event
+func (e *Event) IPPrefix(key string, pfx net.IPNet) *Event {
+	if e == nil {
+		return e
+	}
+	e.buf = enc.AppendIPPrefix(enc.AppendKey(e.buf, key), pfx)
+	return e
+}
+
+// MACAddr adds MAC address to the event
+func (e *Event) MACAddr(key string, ha net.HardwareAddr) *Event {
+	if e == nil {
+		return e
+	}
+	e.buf = enc.AppendMACAddr(enc.AppendKey(e.buf, key), ha)
 	return e
 }

event_test.go

@@ -0,0 +1,65 @@
+// +build !binary_log
+
+package zerolog
+
+import (
+	"bytes"
+	"errors"
+	"strings"
+	"testing"
+)
+
+type nilError struct{}
+
+func (nilError) Error() string {
+	return ""
+}
+
+func TestEvent_AnErr(t *testing.T) {
+	tests := []struct {
+		name string
+		err  error
+		want string
+	}{
+		{"nil", nil, `{}`},
+		{"error", errors.New("test"), `{"err":"test"}`},
+		{"nil interface", func() *nilError { return nil }(), `{}`},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var buf bytes.Buffer
+			e := newEvent(LevelWriterAdapter{&buf}, DebugLevel)
+			e.AnErr("err", tt.err)
+			_ = e.write()
+			if got, want := strings.TrimSpace(buf.String()), tt.want; got != want {
+				t.Errorf("Event.AnErr() = %v, want %v", got, want)
+			}
+		})
+	}
+}
+
+func TestEvent_ObjectWithNil(t *testing.T) {
+	var buf bytes.Buffer
+	e := newEvent(LevelWriterAdapter{&buf}, DebugLevel)
+	_ = e.Object("obj", nil)
+	_ = e.write()
+
+	want := `{"obj":null}`
+	got := strings.TrimSpace(buf.String())
+	if got != want {
+		t.Errorf("Event.Object() = %q, want %q", got, want)
+	}
+}
+
+func TestEvent_EmbedObjectWithNil(t *testing.T) {
+	var buf bytes.Buffer
+	e := newEvent(LevelWriterAdapter{&buf}, DebugLevel)
+	_ = e.EmbedObject(nil)
+	_ = e.write()
+
+	want := "{}"
+	got := strings.TrimSpace(buf.String())
+	if got != want {
+		t.Errorf("Event.EmbedObject() = %q, want %q", got, want)
+	}
+}

example.jsonl

@@ -0,0 +1,7 @@
+{"time":"5:41PM","level":"info","message":"Starting listener","listen":":8080","pid":37556}
+{"time":"5:41PM","level":"debug","message":"Access","database":"myapp","host":"localhost:4962","pid":37556}
+{"time":"5:41PM","level":"info","message":"Access","method":"GET","path":"/users","pid":37556,"resp_time":23}
+{"time":"5:41PM","level":"info","message":"Access","method":"POST","path":"/posts","pid":37556,"resp_time":532}
+{"time":"5:41PM","level":"warn","message":"Slow request","method":"POST","path":"/posts","pid":37556,"resp_time":532}
+{"time":"5:41PM","level":"info","message":"Access","method":"GET","path":"/users","pid":37556,"resp_time":10}
+{"time":"5:41PM","level":"error","message":"Database connection lost","database":"myapp","pid":37556,"error":"connection reset by peer"}

fields.go

@@ -1,95 +1,291 @@
 package zerolog
 
 import (
+	"encoding/json"
+	"net"
 	"sort"
 	"time"
-
-	"github.com/rs/zerolog/internal/json"
+	"unsafe"
 )
 
-func appendFields(dst []byte, fields map[string]interface{}) []byte {
-	keys := make([]string, 0, len(fields))
-	for key := range fields {
-		keys = append(keys, key)
-	}
-	sort.Strings(keys)
-	for _, key := range keys {
-		dst = json.AppendKey(dst, key)
-		switch val := fields[key].(type) {
-		case string:
-			dst = json.AppendString(dst, val)
-		case []byte:
-			dst = json.AppendBytes(dst, val)
-		case error:
-			dst = json.AppendError(dst, val)
-		case []error:
-			dst = json.AppendErrors(dst, val)
-		case bool:
-			dst = json.AppendBool(dst, val)
-		case int:
-			dst = json.AppendInt(dst, val)
-		case int8:
-			dst = json.AppendInt8(dst, val)
-		case int16:
-			dst = json.AppendInt16(dst, val)
-		case int32:
-			dst = json.AppendInt32(dst, val)
-		case int64:
-			dst = json.AppendInt64(dst, val)
-		case uint:
-			dst = json.AppendUint(dst, val)
-		case uint8:
-			dst = json.AppendUint8(dst, val)
-		case uint16:
-			dst = json.AppendUint16(dst, val)
-		case uint32:
-			dst = json.AppendUint32(dst, val)
-		case uint64:
-			dst = json.AppendUint64(dst, val)
-		case float32:
-			dst = json.AppendFloat32(dst, val)
-		case float64:
-			dst = json.AppendFloat64(dst, val)
-		case time.Time:
-			dst = json.AppendTime(dst, val, TimeFieldFormat)
-		case time.Duration:
-			dst = json.AppendDuration(dst, val, DurationFieldUnit, DurationFieldInteger)
-		case []string:
-			dst = json.AppendStrings(dst, val)
-		case []bool:
-			dst = json.AppendBools(dst, val)
-		case []int:
-			dst = json.AppendInts(dst, val)
-		case []int8:
-			dst = json.AppendInts8(dst, val)
-		case []int16:
-			dst = json.AppendInts16(dst, val)
-		case []int32:
-			dst = json.AppendInts32(dst, val)
-		case []int64:
-			dst = json.AppendInts64(dst, val)
-		case []uint:
-			dst = json.AppendUints(dst, val)
-		// case []uint8:
-		// 	dst = appendUints8(dst, val)
-		case []uint16:
-			dst = json.AppendUints16(dst, val)
-		case []uint32:
-			dst = json.AppendUints32(dst, val)
-		case []uint64:
-			dst = json.AppendUints64(dst, val)
-		case []float32:
-			dst = json.AppendFloats32(dst, val)
-		case []float64:
-			dst = json.AppendFloats64(dst, val)
-		case []time.Time:
-			dst = json.AppendTimes(dst, val, TimeFieldFormat)
-		case []time.Duration:
-			dst = json.AppendDurations(dst, val, DurationFieldUnit, DurationFieldInteger)
-		case nil:
-			dst = append(dst, "null"...)
-		default:
-			dst = json.AppendInterface(dst, val)
+func isNilValue(i interface{}) bool {
+	return (*[2]uintptr)(unsafe.Pointer(&i))[1] == 0
+}
+
+func appendFields(dst []byte, fields interface{}, stack bool) []byte {
+	switch fields := fields.(type) {
+	case []interface{}:
+		if n := len(fields); n&0x1 == 1 { // odd number
+			fields = fields[:n-1]
+		}
+		dst = appendFieldList(dst, fields, stack)
+	case map[string]interface{}:
+		keys := make([]string, 0, len(fields))
+		for key := range fields {
+			keys = append(keys, key)
+		}
+		sort.Strings(keys)
+		kv := make([]interface{}, 2)
+		for _, key := range keys {
+			kv[0], kv[1] = key, fields[key]
+			dst = appendFieldList(dst, kv, stack)
+		}
+	}
+	return dst
+}
+
+func appendFieldList(dst []byte, kvList []interface{}, stack bool) []byte {
+	for i, n := 0, len(kvList); i < n; i += 2 {
+		key, val := kvList[i], kvList[i+1]
+		if key, ok := key.(string); ok {
+			dst = enc.AppendKey(dst, key)
+		} else {
+			continue
+		}
+		if val, ok := val.(LogObjectMarshaler); ok {
+			e := newEvent(nil, 0)
+			e.buf = e.buf[:0]
+			e.appendObject(val)
+			dst = append(dst, e.buf...)
+			putEvent(e)
+			continue
+		}
+		switch val := val.(type) {
+		case string:
+			dst = enc.AppendString(dst, val)
+		case []byte:
+			dst = enc.AppendBytes(dst, val)
+		case error:
+			switch m := ErrorMarshalFunc(val).(type) {
+			case LogObjectMarshaler:
+				e := newEvent(nil, 0)
+				e.buf = e.buf[:0]
+				e.appendObject(m)
+				dst = append(dst, e.buf...)
+				putEvent(e)
+			case error:
+				if m == nil || isNilValue(m) {
+					dst = enc.AppendNil(dst)
+				} else {
+					dst = enc.AppendString(dst, m.Error())
+				}
+			case string:
+				dst = enc.AppendString(dst, m)
+			default:
+				dst = enc.AppendInterface(dst, m)
+			}
+
+			if stack && ErrorStackMarshaler != nil {
+				dst = enc.AppendKey(dst, ErrorStackFieldName)
+				switch m := ErrorStackMarshaler(val).(type) {
+				case nil:
+				case error:
+					if m != nil && !isNilValue(m) {
+						dst = enc.AppendString(dst, m.Error())
+					}
+				case string:
+					dst = enc.AppendString(dst, m)
+				default:
+					dst = enc.AppendInterface(dst, m)
+				}
+			}
+		case []error:
+			dst = enc.AppendArrayStart(dst)
+			for i, err := range val {
+				switch m := ErrorMarshalFunc(err).(type) {
+				case LogObjectMarshaler:
+					e := newEvent(nil, 0)
+					e.buf = e.buf[:0]
+					e.appendObject(m)
+					dst = append(dst, e.buf...)
+					putEvent(e)
+				case error:
+					if m == nil || isNilValue(m) {
+						dst = enc.AppendNil(dst)
+					} else {
+						dst = enc.AppendString(dst, m.Error())
+					}
+				case string:
+					dst = enc.AppendString(dst, m)
+				default:
+					dst = enc.AppendInterface(dst, m)
+				}
+
+				if i < (len(val) - 1) {
+					enc.AppendArrayDelim(dst)
+				}
+			}
+			dst = enc.AppendArrayEnd(dst)
+		case bool:
+			dst = enc.AppendBool(dst, val)
+		case int:
+			dst = enc.AppendInt(dst, val)
+		case int8:
+			dst = enc.AppendInt8(dst, val)
+		case int16:
+			dst = enc.AppendInt16(dst, val)
+		case int32:
+			dst = enc.AppendInt32(dst, val)
+		case int64:
+			dst = enc.AppendInt64(dst, val)
+		case uint:
+			dst = enc.AppendUint(dst, val)
+		case uint8:
+			dst = enc.AppendUint8(dst, val)
+		case uint16:
+			dst = enc.AppendUint16(dst, val)
+		case uint32:
+			dst = enc.AppendUint32(dst, val)
+		case uint64:
+			dst = enc.AppendUint64(dst, val)
+		case float32:
+			dst = enc.AppendFloat32(dst, val, FloatingPointPrecision)
+		case float64:
+			dst = enc.AppendFloat64(dst, val, FloatingPointPrecision)
+		case time.Time:
+			dst = enc.AppendTime(dst, val, TimeFieldFormat)
+		case time.Duration:
+			dst = enc.AppendDuration(dst, val, DurationFieldUnit, DurationFieldInteger, FloatingPointPrecision)
+		case *string:
+			if val != nil {
+				dst = enc.AppendString(dst, *val)
+			} else {
+				dst = enc.AppendNil(dst)
+			}
+		case *bool:
+			if val != nil {
+				dst = enc.AppendBool(dst, *val)
+			} else {
+				dst = enc.AppendNil(dst)
+			}
+		case *int:
+			if val != nil {
+				dst = enc.AppendInt(dst, *val)
+			} else {
+				dst = enc.AppendNil(dst)
+			}
+		case *int8:
+			if val != nil {
+				dst = enc.AppendInt8(dst, *val)
+			} else {
+				dst = enc.AppendNil(dst)
+			}
+		case *int16:
+			if val != nil {
+				dst = enc.AppendInt16(dst, *val)
+			} else {
+				dst = enc.AppendNil(dst)
+			}
+		case *int32:
+			if val != nil {
+				dst = enc.AppendInt32(dst, *val)
+			} else {
+				dst = enc.AppendNil(dst)
+			}
+		case *int64:
+			if val != nil {
+				dst = enc.AppendInt64(dst, *val)
+			} else {
+				dst = enc.AppendNil(dst)
+			}
+		case *uint:
+			if val != nil {
+				dst = enc.AppendUint(dst, *val)
+			} else {
+				dst = enc.AppendNil(dst)
+			}
+		case *uint8:
+			if val != nil {
+				dst = enc.AppendUint8(dst, *val)
+			} else {
+				dst = enc.AppendNil(dst)
+			}
+		case *uint16:
+			if val != nil {
+				dst = enc.AppendUint16(dst, *val)
+			} else {
+				dst = enc.AppendNil(dst)
+			}
+		case *uint32:
+			if val != nil {
+				dst = enc.AppendUint32(dst, *val)
+			} else {
+				dst = enc.AppendNil(dst)
+			}
+		case *uint64:
+			if val != nil {
+				dst = enc.AppendUint64(dst, *val)
+			} else {
+				dst = enc.AppendNil(dst)
+			}
+		case *float32:
+			if val != nil {
+				dst = enc.AppendFloat32(dst, *val, FloatingPointPrecision)
+			} else {
+				dst = enc.AppendNil(dst)
+			}
+		case *float64:
+			if val != nil {
+				dst = enc.AppendFloat64(dst, *val, FloatingPointPrecision)
+			} else {
+				dst = enc.AppendNil(dst)
+			}
+		case *time.Time:
+			if val != nil {
+				dst = enc.AppendTime(dst, *val, TimeFieldFormat)
+			} else {
+				dst = enc.AppendNil(dst)
+			}
+		case *time.Duration:
+			if val != nil {
+				dst = enc.AppendDuration(dst, *val, DurationFieldUnit, DurationFieldInteger, FloatingPointPrecision)
+			} else {
+				dst = enc.AppendNil(dst)
+			}
+		case []string:
+			dst = enc.AppendStrings(dst, val)
+		case []bool:
+			dst = enc.AppendBools(dst, val)
+		case []int:
+			dst = enc.AppendInts(dst, val)
+		case []int8:
+			dst = enc.AppendInts8(dst, val)
+		case []int16:
+			dst = enc.AppendInts16(dst, val)
+		case []int32:
+			dst = enc.AppendInts32(dst, val)
+		case []int64:
+			dst = enc.AppendInts64(dst, val)
+		case []uint:
+			dst = enc.AppendUints(dst, val)
+		// case []uint8:
+		// 	dst = enc.AppendUints8(dst, val)
+		case []uint16:
+			dst = enc.AppendUints16(dst, val)
+		case []uint32:
+			dst = enc.AppendUints32(dst, val)
+		case []uint64:
+			dst = enc.AppendUints64(dst, val)
+		case []float32:
+			dst = enc.AppendFloats32(dst, val, FloatingPointPrecision)
+		case []float64:
+			dst = enc.AppendFloats64(dst, val, FloatingPointPrecision)
+		case []time.Time:
+			dst = enc.AppendTimes(dst, val, TimeFieldFormat)
+		case []time.Duration:
+			dst = enc.AppendDurations(dst, val, DurationFieldUnit, DurationFieldInteger, FloatingPointPrecision)
+		case nil:
+			dst = enc.AppendNil(dst)
+		case net.IP:
+			dst = enc.AppendIPAddr(dst, val)
+		case net.IPNet:
+			dst = enc.AppendIPPrefix(dst, val)
+		case net.HardwareAddr:
+			dst = enc.AppendMACAddr(dst, val)
+		case json.RawMessage:
+			dst = appendJSON(dst, val)
+		default:
+			dst = enc.AppendInterface(dst, val)
 		}
 	}
 	return dst

globals.go

@@ -1,7 +1,30 @@
 package zerolog
 
-import "time"
-import "sync/atomic"
+import (
+	"bytes"
+	"encoding/json"
+	"strconv"
+	"sync/atomic"
+	"time"
+)
+
+const (
+	// TimeFormatUnix defines a time format that makes time fields to be
+	// serialized as Unix timestamp integers.
+	TimeFormatUnix = ""
+
+	// TimeFormatUnixMs defines a time format that makes time fields to be
+	// serialized as Unix timestamp integers in milliseconds.
+	TimeFormatUnixMs = "UNIXMS"
+
+	// TimeFormatUnixMicro defines a time format that makes time fields to be
+	// serialized as Unix timestamp integers in microseconds.
+	TimeFormatUnixMicro = "UNIXMICRO"
+
+	// TimeFormatUnixNano defines a time format that makes time fields to be
+	// serialized as Unix timestamp integers in nanoseconds.
+	TimeFormatUnixNano = "UNIXNANO"
+)
 
 var (
 	// TimestampFieldName is the field name used for the timestamp field.
@@ -10,15 +33,75 @@ var (
 	// LevelFieldName is the field name used for the level field.
 	LevelFieldName = "level"
 
+	// LevelTraceValue is the value used for the trace level field.
+	LevelTraceValue = "trace"
+	// LevelDebugValue is the value used for the debug level field.
+	LevelDebugValue = "debug"
+	// LevelInfoValue is the value used for the info level field.
+	LevelInfoValue = "info"
+	// LevelWarnValue is the value used for the warn level field.
+	LevelWarnValue = "warn"
+	// LevelErrorValue is the value used for the error level field.
+	LevelErrorValue = "error"
+	// LevelFatalValue is the value used for the fatal level field.
+	LevelFatalValue = "fatal"
+	// LevelPanicValue is the value used for the panic level field.
+	LevelPanicValue = "panic"
+
+	// LevelFieldMarshalFunc allows customization of global level field marshaling.
+	LevelFieldMarshalFunc = func(l Level) string {
+		return l.String()
+	}
+
 	// MessageFieldName is the field name used for the message field.
 	MessageFieldName = "message"
 
 	// ErrorFieldName is the field name used for error fields.
 	ErrorFieldName = "error"
 
-	// TimeFieldFormat defines the time format of the Time field type.
-	// If set to an empty string, the time is formatted as an UNIX timestamp
-	// as integer.
+	// CallerFieldName is the field name used for caller field.
+	CallerFieldName = "caller"
+
+	// CallerSkipFrameCount is the number of stack frames to skip to find the caller.
+	CallerSkipFrameCount = 2
+
+	// CallerMarshalFunc allows customization of global caller marshaling
+	CallerMarshalFunc = func(pc uintptr, file string, line int) string {
+		return file + ":" + strconv.Itoa(line)
+	}
+
+	// ErrorStackFieldName is the field name used for error stacks.
+	ErrorStackFieldName = "stack"
+
+	// ErrorStackMarshaler extract the stack from err if any.
+	ErrorStackMarshaler func(err error) interface{}
+
+	// ErrorMarshalFunc allows customization of global error marshaling
+	ErrorMarshalFunc = func(err error) interface{} {
+		return err
+	}
+
+	// InterfaceMarshalFunc allows customization of interface marshaling.
+	// Default: "encoding/json.Marshal" with disabled HTML escaping
+	InterfaceMarshalFunc = func(v interface{}) ([]byte, error) {
+		var buf bytes.Buffer
+		encoder := json.NewEncoder(&buf)
+		encoder.SetEscapeHTML(false)
+		err := encoder.Encode(v)
+		if err != nil {
+			return nil, err
+		}
+		b := buf.Bytes()
+		if len(b) > 0 {
+			// Remove trailing \n which is added by Encode.
+			return b[:len(b)-1], nil
+		}
+		return b, nil
+	}
+
+	// TimeFieldFormat defines the time format of the Time field type. If set to
+	// TimeFormatUnix, TimeFormatUnixMs, TimeFormatUnixMicro or TimeFormatUnixNano, the time is formatted as a UNIX
+	// timestamp as integer.
 	TimeFieldFormat = time.RFC3339
 
 	// TimestampFunc defines the function called to generate a timestamp.
@@ -31,11 +114,53 @@ var (
 	// DurationFieldInteger renders Dur fields as integer instead of float if
 	// set to true.
 	DurationFieldInteger = false
+
+	// ErrorHandler is called whenever zerolog fails to write an event on its
+	// output. If not set, an error is printed on the stderr. This handler must
+	// be thread safe and non-blocking.
+	ErrorHandler func(err error)
+
+	// DefaultContextLogger is returned from Ctx() if there is no logger associated
+	// with the context.
+	DefaultContextLogger *Logger
+
+	// LevelColors are used by ConsoleWriter's consoleDefaultFormatLevel to color
+	// log levels.
+	LevelColors = map[Level]int{
+		TraceLevel: colorBlue,
+		DebugLevel: 0,
+		InfoLevel:  colorGreen,
+		WarnLevel:  colorYellow,
+		ErrorLevel: colorRed,
+		FatalLevel: colorRed,
+		PanicLevel: colorRed,
+	}
+
+	// FormattedLevels are used by ConsoleWriter's consoleDefaultFormatLevel
+	// for a short level name.
+	FormattedLevels = map[Level]string{
+		TraceLevel: "TRC",
+		DebugLevel: "DBG",
+		InfoLevel:  "INF",
+		WarnLevel:  "WRN",
+		ErrorLevel: "ERR",
+		FatalLevel: "FTL",
+		PanicLevel: "PNC",
+	}
+
+	// TriggerLevelWriterBufferReuseLimit is a limit in bytes that a buffer is dropped
+	// from the TriggerLevelWriter buffer pool if the buffer grows above the limit.
+	TriggerLevelWriterBufferReuseLimit = 64 * 1024
+
+	// FloatingPointPrecision, if set to a value other than -1, controls the number
+	// of digits when formatting float numbers in JSON. See strconv.FormatFloat for
+	// more details.
+	FloatingPointPrecision = -1
 )
 
 var (
-	gLevel          = new(uint32)
-	disableSampling = new(uint32)
+	gLevel          = new(int32)
+	disableSampling = new(int32)
 )
 
 // SetGlobalLevel sets the global override for log level. If this
@@ -43,22 +168,23 @@ var (
 //
 // To globally disable logs, set GlobalLevel to Disabled.
 func SetGlobalLevel(l Level) {
-	atomic.StoreUint32(gLevel, uint32(l))
+	atomic.StoreInt32(gLevel, int32(l))
 }
 
-func globalLevel() Level {
-	return Level(atomic.LoadUint32(gLevel))
+// GlobalLevel returns the current global log level
+func GlobalLevel() Level {
+	return Level(atomic.LoadInt32(gLevel))
 }
 
 // DisableSampling will disable sampling in all Loggers if true.
 func DisableSampling(v bool) {
-	var i uint32
+	var i int32
 	if v {
 		i = 1
 	}
-	atomic.StoreUint32(disableSampling, i)
+	atomic.StoreInt32(disableSampling, i)
 }
 
 func samplingDisabled() bool {
-	return atomic.LoadUint32(disableSampling) == 1
+	return atomic.LoadInt32(disableSampling) == 1
 }

go.mod

@@ -0,0 +1,12 @@
+module github.com/rs/zerolog
+
+go 1.15
+
+require (
+	github.com/coreos/go-systemd/v22 v22.5.0
+	github.com/mattn/go-colorable v0.1.13
+	github.com/mattn/go-isatty v0.0.19 // indirect
+	github.com/pkg/errors v0.9.1
+	github.com/rs/xid v1.5.0
+	golang.org/x/sys v0.12.0 // indirect
+)

go.sum

@@ -0,0 +1,23 @@
+github.com/coreos/go-systemd/v22 v22.5.0 h1:RrqgGjYQKalulkV8NGVIfkXQf6YYmOyiJKk8iXXhfZs=
+github.com/coreos/go-systemd/v22 v22.5.0/go.mod h1:Y58oyj3AT4RCenI/lSvhwexgC+NSVTIJ3seZv2GcEnc=
+github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
+github.com/mattn/go-colorable v0.1.12 h1:jF+Du6AlPIjs2BiUiQlKOX0rt3SujHxPnksPKZbaA40=
+github.com/mattn/go-colorable v0.1.12/go.mod h1:u5H1YNBxpqRaxsYJYSkiCWKzEfiAb1Gb520KVy5xxl4=
+github.com/mattn/go-colorable v0.1.13 h1:fFA4WZxdEF4tXPZVKMLwD8oUnCTTo08duU7wxecdEvA=
+github.com/mattn/go-colorable v0.1.13/go.mod h1:7S9/ev0klgBDR4GtXTXX8a3vIGJpMovkB8vQcUbaXHg=
+github.com/mattn/go-isatty v0.0.14 h1:yVuAays6BHfxijgZPzw+3Zlu5yQgKGP2/hcQbHb7S9Y=
+github.com/mattn/go-isatty v0.0.14/go.mod h1:7GGIvUiUoEMVVmxf/4nioHXj79iQHKdU27kJ6hsGG94=
+github.com/mattn/go-isatty v0.0.16/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/yFXSvRLM=
+github.com/mattn/go-isatty v0.0.19 h1:JITubQf0MOLdlGRuRq+jtsDlekdYPia9ZFsB8h/APPA=
+github.com/mattn/go-isatty v0.0.19/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/rs/xid v1.5.0 h1:mKX4bl4iPYJtEIxp6CYiUuLQ/8DYMoz0PUdtGgMFRVc=
+github.com/rs/xid v1.5.0/go.mod h1:trrq9SKmegXys3aeAKXMUTdJsYXVwGY3RLcfgqegfbg=
+golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20210927094055-39ccf1dd6fa6 h1:foEbQz/B0Oz6YIqu/69kfXPYeFQAuuMYFkjaqXzl5Wo=
+golang.org/x/sys v0.0.0-20210927094055-39ccf1dd6fa6/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.12.0 h1:CM0HF96J0hcLAwsHPJZjfdNzs0gftsLfgKt57wWHJ0o=
+golang.org/x/sys v0.12.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=

go112.go

@@ -0,0 +1,7 @@
+// +build go1.12
+
+package zerolog
+
+// Since go 1.12, some auto generated init functions are hidden from
+// runtime.Caller.
+const contextCallerSkipFrameCount = 2

hlog/hlog.go

@@ -5,12 +5,13 @@ import (
 	"context"
 	"net"
 	"net/http"
+	"strings"
 	"time"
 
 	"github.com/rs/xid"
 	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/hlog/internal/mutil"
 	"github.com/rs/zerolog/log"
-	"github.com/zenazn/goji/web/mutil"
 )
 
 // FromRequest gets the logger in the request's context.
@@ -79,10 +80,39 @@ func RequestHandler(fieldKey string) func(next http.Handler) http.Handler {
 func RemoteAddrHandler(fieldKey string) func(next http.Handler) http.Handler {
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-			if host, _, err := net.SplitHostPort(r.RemoteAddr); err == nil {
+			if r.RemoteAddr != "" {
 				log := zerolog.Ctx(r.Context())
 				log.UpdateContext(func(c zerolog.Context) zerolog.Context {
-					return c.Str(fieldKey, host)
+					return c.Str(fieldKey, r.RemoteAddr)
+				})
+			}
+			next.ServeHTTP(w, r)
+		})
+	}
+}
+
+func getHost(hostPort string) string {
+	if hostPort == "" {
+		return ""
+	}
+
+	host, _, err := net.SplitHostPort(hostPort)
+	if err != nil {
+		return hostPort
+	}
+	return host
+}
+
+// RemoteIPHandler is similar to RemoteAddrHandler, but logs only
+// an IP, not a port.
+func RemoteIPHandler(fieldKey string) func(next http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			ip := getHost(r.RemoteAddr)
+			if ip != "" {
+				log := zerolog.Ctx(r.Context())
+				log.UpdateContext(func(c zerolog.Context) zerolog.Context {
+					return c.Str(fieldKey, ip)
 				})
 			}
 			next.ServeHTTP(w, r)
@@ -122,17 +152,56 @@ func RefererHandler(fieldKey string) func(next http.Handler) http.Handler {
 	}
 }
 
+// ProtoHandler adds the requests protocol version as a field to the context logger
+// using fieldKey as field Key.
+func ProtoHandler(fieldKey string) func(next http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			log := zerolog.Ctx(r.Context())
+			log.UpdateContext(func(c zerolog.Context) zerolog.Context {
+				return c.Str(fieldKey, r.Proto)
+			})
+			next.ServeHTTP(w, r)
+		})
+	}
+}
+
+// HTTPVersionHandler is similar to ProtoHandler, but it does not store the "HTTP/"
+// prefix in the protocol name.
+func HTTPVersionHandler(fieldKey string) func(next http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			proto := strings.TrimPrefix(r.Proto, "HTTP/")
+			log := zerolog.Ctx(r.Context())
+			log.UpdateContext(func(c zerolog.Context) zerolog.Context {
+				return c.Str(fieldKey, proto)
+			})
+			next.ServeHTTP(w, r)
+		})
+	}
+}
+
 type idKey struct{}
 
-// IDFromRequest returns the unique id accociated to the request if any.
+// IDFromRequest returns the unique id associated to the request if any.
 func IDFromRequest(r *http.Request) (id xid.ID, ok bool) {
 	if r == nil {
 		return
 	}
-	id, ok = r.Context().Value(idKey{}).(xid.ID)
+	return IDFromCtx(r.Context())
+}
+
+// IDFromCtx returns the unique id associated to the context if any.
+func IDFromCtx(ctx context.Context) (id xid.ID, ok bool) {
+	id, ok = ctx.Value(idKey{}).(xid.ID)
 	return
 }
 
+// CtxWithID adds the given xid.ID to the context
+func CtxWithID(ctx context.Context, id xid.ID) context.Context {
+	return context.WithValue(ctx, idKey{}, id)
+}
+
 // RequestIDHandler returns a handler setting a unique id to the request which can
 // be gathered using IDFromRequest(req). This generated id is added as a field to the
 // logger using the passed fieldKey as field name. The id is also added as a response
@@ -149,7 +218,7 @@ func RequestIDHandler(fieldKey, headerName string) func(next http.Handler) http.
 			id, ok := IDFromRequest(r)
 			if !ok {
 				id = xid.New()
-				ctx = context.WithValue(ctx, idKey{}, id)
+				ctx = CtxWithID(ctx, id)
 				r = r.WithContext(ctx)
 			}
 			if fieldKey != "" {
@@ -166,14 +235,92 @@ func RequestIDHandler(fieldKey, headerName string) func(next http.Handler) http.
 	}
 }
 
+// CustomHeaderHandler adds given header from request's header as a field to
+// the context's logger using fieldKey as field key.
+func CustomHeaderHandler(fieldKey, header string) func(next http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			if val := r.Header.Get(header); val != "" {
+				log := zerolog.Ctx(r.Context())
+				log.UpdateContext(func(c zerolog.Context) zerolog.Context {
+					return c.Str(fieldKey, val)
+				})
+			}
+			next.ServeHTTP(w, r)
+		})
+	}
+}
+
+// EtagHandler adds Etag header from response's header as a field to
+// the context's logger using fieldKey as field key.
+func EtagHandler(fieldKey string) func(next http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			defer func() {
+				etag := w.Header().Get("Etag")
+				if etag != "" {
+					etag = strings.ReplaceAll(etag, `"`, "")
+					log := zerolog.Ctx(r.Context())
+					log.UpdateContext(func(c zerolog.Context) zerolog.Context {
+						return c.Str(fieldKey, etag)
+					})
+				}
+			}()
+			next.ServeHTTP(w, r)
+		})
+	}
+}
+
+func ResponseHeaderHandler(fieldKey, headerName string) func(next http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			defer func() {
+				value := w.Header().Get(headerName)
+				if value != "" {
+					log := zerolog.Ctx(r.Context())
+					log.UpdateContext(func(c zerolog.Context) zerolog.Context {
+						return c.Str(fieldKey, value)
+					})
+				}
+			}()
+			next.ServeHTTP(w, r)
+		})
+	}
+}
+
 // AccessHandler returns a handler that call f after each request.
 func AccessHandler(f func(r *http.Request, status, size int, duration time.Duration)) func(next http.Handler) http.Handler {
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			start := time.Now()
 			lw := mutil.WrapWriter(w)
+			defer func() {
+				f(r, lw.Status(), lw.BytesWritten(), time.Since(start))
+			}()
 			next.ServeHTTP(lw, r)
-			f(r, lw.Status(), lw.BytesWritten(), time.Since(start))
+		})
+	}
+}
+
+// HostHandler adds the request's host as a field to the context's logger
+// using fieldKey as field key. If trimPort is set to true, then port is
+// removed from the host.
+func HostHandler(fieldKey string, trimPort ...bool) func(next http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			var host string
+			if len(trimPort) > 0 && trimPort[0] {
+				host = getHost(r.Host)
+			} else {
+				host = r.Host
+			}
+			if host != "" {
+				log := zerolog.Ctx(r.Context())
+				log.UpdateContext(func(c zerolog.Context) zerolog.Context {
+					return c.Str(fieldKey, host)
+				})
+			}
+			next.ServeHTTP(w, r)
 		})
 	}
 }

hlog/hlog_example_test.go

@@ -1,3 +1,5 @@
+// +build !binary_log
+
 package hlog_test
 
 import (
@@ -46,8 +48,8 @@ func Example_handler() {
 	// Install the logger handler with default output on the console
 	c = c.Append(hlog.NewHandler(log))
 
-	// Install some provided extra handler to set some request's context fields.
-	// Thanks to those handler, all our logs will come with some pre-populated fields.
+	// Install some provided extra handlers to set some request's context fields.
+	// Thanks to those handlers, all our logs will come with some pre-populated fields.
 	c = c.Append(hlog.RemoteAddrHandler("ip"))
 	c = c.Append(hlog.UserAgentHandler("user_agent"))
 	c = c.Append(hlog.RefererHandler("referer"))
@@ -61,11 +63,11 @@ func Example_handler() {
 		hlog.FromRequest(r).Info().
 			Str("user", "current user").
 			Str("status", "ok").
-			Msg("Something happend")
+			Msg("Something happened")
 	}))
 	http.Handle("/", h)
 
 	h.ServeHTTP(httptest.NewRecorder(), &http.Request{})
 
-	// Output: {"time":"2001-02-03T04:05:06Z","level":"info","role":"my-service","host":"local-hostname","user":"current user","status":"ok","message":"Something happend"}
+	// Output: {"level":"info","role":"my-service","host":"local-hostname","user":"current user","status":"ok","time":"2001-02-03T04:05:06Z","message":"Something happened"}
 }

hlog/hlog_test.go

@@ -1,22 +1,32 @@
+//go:build go1.7
 // +build go1.7
 
 package hlog
 
 import (
 	"bytes"
+	"context"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
+	"net/http/httptest"
 	"net/url"
+	"reflect"
 	"testing"
 
-	"reflect"
-
-	"net/http/httptest"
-
+	"github.com/rs/xid"
 	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/internal/cbor"
 )
 
+func decodeIfBinary(out *bytes.Buffer) string {
+	p := out.Bytes()
+	if len(p) == 0 || p[0] < 0x7F {
+		return out.String()
+	}
+	return cbor.DecodeObjectToStr(p) + "\n"
+}
+
 func TestNewHandler(t *testing.T) {
 	log := zerolog.New(nil).With().
 		Str("foo", "bar").
@@ -42,7 +52,7 @@ func TestURLHandler(t *testing.T) {
 	}))
 	h = NewHandler(zerolog.New(out))(h)
 	h.ServeHTTP(nil, r)
-	if want, got := `{"url":"/path?foo=bar"}`+"\n", out.String(); want != got {
+	if want, got := `{"url":"/path?foo=bar"}`+"\n", decodeIfBinary(out); want != got {
 		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
 	}
 }
@@ -58,7 +68,7 @@ func TestMethodHandler(t *testing.T) {
 	}))
 	h = NewHandler(zerolog.New(out))(h)
 	h.ServeHTTP(nil, r)
-	if want, got := `{"method":"POST"}`+"\n", out.String(); want != got {
+	if want, got := `{"method":"POST"}`+"\n", decodeIfBinary(out); want != got {
 		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
 	}
 }
@@ -75,7 +85,7 @@ func TestRequestHandler(t *testing.T) {
 	}))
 	h = NewHandler(zerolog.New(out))(h)
 	h.ServeHTTP(nil, r)
-	if want, got := `{"request":"POST /path?foo=bar"}`+"\n", out.String(); want != got {
+	if want, got := `{"request":"POST /path?foo=bar"}`+"\n", decodeIfBinary(out); want != got {
 		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
 	}
 }
@@ -91,7 +101,7 @@ func TestRemoteAddrHandler(t *testing.T) {
 	}))
 	h = NewHandler(zerolog.New(out))(h)
 	h.ServeHTTP(nil, r)
-	if want, got := `{"ip":"1.2.3.4"}`+"\n", out.String(); want != got {
+	if want, got := `{"ip":"1.2.3.4:1234"}`+"\n", decodeIfBinary(out); want != got {
 		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
 	}
 }
@@ -107,7 +117,39 @@ func TestRemoteAddrHandlerIPv6(t *testing.T) {
 	}))
 	h = NewHandler(zerolog.New(out))(h)
 	h.ServeHTTP(nil, r)
-	if want, got := `{"ip":"2001:db8:a0b:12f0::1"}`+"\n", out.String(); want != got {
+	if want, got := `{"ip":"[2001:db8:a0b:12f0::1]:1234"}`+"\n", decodeIfBinary(out); want != got {
+		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
+	}
+}
+
+func TestRemoteIPHandler(t *testing.T) {
+	out := &bytes.Buffer{}
+	r := &http.Request{
+		RemoteAddr: "1.2.3.4:1234",
+	}
+	h := RemoteIPHandler("ip")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		l := FromRequest(r)
+		l.Log().Msg("")
+	}))
+	h = NewHandler(zerolog.New(out))(h)
+	h.ServeHTTP(nil, r)
+	if want, got := `{"ip":"1.2.3.4"}`+"\n", decodeIfBinary(out); want != got {
+		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
+	}
+}
+
+func TestRemoteIPHandlerIPv6(t *testing.T) {
+	out := &bytes.Buffer{}
+	r := &http.Request{
+		RemoteAddr: "[2001:db8:a0b:12f0::1]:1234",
+	}
+	h := RemoteIPHandler("ip")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		l := FromRequest(r)
+		l.Log().Msg("")
+	}))
+	h = NewHandler(zerolog.New(out))(h)
+	h.ServeHTTP(nil, r)
+	if want, got := `{"ip":"2001:db8:a0b:12f0::1"}`+"\n", decodeIfBinary(out); want != got {
 		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
 	}
 }
@@ -125,7 +167,7 @@ func TestUserAgentHandler(t *testing.T) {
 	}))
 	h = NewHandler(zerolog.New(out))(h)
 	h.ServeHTTP(nil, r)
-	if want, got := `{"ua":"some user agent string"}`+"\n", out.String(); want != got {
+	if want, got := `{"ua":"some user agent string"}`+"\n", decodeIfBinary(out); want != got {
 		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
 	}
 }
@@ -143,7 +185,7 @@ func TestRefererHandler(t *testing.T) {
 	}))
 	h = NewHandler(zerolog.New(out))(h)
 	h.ServeHTTP(nil, r)
-	if want, got := `{"referer":"http://foo.com/bar"}`+"\n", out.String(); want != got {
+	if want, got := `{"referer":"http://foo.com/bar"}`+"\n", decodeIfBinary(out); want != got {
 		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
 	}
 }
@@ -165,7 +207,7 @@ func TestRequestIDHandler(t *testing.T) {
 		}
 		l := FromRequest(r)
 		l.Log().Msg("")
-		if want, got := fmt.Sprintf(`{"id":"%s"}`+"\n", id), out.String(); want != got {
+		if want, got := fmt.Sprintf(`{"id":"%s"}`+"\n", id), decodeIfBinary(out); want != got {
 			t.Errorf("Invalid log output, got: %s, want: %s", got, want)
 		}
 	}))
@@ -173,6 +215,96 @@ func TestRequestIDHandler(t *testing.T) {
 	h.ServeHTTP(httptest.NewRecorder(), r)
 }
 
+func TestCustomHeaderHandler(t *testing.T) {
+	out := &bytes.Buffer{}
+	r := &http.Request{
+		Header: http.Header{
+			"X-Request-Id": []string{"514bbe5bb5251c92bd07a9846f4a1ab6"},
+		},
+	}
+	h := CustomHeaderHandler("reqID", "X-Request-Id")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		l := FromRequest(r)
+		l.Log().Msg("")
+	}))
+	h = NewHandler(zerolog.New(out))(h)
+	h.ServeHTTP(nil, r)
+	if want, got := `{"reqID":"514bbe5bb5251c92bd07a9846f4a1ab6"}`+"\n", decodeIfBinary(out); want != got {
+		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
+	}
+}
+
+func TestEtagHandler(t *testing.T) {
+	out := &bytes.Buffer{}
+	w := httptest.NewRecorder()
+	r := &http.Request{}
+	h := EtagHandler("etag")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Etag", `"abcdef"`)
+		w.WriteHeader(http.StatusOK)
+	}))
+	h2 := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		h.ServeHTTP(w, r)
+		l := FromRequest(r)
+		l.Log().Msg("")
+	})
+	h3 := NewHandler(zerolog.New(out))(h2)
+	h3.ServeHTTP(w, r)
+	if want, got := `{"etag":"abcdef"}`+"\n", decodeIfBinary(out); want != got {
+		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
+	}
+}
+
+func TestResponseHeaderHandler(t *testing.T) {
+	out := &bytes.Buffer{}
+	w := httptest.NewRecorder()
+	r := &http.Request{}
+	h := ResponseHeaderHandler("encoding", "Content-Encoding")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Encoding", `gzip`)
+		w.WriteHeader(http.StatusOK)
+	}))
+	h2 := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		h.ServeHTTP(w, r)
+		l := FromRequest(r)
+		l.Log().Msg("")
+	})
+	h3 := NewHandler(zerolog.New(out))(h2)
+	h3.ServeHTTP(w, r)
+	if want, got := `{"encoding":"gzip"}`+"\n", decodeIfBinary(out); want != got {
+		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
+	}
+}
+
+func TestProtoHandler(t *testing.T) {
+	out := &bytes.Buffer{}
+	r := &http.Request{
+		Proto: "test",
+	}
+	h := ProtoHandler("proto")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		l := FromRequest(r)
+		l.Log().Msg("")
+	}))
+	h = NewHandler(zerolog.New(out))(h)
+	h.ServeHTTP(nil, r)
+	if want, got := `{"proto":"test"}`+"\n", decodeIfBinary(out); want != got {
+		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
+	}
+}
+
+func TestHTTPVersionHandler(t *testing.T) {
+	out := &bytes.Buffer{}
+	r := &http.Request{
+		Proto: "HTTP/1.1",
+	}
+	h := HTTPVersionHandler("proto")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		l := FromRequest(r)
+		l.Log().Msg("")
+	}))
+	h = NewHandler(zerolog.New(out))(h)
+	h.ServeHTTP(nil, r)
+	if want, got := `{"proto":"1.1"}`+"\n", decodeIfBinary(out); want != got {
+		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
+	}
+}
+
 func TestCombinedHandlers(t *testing.T) {
 	out := &bytes.Buffer{}
 	r := &http.Request{
@@ -185,7 +317,7 @@ func TestCombinedHandlers(t *testing.T) {
 	}))))
 	h = NewHandler(zerolog.New(out))(h)
 	h.ServeHTTP(nil, r)
-	if want, got := `{"method":"POST","request":"POST /path?foo=bar","url":"/path?foo=bar"}`+"\n", out.String(); want != got {
+	if want, got := `{"method":"POST","request":"POST /path?foo=bar","url":"/path?foo=bar"}`+"\n", decodeIfBinary(out); want != got {
 		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
 	}
 }
@@ -201,10 +333,10 @@ func BenchmarkHandlers(b *testing.B) {
 	}))
 	h2 := MethodHandler("method")(RequestHandler("request")(h1))
 	handlers := map[string]http.Handler{
-		"Single":           NewHandler(zerolog.New(ioutil.Discard))(h1),
-		"Combined":         NewHandler(zerolog.New(ioutil.Discard))(h2),
-		"SingleDisabled":   NewHandler(zerolog.New(ioutil.Discard).Level(zerolog.Disabled))(h1),
-		"CombinedDisabled": NewHandler(zerolog.New(ioutil.Discard).Level(zerolog.Disabled))(h2),
+		"Single":           NewHandler(zerolog.New(io.Discard))(h1),
+		"Combined":         NewHandler(zerolog.New(io.Discard))(h2),
+		"SingleDisabled":   NewHandler(zerolog.New(io.Discard).Level(zerolog.Disabled))(h1),
+		"CombinedDisabled": NewHandler(zerolog.New(io.Discard).Level(zerolog.Disabled))(h2),
 	}
 	for name := range handlers {
 		h := handlers[name]
@@ -235,3 +367,69 @@ func BenchmarkDataRace(b *testing.B) {
 		}
 	})
 }
+
+func TestCtxWithID(t *testing.T) {
+	ctx := context.Background()
+
+	id, _ := xid.FromString(`c0umremcie6smuu506pg`)
+
+	want := context.Background()
+	want = context.WithValue(want, idKey{}, id)
+
+	if got := CtxWithID(ctx, id); !reflect.DeepEqual(got, want) {
+		t.Errorf("CtxWithID() = %v, want %v", got, want)
+	}
+}
+
+func TestHostHandler(t *testing.T) {
+	out := &bytes.Buffer{}
+	r := &http.Request{Host: "example.com:8080"}
+	h := HostHandler("host")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		l := FromRequest(r)
+		l.Log().Msg("")
+	}))
+	h = NewHandler(zerolog.New(out))(h)
+	h.ServeHTTP(nil, r)
+	if want, got := `{"host":"example.com:8080"}`+"\n", decodeIfBinary(out); want != got {
+		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
+	}
+}
+
+func TestHostHandlerWithoutPort(t *testing.T) {
+	out := &bytes.Buffer{}
+	r := &http.Request{Host: "example.com:8080"}
+	h := HostHandler("host", true)(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		l := FromRequest(r)
+		l.Log().Msg("")
+	}))
+	h = NewHandler(zerolog.New(out))(h)
+	h.ServeHTTP(nil, r)
+	if want, got := `{"host":"example.com"}`+"\n", decodeIfBinary(out); want != got {
+		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
+	}
+}
+
+func TestGetHost(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected string
+	}{
+		{"", ""},
+		{"example.com:8080", "example.com"},
+		{"example.com", "example.com"},
+		{"invalid", "invalid"},
+		{"192.168.0.1:8080", "192.168.0.1"},
+		{"[2001:0db8:85a3:0000:0000:8a2e:0370:7334]:8080", "2001:0db8:85a3:0000:0000:8a2e:0370:7334"},
+		{"こんにちは.com:8080", "こんにちは.com"},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.input, func(t *testing.T) {
+			result := getHost(tt.input)
+			if tt.expected != result {
+				t.Errorf("Invalid log output, got: %s, want: %s", result, tt.expected)
+			}
+		})
+	}
+}

hlog/internal/mutil/LICENSE

@@ -0,0 +1,20 @@
+Copyright (c) 2014, 2015, 2016 Carl Jackson (carl@avtok.com)
+
+MIT License
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

hlog/internal/mutil/mutil.go

@@ -0,0 +1,6 @@
+// Package mutil contains various functions that are helpful when writing http
+// middleware.
+//
+// It has been vendored from Goji v1.0, with the exception of the code for Go 1.8:
+// https://github.com/zenazn/goji/
+package mutil

hlog/internal/mutil/writer_proxy.go

@@ -0,0 +1,154 @@
+package mutil
+
+import (
+	"bufio"
+	"io"
+	"net"
+	"net/http"
+)
+
+// WriterProxy is a proxy around an http.ResponseWriter that allows you to hook
+// into various parts of the response process.
+type WriterProxy interface {
+	http.ResponseWriter
+	// Status returns the HTTP status of the request, or 0 if one has not
+	// yet been sent.
+	Status() int
+	// BytesWritten returns the total number of bytes sent to the client.
+	BytesWritten() int
+	// Tee causes the response body to be written to the given io.Writer in
+	// addition to proxying the writes through. Only one io.Writer can be
+	// tee'd to at once: setting a second one will overwrite the first.
+	// Writes will be sent to the proxy before being written to this
+	// io.Writer. It is illegal for the tee'd writer to be modified
+	// concurrently with writes.
+	Tee(io.Writer)
+	// Unwrap returns the original proxied target.
+	Unwrap() http.ResponseWriter
+}
+
+// WrapWriter wraps an http.ResponseWriter, returning a proxy that allows you to
+// hook into various parts of the response process.
+func WrapWriter(w http.ResponseWriter) WriterProxy {
+	_, cn := w.(http.CloseNotifier)
+	_, fl := w.(http.Flusher)
+	_, hj := w.(http.Hijacker)
+	_, rf := w.(io.ReaderFrom)
+
+	bw := basicWriter{ResponseWriter: w}
+	if cn && fl && hj && rf {
+		return &fancyWriter{bw}
+	}
+	if fl {
+		return &flushWriter{bw}
+	}
+	return &bw
+}
+
+// basicWriter wraps a http.ResponseWriter that implements the minimal
+// http.ResponseWriter interface.
+type basicWriter struct {
+	http.ResponseWriter
+	wroteHeader bool
+	code        int
+	bytes       int
+	tee         io.Writer
+}
+
+func (b *basicWriter) WriteHeader(code int) {
+	if !b.wroteHeader {
+		b.code = code
+		b.wroteHeader = true
+		b.ResponseWriter.WriteHeader(code)
+	}
+}
+
+func (b *basicWriter) Write(buf []byte) (int, error) {
+	b.WriteHeader(http.StatusOK)
+	n, err := b.ResponseWriter.Write(buf)
+	if b.tee != nil {
+		_, err2 := b.tee.Write(buf[:n])
+		// Prefer errors generated by the proxied writer.
+		if err == nil {
+			err = err2
+		}
+	}
+	b.bytes += n
+	return n, err
+}
+
+func (b *basicWriter) maybeWriteHeader() {
+	if !b.wroteHeader {
+		b.WriteHeader(http.StatusOK)
+	}
+}
+
+func (b *basicWriter) Status() int {
+	return b.code
+}
+
+func (b *basicWriter) BytesWritten() int {
+	return b.bytes
+}
+
+func (b *basicWriter) Tee(w io.Writer) {
+	b.tee = w
+}
+
+func (b *basicWriter) Unwrap() http.ResponseWriter {
+	return b.ResponseWriter
+}
+
+// fancyWriter is a writer that additionally satisfies http.CloseNotifier,
+// http.Flusher, http.Hijacker, and io.ReaderFrom. It exists for the common case
+// of wrapping the http.ResponseWriter that package http gives you, in order to
+// make the proxied object support the full method set of the proxied object.
+type fancyWriter struct {
+	basicWriter
+}
+
+func (f *fancyWriter) CloseNotify() <-chan bool {
+	cn := f.basicWriter.ResponseWriter.(http.CloseNotifier)
+	return cn.CloseNotify()
+}
+
+func (f *fancyWriter) Flush() {
+	fl := f.basicWriter.ResponseWriter.(http.Flusher)
+	fl.Flush()
+}
+
+func (f *fancyWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	hj := f.basicWriter.ResponseWriter.(http.Hijacker)
+	return hj.Hijack()
+}
+
+func (f *fancyWriter) ReadFrom(r io.Reader) (int64, error) {
+	if f.basicWriter.tee != nil {
+		n, err := io.Copy(&f.basicWriter, r)
+		f.bytes += int(n)
+		return n, err
+	}
+	rf := f.basicWriter.ResponseWriter.(io.ReaderFrom)
+	f.basicWriter.maybeWriteHeader()
+
+	n, err := rf.ReadFrom(r)
+	f.bytes += int(n)
+	return n, err
+}
+
+type flushWriter struct {
+	basicWriter
+}
+
+func (f *flushWriter) Flush() {
+	fl := f.basicWriter.ResponseWriter.(http.Flusher)
+	fl.Flush()
+}
+
+var (
+	_ http.CloseNotifier = &fancyWriter{}
+	_ http.Flusher       = &fancyWriter{}
+	_ http.Hijacker      = &fancyWriter{}
+	_ io.ReaderFrom      = &fancyWriter{}
+	_ http.Flusher       = &flushWriter{}
+)

hook.go

@@ -0,0 +1,64 @@
+package zerolog
+
+// Hook defines an interface to a log hook.
+type Hook interface {
+	// Run runs the hook with the event.
+	Run(e *Event, level Level, message string)
+}
+
+// HookFunc is an adaptor to allow the use of an ordinary function
+// as a Hook.
+type HookFunc func(e *Event, level Level, message string)
+
+// Run implements the Hook interface.
+func (h HookFunc) Run(e *Event, level Level, message string) {
+	h(e, level, message)
+}
+
+// LevelHook applies a different hook for each level.
+type LevelHook struct {
+	NoLevelHook, TraceHook, DebugHook, InfoHook, WarnHook, ErrorHook, FatalHook, PanicHook Hook
+}
+
+// Run implements the Hook interface.
+func (h LevelHook) Run(e *Event, level Level, message string) {
+	switch level {
+	case TraceLevel:
+		if h.TraceHook != nil {
+			h.TraceHook.Run(e, level, message)
+		}
+	case DebugLevel:
+		if h.DebugHook != nil {
+			h.DebugHook.Run(e, level, message)
+		}
+	case InfoLevel:
+		if h.InfoHook != nil {
+			h.InfoHook.Run(e, level, message)
+		}
+	case WarnLevel:
+		if h.WarnHook != nil {
+			h.WarnHook.Run(e, level, message)
+		}
+	case ErrorLevel:
+		if h.ErrorHook != nil {
+			h.ErrorHook.Run(e, level, message)
+		}
+	case FatalLevel:
+		if h.FatalHook != nil {
+			h.FatalHook.Run(e, level, message)
+		}
+	case PanicLevel:
+		if h.PanicHook != nil {
+			h.PanicHook.Run(e, level, message)
+		}
+	case NoLevel:
+		if h.NoLevelHook != nil {
+			h.NoLevelHook.Run(e, level, message)
+		}
+	}
+}
+
+// NewLevelHook returns a new LevelHook.
+func NewLevelHook() LevelHook {
+	return LevelHook{}
+}

hook_test.go

@@ -0,0 +1,201 @@
+package zerolog
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"testing"
+)
+
+type contextKeyType int
+
+var contextKey contextKeyType
+
+var (
+	levelNameHook = HookFunc(func(e *Event, level Level, msg string) {
+		levelName := level.String()
+		if level == NoLevel {
+			levelName = "nolevel"
+		}
+		e.Str("level_name", levelName)
+	})
+	simpleHook = HookFunc(func(e *Event, level Level, msg string) {
+		e.Bool("has_level", level != NoLevel)
+		e.Str("test", "logged")
+	})
+	copyHook = HookFunc(func(e *Event, level Level, msg string) {
+		hasLevel := level != NoLevel
+		e.Bool("copy_has_level", hasLevel)
+		if hasLevel {
+			e.Str("copy_level", level.String())
+		}
+		e.Str("copy_msg", msg)
+	})
+	nopHook = HookFunc(func(e *Event, level Level, message string) {
+	})
+	discardHook = HookFunc(func(e *Event, level Level, message string) {
+		e.Discard()
+	})
+	contextHook = HookFunc(func(e *Event, level Level, message string) {
+		contextData, ok := e.GetCtx().Value(contextKey).(string)
+		if ok {
+			e.Str("context-data", contextData)
+		}
+	})
+)
+
+func TestHook(t *testing.T) {
+	tests := []struct {
+		name string
+		want string
+		test func(log Logger)
+	}{
+		{"Message", `{"level_name":"nolevel","message":"test message"}` + "\n", func(log Logger) {
+			log = log.Hook(levelNameHook)
+			log.Log().Msg("test message")
+		}},
+		{"NoLevel", `{"level_name":"nolevel"}` + "\n", func(log Logger) {
+			log = log.Hook(levelNameHook)
+			log.Log().Msg("")
+		}},
+		{"Print", `{"level":"debug","level_name":"debug"}` + "\n", func(log Logger) {
+			log = log.Hook(levelNameHook)
+			log.Print("")
+		}},
+		{"Error", `{"level":"error","level_name":"error"}` + "\n", func(log Logger) {
+			log = log.Hook(levelNameHook)
+			log.Error().Msg("")
+		}},
+		{"Copy/1", `{"copy_has_level":false,"copy_msg":""}` + "\n", func(log Logger) {
+			log = log.Hook(copyHook)
+			log.Log().Msg("")
+		}},
+		{"Copy/2", `{"level":"info","copy_has_level":true,"copy_level":"info","copy_msg":"a message","message":"a message"}` + "\n", func(log Logger) {
+			log = log.Hook(copyHook)
+			log.Info().Msg("a message")
+		}},
+		{"Multi", `{"level":"error","level_name":"error","has_level":true,"test":"logged"}` + "\n", func(log Logger) {
+			log = log.Hook(levelNameHook).Hook(simpleHook)
+			log.Error().Msg("")
+		}},
+		{"Multi/Message", `{"level":"error","level_name":"error","has_level":true,"test":"logged","message":"a message"}` + "\n", func(log Logger) {
+			log = log.Hook(levelNameHook).Hook(simpleHook)
+			log.Error().Msg("a message")
+		}},
+		{"Output/single/pre", `{"level":"error","level_name":"error"}` + "\n", func(log Logger) {
+			ignored := &bytes.Buffer{}
+			log = New(ignored).Hook(levelNameHook).Output(log.w)
+			log.Error().Msg("")
+		}},
+		{"Output/single/post", `{"level":"error","level_name":"error"}` + "\n", func(log Logger) {
+			ignored := &bytes.Buffer{}
+			log = New(ignored).Output(log.w).Hook(levelNameHook)
+			log.Error().Msg("")
+		}},
+		{"Output/multi/pre", `{"level":"error","level_name":"error","has_level":true,"test":"logged"}` + "\n", func(log Logger) {
+			ignored := &bytes.Buffer{}
+			log = New(ignored).Hook(levelNameHook).Hook(simpleHook).Output(log.w)
+			log.Error().Msg("")
+		}},
+		{"Output/multi/post", `{"level":"error","level_name":"error","has_level":true,"test":"logged"}` + "\n", func(log Logger) {
+			ignored := &bytes.Buffer{}
+			log = New(ignored).Output(log.w).Hook(levelNameHook).Hook(simpleHook)
+			log.Error().Msg("")
+		}},
+		{"Output/mixed", `{"level":"error","level_name":"error","has_level":true,"test":"logged"}` + "\n", func(log Logger) {
+			ignored := &bytes.Buffer{}
+			log = New(ignored).Hook(levelNameHook).Output(log.w).Hook(simpleHook)
+			log.Error().Msg("")
+		}},
+		{"With/single/pre", `{"level":"error","with":"pre","level_name":"error"}` + "\n", func(log Logger) {
+			log = log.Hook(levelNameHook).With().Str("with", "pre").Logger()
+			log.Error().Msg("")
+		}},
+		{"With/single/post", `{"level":"error","with":"post","level_name":"error"}` + "\n", func(log Logger) {
+			log = log.With().Str("with", "post").Logger().Hook(levelNameHook)
+			log.Error().Msg("")
+		}},
+		{"With/multi/pre", `{"level":"error","with":"pre","level_name":"error","has_level":true,"test":"logged"}` + "\n", func(log Logger) {
+			log = log.Hook(levelNameHook).Hook(simpleHook).With().Str("with", "pre").Logger()
+			log.Error().Msg("")
+		}},
+		{"With/multi/post", `{"level":"error","with":"post","level_name":"error","has_level":true,"test":"logged"}` + "\n", func(log Logger) {
+			log = log.With().Str("with", "post").Logger().Hook(levelNameHook).Hook(simpleHook)
+			log.Error().Msg("")
+		}},
+		{"With/mixed", `{"level":"error","with":"mixed","level_name":"error","has_level":true,"test":"logged"}` + "\n", func(log Logger) {
+			log = log.Hook(levelNameHook).With().Str("with", "mixed").Logger().Hook(simpleHook)
+			log.Error().Msg("")
+		}},
+		{"Discard", "", func(log Logger) {
+			log = log.Hook(discardHook)
+			log.Log().Msg("test message")
+		}},
+		{"Context/Background", `{"level":"info","message":"test message"}` + "\n", func(log Logger) {
+			log = log.Hook(contextHook)
+			log.Info().Ctx(context.Background()).Msg("test message")
+		}},
+		{"Context/nil", `{"level":"info","message":"test message"}` + "\n", func(log Logger) {
+			// passing `nil` where a context is wanted is against
+			// the rules, but people still do it.
+			log = log.Hook(contextHook)
+			log.Info().Ctx(nil).Msg("test message") // nolint
+		}},
+		{"Context/valid", `{"level":"info","context-data":"12345abcdef","message":"test message"}` + "\n", func(log Logger) {
+			ctx := context.Background()
+			ctx = context.WithValue(ctx, contextKey, "12345abcdef")
+			log = log.Hook(contextHook)
+			log.Info().Ctx(ctx).Msg("test message")
+		}},
+		{"Context/With/valid", `{"level":"info","context-data":"12345abcdef","message":"test message"}` + "\n", func(log Logger) {
+			ctx := context.Background()
+			ctx = context.WithValue(ctx, contextKey, "12345abcdef")
+			log = log.Hook(contextHook)
+			log = log.With().Ctx(ctx).Logger()
+			log.Info().Msg("test message")
+		}},
+		{"None", `{"level":"error"}` + "\n", func(log Logger) {
+			log.Error().Msg("")
+		}},
+	}
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			out := &bytes.Buffer{}
+			log := New(out)
+			tt.test(log)
+			if got, want := decodeIfBinaryToString(out.Bytes()), tt.want; got != want {
+				t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+			}
+		})
+	}
+}
+
+func BenchmarkHooks(b *testing.B) {
+	logger := New(io.Discard)
+	b.ResetTimer()
+	b.Run("Nop/Single", func(b *testing.B) {
+		log := logger.Hook(nopHook)
+		b.RunParallel(func(pb *testing.PB) {
+			for pb.Next() {
+				log.Log().Msg("")
+			}
+		})
+	})
+	b.Run("Nop/Multi", func(b *testing.B) {
+		log := logger.Hook(nopHook).Hook(nopHook)
+		b.RunParallel(func(pb *testing.PB) {
+			for pb.Next() {
+				log.Log().Msg("")
+			}
+		})
+	})
+	b.Run("Simple", func(b *testing.B) {
+		log := logger.Hook(simpleHook)
+		b.RunParallel(func(pb *testing.PB) {
+			for pb.Next() {
+				log.Log().Msg("")
+			}
+		})
+	})
+}

internal/cbor/README.md

@@ -0,0 +1,56 @@
+## Reference:
+   CBOR Encoding is described in [RFC7049](https://tools.ietf.org/html/rfc7049)
+
+## Comparison of JSON vs CBOR
+
+Two main areas of reduction are:
+
+1. CPU usage to write a log msg 
+2. Size (in bytes) of log messages.
+
+
+CPU Usage savings are below:
+```
+name                                    JSON time/op    CBOR time/op   delta
+Info-32                                   15.3ns ± 1%    11.7ns ± 3%  -23.78%  (p=0.000 n=9+10)      
+ContextFields-32                          16.2ns ± 2%    12.3ns ± 3%  -23.97%  (p=0.000 n=9+9)       
+ContextAppend-32                          6.70ns ± 0%    6.20ns ± 0%   -7.44%  (p=0.000 n=9+9)       
+LogFields-32                              66.4ns ± 0%    24.6ns ± 2%  -62.89%  (p=0.000 n=10+9)      
+LogArrayObject-32                          911ns ±11%     768ns ± 6%  -15.64%  (p=0.000 n=10+10)     
+LogFieldType/Floats-32                    70.3ns ± 2%    29.5ns ± 1%  -57.98%  (p=0.000 n=10+10)     
+LogFieldType/Err-32                       14.0ns ± 3%    12.1ns ± 8%  -13.20%  (p=0.000 n=8+10)      
+LogFieldType/Dur-32                       17.2ns ± 2%    13.1ns ± 1%  -24.27%  (p=0.000 n=10+9)      
+LogFieldType/Object-32                    54.3ns ±11%    52.3ns ± 7%     ~     (p=0.239 n=10+10)     
+LogFieldType/Ints-32                      20.3ns ± 2%    15.1ns ± 2%  -25.50%  (p=0.000 n=9+10)      
+LogFieldType/Interfaces-32                 642ns ±11%     621ns ± 9%     ~     (p=0.118 n=10+10)     
+LogFieldType/Interface(Objects)-32         635ns ±13%     632ns ± 9%     ~     (p=0.592 n=10+10)     
+LogFieldType/Times-32                      294ns ± 0%      27ns ± 1%  -90.71%  (p=0.000 n=10+9)      
+LogFieldType/Durs-32                       121ns ± 0%      33ns ± 2%  -72.44%  (p=0.000 n=9+9)       
+LogFieldType/Interface(Object)-32         56.6ns ± 8%    52.3ns ± 8%   -7.54%  (p=0.007 n=10+10)     
+LogFieldType/Errs-32                      17.8ns ± 3%    16.1ns ± 2%   -9.71%  (p=0.000 n=10+9)      
+LogFieldType/Time-32                      40.5ns ± 1%    12.7ns ± 6%  -68.66%  (p=0.000 n=8+9)       
+LogFieldType/Bool-32                      12.0ns ± 5%    10.2ns ± 2%  -15.18%  (p=0.000 n=10+8)      
+LogFieldType/Bools-32                     17.2ns ± 2%    12.6ns ± 4%  -26.63%  (p=0.000 n=10+10)     
+LogFieldType/Int-32                       12.3ns ± 2%    11.2ns ± 4%   -9.27%  (p=0.000 n=9+10)      
+LogFieldType/Float-32                     16.7ns ± 1%    12.6ns ± 2%  -24.42%  (p=0.000 n=7+9)       
+LogFieldType/Str-32                       12.7ns ± 7%    11.3ns ± 7%  -10.88%  (p=0.000 n=10+9)      
+LogFieldType/Strs-32                      20.3ns ± 3%    18.2ns ± 3%  -10.25%  (p=0.000 n=9+10)      
+LogFieldType/Interface-32                  183ns ±12%     175ns ± 9%     ~     (p=0.078 n=10+10)     
+```
+
+Log message size savings is greatly dependent on the number and type of fields in the log message.
+Assuming this log message (with an Integer, timestamp and string, in addition to level).
+
+`{"level":"error","Fault":41650,"time":"2018-04-01T15:18:19-07:00","message":"Some Message"}`
+
+Two measurements were done for the log file sizes - one without any compression, second
+using [compress/zlib](https://golang.org/pkg/compress/zlib/). 
+
+Results for 10,000 log messages:
+
+| Log Format |  Plain File Size (in KB) | Compressed File Size (in KB) |
+| :--- | :---: | :---: |
+| JSON | 920 | 28 |
+| CBOR | 550 | 28 |
+
+The example used to calculate the above data is available in [Examples](examples).

internal/cbor/base.go

@@ -0,0 +1,19 @@
+package cbor
+
+// JSONMarshalFunc is used to marshal interface to JSON encoded byte slice.
+// Making it package level instead of embedded in Encoder brings
+// some extra efforts at importing, but avoids value copy when the functions
+// of Encoder being invoked.
+// DO REMEMBER to set this variable at importing, or
+// you might get a nil pointer dereference panic at runtime.
+var JSONMarshalFunc func(v interface{}) ([]byte, error)
+
+type Encoder struct{}
+
+// AppendKey adds a key (string) to the binary encoded log message
+func (e Encoder) AppendKey(dst []byte, key string) []byte {
+	if len(dst) < 1 {
+		dst = e.AppendBeginMarker(dst)
+	}
+	return e.AppendString(dst, key)
+}

internal/cbor/cbor.go

@@ -0,0 +1,102 @@
+// Package cbor provides primitives for storing different data
+// in the CBOR (binary) format. CBOR is defined in RFC7049.
+package cbor
+
+import "time"
+
+const (
+	majorOffset   = 5
+	additionalMax = 23
+
+	// Non Values.
+	additionalTypeBoolFalse byte = 20
+	additionalTypeBoolTrue  byte = 21
+	additionalTypeNull      byte = 22
+
+	// Integer (+ve and -ve) Sub-types.
+	additionalTypeIntUint8  byte = 24
+	additionalTypeIntUint16 byte = 25
+	additionalTypeIntUint32 byte = 26
+	additionalTypeIntUint64 byte = 27
+
+	// Float Sub-types.
+	additionalTypeFloat16 byte = 25
+	additionalTypeFloat32 byte = 26
+	additionalTypeFloat64 byte = 27
+	additionalTypeBreak   byte = 31
+
+	// Tag Sub-types.
+	additionalTypeTimestamp    byte = 01
+	additionalTypeEmbeddedCBOR byte = 63
+
+	// Extended Tags - from https://www.iana.org/assignments/cbor-tags/cbor-tags.xhtml
+	additionalTypeTagNetworkAddr   uint16 = 260
+	additionalTypeTagNetworkPrefix uint16 = 261
+	additionalTypeEmbeddedJSON     uint16 = 262
+	additionalTypeTagHexString     uint16 = 263
+
+	// Unspecified number of elements.
+	additionalTypeInfiniteCount byte = 31
+)
+const (
+	majorTypeUnsignedInt    byte = iota << majorOffset // Major type 0
+	majorTypeNegativeInt                               // Major type 1
+	majorTypeByteString                                // Major type 2
+	majorTypeUtf8String                                // Major type 3
+	majorTypeArray                                     // Major type 4
+	majorTypeMap                                       // Major type 5
+	majorTypeTags                                      // Major type 6
+	majorTypeSimpleAndFloat                            // Major type 7
+)
+
+const (
+	maskOutAdditionalType byte = (7 << majorOffset)
+	maskOutMajorType      byte = 31
+)
+
+const (
+	float32Nan         = "\xfa\x7f\xc0\x00\x00"
+	float32PosInfinity = "\xfa\x7f\x80\x00\x00"
+	float32NegInfinity = "\xfa\xff\x80\x00\x00"
+	float64Nan         = "\xfb\x7f\xf8\x00\x00\x00\x00\x00\x00"
+	float64PosInfinity = "\xfb\x7f\xf0\x00\x00\x00\x00\x00\x00"
+	float64NegInfinity = "\xfb\xff\xf0\x00\x00\x00\x00\x00\x00"
+)
+
+// IntegerTimeFieldFormat indicates the format of timestamp decoded
+// from an integer (time in seconds).
+var IntegerTimeFieldFormat = time.RFC3339
+
+// NanoTimeFieldFormat indicates the format of timestamp decoded
+// from a float value (time in seconds and nanoseconds).
+var NanoTimeFieldFormat = time.RFC3339Nano
+
+func appendCborTypePrefix(dst []byte, major byte, number uint64) []byte {
+	byteCount := 8
+	var minor byte
+	switch {
+	case number < 256:
+		byteCount = 1
+		minor = additionalTypeIntUint8
+
+	case number < 65536:
+		byteCount = 2
+		minor = additionalTypeIntUint16
+
+	case number < 4294967296:
+		byteCount = 4
+		minor = additionalTypeIntUint32
+
+	default:
+		byteCount = 8
+		minor = additionalTypeIntUint64
+
+	}
+
+	dst = append(dst, major|minor)
+	byteCount--
+	for ; byteCount >= 0; byteCount-- {
+		dst = append(dst, byte(number>>(uint(byteCount)*8)))
+	}
+	return dst
+}

internal/cbor/decode_stream.go

@@ -0,0 +1,654 @@
+package cbor
+
+// This file contains code to decode a stream of CBOR Data into JSON.
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/base64"
+	"fmt"
+	"io"
+	"math"
+	"net"
+	"runtime"
+	"strconv"
+	"strings"
+	"time"
+	"unicode/utf8"
+)
+
+var decodeTimeZone *time.Location
+
+const hexTable = "0123456789abcdef"
+
+const isFloat32 = 4
+const isFloat64 = 8
+
+func readNBytes(src *bufio.Reader, n int) []byte {
+	ret := make([]byte, n)
+	for i := 0; i < n; i++ {
+		ch, e := src.ReadByte()
+		if e != nil {
+			panic(fmt.Errorf("Tried to Read %d Bytes.. But hit end of file", n))
+		}
+		ret[i] = ch
+	}
+	return ret
+}
+
+func readByte(src *bufio.Reader) byte {
+	b, e := src.ReadByte()
+	if e != nil {
+		panic(fmt.Errorf("Tried to Read 1 Byte.. But hit end of file"))
+	}
+	return b
+}
+
+func decodeIntAdditionalType(src *bufio.Reader, minor byte) int64 {
+	val := int64(0)
+	if minor <= 23 {
+		val = int64(minor)
+	} else {
+		bytesToRead := 0
+		switch minor {
+		case additionalTypeIntUint8:
+			bytesToRead = 1
+		case additionalTypeIntUint16:
+			bytesToRead = 2
+		case additionalTypeIntUint32:
+			bytesToRead = 4
+		case additionalTypeIntUint64:
+			bytesToRead = 8
+		default:
+			panic(fmt.Errorf("Invalid Additional Type: %d in decodeInteger (expected <28)", minor))
+		}
+		pb := readNBytes(src, bytesToRead)
+		for i := 0; i < bytesToRead; i++ {
+			val = val * 256
+			val += int64(pb[i])
+		}
+	}
+	return val
+}
+
+func decodeInteger(src *bufio.Reader) int64 {
+	pb := readByte(src)
+	major := pb & maskOutAdditionalType
+	minor := pb & maskOutMajorType
+	if major != majorTypeUnsignedInt && major != majorTypeNegativeInt {
+		panic(fmt.Errorf("Major type is: %d in decodeInteger!! (expected 0 or 1)", major))
+	}
+	val := decodeIntAdditionalType(src, minor)
+	if major == 0 {
+		return val
+	}
+	return (-1 - val)
+}
+
+func decodeFloat(src *bufio.Reader) (float64, int) {
+	pb := readByte(src)
+	major := pb & maskOutAdditionalType
+	minor := pb & maskOutMajorType
+	if major != majorTypeSimpleAndFloat {
+		panic(fmt.Errorf("Incorrect Major type is: %d in decodeFloat", major))
+	}
+
+	switch minor {
+	case additionalTypeFloat16:
+		panic(fmt.Errorf("float16 is not supported in decodeFloat"))
+
+	case additionalTypeFloat32:
+		pb := readNBytes(src, 4)
+		switch string(pb) {
+		case float32Nan:
+			return math.NaN(), isFloat32
+		case float32PosInfinity:
+			return math.Inf(0), isFloat32
+		case float32NegInfinity:
+			return math.Inf(-1), isFloat32
+		}
+		n := uint32(0)
+		for i := 0; i < 4; i++ {
+			n = n * 256
+			n += uint32(pb[i])
+		}
+		val := math.Float32frombits(n)
+		return float64(val), isFloat32
+	case additionalTypeFloat64:
+		pb := readNBytes(src, 8)
+		switch string(pb) {
+		case float64Nan:
+			return math.NaN(), isFloat64
+		case float64PosInfinity:
+			return math.Inf(0), isFloat64
+		case float64NegInfinity:
+			return math.Inf(-1), isFloat64
+		}
+		n := uint64(0)
+		for i := 0; i < 8; i++ {
+			n = n * 256
+			n += uint64(pb[i])
+		}
+		val := math.Float64frombits(n)
+		return val, isFloat64
+	}
+	panic(fmt.Errorf("Invalid Additional Type: %d in decodeFloat", minor))
+}
+
+func decodeStringComplex(dst []byte, s string, pos uint) []byte {
+	i := int(pos)
+	start := 0
+
+	for i < len(s) {
+		b := s[i]
+		if b >= utf8.RuneSelf {
+			r, size := utf8.DecodeRuneInString(s[i:])
+			if r == utf8.RuneError && size == 1 {
+				// In case of error, first append previous simple characters to
+				// the byte slice if any and append a replacement character code
+				// in place of the invalid sequence.
+				if start < i {
+					dst = append(dst, s[start:i]...)
+				}
+				dst = append(dst, `\ufffd`...)
+				i += size
+				start = i
+				continue
+			}
+			i += size
+			continue
+		}
+		if b >= 0x20 && b <= 0x7e && b != '\\' && b != '"' {
+			i++
+			continue
+		}
+		// We encountered a character that needs to be encoded.
+		// Let's append the previous simple characters to the byte slice
+		// and switch our operation to read and encode the remainder
+		// characters byte-by-byte.
+		if start < i {
+			dst = append(dst, s[start:i]...)
+		}
+		switch b {
+		case '"', '\\':
+			dst = append(dst, '\\', b)
+		case '\b':
+			dst = append(dst, '\\', 'b')
+		case '\f':
+			dst = append(dst, '\\', 'f')
+		case '\n':
+			dst = append(dst, '\\', 'n')
+		case '\r':
+			dst = append(dst, '\\', 'r')
+		case '\t':
+			dst = append(dst, '\\', 't')
+		default:
+			dst = append(dst, '\\', 'u', '0', '0', hexTable[b>>4], hexTable[b&0xF])
+		}
+		i++
+		start = i
+	}
+	if start < len(s) {
+		dst = append(dst, s[start:]...)
+	}
+	return dst
+}
+
+func decodeString(src *bufio.Reader, noQuotes bool) []byte {
+	pb := readByte(src)
+	major := pb & maskOutAdditionalType
+	minor := pb & maskOutMajorType
+	if major != majorTypeByteString {
+		panic(fmt.Errorf("Major type is: %d in decodeString", major))
+	}
+	result := []byte{}
+	if !noQuotes {
+		result = append(result, '"')
+	}
+	length := decodeIntAdditionalType(src, minor)
+	len := int(length)
+	pbs := readNBytes(src, len)
+	result = append(result, pbs...)
+	if noQuotes {
+		return result
+	}
+	return append(result, '"')
+}
+func decodeStringToDataUrl(src *bufio.Reader, mimeType string) []byte {
+	pb := readByte(src)
+	major := pb & maskOutAdditionalType
+	minor := pb & maskOutMajorType
+	if major != majorTypeByteString {
+		panic(fmt.Errorf("Major type is: %d in decodeString", major))
+	}
+	length := decodeIntAdditionalType(src, minor)
+	l := int(length)
+	enc := base64.StdEncoding
+	lEnc := enc.EncodedLen(l)
+	result := make([]byte, len("\"data:;base64,\"")+len(mimeType)+lEnc)
+	dest := result
+	u := copy(dest, "\"data:")
+	dest = dest[u:]
+	u = copy(dest, mimeType)
+	dest = dest[u:]
+	u = copy(dest, ";base64,")
+	dest = dest[u:]
+	pbs := readNBytes(src, l)
+	enc.Encode(dest, pbs)
+	dest = dest[lEnc:]
+	dest[0] = '"'
+	return result
+}
+
+func decodeUTF8String(src *bufio.Reader) []byte {
+	pb := readByte(src)
+	major := pb & maskOutAdditionalType
+	minor := pb & maskOutMajorType
+	if major != majorTypeUtf8String {
+		panic(fmt.Errorf("Major type is: %d in decodeUTF8String", major))
+	}
+	result := []byte{'"'}
+	length := decodeIntAdditionalType(src, minor)
+	len := int(length)
+	pbs := readNBytes(src, len)
+
+	for i := 0; i < len; i++ {
+		// Check if the character needs encoding. Control characters, slashes,
+		// and the double quote need json encoding. Bytes above the ascii
+		// boundary needs utf8 encoding.
+		if pbs[i] < 0x20 || pbs[i] > 0x7e || pbs[i] == '\\' || pbs[i] == '"' {
+			// We encountered a character that needs to be encoded. Switch
+			// to complex version of the algorithm.
+			dst := []byte{'"'}
+			dst = decodeStringComplex(dst, string(pbs), uint(i))
+			return append(dst, '"')
+		}
+	}
+	// The string has no need for encoding and therefore is directly
+	// appended to the byte slice.
+	result = append(result, pbs...)
+	return append(result, '"')
+}
+
+func array2Json(src *bufio.Reader, dst io.Writer) {
+	dst.Write([]byte{'['})
+	pb := readByte(src)
+	major := pb & maskOutAdditionalType
+	minor := pb & maskOutMajorType
+	if major != majorTypeArray {
+		panic(fmt.Errorf("Major type is: %d in array2Json", major))
+	}
+	len := 0
+	unSpecifiedCount := false
+	if minor == additionalTypeInfiniteCount {
+		unSpecifiedCount = true
+	} else {
+		length := decodeIntAdditionalType(src, minor)
+		len = int(length)
+	}
+	for i := 0; unSpecifiedCount || i < len; i++ {
+		if unSpecifiedCount {
+			pb, e := src.Peek(1)
+			if e != nil {
+				panic(e)
+			}
+			if pb[0] == majorTypeSimpleAndFloat|additionalTypeBreak {
+				readByte(src)
+				break
+			}
+		}
+		cbor2JsonOneObject(src, dst)
+		if unSpecifiedCount {
+			pb, e := src.Peek(1)
+			if e != nil {
+				panic(e)
+			}
+			if pb[0] == majorTypeSimpleAndFloat|additionalTypeBreak {
+				readByte(src)
+				break
+			}
+			dst.Write([]byte{','})
+		} else if i+1 < len {
+			dst.Write([]byte{','})
+		}
+	}
+	dst.Write([]byte{']'})
+}
+
+func map2Json(src *bufio.Reader, dst io.Writer) {
+	pb := readByte(src)
+	major := pb & maskOutAdditionalType
+	minor := pb & maskOutMajorType
+	if major != majorTypeMap {
+		panic(fmt.Errorf("Major type is: %d in map2Json", major))
+	}
+	len := 0
+	unSpecifiedCount := false
+	if minor == additionalTypeInfiniteCount {
+		unSpecifiedCount = true
+	} else {
+		length := decodeIntAdditionalType(src, minor)
+		len = int(length)
+	}
+	dst.Write([]byte{'{'})
+	for i := 0; unSpecifiedCount || i < len; i++ {
+		if unSpecifiedCount {
+			pb, e := src.Peek(1)
+			if e != nil {
+				panic(e)
+			}
+			if pb[0] == majorTypeSimpleAndFloat|additionalTypeBreak {
+				readByte(src)
+				break
+			}
+		}
+		cbor2JsonOneObject(src, dst)
+		if i%2 == 0 {
+			// Even position values are keys.
+			dst.Write([]byte{':'})
+		} else {
+			if unSpecifiedCount {
+				pb, e := src.Peek(1)
+				if e != nil {
+					panic(e)
+				}
+				if pb[0] == majorTypeSimpleAndFloat|additionalTypeBreak {
+					readByte(src)
+					break
+				}
+				dst.Write([]byte{','})
+			} else if i+1 < len {
+				dst.Write([]byte{','})
+			}
+		}
+	}
+	dst.Write([]byte{'}'})
+}
+
+func decodeTagData(src *bufio.Reader) []byte {
+	pb := readByte(src)
+	major := pb & maskOutAdditionalType
+	minor := pb & maskOutMajorType
+	if major != majorTypeTags {
+		panic(fmt.Errorf("Major type is: %d in decodeTagData", major))
+	}
+	switch minor {
+	case additionalTypeTimestamp:
+		return decodeTimeStamp(src)
+	case additionalTypeIntUint8:
+		val := decodeIntAdditionalType(src, minor)
+		switch byte(val) {
+		case additionalTypeEmbeddedCBOR:
+			pb := readByte(src)
+			dataMajor := pb & maskOutAdditionalType
+			if dataMajor != majorTypeByteString {
+				panic(fmt.Errorf("Unsupported embedded Type: %d in decodeEmbeddedCBOR", dataMajor))
+			}
+			src.UnreadByte()
+			return decodeStringToDataUrl(src, "application/cbor")
+		default:
+			panic(fmt.Errorf("Unsupported Additional Tag Type: %d in decodeTagData", val))
+		}
+
+	// Tag value is larger than 256 (so uint16).
+	case additionalTypeIntUint16:
+		val := decodeIntAdditionalType(src, minor)
+
+		switch uint16(val) {
+		case additionalTypeEmbeddedJSON:
+			pb := readByte(src)
+			dataMajor := pb & maskOutAdditionalType
+			if dataMajor != majorTypeByteString {
+				panic(fmt.Errorf("Unsupported embedded Type: %d in decodeEmbeddedJSON", dataMajor))
+			}
+			src.UnreadByte()
+			return decodeString(src, true)
+
+		case additionalTypeTagNetworkAddr:
+			octets := decodeString(src, true)
+			ss := []byte{'"'}
+			switch len(octets) {
+			case 6: // MAC address.
+				ha := net.HardwareAddr(octets)
+				ss = append(append(ss, ha.String()...), '"')
+			case 4: // IPv4 address.
+				fallthrough
+			case 16: // IPv6 address.
+				ip := net.IP(octets)
+				ss = append(append(ss, ip.String()...), '"')
+			default:
+				panic(fmt.Errorf("Unexpected Network Address length: %d (expected 4,6,16)", len(octets)))
+			}
+			return ss
+
+		case additionalTypeTagNetworkPrefix:
+			pb := readByte(src)
+			if pb != majorTypeMap|0x1 {
+				panic(fmt.Errorf("IP Prefix is NOT of MAP of 1 elements as expected"))
+			}
+			octets := decodeString(src, true)
+			val := decodeInteger(src)
+			ip := net.IP(octets)
+			var mask net.IPMask
+			pfxLen := int(val)
+			if len(octets) == 4 {
+				mask = net.CIDRMask(pfxLen, 32)
+			} else {
+				mask = net.CIDRMask(pfxLen, 128)
+			}
+			ipPfx := net.IPNet{IP: ip, Mask: mask}
+			ss := []byte{'"'}
+			ss = append(append(ss, ipPfx.String()...), '"')
+			return ss
+
+		case additionalTypeTagHexString:
+			octets := decodeString(src, true)
+			ss := []byte{'"'}
+			for _, v := range octets {
+				ss = append(ss, hexTable[v>>4], hexTable[v&0x0f])
+			}
+			return append(ss, '"')
+
+		default:
+			panic(fmt.Errorf("Unsupported Additional Tag Type: %d in decodeTagData", val))
+		}
+	}
+	panic(fmt.Errorf("Unsupported Additional Type: %d in decodeTagData", minor))
+}
+
+func decodeTimeStamp(src *bufio.Reader) []byte {
+	pb := readByte(src)
+	src.UnreadByte()
+	tsMajor := pb & maskOutAdditionalType
+	if tsMajor == majorTypeUnsignedInt || tsMajor == majorTypeNegativeInt {
+		n := decodeInteger(src)
+		t := time.Unix(n, 0)
+		if decodeTimeZone != nil {
+			t = t.In(decodeTimeZone)
+		} else {
+			t = t.In(time.UTC)
+		}
+		tsb := []byte{}
+		tsb = append(tsb, '"')
+		tsb = t.AppendFormat(tsb, IntegerTimeFieldFormat)
+		tsb = append(tsb, '"')
+		return tsb
+	} else if tsMajor == majorTypeSimpleAndFloat {
+		n, _ := decodeFloat(src)
+		secs := int64(n)
+		n -= float64(secs)
+		n *= float64(1e9)
+		t := time.Unix(secs, int64(n))
+		if decodeTimeZone != nil {
+			t = t.In(decodeTimeZone)
+		} else {
+			t = t.In(time.UTC)
+		}
+		tsb := []byte{}
+		tsb = append(tsb, '"')
+		tsb = t.AppendFormat(tsb, NanoTimeFieldFormat)
+		tsb = append(tsb, '"')
+		return tsb
+	}
+	panic(fmt.Errorf("TS format is neigther int nor float: %d", tsMajor))
+}
+
+func decodeSimpleFloat(src *bufio.Reader) []byte {
+	pb := readByte(src)
+	major := pb & maskOutAdditionalType
+	minor := pb & maskOutMajorType
+	if major != majorTypeSimpleAndFloat {
+		panic(fmt.Errorf("Major type is: %d in decodeSimpleFloat", major))
+	}
+	switch minor {
+	case additionalTypeBoolTrue:
+		return []byte("true")
+	case additionalTypeBoolFalse:
+		return []byte("false")
+	case additionalTypeNull:
+		return []byte("null")
+	case additionalTypeFloat16:
+		fallthrough
+	case additionalTypeFloat32:
+		fallthrough
+	case additionalTypeFloat64:
+		src.UnreadByte()
+		v, bc := decodeFloat(src)
+		ba := []byte{}
+		switch {
+		case math.IsNaN(v):
+			return []byte("\"NaN\"")
+		case math.IsInf(v, 1):
+			return []byte("\"+Inf\"")
+		case math.IsInf(v, -1):
+			return []byte("\"-Inf\"")
+		}
+		if bc == isFloat32 {
+			ba = strconv.AppendFloat(ba, v, 'f', -1, 32)
+		} else if bc == isFloat64 {
+			ba = strconv.AppendFloat(ba, v, 'f', -1, 64)
+		} else {
+			panic(fmt.Errorf("Invalid Float precision from decodeFloat: %d", bc))
+		}
+		return ba
+	default:
+		panic(fmt.Errorf("Invalid Additional Type: %d in decodeSimpleFloat", minor))
+	}
+}
+
+func cbor2JsonOneObject(src *bufio.Reader, dst io.Writer) {
+	pb, e := src.Peek(1)
+	if e != nil {
+		panic(e)
+	}
+	major := (pb[0] & maskOutAdditionalType)
+
+	switch major {
+	case majorTypeUnsignedInt:
+		fallthrough
+	case majorTypeNegativeInt:
+		n := decodeInteger(src)
+		dst.Write([]byte(strconv.Itoa(int(n))))
+
+	case majorTypeByteString:
+		s := decodeString(src, false)
+		dst.Write(s)
+
+	case majorTypeUtf8String:
+		s := decodeUTF8String(src)
+		dst.Write(s)
+
+	case majorTypeArray:
+		array2Json(src, dst)
+
+	case majorTypeMap:
+		map2Json(src, dst)
+
+	case majorTypeTags:
+		s := decodeTagData(src)
+		dst.Write(s)
+
+	case majorTypeSimpleAndFloat:
+		s := decodeSimpleFloat(src)
+		dst.Write(s)
+	}
+}
+
+func moreBytesToRead(src *bufio.Reader) bool {
+	_, e := src.ReadByte()
+	if e == nil {
+		src.UnreadByte()
+		return true
+	}
+	return false
+}
+
+// Cbor2JsonManyObjects decodes all the CBOR Objects read from src
+// reader. It keeps on decoding until reader returns EOF (error when reading).
+// Decoded string is written to the dst. At the end of every CBOR Object
+// newline is written to the output stream.
+//
+// Returns error (if any) that was encountered during decode.
+// The child functions will generate a panic when error is encountered and
+// this function will recover non-runtime Errors and return the reason as error.
+func Cbor2JsonManyObjects(src io.Reader, dst io.Writer) (err error) {
+	defer func() {
+		if r := recover(); r != nil {
+			if _, ok := r.(runtime.Error); ok {
+				panic(r)
+			}
+			err = r.(error)
+		}
+	}()
+	bufRdr := bufio.NewReader(src)
+	for moreBytesToRead(bufRdr) {
+		cbor2JsonOneObject(bufRdr, dst)
+		dst.Write([]byte("\n"))
+	}
+	return nil
+}
+
+// Detect if the bytes to be printed is Binary or not.
+func binaryFmt(p []byte) bool {
+	if len(p) > 0 && p[0] > 0x7F {
+		return true
+	}
+	return false
+}
+
+func getReader(str string) *bufio.Reader {
+	return bufio.NewReader(strings.NewReader(str))
+}
+
+// DecodeIfBinaryToString converts a binary formatted log msg to a
+// JSON formatted String Log message - suitable for printing to Console/Syslog.
+func DecodeIfBinaryToString(in []byte) string {
+	if binaryFmt(in) {
+		var b bytes.Buffer
+		Cbor2JsonManyObjects(strings.NewReader(string(in)), &b)
+		return b.String()
+	}
+	return string(in)
+}
+
+// DecodeObjectToStr checks if the input is a binary format, if so,
+// it will decode a single Object and return the decoded string.
+func DecodeObjectToStr(in []byte) string {
+	if binaryFmt(in) {
+		var b bytes.Buffer
+		cbor2JsonOneObject(getReader(string(in)), &b)
+		return b.String()
+	}
+	return string(in)
+}
+
+// DecodeIfBinaryToBytes checks if the input is a binary format, if so,
+// it will decode all Objects and return the decoded string as byte array.
+func DecodeIfBinaryToBytes(in []byte) []byte {
+	if binaryFmt(in) {
+		var b bytes.Buffer
+		Cbor2JsonManyObjects(bytes.NewReader(in), &b)
+		return b.Bytes()
+	}
+	return in
+}

internal/cbor/decoder_test.go

@@ -0,0 +1,205 @@
+package cbor
+
+import (
+	"bytes"
+	"encoding/hex"
+	"testing"
+	"time"
+)
+
+func TestDecodeInteger(t *testing.T) {
+	for _, tc := range integerTestCases {
+		gotv := decodeInteger(getReader(tc.binary))
+		if gotv != int64(tc.val) {
+			t.Errorf("decodeInteger(0x%s)=0x%d, want: 0x%d",
+				hex.EncodeToString([]byte(tc.binary)), gotv, tc.val)
+		}
+	}
+}
+
+func TestDecodeString(t *testing.T) {
+	for _, tt := range encodeStringTests {
+		got := decodeUTF8String(getReader(tt.binary))
+		if string(got) != "\""+tt.json+"\"" {
+			t.Errorf("DecodeString(0x%s)=%s, want:\"%s\"\n", hex.EncodeToString([]byte(tt.binary)), string(got),
+				hex.EncodeToString([]byte(tt.json)))
+		}
+	}
+}
+
+func TestDecodeArray(t *testing.T) {
+	for _, tc := range integerArrayTestCases {
+		buf := bytes.NewBuffer([]byte{})
+		array2Json(getReader(tc.binary), buf)
+		if buf.String() != tc.json {
+			t.Errorf("array2Json(0x%s)=%s, want: %s", hex.EncodeToString([]byte(tc.binary)), buf.String(), tc.json)
+		}
+	}
+	//Unspecified Length Array
+	var infiniteArrayTestCases = []struct {
+		in  string
+		out string
+	}{
+		{"\x9f\x20\x00\x18\xc8\x14\xff", "[-1,0,200,20]"},
+		{"\x9f\x38\xc7\x29\x18\xc8\x19\x01\x90\xff", "[-200,-10,200,400]"},
+		{"\x9f\x01\x02\x03\xff", "[1,2,3]"},
+		{"\x9f\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x18\x18\x19\xff",
+			"[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25]"},
+	}
+	for _, tc := range infiniteArrayTestCases {
+		buf := bytes.NewBuffer([]byte{})
+		array2Json(getReader(tc.in), buf)
+		if buf.String() != tc.out {
+			t.Errorf("array2Json(0x%s)=%s, want: %s", hex.EncodeToString([]byte(tc.out)), buf.String(), tc.out)
+		}
+	}
+	for _, tc := range booleanArrayTestCases {
+		buf := bytes.NewBuffer([]byte{})
+		array2Json(getReader(tc.binary), buf)
+		if buf.String() != tc.json {
+			t.Errorf("array2Json(0x%s)=%s, want: %s", hex.EncodeToString([]byte(tc.binary)), buf.String(), tc.json)
+		}
+	}
+	//TODO add cases for arrays of other types
+}
+
+var infiniteMapDecodeTestCases = []struct {
+	bin  []byte
+	json string
+}{
+	{[]byte("\xbf\x64IETF\x20\xff"), "{\"IETF\":-1}"},
+	{[]byte("\xbf\x65Array\x84\x20\x00\x18\xc8\x14\xff"), "{\"Array\":[-1,0,200,20]}"},
+}
+
+var mapDecodeTestCases = []struct {
+	bin  []byte
+	json string
+}{
+	{[]byte("\xa2\x64IETF\x20"), "{\"IETF\":-1}"},
+	{[]byte("\xa2\x65Array\x84\x20\x00\x18\xc8\x14"), "{\"Array\":[-1,0,200,20]}"},
+}
+
+func TestDecodeMap(t *testing.T) {
+	for _, tc := range mapDecodeTestCases {
+		buf := bytes.NewBuffer([]byte{})
+		map2Json(getReader(string(tc.bin)), buf)
+		if buf.String() != tc.json {
+			t.Errorf("map2Json(0x%s)=%s, want: %s", hex.EncodeToString(tc.bin), buf.String(), tc.json)
+		}
+	}
+	for _, tc := range infiniteMapDecodeTestCases {
+		buf := bytes.NewBuffer([]byte{})
+		map2Json(getReader(string(tc.bin)), buf)
+		if buf.String() != tc.json {
+			t.Errorf("map2Json(0x%s)=%s, want: %s", hex.EncodeToString(tc.bin), buf.String(), tc.json)
+		}
+	}
+}
+
+func TestDecodeBool(t *testing.T) {
+	for _, tc := range booleanTestCases {
+		got := decodeSimpleFloat(getReader(tc.binary))
+		if string(got) != tc.json {
+			t.Errorf("decodeSimpleFloat(0x%s)=%s, want:%s", hex.EncodeToString([]byte(tc.binary)), string(got), tc.json)
+		}
+	}
+}
+
+func TestDecodeFloat(t *testing.T) {
+	for _, tc := range float32TestCases {
+		got, _ := decodeFloat(getReader(tc.binary))
+		if got != float64(tc.val) {
+			t.Errorf("decodeFloat(0x%s)=%f, want:%f", hex.EncodeToString([]byte(tc.binary)), got, tc.val)
+		}
+	}
+}
+
+func TestDecodeTimestamp(t *testing.T) {
+	decodeTimeZone, _ = time.LoadLocation("UTC")
+	for _, tc := range timeIntegerTestcases {
+		tm := decodeTagData(getReader(tc.binary))
+		if string(tm) != "\""+tc.rfcStr+"\"" {
+			t.Errorf("decodeFloat(0x%s)=%s, want:%s", hex.EncodeToString([]byte(tc.binary)), tm, tc.rfcStr)
+		}
+	}
+	for _, tc := range timeFloatTestcases {
+		tm := decodeTagData(getReader(tc.out))
+		//Since we convert to float and back - it may be slightly off - so
+		//we cannot check for exact equality instead, we'll check it is
+		//very close to each other Less than a Microsecond (lets not yet do nanosec)
+
+		got, _ := time.Parse(string(tm), string(tm))
+		want, _ := time.Parse(tc.rfcStr, tc.rfcStr)
+		if got.Sub(want) > time.Microsecond {
+			t.Errorf("decodeFloat(0x%s)=%s, want:%s", hex.EncodeToString([]byte(tc.out)), tm, tc.rfcStr)
+		}
+	}
+}
+
+func TestDecodeNetworkAddr(t *testing.T) {
+	for _, tc := range ipAddrTestCases {
+		d1 := decodeTagData(getReader(tc.binary))
+		if string(d1) != tc.text {
+			t.Errorf("decodeNetworkAddr(0x%s)=%s, want:%s", hex.EncodeToString([]byte(tc.binary)), d1, tc.text)
+		}
+	}
+}
+
+func TestDecodeMACAddr(t *testing.T) {
+	for _, tc := range macAddrTestCases {
+		d1 := decodeTagData(getReader(tc.binary))
+		if string(d1) != tc.text {
+			t.Errorf("decodeNetworkAddr(0x%s)=%s, want:%s", hex.EncodeToString([]byte(tc.binary)), d1, tc.text)
+		}
+	}
+}
+
+func TestDecodeIPPrefix(t *testing.T) {
+	for _, tc := range IPPrefixTestCases {
+		d1 := decodeTagData(getReader(tc.binary))
+		if string(d1) != tc.text {
+			t.Errorf("decodeIPPrefix(0x%s)=%s, want:%s", hex.EncodeToString([]byte(tc.binary)), d1, tc.text)
+		}
+	}
+}
+
+var compositeCborTestCases = []struct {
+	binary []byte
+	json   string
+}{
+	{[]byte("\xbf\x64IETF\x20\x65Array\x9f\x20\x00\x18\xc8\x14\xff\xff"), "{\"IETF\":-1,\"Array\":[-1,0,200,20]}\n"},
+	{[]byte("\xbf\x64IETF\x64YES!\x65Array\x9f\x20\x00\x18\xc8\x14\xff\xff"), "{\"IETF\":\"YES!\",\"Array\":[-1,0,200,20]}\n"},
+}
+
+func TestDecodeCbor2Json(t *testing.T) {
+	for _, tc := range compositeCborTestCases {
+		buf := bytes.NewBuffer([]byte{})
+		err := Cbor2JsonManyObjects(getReader(string(tc.binary)), buf)
+		if buf.String() != tc.json || err != nil {
+			t.Errorf("cbor2JsonManyObjects(0x%s)=%s, want: %s, err:%s", hex.EncodeToString(tc.binary), buf.String(), tc.json, err.Error())
+		}
+	}
+}
+
+var negativeCborTestCases = []struct {
+	binary []byte
+	errStr string
+}{
+	{[]byte("\xb9\x64IETF\x20\x65Array\x9f\x20\x00\x18\xc8\x14"), "Tried to Read 18 Bytes.. But hit end of file"},
+	{[]byte("\xbf\x64IETF\x20\x65Array\x9f\x20\x00\x18\xc8\x14"), "EOF"},
+	{[]byte("\xbf\x14IETF\x20\x65Array\x9f\x20\x00\x18\xc8\x14"), "Tried to Read 40736 Bytes.. But hit end of file"},
+	{[]byte("\xbf\x64IETF"), "EOF"},
+	{[]byte("\xbf\x64IETF\x20\x65Array\x9f\x20\x00\x18\xc8\xff\xff\xff"), "Invalid Additional Type: 31 in decodeSimpleFloat"},
+	{[]byte("\xbf\x64IETF\x20\x65Array"), "EOF"},
+	{[]byte("\xbf\x64"), "Tried to Read 4 Bytes.. But hit end of file"},
+}
+
+func TestDecodeNegativeCbor2Json(t *testing.T) {
+	for _, tc := range negativeCborTestCases {
+		buf := bytes.NewBuffer([]byte{})
+		err := Cbor2JsonManyObjects(getReader(string(tc.binary)), buf)
+		if err == nil || err.Error() != tc.errStr {
+			t.Errorf("Expected error got:%s, want:%s", err, tc.errStr)
+		}
+	}
+}

internal/cbor/examples/genLog.go

@@ -0,0 +1,55 @@
+package main
+
+import (
+	"compress/zlib"
+	"flag"
+	"io"
+	"log"
+	"os"
+	"time"
+
+	"github.com/rs/zerolog"
+)
+
+func writeLog(fname string, count int, useCompress bool) {
+	opFile := os.Stdout
+	if fname != "<stdout>" {
+		fil, _ := os.Create(fname)
+		opFile = fil
+		defer func() {
+			if err := fil.Close(); err != nil {
+				log.Fatal(err)
+			}
+		}()
+	}
+
+	var f io.WriteCloser = opFile
+	if useCompress {
+		f = zlib.NewWriter(f)
+		defer func() {
+			if err := f.Close(); err != nil {
+				log.Fatal(err)
+			}
+		}()
+
+	}
+
+	zerolog.TimestampFunc = func() time.Time { return time.Now().Round(time.Second) }
+	log := zerolog.New(f).With().
+		Timestamp().
+		Logger()
+	for i := 0; i < count; i++ {
+		log.Error().
+			Int("Fault", 41650+i).Msg("Some Message")
+	}
+}
+
+func main() {
+	outFile := flag.String("out", "<stdout>", "Output File to which logs will be written to (WILL overwrite if already present).")
+	numLogs := flag.Int("num", 10, "Number of log messages to generate.")
+	doCompress := flag.Bool("compress", false, "Enable inline compressed writer")
+
+	flag.Parse()
+
+	writeLog(*outFile, *numLogs, *doCompress)
+}

internal/cbor/examples/makefile

@@ -0,0 +1,10 @@
+all: genLogJSON genLogCBOR
+
+genLogJSON: genLog.go
+	go build -o genLogJSON genLog.go 
+
+genLogCBOR: genLog.go
+	go build -tags binary_log -o genLogCBOR genLog.go 
+
+clean:
+	rm -f genLogJSON genLogCBOR

internal/cbor/string.go

@@ -0,0 +1,117 @@
+package cbor
+
+import "fmt"
+
+// AppendStrings encodes and adds an array of strings to the dst byte array.
+func (e Encoder) AppendStrings(dst []byte, vals []string) []byte {
+	major := majorTypeArray
+	l := len(vals)
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	for _, v := range vals {
+		dst = e.AppendString(dst, v)
+	}
+	return dst
+}
+
+// AppendString encodes and adds a string to the dst byte array.
+func (Encoder) AppendString(dst []byte, s string) []byte {
+	major := majorTypeUtf8String
+
+	l := len(s)
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, majorTypeUtf8String, uint64(l))
+	}
+	return append(dst, s...)
+}
+
+// AppendStringers encodes and adds an array of Stringer values
+// to the dst byte array.
+func (e Encoder) AppendStringers(dst []byte, vals []fmt.Stringer) []byte {
+	if len(vals) == 0 {
+		return e.AppendArrayEnd(e.AppendArrayStart(dst))
+	}
+	dst = e.AppendArrayStart(dst)
+	dst = e.AppendStringer(dst, vals[0])
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = e.AppendStringer(dst, val)
+		}
+	}
+	return e.AppendArrayEnd(dst)
+}
+
+// AppendStringer encodes and adds the Stringer value to the dst
+// byte array.
+func (e Encoder) AppendStringer(dst []byte, val fmt.Stringer) []byte {
+	if val == nil {
+		return e.AppendNil(dst)
+	}
+	return e.AppendString(dst, val.String())
+}
+
+// AppendBytes encodes and adds an array of bytes to the dst byte array.
+func (Encoder) AppendBytes(dst, s []byte) []byte {
+	major := majorTypeByteString
+
+	l := len(s)
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	return append(dst, s...)
+}
+
+// AppendEmbeddedJSON adds a tag and embeds input JSON as such.
+func AppendEmbeddedJSON(dst, s []byte) []byte {
+	major := majorTypeTags
+	minor := additionalTypeEmbeddedJSON
+
+	// Append the TAG to indicate this is Embedded JSON.
+	dst = append(dst, major|additionalTypeIntUint16)
+	dst = append(dst, byte(minor>>8))
+	dst = append(dst, byte(minor&0xff))
+
+	// Append the JSON Object as Byte String.
+	major = majorTypeByteString
+
+	l := len(s)
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	return append(dst, s...)
+}
+
+// AppendEmbeddedCBOR adds a tag and embeds input CBOR as such.
+func AppendEmbeddedCBOR(dst, s []byte) []byte {
+	major := majorTypeTags
+	minor := additionalTypeEmbeddedCBOR
+
+	// Append the TAG to indicate this is Embedded JSON.
+	dst = append(dst, major|additionalTypeIntUint8)
+	dst = append(dst, minor)
+
+	// Append the CBOR Object as Byte String.
+	major = majorTypeByteString
+
+	l := len(s)
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	return append(dst, s...)
+}

internal/cbor/string_test.go

@@ -0,0 +1,118 @@
+package cbor
+
+import (
+	"bytes"
+	"testing"
+)
+
+var encodeStringTests = []struct {
+	plain  string
+	binary string
+	json   string //begin and end quotes are implied
+}{
+	{"", "\x60", ""},
+	{"\\", "\x61\x5c", "\\\\"},
+	{"\x00", "\x61\x00", "\\u0000"},
+	{"\x01", "\x61\x01", "\\u0001"},
+	{"\x02", "\x61\x02", "\\u0002"},
+	{"\x03", "\x61\x03", "\\u0003"},
+	{"\x04", "\x61\x04", "\\u0004"},
+	{"*", "\x61*", "*"},
+	{"a", "\x61a", "a"},
+	{"IETF", "\x64IETF", "IETF"},
+	{"abcdefghijklmnopqrstuvwxyzABCD", "\x78\x1eabcdefghijklmnopqrstuvwxyzABCD", "abcdefghijklmnopqrstuvwxyzABCD"},
+	{"<------------------------------------  This is a 100 character string ----------------------------->" +
+		"<------------------------------------  This is a 100 character string ----------------------------->" +
+		"<------------------------------------  This is a 100 character string ----------------------------->",
+		"\x79\x01\x2c<------------------------------------  This is a 100 character string ----------------------------->" +
+			"<------------------------------------  This is a 100 character string ----------------------------->" +
+			"<------------------------------------  This is a 100 character string ----------------------------->",
+		"<------------------------------------  This is a 100 character string ----------------------------->" +
+			"<------------------------------------  This is a 100 character string ----------------------------->" +
+			"<------------------------------------  This is a 100 character string ----------------------------->"},
+	{"emoji \u2764\ufe0f!", "\x6demoji ❤️!", "emoji \u2764\ufe0f!"},
+}
+
+var encodeByteTests = []struct {
+	plain  []byte
+	binary string
+}{
+	{[]byte{}, "\x40"},
+	{[]byte("\\"), "\x41\x5c"},
+	{[]byte("\x00"), "\x41\x00"},
+	{[]byte("\x01"), "\x41\x01"},
+	{[]byte("\x02"), "\x41\x02"},
+	{[]byte("\x03"), "\x41\x03"},
+	{[]byte("\x04"), "\x41\x04"},
+	{[]byte("*"), "\x41*"},
+	{[]byte("a"), "\x41a"},
+	{[]byte("IETF"), "\x44IETF"},
+	{[]byte("abcdefghijklmnopqrstuvwxyzABCD"), "\x58\x1eabcdefghijklmnopqrstuvwxyzABCD"},
+	{[]byte("<------------------------------------  This is a 100 character string ----------------------------->" +
+		"<------------------------------------  This is a 100 character string ----------------------------->" +
+		"<------------------------------------  This is a 100 character string ----------------------------->"),
+		"\x59\x01\x2c<------------------------------------  This is a 100 character string ----------------------------->" +
+			"<------------------------------------  This is a 100 character string ----------------------------->" +
+			"<------------------------------------  This is a 100 character string ----------------------------->"},
+	{[]byte("emoji \u2764\ufe0f!"), "\x4demoji ❤️!"},
+}
+
+func TestAppendString(t *testing.T) {
+	for _, tt := range encodeStringTests {
+		b := enc.AppendString([]byte{}, tt.plain)
+		if got, want := string(b), tt.binary; got != want {
+			t.Errorf("appendString(%q) = %#q, want %#q", tt.plain, got, want)
+		}
+	}
+	//Test a large string > 65535 length
+
+	var buffer bytes.Buffer
+	for i := 0; i < 0x00011170; i++ { //70,000 character string
+		buffer.WriteString("a")
+	}
+	inp := buffer.String()
+	want := "\x7a\x00\x01\x11\x70" + inp
+	b := enc.AppendString([]byte{}, inp)
+	if got := string(b); got != want {
+		t.Errorf("appendString(%q) = %#q, want %#q", inp, got, want)
+	}
+}
+
+func TestAppendBytes(t *testing.T) {
+	for _, tt := range encodeByteTests {
+		b := enc.AppendBytes([]byte{}, tt.plain)
+		if got, want := string(b), tt.binary; got != want {
+			t.Errorf("appendString(%q) = %#q, want %#q", tt.plain, got, want)
+		}
+	}
+	//Test a large string > 65535 length
+
+	inp := []byte{}
+	for i := 0; i < 0x00011170; i++ { //70,000 character string
+		inp = append(inp, byte('a'))
+	}
+	want := "\x5a\x00\x01\x11\x70" + string(inp)
+	b := enc.AppendBytes([]byte{}, inp)
+	if got := string(b); got != want {
+		t.Errorf("appendString(%q) = %#q, want %#q", inp, got, want)
+	}
+}
+func BenchmarkAppendString(b *testing.B) {
+	tests := map[string]string{
+		"NoEncoding":       `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,
+		"EncodingFirst":    `"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,
+		"EncodingMiddle":   `aaaaaaaaaaaaaaaaaaaaaaaaa"aaaaaaaaaaaaaaaaaaaaaaaa`,
+		"EncodingLast":     `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"`,
+		"MultiBytesFirst":  `❤️aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,
+		"MultiBytesMiddle": `aaaaaaaaaaaaaaaaaaaaaaaaa❤️aaaaaaaaaaaaaaaaaaaaaaaa`,
+		"MultiBytesLast":   `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa❤️`,
+	}
+	for name, str := range tests {
+		b.Run(name, func(b *testing.B) {
+			buf := make([]byte, 0, 120)
+			for i := 0; i < b.N; i++ {
+				_ = enc.AppendString(buf, str)
+			}
+		})
+	}
+}

internal/cbor/time.go

@@ -0,0 +1,93 @@
+package cbor
+
+import (
+	"time"
+)
+
+func appendIntegerTimestamp(dst []byte, t time.Time) []byte {
+	major := majorTypeTags
+	minor := additionalTypeTimestamp
+	dst = append(dst, major|minor)
+	secs := t.Unix()
+	var val uint64
+	if secs < 0 {
+		major = majorTypeNegativeInt
+		val = uint64(-secs - 1)
+	} else {
+		major = majorTypeUnsignedInt
+		val = uint64(secs)
+	}
+	dst = appendCborTypePrefix(dst, major, val)
+	return dst
+}
+
+func (e Encoder) appendFloatTimestamp(dst []byte, t time.Time) []byte {
+	major := majorTypeTags
+	minor := additionalTypeTimestamp
+	dst = append(dst, major|minor)
+	secs := t.Unix()
+	nanos := t.Nanosecond()
+	var val float64
+	val = float64(secs)*1.0 + float64(nanos)*1e-9
+	return e.AppendFloat64(dst, val, -1)
+}
+
+// AppendTime encodes and adds a timestamp to the dst byte array.
+func (e Encoder) AppendTime(dst []byte, t time.Time, unused string) []byte {
+	utc := t.UTC()
+	if utc.Nanosecond() == 0 {
+		return appendIntegerTimestamp(dst, utc)
+	}
+	return e.appendFloatTimestamp(dst, utc)
+}
+
+// AppendTimes encodes and adds an array of timestamps to the dst byte array.
+func (e Encoder) AppendTimes(dst []byte, vals []time.Time, unused string) []byte {
+	major := majorTypeArray
+	l := len(vals)
+	if l == 0 {
+		return e.AppendArrayEnd(e.AppendArrayStart(dst))
+	}
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+
+	for _, t := range vals {
+		dst = e.AppendTime(dst, t, unused)
+	}
+	return dst
+}
+
+// AppendDuration encodes and adds a duration to the dst byte array.
+// useInt field indicates whether to store the duration as seconds (integer) or
+// as seconds+nanoseconds (float).
+func (e Encoder) AppendDuration(dst []byte, d time.Duration, unit time.Duration, useInt bool, unused int) []byte {
+	if useInt {
+		return e.AppendInt64(dst, int64(d/unit))
+	}
+	return e.AppendFloat64(dst, float64(d)/float64(unit), unused)
+}
+
+// AppendDurations encodes and adds an array of durations to the dst byte array.
+// useInt field indicates whether to store the duration as seconds (integer) or
+// as seconds+nanoseconds (float).
+func (e Encoder) AppendDurations(dst []byte, vals []time.Duration, unit time.Duration, useInt bool, unused int) []byte {
+	major := majorTypeArray
+	l := len(vals)
+	if l == 0 {
+		return e.AppendArrayEnd(e.AppendArrayStart(dst))
+	}
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	for _, d := range vals {
+		dst = e.AppendDuration(dst, d, unit, useInt, unused)
+	}
+	return dst
+}

internal/cbor/time_test.go

@@ -0,0 +1,99 @@
+package cbor
+
+import (
+	"encoding/hex"
+	"fmt"
+	"math"
+	"testing"
+	"time"
+)
+
+func TestAppendTimeNow(t *testing.T) {
+	tm := time.Now()
+	s := enc.AppendTime([]byte{}, tm, "unused")
+	got := string(s)
+
+	tm1 := float64(tm.Unix()) + float64(tm.Nanosecond())*1E-9
+	tm2 := math.Float64bits(tm1)
+	var tm3 [8]byte
+	for i := uint(0); i < 8; i++ {
+		tm3[i] = byte(tm2 >> ((8 - i - 1) * 8))
+	}
+	want := append([]byte{0xc1, 0xfb}, tm3[:]...)
+	if got != string(want) {
+		t.Errorf("Appendtime(%s)=0x%s, want: 0x%s",
+			"time.Now()", hex.EncodeToString(s),
+			hex.EncodeToString(want))
+	}
+}
+
+var timeIntegerTestcases = []struct {
+	txt    string
+	binary string
+	rfcStr string
+}{
+	{"2013-02-03T19:54:00-08:00", "\xc1\x1a\x51\x0f\x30\xd8", "2013-02-04T03:54:00Z"},
+	{"1950-02-03T19:54:00-08:00", "\xc1\x3a\x25\x71\x93\xa7", "1950-02-04T03:54:00Z"},
+}
+
+func TestAppendTimePastPresentInteger(t *testing.T) {
+	for _, tt := range timeIntegerTestcases {
+		tin, err := time.Parse(time.RFC3339, tt.txt)
+		if err != nil {
+			fmt.Println("Cannot parse input", tt.txt, ".. Skipping!", err)
+			continue
+		}
+		b := enc.AppendTime([]byte{}, tin, "unused")
+		if got, want := string(b), tt.binary; got != want {
+			t.Errorf("appendString(%s) = 0x%s, want 0x%s", tt.txt,
+				hex.EncodeToString(b),
+				hex.EncodeToString([]byte(want)))
+		}
+	}
+}
+
+var timeFloatTestcases = []struct {
+	rfcStr string
+	out    string
+}{
+	{"2006-01-02T15:04:05.999999-08:00", "\xc1\xfb\x41\xd0\xee\x6c\x59\x7f\xff\xfc"},
+	{"1956-01-02T15:04:05.999999-08:00", "\xc1\xfb\xc1\xba\x53\x81\x1a\x00\x00\x11"},
+}
+
+func TestAppendTimePastPresentFloat(t *testing.T) {
+	const timeFloatFmt = "2006-01-02T15:04:05.999999-07:00"
+	for _, tt := range timeFloatTestcases {
+		tin, err := time.Parse(timeFloatFmt, tt.rfcStr)
+		if err != nil {
+			fmt.Println("Cannot parse input", tt.rfcStr, ".. Skipping!")
+			continue
+		}
+		b := enc.AppendTime([]byte{}, tin, "unused")
+		if got, want := string(b), tt.out; got != want {
+			t.Errorf("appendString(%s) = 0x%s, want 0x%s", tt.rfcStr,
+				hex.EncodeToString(b),
+				hex.EncodeToString([]byte(want)))
+		}
+	}
+}
+
+func BenchmarkAppendTime(b *testing.B) {
+	tests := map[string]string{
+		"Integer": "Feb 3, 2013 at 7:54pm (PST)",
+		"Float":   "2006-01-02T15:04:05.999999-08:00",
+	}
+	const timeFloatFmt = "2006-01-02T15:04:05.999999-07:00"
+
+	for name, str := range tests {
+		t, err := time.Parse(time.RFC3339, str)
+		if err != nil {
+			t, _ = time.Parse(timeFloatFmt, str)
+		}
+		b.Run(name, func(b *testing.B) {
+			buf := make([]byte, 0, 100)
+			for i := 0; i < b.N; i++ {
+				_ = enc.AppendTime(buf, t, "unused")
+			}
+		})
+	}
+}

internal/cbor/types.go

@@ -0,0 +1,486 @@
+package cbor
+
+import (
+	"fmt"
+	"math"
+	"net"
+	"reflect"
+)
+
+// AppendNil inserts a 'Nil' object into the dst byte array.
+func (Encoder) AppendNil(dst []byte) []byte {
+	return append(dst, majorTypeSimpleAndFloat|additionalTypeNull)
+}
+
+// AppendBeginMarker inserts a map start into the dst byte array.
+func (Encoder) AppendBeginMarker(dst []byte) []byte {
+	return append(dst, majorTypeMap|additionalTypeInfiniteCount)
+}
+
+// AppendEndMarker inserts a map end into the dst byte array.
+func (Encoder) AppendEndMarker(dst []byte) []byte {
+	return append(dst, majorTypeSimpleAndFloat|additionalTypeBreak)
+}
+
+// AppendObjectData takes an object in form of a byte array and appends to dst.
+func (Encoder) AppendObjectData(dst []byte, o []byte) []byte {
+	// BeginMarker is present in the dst, which
+	// should not be copied when appending to existing data.
+	return append(dst, o[1:]...)
+}
+
+// AppendArrayStart adds markers to indicate the start of an array.
+func (Encoder) AppendArrayStart(dst []byte) []byte {
+	return append(dst, majorTypeArray|additionalTypeInfiniteCount)
+}
+
+// AppendArrayEnd adds markers to indicate the end of an array.
+func (Encoder) AppendArrayEnd(dst []byte) []byte {
+	return append(dst, majorTypeSimpleAndFloat|additionalTypeBreak)
+}
+
+// AppendArrayDelim adds markers to indicate end of a particular array element.
+func (Encoder) AppendArrayDelim(dst []byte) []byte {
+	//No delimiters needed in cbor
+	return dst
+}
+
+// AppendLineBreak is a noop that keep API compat with json encoder.
+func (Encoder) AppendLineBreak(dst []byte) []byte {
+	// No line breaks needed in binary format.
+	return dst
+}
+
+// AppendBool encodes and inserts a boolean value into the dst byte array.
+func (Encoder) AppendBool(dst []byte, val bool) []byte {
+	b := additionalTypeBoolFalse
+	if val {
+		b = additionalTypeBoolTrue
+	}
+	return append(dst, majorTypeSimpleAndFloat|b)
+}
+
+// AppendBools encodes and inserts an array of boolean values into the dst byte array.
+func (e Encoder) AppendBools(dst []byte, vals []bool) []byte {
+	major := majorTypeArray
+	l := len(vals)
+	if l == 0 {
+		return e.AppendArrayEnd(e.AppendArrayStart(dst))
+	}
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	for _, v := range vals {
+		dst = e.AppendBool(dst, v)
+	}
+	return dst
+}
+
+// AppendInt encodes and inserts an integer value into the dst byte array.
+func (Encoder) AppendInt(dst []byte, val int) []byte {
+	major := majorTypeUnsignedInt
+	contentVal := val
+	if val < 0 {
+		major = majorTypeNegativeInt
+		contentVal = -val - 1
+	}
+	if contentVal <= additionalMax {
+		lb := byte(contentVal)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(contentVal))
+	}
+	return dst
+}
+
+// AppendInts encodes and inserts an array of integer values into the dst byte array.
+func (e Encoder) AppendInts(dst []byte, vals []int) []byte {
+	major := majorTypeArray
+	l := len(vals)
+	if l == 0 {
+		return e.AppendArrayEnd(e.AppendArrayStart(dst))
+	}
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	for _, v := range vals {
+		dst = e.AppendInt(dst, v)
+	}
+	return dst
+}
+
+// AppendInt8 encodes and inserts an int8 value into the dst byte array.
+func (e Encoder) AppendInt8(dst []byte, val int8) []byte {
+	return e.AppendInt(dst, int(val))
+}
+
+// AppendInts8 encodes and inserts an array of integer values into the dst byte array.
+func (e Encoder) AppendInts8(dst []byte, vals []int8) []byte {
+	major := majorTypeArray
+	l := len(vals)
+	if l == 0 {
+		return e.AppendArrayEnd(e.AppendArrayStart(dst))
+	}
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	for _, v := range vals {
+		dst = e.AppendInt(dst, int(v))
+	}
+	return dst
+}
+
+// AppendInt16 encodes and inserts a int16 value into the dst byte array.
+func (e Encoder) AppendInt16(dst []byte, val int16) []byte {
+	return e.AppendInt(dst, int(val))
+}
+
+// AppendInts16 encodes and inserts an array of int16 values into the dst byte array.
+func (e Encoder) AppendInts16(dst []byte, vals []int16) []byte {
+	major := majorTypeArray
+	l := len(vals)
+	if l == 0 {
+		return e.AppendArrayEnd(e.AppendArrayStart(dst))
+	}
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	for _, v := range vals {
+		dst = e.AppendInt(dst, int(v))
+	}
+	return dst
+}
+
+// AppendInt32 encodes and inserts a int32 value into the dst byte array.
+func (e Encoder) AppendInt32(dst []byte, val int32) []byte {
+	return e.AppendInt(dst, int(val))
+}
+
+// AppendInts32 encodes and inserts an array of int32 values into the dst byte array.
+func (e Encoder) AppendInts32(dst []byte, vals []int32) []byte {
+	major := majorTypeArray
+	l := len(vals)
+	if l == 0 {
+		return e.AppendArrayEnd(e.AppendArrayStart(dst))
+	}
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	for _, v := range vals {
+		dst = e.AppendInt(dst, int(v))
+	}
+	return dst
+}
+
+// AppendInt64 encodes and inserts a int64 value into the dst byte array.
+func (Encoder) AppendInt64(dst []byte, val int64) []byte {
+	major := majorTypeUnsignedInt
+	contentVal := val
+	if val < 0 {
+		major = majorTypeNegativeInt
+		contentVal = -val - 1
+	}
+	if contentVal <= additionalMax {
+		lb := byte(contentVal)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(contentVal))
+	}
+	return dst
+}
+
+// AppendInts64 encodes and inserts an array of int64 values into the dst byte array.
+func (e Encoder) AppendInts64(dst []byte, vals []int64) []byte {
+	major := majorTypeArray
+	l := len(vals)
+	if l == 0 {
+		return e.AppendArrayEnd(e.AppendArrayStart(dst))
+	}
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	for _, v := range vals {
+		dst = e.AppendInt64(dst, v)
+	}
+	return dst
+}
+
+// AppendUint encodes and inserts an unsigned integer value into the dst byte array.
+func (e Encoder) AppendUint(dst []byte, val uint) []byte {
+	return e.AppendInt64(dst, int64(val))
+}
+
+// AppendUints encodes and inserts an array of unsigned integer values into the dst byte array.
+func (e Encoder) AppendUints(dst []byte, vals []uint) []byte {
+	major := majorTypeArray
+	l := len(vals)
+	if l == 0 {
+		return e.AppendArrayEnd(e.AppendArrayStart(dst))
+	}
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	for _, v := range vals {
+		dst = e.AppendUint(dst, v)
+	}
+	return dst
+}
+
+// AppendUint8 encodes and inserts a unsigned int8 value into the dst byte array.
+func (e Encoder) AppendUint8(dst []byte, val uint8) []byte {
+	return e.AppendUint(dst, uint(val))
+}
+
+// AppendUints8 encodes and inserts an array of uint8 values into the dst byte array.
+func (e Encoder) AppendUints8(dst []byte, vals []uint8) []byte {
+	major := majorTypeArray
+	l := len(vals)
+	if l == 0 {
+		return e.AppendArrayEnd(e.AppendArrayStart(dst))
+	}
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	for _, v := range vals {
+		dst = e.AppendUint8(dst, v)
+	}
+	return dst
+}
+
+// AppendUint16 encodes and inserts a uint16 value into the dst byte array.
+func (e Encoder) AppendUint16(dst []byte, val uint16) []byte {
+	return e.AppendUint(dst, uint(val))
+}
+
+// AppendUints16 encodes and inserts an array of uint16 values into the dst byte array.
+func (e Encoder) AppendUints16(dst []byte, vals []uint16) []byte {
+	major := majorTypeArray
+	l := len(vals)
+	if l == 0 {
+		return e.AppendArrayEnd(e.AppendArrayStart(dst))
+	}
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	for _, v := range vals {
+		dst = e.AppendUint16(dst, v)
+	}
+	return dst
+}
+
+// AppendUint32 encodes and inserts a uint32 value into the dst byte array.
+func (e Encoder) AppendUint32(dst []byte, val uint32) []byte {
+	return e.AppendUint(dst, uint(val))
+}
+
+// AppendUints32 encodes and inserts an array of uint32 values into the dst byte array.
+func (e Encoder) AppendUints32(dst []byte, vals []uint32) []byte {
+	major := majorTypeArray
+	l := len(vals)
+	if l == 0 {
+		return e.AppendArrayEnd(e.AppendArrayStart(dst))
+	}
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	for _, v := range vals {
+		dst = e.AppendUint32(dst, v)
+	}
+	return dst
+}
+
+// AppendUint64 encodes and inserts a uint64 value into the dst byte array.
+func (Encoder) AppendUint64(dst []byte, val uint64) []byte {
+	major := majorTypeUnsignedInt
+	contentVal := val
+	if contentVal <= additionalMax {
+		lb := byte(contentVal)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, contentVal)
+	}
+	return dst
+}
+
+// AppendUints64 encodes and inserts an array of uint64 values into the dst byte array.
+func (e Encoder) AppendUints64(dst []byte, vals []uint64) []byte {
+	major := majorTypeArray
+	l := len(vals)
+	if l == 0 {
+		return e.AppendArrayEnd(e.AppendArrayStart(dst))
+	}
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	for _, v := range vals {
+		dst = e.AppendUint64(dst, v)
+	}
+	return dst
+}
+
+// AppendFloat32 encodes and inserts a single precision float value into the dst byte array.
+func (Encoder) AppendFloat32(dst []byte, val float32, unused int) []byte {
+	switch {
+	case math.IsNaN(float64(val)):
+		return append(dst, "\xfa\x7f\xc0\x00\x00"...)
+	case math.IsInf(float64(val), 1):
+		return append(dst, "\xfa\x7f\x80\x00\x00"...)
+	case math.IsInf(float64(val), -1):
+		return append(dst, "\xfa\xff\x80\x00\x00"...)
+	}
+	major := majorTypeSimpleAndFloat
+	subType := additionalTypeFloat32
+	n := math.Float32bits(val)
+	var buf [4]byte
+	for i := uint(0); i < 4; i++ {
+		buf[i] = byte(n >> ((3 - i) * 8))
+	}
+	return append(append(dst, major|subType), buf[0], buf[1], buf[2], buf[3])
+}
+
+// AppendFloats32 encodes and inserts an array of single precision float value into the dst byte array.
+func (e Encoder) AppendFloats32(dst []byte, vals []float32, unused int) []byte {
+	major := majorTypeArray
+	l := len(vals)
+	if l == 0 {
+		return e.AppendArrayEnd(e.AppendArrayStart(dst))
+	}
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	for _, v := range vals {
+		dst = e.AppendFloat32(dst, v, unused)
+	}
+	return dst
+}
+
+// AppendFloat64 encodes and inserts a double precision float value into the dst byte array.
+func (Encoder) AppendFloat64(dst []byte, val float64, unused int) []byte {
+	switch {
+	case math.IsNaN(val):
+		return append(dst, "\xfb\x7f\xf8\x00\x00\x00\x00\x00\x00"...)
+	case math.IsInf(val, 1):
+		return append(dst, "\xfb\x7f\xf0\x00\x00\x00\x00\x00\x00"...)
+	case math.IsInf(val, -1):
+		return append(dst, "\xfb\xff\xf0\x00\x00\x00\x00\x00\x00"...)
+	}
+	major := majorTypeSimpleAndFloat
+	subType := additionalTypeFloat64
+	n := math.Float64bits(val)
+	dst = append(dst, major|subType)
+	for i := uint(1); i <= 8; i++ {
+		b := byte(n >> ((8 - i) * 8))
+		dst = append(dst, b)
+	}
+	return dst
+}
+
+// AppendFloats64 encodes and inserts an array of double precision float values into the dst byte array.
+func (e Encoder) AppendFloats64(dst []byte, vals []float64, unused int) []byte {
+	major := majorTypeArray
+	l := len(vals)
+	if l == 0 {
+		return e.AppendArrayEnd(e.AppendArrayStart(dst))
+	}
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, major|lb)
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	for _, v := range vals {
+		dst = e.AppendFloat64(dst, v, unused)
+	}
+	return dst
+}
+
+// AppendInterface takes an arbitrary object and converts it to JSON and embeds it dst.
+func (e Encoder) AppendInterface(dst []byte, i interface{}) []byte {
+	marshaled, err := JSONMarshalFunc(i)
+	if err != nil {
+		return e.AppendString(dst, fmt.Sprintf("marshaling error: %v", err))
+	}
+	return AppendEmbeddedJSON(dst, marshaled)
+}
+
+// AppendType appends the parameter type (as a string) to the input byte slice.
+func (e Encoder) AppendType(dst []byte, i interface{}) []byte {
+	if i == nil {
+		return e.AppendString(dst, "<nil>")
+	}
+	return e.AppendString(dst, reflect.TypeOf(i).String())
+}
+
+// AppendIPAddr encodes and inserts an IP Address (IPv4 or IPv6).
+func (e Encoder) AppendIPAddr(dst []byte, ip net.IP) []byte {
+	dst = append(dst, majorTypeTags|additionalTypeIntUint16)
+	dst = append(dst, byte(additionalTypeTagNetworkAddr>>8))
+	dst = append(dst, byte(additionalTypeTagNetworkAddr&0xff))
+	return e.AppendBytes(dst, ip)
+}
+
+// AppendIPPrefix encodes and inserts an IP Address Prefix (Address + Mask Length).
+func (e Encoder) AppendIPPrefix(dst []byte, pfx net.IPNet) []byte {
+	dst = append(dst, majorTypeTags|additionalTypeIntUint16)
+	dst = append(dst, byte(additionalTypeTagNetworkPrefix>>8))
+	dst = append(dst, byte(additionalTypeTagNetworkPrefix&0xff))
+
+	// Prefix is a tuple (aka MAP of 1 pair of elements) -
+	// first element is prefix, second is mask length.
+	dst = append(dst, majorTypeMap|0x1)
+	dst = e.AppendBytes(dst, pfx.IP)
+	maskLen, _ := pfx.Mask.Size()
+	return e.AppendUint8(dst, uint8(maskLen))
+}
+
+// AppendMACAddr encodes and inserts a Hardware (MAC) address.
+func (e Encoder) AppendMACAddr(dst []byte, ha net.HardwareAddr) []byte {
+	dst = append(dst, majorTypeTags|additionalTypeIntUint16)
+	dst = append(dst, byte(additionalTypeTagNetworkAddr>>8))
+	dst = append(dst, byte(additionalTypeTagNetworkAddr&0xff))
+	return e.AppendBytes(dst, ha)
+}
+
+// AppendHex adds a TAG and inserts a hex bytes as a string.
+func (e Encoder) AppendHex(dst []byte, val []byte) []byte {
+	dst = append(dst, majorTypeTags|additionalTypeIntUint16)
+	dst = append(dst, byte(additionalTypeTagHexString>>8))
+	dst = append(dst, byte(additionalTypeTagHexString&0xff))
+	return e.AppendBytes(dst, val)
+}

internal/cbor/types_64_test.go

@@ -0,0 +1,34 @@
+// +build !386
+
+package cbor
+
+import (
+	"encoding/hex"
+	"testing"
+)
+
+var enc2 = Encoder{}
+
+var integerTestCases_64bit = []struct {
+	val    int
+	binary string
+}{
+	// Value in 8 bytes.
+	{0xabcd100000000, "\x1b\x00\x0a\xbc\xd1\x00\x00\x00\x00"},
+	{1000000000000, "\x1b\x00\x00\x00\xe8\xd4\xa5\x10\x00"},
+	// Value in 8 bytes.
+	{-0xabcd100000001, "\x3b\x00\x0a\xbc\xd1\x00\x00\x00\x00"},
+	{-1000000000001, "\x3b\x00\x00\x00\xe8\xd4\xa5\x10\x00"},
+}
+
+func TestAppendInt_64bit(t *testing.T) {
+	for _, tc := range integerTestCases_64bit {
+		s := enc2.AppendInt([]byte{}, tc.val)
+		got := string(s)
+		if got != tc.binary {
+			t.Errorf("AppendInt(0x%x)=0x%s, want: 0x%s",
+				tc.val, hex.EncodeToString(s),
+				hex.EncodeToString([]byte(tc.binary)))
+		}
+	}
+}

internal/cbor/types_test.go

@@ -0,0 +1,316 @@
+package cbor
+
+import (
+	"encoding/hex"
+	"net"
+	"testing"
+)
+
+var enc = Encoder{}
+
+func TestAppendNil(t *testing.T) {
+	s := enc.AppendNil([]byte{})
+	got := string(s)
+	want := "\xf6"
+	if got != want {
+		t.Errorf("appendNull() = 0x%s, want: 0x%s", hex.EncodeToString(s),
+			hex.EncodeToString([]byte(want)))
+	}
+}
+
+var booleanTestCases = []struct {
+	val    bool
+	binary string
+	json   string
+}{
+	{true, "\xf5", "true"},
+	{false, "\xf4", "false"},
+}
+
+func TestAppendBool(t *testing.T) {
+	for _, tc := range booleanTestCases {
+		s := enc.AppendBool([]byte{}, tc.val)
+		got := string(s)
+		if got != tc.binary {
+			t.Errorf("AppendBool(%s)=0x%s, want: 0x%s",
+				tc.json, hex.EncodeToString(s),
+				hex.EncodeToString([]byte(tc.binary)))
+		}
+	}
+}
+
+var booleanArrayTestCases = []struct {
+	val    []bool
+	binary string
+	json   string
+}{
+	{[]bool{true, false, true}, "\x83\xf5\xf4\xf5", "[true,false,true]"},
+	{[]bool{true, false, false, true, false, true}, "\x86\xf5\xf4\xf4\xf5\xf4\xf5", "[true,false,false,true,false,true]"},
+}
+
+func TestAppendBoolArray(t *testing.T) {
+	for _, tc := range booleanArrayTestCases {
+		s := enc.AppendBools([]byte{}, tc.val)
+		got := string(s)
+		if got != tc.binary {
+			t.Errorf("AppendBools(%s)=0x%s, want: 0x%s",
+				tc.json, hex.EncodeToString(s),
+				hex.EncodeToString([]byte(tc.binary)))
+		}
+	}
+}
+
+var integerTestCases = []struct {
+	val    int
+	binary string
+}{
+	// Value included in the type.
+	{0, "\x00"},
+	{1, "\x01"},
+	{2, "\x02"},
+	{3, "\x03"},
+	{8, "\x08"},
+	{9, "\x09"},
+	{10, "\x0a"},
+	{22, "\x16"},
+	{23, "\x17"},
+	// Value in 1 byte.
+	{24, "\x18\x18"},
+	{25, "\x18\x19"},
+	{26, "\x18\x1a"},
+	{100, "\x18\x64"},
+	{254, "\x18\xfe"},
+	{255, "\x18\xff"},
+	// Value in 2 bytes.
+	{256, "\x19\x01\x00"},
+	{257, "\x19\x01\x01"},
+	{1000, "\x19\x03\xe8"},
+	{0xFFFF, "\x19\xff\xff"},
+	// Value in 4 bytes.
+	{0x10000, "\x1a\x00\x01\x00\x00"},
+	{0x7FFFFFFE, "\x1a\x7f\xff\xff\xfe"},
+	{1000000, "\x1a\x00\x0f\x42\x40"},
+	// Negative number test cases.
+	// Value included in the type.
+	{-1, "\x20"},
+	{-2, "\x21"},
+	{-3, "\x22"},
+	{-10, "\x29"},
+	{-21, "\x34"},
+	{-22, "\x35"},
+	{-23, "\x36"},
+	{-24, "\x37"},
+	// Value in 1 byte.
+	{-25, "\x38\x18"},
+	{-26, "\x38\x19"},
+	{-100, "\x38\x63"},
+	{-254, "\x38\xfd"},
+	{-255, "\x38\xfe"},
+	{-256, "\x38\xff"},
+	// Value in 2 bytes.
+	{-257, "\x39\x01\x00"},
+	{-258, "\x39\x01\x01"},
+	{-1000, "\x39\x03\xe7"},
+	// Value in 4 bytes.
+	{-0x10001, "\x3a\x00\x01\x00\x00"},
+	{-0x7FFFFFFE, "\x3a\x7f\xff\xff\xfd"},
+	{-1000000, "\x3a\x00\x0f\x42\x3f"},
+}
+
+func TestAppendInt(t *testing.T) {
+	for _, tc := range integerTestCases {
+		s := enc.AppendInt([]byte{}, tc.val)
+		got := string(s)
+		if got != tc.binary {
+			t.Errorf("AppendInt(0x%x)=0x%s, want: 0x%s",
+				tc.val, hex.EncodeToString(s),
+				hex.EncodeToString([]byte(tc.binary)))
+		}
+	}
+}
+
+var integerArrayTestCases = []struct {
+	val    []int
+	binary string
+	json   string
+}{
+	{[]int{-1, 0, 200, 20}, "\x84\x20\x00\x18\xc8\x14", "[-1,0,200,20]"},
+	{[]int{-200, -10, 200, 400}, "\x84\x38\xc7\x29\x18\xc8\x19\x01\x90", "[-200,-10,200,400]"},
+	{[]int{1, 2, 3}, "\x83\x01\x02\x03", "[1,2,3]"},
+	{[]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25},
+		"\x98\x19\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x18\x18\x19",
+		"[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25]"},
+}
+
+func TestAppendIntArray(t *testing.T) {
+	for _, tc := range integerArrayTestCases {
+		s := enc.AppendInts([]byte{}, tc.val)
+		got := string(s)
+		if got != tc.binary {
+			t.Errorf("AppendInts(%s)=0x%s, want: 0x%s",
+				tc.json, hex.EncodeToString(s),
+				hex.EncodeToString([]byte(tc.binary)))
+		}
+	}
+}
+
+var float32TestCases = []struct {
+	val    float32
+	binary string
+}{
+	{0.0, "\xfa\x00\x00\x00\x00"},
+	{-0.0, "\xfa\x00\x00\x00\x00"},
+	{1.0, "\xfa\x3f\x80\x00\x00"},
+	{1.5, "\xfa\x3f\xc0\x00\x00"},
+	{65504.0, "\xfa\x47\x7f\xe0\x00"},
+	{-4.0, "\xfa\xc0\x80\x00\x00"},
+	{0.00006103515625, "\xfa\x38\x80\x00\x00"},
+}
+
+func TestAppendFloat32(t *testing.T) {
+	for _, tc := range float32TestCases {
+		s := enc.AppendFloat32([]byte{}, tc.val, -1)
+		got := string(s)
+		if got != tc.binary {
+			t.Errorf("AppendFloat32(%f)=0x%s, want: 0x%s",
+				tc.val, hex.EncodeToString(s),
+				hex.EncodeToString([]byte(tc.binary)))
+		}
+	}
+}
+
+var ipAddrTestCases = []struct {
+	ipaddr net.IP
+	text   string // ASCII representation of ipaddr
+	binary string // CBOR representation of ipaddr
+}{
+	{net.IP{10, 0, 0, 1}, "\"10.0.0.1\"", "\xd9\x01\x04\x44\x0a\x00\x00\x01"},
+	{net.IP{0x20, 0x01, 0x0d, 0xb8, 0x85, 0xa3, 0x0, 0x0, 0x0, 0x0, 0x8a, 0x2e, 0x03, 0x70, 0x73, 0x34},
+		"\"2001:db8:85a3::8a2e:370:7334\"",
+		"\xd9\x01\x04\x50\x20\x01\x0d\xb8\x85\xa3\x00\x00\x00\x00\x8a\x2e\x03\x70\x73\x34"},
+}
+
+func TestAppendNetworkAddr(t *testing.T) {
+	for _, tc := range ipAddrTestCases {
+		s := enc.AppendIPAddr([]byte{}, tc.ipaddr)
+		got := string(s)
+		if got != tc.binary {
+			t.Errorf("AppendIPAddr(%s)=0x%s, want: 0x%s",
+				tc.ipaddr, hex.EncodeToString(s),
+				hex.EncodeToString([]byte(tc.binary)))
+		}
+	}
+}
+
+var macAddrTestCases = []struct {
+	macaddr net.HardwareAddr
+	text    string // ASCII representation of macaddr
+	binary  string // CBOR representation of macaddr
+}{
+	{net.HardwareAddr{0x12, 0x34, 0x56, 0x78, 0x90, 0xab}, "\"12:34:56:78:90:ab\"", "\xd9\x01\x04\x46\x12\x34\x56\x78\x90\xab"},
+	{net.HardwareAddr{0x20, 0x01, 0x0d, 0xb8, 0x85, 0xa3}, "\"20:01:0d:b8:85:a3\"", "\xd9\x01\x04\x46\x20\x01\x0d\xb8\x85\xa3"},
+}
+
+func TestAppendMACAddr(t *testing.T) {
+	for _, tc := range macAddrTestCases {
+		s := enc.AppendMACAddr([]byte{}, tc.macaddr)
+		got := string(s)
+		if got != tc.binary {
+			t.Errorf("AppendMACAddr(%s)=0x%s, want: 0x%s",
+				tc.macaddr.String(), hex.EncodeToString(s),
+				hex.EncodeToString([]byte(tc.binary)))
+		}
+	}
+}
+
+var IPPrefixTestCases = []struct {
+	pfx    net.IPNet
+	text   string // ASCII representation of pfx
+	binary string // CBOR representation of pfx
+}{
+	{net.IPNet{IP: net.IP{0, 0, 0, 0}, Mask: net.CIDRMask(0, 32)}, "\"0.0.0.0/0\"", "\xd9\x01\x05\xa1\x44\x00\x00\x00\x00\x00"},
+	{net.IPNet{IP: net.IP{192, 168, 0, 100}, Mask: net.CIDRMask(24, 32)}, "\"192.168.0.100/24\"",
+		"\xd9\x01\x05\xa1\x44\xc0\xa8\x00\x64\x18\x18"},
+}
+
+func TestAppendIPPrefix(t *testing.T) {
+	for _, tc := range IPPrefixTestCases {
+		s := enc.AppendIPPrefix([]byte{}, tc.pfx)
+		got := string(s)
+		if got != tc.binary {
+			t.Errorf("AppendIPPrefix(%s)=0x%s, want: 0x%s",
+				tc.pfx.String(), hex.EncodeToString(s),
+				hex.EncodeToString([]byte(tc.binary)))
+		}
+	}
+}
+
+func BenchmarkAppendInt(b *testing.B) {
+	type st struct {
+		sz  byte
+		val int64
+	}
+	tests := map[string]st{
+		"int-Positive": {sz: 0, val: 10000},
+		"int-Negative": {sz: 0, val: -10000},
+		"uint8":        {sz: 1, val: 100},
+		"uint16":       {sz: 2, val: 0xfff},
+		"uint32":       {sz: 4, val: 0xffffff},
+		"uint64":       {sz: 8, val: 0xffffffffff},
+		"int8":         {sz: 21, val: -120},
+		"int16":        {sz: 22, val: -1200},
+		"int32":        {sz: 23, val: 32000},
+		"int64":        {sz: 24, val: 0xffffffffff},
+	}
+	for name, str := range tests {
+		b.Run(name, func(b *testing.B) {
+			buf := make([]byte, 0, 100)
+			for i := 0; i < b.N; i++ {
+				switch str.sz {
+				case 0:
+					_ = enc.AppendInt(buf, int(str.val))
+				case 1:
+					_ = enc.AppendUint8(buf, uint8(str.val))
+				case 2:
+					_ = enc.AppendUint16(buf, uint16(str.val))
+				case 4:
+					_ = enc.AppendUint32(buf, uint32(str.val))
+				case 8:
+					_ = enc.AppendUint64(buf, uint64(str.val))
+				case 21:
+					_ = enc.AppendInt8(buf, int8(str.val))
+				case 22:
+					_ = enc.AppendInt16(buf, int16(str.val))
+				case 23:
+					_ = enc.AppendInt32(buf, int32(str.val))
+				case 24:
+					_ = enc.AppendInt64(buf, int64(str.val))
+				}
+			}
+		})
+	}
+}
+
+func BenchmarkAppendFloat(b *testing.B) {
+	type st struct {
+		sz  byte
+		val float64
+	}
+	tests := map[string]st{
+		"Float32": {sz: 4, val: 10000.12345},
+		"Float64": {sz: 8, val: -10000.54321},
+	}
+	for name, str := range tests {
+		b.Run(name, func(b *testing.B) {
+			buf := make([]byte, 0, 100)
+			for i := 0; i < b.N; i++ {
+				switch str.sz {
+				case 4:
+					_ = enc.AppendFloat32(buf, float32(str.val), -1)
+				case 8:
+					_ = enc.AppendFloat64(buf, str.val, -1)
+				}
+			}
+		})
+	}
+}

internal/json/base.go

@@ -1,39 +1,19 @@
 package json
 
-func AppendKey(dst []byte, key string) []byte {
-	if len(dst) > 1 {
+// JSONMarshalFunc is used to marshal interface to JSON encoded byte slice.
+// Making it package level instead of embedded in Encoder brings
+// some extra efforts at importing, but avoids value copy when the functions
+// of Encoder being invoked.
+// DO REMEMBER to set this variable at importing, or
+// you might get a nil pointer dereference panic at runtime.
+var JSONMarshalFunc func(v interface{}) ([]byte, error)
+
+type Encoder struct{}
+
+// AppendKey appends a new key to the output JSON.
+func (e Encoder) AppendKey(dst []byte, key string) []byte {
+	if dst[len(dst)-1] != '{' {
 		dst = append(dst, ',')
 	}
-	dst = AppendString(dst, key)
-	return append(dst, ':')
-}
-
-func AppendError(dst []byte, err error) []byte {
-	if err == nil {
-		return append(dst, `null`...)
-	}
-	return AppendString(dst, err.Error())
-}
-
-func AppendErrors(dst []byte, errs []error) []byte {
-	if len(errs) == 0 {
-		return append(dst, '[', ']')
-	}
-	dst = append(dst, '[')
-	if errs[0] != nil {
-		dst = AppendString(dst, errs[0].Error())
-	} else {
-		dst = append(dst, "null"...)
-	}
-	if len(errs) > 1 {
-		for _, err := range errs[1:] {
-			if err == nil {
-				dst = append(dst, ",null"...)
-				continue
-			}
-			dst = AppendString(append(dst, ','), err.Error())
-		}
-	}
-	dst = append(dst, ']')
-	return dst
+	return append(e.AppendString(dst, key), ':')
 }

internal/json/bytes.go

@@ -0,0 +1,85 @@
+package json
+
+import "unicode/utf8"
+
+// AppendBytes is a mirror of appendString with []byte arg
+func (Encoder) AppendBytes(dst, s []byte) []byte {
+	dst = append(dst, '"')
+	for i := 0; i < len(s); i++ {
+		if !noEscapeTable[s[i]] {
+			dst = appendBytesComplex(dst, s, i)
+			return append(dst, '"')
+		}
+	}
+	dst = append(dst, s...)
+	return append(dst, '"')
+}
+
+// AppendHex encodes the input bytes to a hex string and appends
+// the encoded string to the input byte slice.
+//
+// The operation loops though each byte and encodes it as hex using
+// the hex lookup table.
+func (Encoder) AppendHex(dst, s []byte) []byte {
+	dst = append(dst, '"')
+	for _, v := range s {
+		dst = append(dst, hex[v>>4], hex[v&0x0f])
+	}
+	return append(dst, '"')
+}
+
+// appendBytesComplex is a mirror of the appendStringComplex
+// with []byte arg
+func appendBytesComplex(dst, s []byte, i int) []byte {
+	start := 0
+	for i < len(s) {
+		b := s[i]
+		if b >= utf8.RuneSelf {
+			r, size := utf8.DecodeRune(s[i:])
+			if r == utf8.RuneError && size == 1 {
+				if start < i {
+					dst = append(dst, s[start:i]...)
+				}
+				dst = append(dst, `\ufffd`...)
+				i += size
+				start = i
+				continue
+			}
+			i += size
+			continue
+		}
+		if noEscapeTable[b] {
+			i++
+			continue
+		}
+		// We encountered a character that needs to be encoded.
+		// Let's append the previous simple characters to the byte slice
+		// and switch our operation to read and encode the remainder
+		// characters byte-by-byte.
+		if start < i {
+			dst = append(dst, s[start:i]...)
+		}
+		switch b {
+		case '"', '\\':
+			dst = append(dst, '\\', b)
+		case '\b':
+			dst = append(dst, '\\', 'b')
+		case '\f':
+			dst = append(dst, '\\', 'f')
+		case '\n':
+			dst = append(dst, '\\', 'n')
+		case '\r':
+			dst = append(dst, '\\', 'r')
+		case '\t':
+			dst = append(dst, '\\', 't')
+		default:
+			dst = append(dst, '\\', 'u', '0', '0', hex[b>>4], hex[b&0xF])
+		}
+		i++
+		start = i
+	}
+	if start < len(s) {
+		dst = append(dst, s[start:]...)
+	}
+	return dst
+}

internal/json/bytes_test.go

@@ -0,0 +1,84 @@
+package json
+
+import (
+	"testing"
+	"unicode"
+)
+
+var enc = Encoder{}
+
+func TestAppendBytes(t *testing.T) {
+	for _, tt := range encodeStringTests {
+		b := enc.AppendBytes([]byte{}, []byte(tt.in))
+		if got, want := string(b), tt.out; got != want {
+			t.Errorf("appendBytes(%q) = %#q, want %#q", tt.in, got, want)
+		}
+	}
+}
+
+func TestAppendHex(t *testing.T) {
+	for _, tt := range encodeHexTests {
+		b := enc.AppendHex([]byte{}, []byte{tt.in})
+		if got, want := string(b), tt.out; got != want {
+			t.Errorf("appendHex(%x) = %s, want %s", tt.in, got, want)
+		}
+	}
+}
+
+func TestStringBytes(t *testing.T) {
+	t.Parallel()
+	// Test that encodeState.stringBytes and encodeState.string use the same encoding.
+	var r []rune
+	for i := '\u0000'; i <= unicode.MaxRune; i++ {
+		r = append(r, i)
+	}
+	s := string(r) + "\xff\xff\xffhello" // some invalid UTF-8 too
+
+	encStr := string(enc.AppendString([]byte{}, s))
+	encBytes := string(enc.AppendBytes([]byte{}, []byte(s)))
+
+	if encStr != encBytes {
+		i := 0
+		for i < len(encStr) && i < len(encBytes) && encStr[i] == encBytes[i] {
+			i++
+		}
+		encStr = encStr[i:]
+		encBytes = encBytes[i:]
+		i = 0
+		for i < len(encStr) && i < len(encBytes) && encStr[len(encStr)-i-1] == encBytes[len(encBytes)-i-1] {
+			i++
+		}
+		encStr = encStr[:len(encStr)-i]
+		encBytes = encBytes[:len(encBytes)-i]
+
+		if len(encStr) > 20 {
+			encStr = encStr[:20] + "..."
+		}
+		if len(encBytes) > 20 {
+			encBytes = encBytes[:20] + "..."
+		}
+
+		t.Errorf("encodings differ at %#q vs %#q", encStr, encBytes)
+	}
+}
+
+func BenchmarkAppendBytes(b *testing.B) {
+	tests := map[string]string{
+		"NoEncoding":       `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,
+		"EncodingFirst":    `"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,
+		"EncodingMiddle":   `aaaaaaaaaaaaaaaaaaaaaaaaa"aaaaaaaaaaaaaaaaaaaaaaaa`,
+		"EncodingLast":     `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"`,
+		"MultiBytesFirst":  `❤️aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,
+		"MultiBytesMiddle": `aaaaaaaaaaaaaaaaaaaaaaaaa❤️aaaaaaaaaaaaaaaaaaaaaaaa`,
+		"MultiBytesLast":   `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa❤️`,
+	}
+	for name, str := range tests {
+		byt := []byte(str)
+		b.Run(name, func(b *testing.B) {
+			buf := make([]byte, 0, 100)
+			for i := 0; i < b.N; i++ {
+				_ = enc.AppendBytes(buf, byt)
+			}
+		})
+	}
+}

internal/json/string.go

@@ -1,18 +1,31 @@
 package json
 
-import "unicode/utf8"
+import (
+	"fmt"
+	"unicode/utf8"
+)
 
 const hex = "0123456789abcdef"
 
-func AppendStrings(dst []byte, vals []string) []byte {
+var noEscapeTable = [256]bool{}
+
+func init() {
+	for i := 0; i <= 0x7e; i++ {
+		noEscapeTable[i] = i >= 0x20 && i != '\\' && i != '"'
+	}
+}
+
+// AppendStrings encodes the input strings to json and
+// appends the encoded string list to the input byte slice.
+func (e Encoder) AppendStrings(dst []byte, vals []string) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
 	dst = append(dst, '[')
-	dst = AppendString(dst, vals[0])
+	dst = e.AppendString(dst, vals[0])
 	if len(vals) > 1 {
 		for _, val := range vals[1:] {
-			dst = AppendString(append(dst, ','), val)
+			dst = e.AppendString(append(dst, ','), val)
 		}
 	}
 	dst = append(dst, ']')
@@ -24,11 +37,11 @@ func AppendStrings(dst []byte, vals []string) []byte {
 //
 // The operation loops though each byte in the string looking
 // for characters that need json or utf8 encoding. If the string
-// does not need encoding, then the string is appended in it's
+// does not need encoding, then the string is appended in its
 // entirety to the byte slice.
 // If we encounter a byte that does need encoding, switch up
 // the operation and perform a byte-by-byte read-encode-append.
-func AppendString(dst []byte, s string) []byte {
+func (Encoder) AppendString(dst []byte, s string) []byte {
 	// Start with a double quote.
 	dst = append(dst, '"')
 	// Loop through each character in the string.
@@ -36,21 +49,46 @@ func AppendString(dst []byte, s string) []byte {
 		// Check if the character needs encoding. Control characters, slashes,
 		// and the double quote need json encoding. Bytes above the ascii
 		// boundary needs utf8 encoding.
-		if s[i] < 0x20 || s[i] > 0x7e || s[i] == '\\' || s[i] == '"' {
+		if !noEscapeTable[s[i]] {
 			// We encountered a character that needs to be encoded. Switch
 			// to complex version of the algorithm.
 			dst = appendStringComplex(dst, s, i)
 			return append(dst, '"')
 		}
 	}
-	// The string has no need for encoding an therefore is directly
+	// The string has no need for encoding and therefore is directly
 	// appended to the byte slice.
 	dst = append(dst, s...)
 	// End with a double quote
 	return append(dst, '"')
 }
 
-// appendStringComplex is used by appendString to take over an in
+// AppendStringers encodes the provided Stringer list to json and
+// appends the encoded Stringer list to the input byte slice.
+func (e Encoder) AppendStringers(dst []byte, vals []fmt.Stringer) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = e.AppendStringer(dst, vals[0])
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = e.AppendStringer(append(dst, ','), val)
+		}
+	}
+	return append(dst, ']')
+}
+
+// AppendStringer encodes the input Stringer to json and appends the
+// encoded Stringer value to the input byte slice.
+func (e Encoder) AppendStringer(dst []byte, val fmt.Stringer) []byte {
+	if val == nil {
+		return e.AppendInterface(dst, nil)
+	}
+	return e.AppendString(dst, val.String())
+}
+
+//// appendStringComplex is used by appendString to take over an in
 // progress JSON string encoding that encountered a character that needs
 // to be encoded.
 func appendStringComplex(dst []byte, s string, i int) []byte {
@@ -61,7 +99,7 @@ func appendStringComplex(dst []byte, s string, i int) []byte {
 			r, size := utf8.DecodeRuneInString(s[i:])
 			if r == utf8.RuneError && size == 1 {
 				// In case of error, first append previous simple characters to
-				// the byte slice if any and append a remplacement character code
+				// the byte slice if any and append a replacement character code
 				// in place of the invalid sequence.
 				if start < i {
 					dst = append(dst, s[start:i]...)
@@ -74,76 +112,7 @@ func appendStringComplex(dst []byte, s string, i int) []byte {
 			i += size
 			continue
 		}
-		if b >= 0x20 && b <= 0x7e && b != '\\' && b != '"' {
-			i++
-			continue
-		}
-		// We encountered a character that needs to be encoded.
-		// Let's append the previous simple characters to the byte slice
-		// and switch our operation to read and encode the remainder
-		// characters byte-by-byte.
-		if start < i {
-			dst = append(dst, s[start:i]...)
-		}
-		switch b {
-		case '"', '\\':
-			dst = append(dst, '\\', b)
-		case '\b':
-			dst = append(dst, '\\', 'b')
-		case '\f':
-			dst = append(dst, '\\', 'f')
-		case '\n':
-			dst = append(dst, '\\', 'n')
-		case '\r':
-			dst = append(dst, '\\', 'r')
-		case '\t':
-			dst = append(dst, '\\', 't')
-		default:
-			dst = append(dst, '\\', 'u', '0', '0', hex[b>>4], hex[b&0xF])
-		}
-		i++
-		start = i
-	}
-	if start < len(s) {
-		dst = append(dst, s[start:]...)
-	}
-	return dst
-}
-
-// AppendBytes is a mirror of appendString with []byte arg
-func AppendBytes(dst, s []byte) []byte {
-	dst = append(dst, '"')
-	for i := 0; i < len(s); i++ {
-		if s[i] < 0x20 || s[i] > 0x7e || s[i] == '\\' || s[i] == '"' {
-			dst = appendBytesComplex(dst, s, i)
-			return append(dst, '"')
-		}
-	}
-	dst = append(dst, s...)
-	return append(dst, '"')
-}
-
-// appendBytesComplex is a mirror of the appendStringComplex
-// with []byte arg
-func appendBytesComplex(dst, s []byte, i int) []byte {
-	start := 0
-	for i < len(s) {
-		b := s[i]
-		if b >= utf8.RuneSelf {
-			r, size := utf8.DecodeRune(s[i:])
-			if r == utf8.RuneError && size == 1 {
-				if start < i {
-					dst = append(dst, s[start:i]...)
-				}
-				dst = append(dst, `\ufffd`...)
-				i += size
-				start = i
-				continue
-			}
-			i += size
-			continue
-		}
-		if b >= 0x20 && b <= 0x7e && b != '\\' && b != '"' {
+		if noEscapeTable[b] {
 			i++
 			continue
 		}

internal/json/string_test.go

@@ -2,7 +2,6 @@ package json
 
 import (
 	"testing"
-	"unicode"
 )
 
 var encodeStringTests = []struct {
@@ -53,62 +52,27 @@ var encodeStringTests = []struct {
 	{"emoji \u2764\ufe0f!", `"emoji ❤️!"`},
 }
 
-func TestappendString(t *testing.T) {
+var encodeHexTests = []struct {
+	in  byte
+	out string
+}{
+	{0x00, `"00"`},
+	{0x0f, `"0f"`},
+	{0x10, `"10"`},
+	{0xf0, `"f0"`},
+	{0xff, `"ff"`},
+}
+
+func TestAppendString(t *testing.T) {
 	for _, tt := range encodeStringTests {
-		b := AppendString([]byte{}, tt.in)
+		b := enc.AppendString([]byte{}, tt.in)
 		if got, want := string(b), tt.out; got != want {
 			t.Errorf("appendString(%q) = %#q, want %#q", tt.in, got, want)
 		}
 	}
 }
 
-func TestappendBytes(t *testing.T) {
-	for _, tt := range encodeStringTests {
-		b := AppendBytes([]byte{}, []byte(tt.in))
-		if got, want := string(b), tt.out; got != want {
-			t.Errorf("appendBytes(%q) = %#q, want %#q", tt.in, got, want)
-		}
-	}
-}
-
-func TestStringBytes(t *testing.T) {
-	t.Parallel()
-	// Test that encodeState.stringBytes and encodeState.string use the same encoding.
-	var r []rune
-	for i := '\u0000'; i <= unicode.MaxRune; i++ {
-		r = append(r, i)
-	}
-	s := string(r) + "\xff\xff\xffhello" // some invalid UTF-8 too
-
-	enc := string(AppendString([]byte{}, s))
-	encBytes := string(AppendBytes([]byte{}, []byte(s)))
-
-	if enc != encBytes {
-		i := 0
-		for i < len(enc) && i < len(encBytes) && enc[i] == encBytes[i] {
-			i++
-		}
-		enc = enc[i:]
-		encBytes = encBytes[i:]
-		i = 0
-		for i < len(enc) && i < len(encBytes) && enc[len(enc)-i-1] == encBytes[len(encBytes)-i-1] {
-			i++
-		}
-		enc = enc[:len(enc)-i]
-		encBytes = encBytes[:len(encBytes)-i]
-
-		if len(enc) > 20 {
-			enc = enc[:20] + "..."
-		}
-		if len(encBytes) > 20 {
-			encBytes = encBytes[:20] + "..."
-		}
-
-		t.Errorf("encodings differ at %#q vs %#q", enc, encBytes)
-	}
-}
-
-func BenchmarkappendString(b *testing.B) {
+func BenchmarkAppendString(b *testing.B) {
 	tests := map[string]string{
 		"NoEncoding":       `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,
 		"EncodingFirst":    `"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,
@@ -122,28 +86,7 @@ func BenchmarkappendString(b *testing.B) {
 		b.Run(name, func(b *testing.B) {
 			buf := make([]byte, 0, 100)
 			for i := 0; i < b.N; i++ {
-				_ = AppendString(buf, str)
-			}
-		})
-	}
-}
-
-func BenchmarkappendBytes(b *testing.B) {
-	tests := map[string]string{
-		"NoEncoding":       `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,
-		"EncodingFirst":    `"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,
-		"EncodingMiddle":   `aaaaaaaaaaaaaaaaaaaaaaaaa"aaaaaaaaaaaaaaaaaaaaaaaa`,
-		"EncodingLast":     `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"`,
-		"MultiBytesFirst":  `❤️aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,
-		"MultiBytesMiddle": `aaaaaaaaaaaaaaaaaaaaaaaaa❤️aaaaaaaaaaaaaaaaaaaaaaaa`,
-		"MultiBytesLast":   `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa❤️`,
-	}
-	for name, str := range tests {
-		byt := []byte(str)
-		b.Run(name, func(b *testing.B) {
-			buf := make([]byte, 0, 100)
-			for i := 0; i < b.N; i++ {
-				_ = AppendBytes(buf, byt)
+				_ = enc.AppendString(buf, str)
 			}
 		})
 	}

internal/json/time.go

@@ -5,16 +5,42 @@ import (
 	"time"
 )
 
-func AppendTime(dst []byte, t time.Time, format string) []byte {
-	if format == "" {
-		return AppendInt64(dst, t.Unix())
+const (
+	// Import from zerolog/global.go
+	timeFormatUnix      = ""
+	timeFormatUnixMs    = "UNIXMS"
+	timeFormatUnixMicro = "UNIXMICRO"
+	timeFormatUnixNano  = "UNIXNANO"
+)
+
+// AppendTime formats the input time with the given format
+// and appends the encoded string to the input byte slice.
+func (e Encoder) AppendTime(dst []byte, t time.Time, format string) []byte {
+	switch format {
+	case timeFormatUnix:
+		return e.AppendInt64(dst, t.Unix())
+	case timeFormatUnixMs:
+		return e.AppendInt64(dst, t.UnixNano()/1000000)
+	case timeFormatUnixMicro:
+		return e.AppendInt64(dst, t.UnixNano()/1000)
+	case timeFormatUnixNano:
+		return e.AppendInt64(dst, t.UnixNano())
 	}
 	return append(t.AppendFormat(append(dst, '"'), format), '"')
 }
 
-func AppendTimes(dst []byte, vals []time.Time, format string) []byte {
-	if format == "" {
+// AppendTimes converts the input times with the given format
+// and appends the encoded string list to the input byte slice.
+func (Encoder) AppendTimes(dst []byte, vals []time.Time, format string) []byte {
+	switch format {
+	case timeFormatUnix:
 		return appendUnixTimes(dst, vals)
+	case timeFormatUnixMs:
+		return appendUnixNanoTimes(dst, vals, 1000000)
+	case timeFormatUnixMicro:
+		return appendUnixNanoTimes(dst, vals, 1000)
+	case timeFormatUnixNano:
+		return appendUnixNanoTimes(dst, vals, 1)
 	}
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
@@ -38,29 +64,48 @@ func appendUnixTimes(dst []byte, vals []time.Time) []byte {
 	dst = strconv.AppendInt(dst, vals[0].Unix(), 10)
 	if len(vals) > 1 {
 		for _, t := range vals[1:] {
-			dst = strconv.AppendInt(dst, t.Unix(), 10)
+			dst = strconv.AppendInt(append(dst, ','), t.Unix(), 10)
 		}
 	}
 	dst = append(dst, ']')
 	return dst
 }
 
-func AppendDuration(dst []byte, d time.Duration, unit time.Duration, useInt bool) []byte {
-	if useInt {
-		return strconv.AppendInt(dst, int64(d/unit), 10)
-	}
-	return AppendFloat64(dst, float64(d)/float64(unit))
-}
-
-func AppendDurations(dst []byte, vals []time.Duration, unit time.Duration, useInt bool) []byte {
+func appendUnixNanoTimes(dst []byte, vals []time.Time, div int64) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
 	dst = append(dst, '[')
-	dst = AppendDuration(dst, vals[0], unit, useInt)
+	dst = strconv.AppendInt(dst, vals[0].UnixNano()/div, 10)
 	if len(vals) > 1 {
-		for _, d := range vals[1:] {
-			dst = AppendDuration(append(dst, ','), d, unit, useInt)
+		for _, t := range vals[1:] {
+			dst = strconv.AppendInt(append(dst, ','), t.UnixNano()/div, 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+// AppendDuration formats the input duration with the given unit & format
+// and appends the encoded string to the input byte slice.
+func (e Encoder) AppendDuration(dst []byte, d time.Duration, unit time.Duration, useInt bool, precision int) []byte {
+	if useInt {
+		return strconv.AppendInt(dst, int64(d/unit), 10)
+	}
+	return e.AppendFloat64(dst, float64(d)/float64(unit), precision)
+}
+
+// AppendDurations formats the input durations with the given unit & format
+// and appends the encoded string list to the input byte slice.
+func (e Encoder) AppendDurations(dst []byte, vals []time.Duration, unit time.Duration, useInt bool, precision int) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = e.AppendDuration(dst, vals[0], unit, useInt, precision)
+	if len(vals) > 1 {
+		for _, d := range vals[1:] {
+			dst = e.AppendDuration(append(dst, ','), d, unit, useInt, precision)
 		}
 	}
 	dst = append(dst, ']')

internal/json/types.go

@@ -1,17 +1,60 @@
 package json
 
 import (
-	"encoding/json"
 	"fmt"
 	"math"
+	"net"
+	"reflect"
 	"strconv"
 )
 
-func AppendBool(dst []byte, val bool) []byte {
+// AppendNil inserts a 'Nil' object into the dst byte array.
+func (Encoder) AppendNil(dst []byte) []byte {
+	return append(dst, "null"...)
+}
+
+// AppendBeginMarker inserts a map start into the dst byte array.
+func (Encoder) AppendBeginMarker(dst []byte) []byte {
+	return append(dst, '{')
+}
+
+// AppendEndMarker inserts a map end into the dst byte array.
+func (Encoder) AppendEndMarker(dst []byte) []byte {
+	return append(dst, '}')
+}
+
+// AppendLineBreak appends a line break.
+func (Encoder) AppendLineBreak(dst []byte) []byte {
+	return append(dst, '\n')
+}
+
+// AppendArrayStart adds markers to indicate the start of an array.
+func (Encoder) AppendArrayStart(dst []byte) []byte {
+	return append(dst, '[')
+}
+
+// AppendArrayEnd adds markers to indicate the end of an array.
+func (Encoder) AppendArrayEnd(dst []byte) []byte {
+	return append(dst, ']')
+}
+
+// AppendArrayDelim adds markers to indicate end of a particular array element.
+func (Encoder) AppendArrayDelim(dst []byte) []byte {
+	if len(dst) > 0 {
+		return append(dst, ',')
+	}
+	return dst
+}
+
+// AppendBool converts the input bool to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendBool(dst []byte, val bool) []byte {
 	return strconv.AppendBool(dst, val)
 }
 
-func AppendBools(dst []byte, vals []bool) []byte {
+// AppendBools encodes the input bools to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendBools(dst []byte, vals []bool) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -26,11 +69,15 @@ func AppendBools(dst []byte, vals []bool) []byte {
 	return dst
 }
 
-func AppendInt(dst []byte, val int) []byte {
+// AppendInt converts the input int to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendInt(dst []byte, val int) []byte {
 	return strconv.AppendInt(dst, int64(val), 10)
 }
 
-func AppendInts(dst []byte, vals []int) []byte {
+// AppendInts encodes the input ints to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendInts(dst []byte, vals []int) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -45,11 +92,15 @@ func AppendInts(dst []byte, vals []int) []byte {
 	return dst
 }
 
-func AppendInt8(dst []byte, val int8) []byte {
+// AppendInt8 converts the input []int8 to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendInt8(dst []byte, val int8) []byte {
 	return strconv.AppendInt(dst, int64(val), 10)
 }
 
-func AppendInts8(dst []byte, vals []int8) []byte {
+// AppendInts8 encodes the input int8s to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendInts8(dst []byte, vals []int8) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -64,11 +115,15 @@ func AppendInts8(dst []byte, vals []int8) []byte {
 	return dst
 }
 
-func AppendInt16(dst []byte, val int16) []byte {
+// AppendInt16 converts the input int16 to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendInt16(dst []byte, val int16) []byte {
 	return strconv.AppendInt(dst, int64(val), 10)
 }
 
-func AppendInts16(dst []byte, vals []int16) []byte {
+// AppendInts16 encodes the input int16s to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendInts16(dst []byte, vals []int16) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -83,11 +138,15 @@ func AppendInts16(dst []byte, vals []int16) []byte {
 	return dst
 }
 
-func AppendInt32(dst []byte, val int32) []byte {
+// AppendInt32 converts the input int32 to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendInt32(dst []byte, val int32) []byte {
 	return strconv.AppendInt(dst, int64(val), 10)
 }
 
-func AppendInts32(dst []byte, vals []int32) []byte {
+// AppendInts32 encodes the input int32s to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendInts32(dst []byte, vals []int32) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -102,11 +161,15 @@ func AppendInts32(dst []byte, vals []int32) []byte {
 	return dst
 }
 
-func AppendInt64(dst []byte, val int64) []byte {
+// AppendInt64 converts the input int64 to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendInt64(dst []byte, val int64) []byte {
 	return strconv.AppendInt(dst, val, 10)
 }
 
-func AppendInts64(dst []byte, vals []int64) []byte {
+// AppendInts64 encodes the input int64s to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendInts64(dst []byte, vals []int64) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -121,11 +184,15 @@ func AppendInts64(dst []byte, vals []int64) []byte {
 	return dst
 }
 
-func AppendUint(dst []byte, val uint) []byte {
+// AppendUint converts the input uint to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendUint(dst []byte, val uint) []byte {
 	return strconv.AppendUint(dst, uint64(val), 10)
 }
 
-func AppendUints(dst []byte, vals []uint) []byte {
+// AppendUints encodes the input uints to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendUints(dst []byte, vals []uint) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -140,11 +207,15 @@ func AppendUints(dst []byte, vals []uint) []byte {
 	return dst
 }
 
-func AppendUint8(dst []byte, val uint8) []byte {
+// AppendUint8 converts the input uint8 to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendUint8(dst []byte, val uint8) []byte {
 	return strconv.AppendUint(dst, uint64(val), 10)
 }
 
-func AppendUints8(dst []byte, vals []uint8) []byte {
+// AppendUints8 encodes the input uint8s to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendUints8(dst []byte, vals []uint8) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -159,11 +230,15 @@ func AppendUints8(dst []byte, vals []uint8) []byte {
 	return dst
 }
 
-func AppendUint16(dst []byte, val uint16) []byte {
+// AppendUint16 converts the input uint16 to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendUint16(dst []byte, val uint16) []byte {
 	return strconv.AppendUint(dst, uint64(val), 10)
 }
 
-func AppendUints16(dst []byte, vals []uint16) []byte {
+// AppendUints16 encodes the input uint16s to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendUints16(dst []byte, vals []uint16) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -178,11 +253,15 @@ func AppendUints16(dst []byte, vals []uint16) []byte {
 	return dst
 }
 
-func AppendUint32(dst []byte, val uint32) []byte {
+// AppendUint32 converts the input uint32 to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendUint32(dst []byte, val uint32) []byte {
 	return strconv.AppendUint(dst, uint64(val), 10)
 }
 
-func AppendUints32(dst []byte, vals []uint32) []byte {
+// AppendUints32 encodes the input uint32s to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendUints32(dst []byte, vals []uint32) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -197,11 +276,15 @@ func AppendUints32(dst []byte, vals []uint32) []byte {
 	return dst
 }
 
-func AppendUint64(dst []byte, val uint64) []byte {
-	return strconv.AppendUint(dst, uint64(val), 10)
+// AppendUint64 converts the input uint64 to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendUint64(dst []byte, val uint64) []byte {
+	return strconv.AppendUint(dst, val, 10)
 }
 
-func AppendUints64(dst []byte, vals []uint64) []byte {
+// AppendUints64 encodes the input uint64s to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendUints64(dst []byte, vals []uint64) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -216,9 +299,9 @@ func AppendUints64(dst []byte, vals []uint64) []byte {
 	return dst
 }
 
-func AppendFloat(dst []byte, val float64, bitSize int) []byte {
+func appendFloat(dst []byte, val float64, bitSize, precision int) []byte {
 	// JSON does not permit NaN or Infinity. A typical JSON encoder would fail
-	// with an error, but a logging library wants the data to get thru so we
+	// with an error, but a logging library wants the data to get through so we
 	// make a tradeoff and store those types as string.
 	switch {
 	case math.IsNaN(val):
@@ -228,51 +311,125 @@ func AppendFloat(dst []byte, val float64, bitSize int) []byte {
 	case math.IsInf(val, -1):
 		return append(dst, `"-Inf"`...)
 	}
-	return strconv.AppendFloat(dst, val, 'f', -1, bitSize)
+	// convert as if by es6 number to string conversion
+	// see also https://cs.opensource.google/go/go/+/refs/tags/go1.20.3:src/encoding/json/encode.go;l=573
+	strFmt := byte('f')
+	// If precision is set to a value other than -1, we always just format the float using that precision.
+	if precision == -1 {
+		// Use float32 comparisons for underlying float32 value to get precise cutoffs right.
+		if abs := math.Abs(val); abs != 0 {
+			if bitSize == 64 && (abs < 1e-6 || abs >= 1e21) || bitSize == 32 && (float32(abs) < 1e-6 || float32(abs) >= 1e21) {
+				strFmt = 'e'
+			}
+		}
+	}
+	dst = strconv.AppendFloat(dst, val, strFmt, precision, bitSize)
+	if strFmt == 'e' {
+		// Clean up e-09 to e-9
+		n := len(dst)
+		if n >= 4 && dst[n-4] == 'e' && dst[n-3] == '-' && dst[n-2] == '0' {
+			dst[n-2] = dst[n-1]
+			dst = dst[:n-1]
+		}
+	}
+	return dst
 }
 
-func AppendFloat32(dst []byte, val float32) []byte {
-	return AppendFloat(dst, float64(val), 32)
+// AppendFloat32 converts the input float32 to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendFloat32(dst []byte, val float32, precision int) []byte {
+	return appendFloat(dst, float64(val), 32, precision)
 }
 
-func AppendFloats32(dst []byte, vals []float32) []byte {
+// AppendFloats32 encodes the input float32s to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendFloats32(dst []byte, vals []float32, precision int) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
 	dst = append(dst, '[')
-	dst = AppendFloat(dst, float64(vals[0]), 32)
+	dst = appendFloat(dst, float64(vals[0]), 32, precision)
 	if len(vals) > 1 {
 		for _, val := range vals[1:] {
-			dst = AppendFloat(append(dst, ','), float64(val), 32)
+			dst = appendFloat(append(dst, ','), float64(val), 32, precision)
 		}
 	}
 	dst = append(dst, ']')
 	return dst
 }
 
-func AppendFloat64(dst []byte, val float64) []byte {
-	return AppendFloat(dst, val, 64)
+// AppendFloat64 converts the input float64 to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendFloat64(dst []byte, val float64, precision int) []byte {
+	return appendFloat(dst, val, 64, precision)
 }
 
-func AppendFloats64(dst []byte, vals []float64) []byte {
+// AppendFloats64 encodes the input float64s to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendFloats64(dst []byte, vals []float64, precision int) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
 	dst = append(dst, '[')
-	dst = AppendFloat(dst, vals[0], 32)
+	dst = appendFloat(dst, vals[0], 64, precision)
 	if len(vals) > 1 {
 		for _, val := range vals[1:] {
-			dst = AppendFloat(append(dst, ','), val, 64)
+			dst = appendFloat(append(dst, ','), val, 64, precision)
 		}
 	}
 	dst = append(dst, ']')
 	return dst
 }
 
-func AppendInterface(dst []byte, i interface{}) []byte {
-	marshaled, err := json.Marshal(i)
+// AppendInterface marshals the input interface to a string and
+// appends the encoded string to the input byte slice.
+func (e Encoder) AppendInterface(dst []byte, i interface{}) []byte {
+	marshaled, err := JSONMarshalFunc(i)
 	if err != nil {
-		return AppendString(dst, fmt.Sprintf("marshaling error: %v", err))
+		return e.AppendString(dst, fmt.Sprintf("marshaling error: %v", err))
 	}
 	return append(dst, marshaled...)
 }
+
+// AppendType appends the parameter type (as a string) to the input byte slice.
+func (e Encoder) AppendType(dst []byte, i interface{}) []byte {
+	if i == nil {
+		return e.AppendString(dst, "<nil>")
+	}
+	return e.AppendString(dst, reflect.TypeOf(i).String())
+}
+
+// AppendObjectData takes in an object that is already in a byte array
+// and adds it to the dst.
+func (Encoder) AppendObjectData(dst []byte, o []byte) []byte {
+	// Three conditions apply here:
+	// 1. new content starts with '{' - which should be dropped   OR
+	// 2. new content starts with '{' - which should be replaced with ','
+	//    to separate with existing content OR
+	// 3. existing content has already other fields
+	if o[0] == '{' {
+		if len(dst) > 1 {
+			dst = append(dst, ',')
+		}
+		o = o[1:]
+	} else if len(dst) > 1 {
+		dst = append(dst, ',')
+	}
+	return append(dst, o...)
+}
+
+// AppendIPAddr adds IPv4 or IPv6 address to dst.
+func (e Encoder) AppendIPAddr(dst []byte, ip net.IP) []byte {
+	return e.AppendString(dst, ip.String())
+}
+
+// AppendIPPrefix adds IPv4 or IPv6 Prefix (address & mask) to dst.
+func (e Encoder) AppendIPPrefix(dst []byte, pfx net.IPNet) []byte {
+	return e.AppendString(dst, pfx.String())
+
+}
+
+// AppendMACAddr adds MAC address to dst.
+func (e Encoder) AppendMACAddr(dst []byte, ha net.HardwareAddr) []byte {
+	return e.AppendString(dst, ha.String())
+}

internal/json/types_test.go

@@ -1,33 +1,553 @@
 package json
 
 import (
+	"encoding/json"
 	"math"
+	"math/rand"
+	"net"
 	"reflect"
 	"testing"
 )
 
-func Test_appendFloat64(t *testing.T) {
+func TestAppendType(t *testing.T) {
+	w := map[string]func(interface{}) []byte{
+		"AppendInt":                   func(v interface{}) []byte { return enc.AppendInt([]byte{}, v.(int)) },
+		"AppendInt8":                  func(v interface{}) []byte { return enc.AppendInt8([]byte{}, v.(int8)) },
+		"AppendInt16":                 func(v interface{}) []byte { return enc.AppendInt16([]byte{}, v.(int16)) },
+		"AppendInt32":                 func(v interface{}) []byte { return enc.AppendInt32([]byte{}, v.(int32)) },
+		"AppendInt64":                 func(v interface{}) []byte { return enc.AppendInt64([]byte{}, v.(int64)) },
+		"AppendUint":                  func(v interface{}) []byte { return enc.AppendUint([]byte{}, v.(uint)) },
+		"AppendUint8":                 func(v interface{}) []byte { return enc.AppendUint8([]byte{}, v.(uint8)) },
+		"AppendUint16":                func(v interface{}) []byte { return enc.AppendUint16([]byte{}, v.(uint16)) },
+		"AppendUint32":                func(v interface{}) []byte { return enc.AppendUint32([]byte{}, v.(uint32)) },
+		"AppendUint64":                func(v interface{}) []byte { return enc.AppendUint64([]byte{}, v.(uint64)) },
+		"AppendFloat32":               func(v interface{}) []byte { return enc.AppendFloat32([]byte{}, v.(float32), -1) },
+		"AppendFloat64":               func(v interface{}) []byte { return enc.AppendFloat64([]byte{}, v.(float64), -1) },
+		"AppendFloat32SmallPrecision": func(v interface{}) []byte { return enc.AppendFloat32([]byte{}, v.(float32), 1) },
+		"AppendFloat64SmallPrecision": func(v interface{}) []byte { return enc.AppendFloat64([]byte{}, v.(float64), 1) },
+	}
 	tests := []struct {
 		name  string
-		input float64
+		fn    string
+		input interface{}
 		want  []byte
 	}{
-		{"-Inf", math.Inf(-1), []byte(`"-Inf"`)},
-		{"+Inf", math.Inf(1), []byte(`"+Inf"`)},
-		{"NaN", math.NaN(), []byte(`"NaN"`)},
-		{"0", 0, []byte(`0`)},
-		{"-1.1", -1.1, []byte(`-1.1`)},
-		{"1e20", 1e20, []byte(`100000000000000000000`)},
-		{"1e21", 1e21, []byte(`1000000000000000000000`)},
+		{"AppendInt8(math.MaxInt8)", "AppendInt8", int8(math.MaxInt8), []byte("127")},
+		{"AppendInt16(math.MaxInt16)", "AppendInt16", int16(math.MaxInt16), []byte("32767")},
+		{"AppendInt32(math.MaxInt32)", "AppendInt32", int32(math.MaxInt32), []byte("2147483647")},
+		{"AppendInt64(math.MaxInt64)", "AppendInt64", int64(math.MaxInt64), []byte("9223372036854775807")},
+
+		{"AppendUint8(math.MaxUint8)", "AppendUint8", uint8(math.MaxUint8), []byte("255")},
+		{"AppendUint16(math.MaxUint16)", "AppendUint16", uint16(math.MaxUint16), []byte("65535")},
+		{"AppendUint32(math.MaxUint32)", "AppendUint32", uint32(math.MaxUint32), []byte("4294967295")},
+		{"AppendUint64(math.MaxUint64)", "AppendUint64", uint64(math.MaxUint64), []byte("18446744073709551615")},
+
+		{"AppendFloat32(-Inf)", "AppendFloat32", float32(math.Inf(-1)), []byte(`"-Inf"`)},
+		{"AppendFloat32(+Inf)", "AppendFloat32", float32(math.Inf(1)), []byte(`"+Inf"`)},
+		{"AppendFloat32(NaN)", "AppendFloat32", float32(math.NaN()), []byte(`"NaN"`)},
+		{"AppendFloat32(0)", "AppendFloat32", float32(0), []byte(`0`)},
+		{"AppendFloat32(-1.1)", "AppendFloat32", float32(-1.1), []byte(`-1.1`)},
+		{"AppendFloat32(1e20)", "AppendFloat32", float32(1e20), []byte(`100000000000000000000`)},
+		{"AppendFloat32(1e21)", "AppendFloat32", float32(1e21), []byte(`1e+21`)},
+
+		{"AppendFloat64(-Inf)", "AppendFloat64", float64(math.Inf(-1)), []byte(`"-Inf"`)},
+		{"AppendFloat64(+Inf)", "AppendFloat64", float64(math.Inf(1)), []byte(`"+Inf"`)},
+		{"AppendFloat64(NaN)", "AppendFloat64", float64(math.NaN()), []byte(`"NaN"`)},
+		{"AppendFloat64(0)", "AppendFloat64", float64(0), []byte(`0`)},
+		{"AppendFloat64(-1.1)", "AppendFloat64", float64(-1.1), []byte(`-1.1`)},
+		{"AppendFloat64(1e20)", "AppendFloat64", float64(1e20), []byte(`100000000000000000000`)},
+		{"AppendFloat64(1e21)", "AppendFloat64", float64(1e21), []byte(`1e+21`)},
+
+		{"AppendFloat32SmallPrecision(-1.123)", "AppendFloat32SmallPrecision", float32(-1.123), []byte(`-1.1`)},
+		{"AppendFloat64SmallPrecision(-1.123)", "AppendFloat64SmallPrecision", float64(-1.123), []byte(`-1.1`)},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			if got := AppendFloat32([]byte{}, float32(tt.input)); !reflect.DeepEqual(got, tt.want) {
-				t.Errorf("appendFloat32() = %s, want %s", got, tt.want)
-			}
-			if got := AppendFloat64([]byte{}, tt.input); !reflect.DeepEqual(got, tt.want) {
-				t.Errorf("appendFloat32() = %s, want %s", got, tt.want)
+			if got := w[tt.fn](tt.input); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("got %s, want %s", got, tt.want)
 			}
 		})
 	}
 }
+
+func Test_appendMAC(t *testing.T) {
+	MACtests := []struct {
+		input string
+		want  []byte
+	}{
+		{"01:23:45:67:89:ab", []byte(`"01:23:45:67:89:ab"`)},
+		{"cd:ef:11:22:33:44", []byte(`"cd:ef:11:22:33:44"`)},
+	}
+	for _, tt := range MACtests {
+		t.Run("MAC", func(t *testing.T) {
+			ha, _ := net.ParseMAC(tt.input)
+			if got := enc.AppendMACAddr([]byte{}, ha); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("appendMACAddr() = %s, want %s", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_appendIP(t *testing.T) {
+	IPv4tests := []struct {
+		input net.IP
+		want  []byte
+	}{
+		{net.IP{0, 0, 0, 0}, []byte(`"0.0.0.0"`)},
+		{net.IP{192, 0, 2, 200}, []byte(`"192.0.2.200"`)},
+	}
+
+	for _, tt := range IPv4tests {
+		t.Run("IPv4", func(t *testing.T) {
+			if got := enc.AppendIPAddr([]byte{}, tt.input); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("appendIPAddr() = %s, want %s", got, tt.want)
+			}
+		})
+	}
+	IPv6tests := []struct {
+		input net.IP
+		want  []byte
+	}{
+		{net.IPv6zero, []byte(`"::"`)},
+		{net.IPv6linklocalallnodes, []byte(`"ff02::1"`)},
+		{net.IP{0x20, 0x01, 0x0d, 0xb8, 0x85, 0xa3, 0x00, 0x00, 0x00, 0x00, 0x8a, 0x2e, 0x03, 0x70, 0x73, 0x34}, []byte(`"2001:db8:85a3::8a2e:370:7334"`)},
+	}
+	for _, tt := range IPv6tests {
+		t.Run("IPv6", func(t *testing.T) {
+			if got := enc.AppendIPAddr([]byte{}, tt.input); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("appendIPAddr() = %s, want %s", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_appendIPPrefix(t *testing.T) {
+	IPv4Prefixtests := []struct {
+		input net.IPNet
+		want  []byte
+	}{
+		{net.IPNet{IP: net.IP{0, 0, 0, 0}, Mask: net.IPv4Mask(0, 0, 0, 0)}, []byte(`"0.0.0.0/0"`)},
+		{net.IPNet{IP: net.IP{192, 0, 2, 200}, Mask: net.IPv4Mask(255, 255, 255, 0)}, []byte(`"192.0.2.200/24"`)},
+	}
+	for _, tt := range IPv4Prefixtests {
+		t.Run("IPv4", func(t *testing.T) {
+			if got := enc.AppendIPPrefix([]byte{}, tt.input); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("appendIPPrefix() = %s, want %s", got, tt.want)
+			}
+		})
+	}
+	IPv6Prefixtests := []struct {
+		input net.IPNet
+		want  []byte
+	}{
+		{net.IPNet{IP: net.IPv6zero, Mask: net.CIDRMask(0, 128)}, []byte(`"::/0"`)},
+		{net.IPNet{IP: net.IPv6linklocalallnodes, Mask: net.CIDRMask(128, 128)}, []byte(`"ff02::1/128"`)},
+		{net.IPNet{IP: net.IP{0x20, 0x01, 0x0d, 0xb8, 0x85, 0xa3, 0x00, 0x00, 0x00, 0x00, 0x8a, 0x2e, 0x03, 0x70, 0x73, 0x34},
+			Mask: net.CIDRMask(64, 128)},
+			[]byte(`"2001:db8:85a3::8a2e:370:7334/64"`)},
+	}
+	for _, tt := range IPv6Prefixtests {
+		t.Run("IPv6", func(t *testing.T) {
+			if got := enc.AppendIPPrefix([]byte{}, tt.input); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("appendIPPrefix() = %s, want %s", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_appendMac(t *testing.T) {
+	MACtests := []struct {
+		input net.HardwareAddr
+		want  []byte
+	}{
+		{net.HardwareAddr{0x12, 0x34, 0x56, 0x78, 0x90, 0xab}, []byte(`"12:34:56:78:90:ab"`)},
+		{net.HardwareAddr{0x12, 0x34, 0x00, 0x00, 0x90, 0xab}, []byte(`"12:34:00:00:90:ab"`)},
+	}
+
+	for _, tt := range MACtests {
+		t.Run("MAC", func(t *testing.T) {
+			if got := enc.AppendMACAddr([]byte{}, tt.input); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("appendMAC() = %s, want %s", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_appendType(t *testing.T) {
+	typeTests := []struct {
+		label string
+		input interface{}
+		want  []byte
+	}{
+		{"int", 42, []byte(`"int"`)},
+		{"MAC", net.HardwareAddr{0x12, 0x34, 0x00, 0x00, 0x90, 0xab}, []byte(`"net.HardwareAddr"`)},
+		{"float64", float64(2.50), []byte(`"float64"`)},
+		{"nil", nil, []byte(`"<nil>"`)},
+		{"bool", true, []byte(`"bool"`)},
+	}
+
+	for _, tt := range typeTests {
+		t.Run(tt.label, func(t *testing.T) {
+			if got := enc.AppendType([]byte{}, tt.input); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("appendType() = %s, want %s", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_appendObjectData(t *testing.T) {
+	tests := []struct {
+		dst  []byte
+		obj  []byte
+		want []byte
+	}{
+		{[]byte{}, []byte(`{"foo":"bar"}`), []byte(`"foo":"bar"}`)},
+		{[]byte(`{"qux":"quz"`), []byte(`{"foo":"bar"}`), []byte(`{"qux":"quz","foo":"bar"}`)},
+		{[]byte{}, []byte(`"foo":"bar"`), []byte(`"foo":"bar"`)},
+		{[]byte(`{"qux":"quz"`), []byte(`"foo":"bar"`), []byte(`{"qux":"quz","foo":"bar"`)},
+	}
+	for _, tt := range tests {
+		t.Run("ObjectData", func(t *testing.T) {
+			if got := enc.AppendObjectData(tt.dst, tt.obj); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("appendObjectData() = %s, want %s", got, tt.want)
+			}
+		})
+	}
+}
+
+var float64Tests = []struct {
+	Name string
+	Val  float64
+	Want string
+}{
+	{
+		Name: "Positive integer",
+		Val:  1234.0,
+		Want: "1234",
+	},
+	{
+		Name: "Negative integer",
+		Val:  -5678.0,
+		Want: "-5678",
+	},
+	{
+		Name: "Positive decimal",
+		Val:  12.3456,
+		Want: "12.3456",
+	},
+	{
+		Name: "Negative decimal",
+		Val:  -78.9012,
+		Want: "-78.9012",
+	},
+	{
+		Name: "Large positive number",
+		Val:  123456789.0,
+		Want: "123456789",
+	},
+	{
+		Name: "Large negative number",
+		Val:  -987654321.0,
+		Want: "-987654321",
+	},
+	{
+		Name: "Zero",
+		Val:  0.0,
+		Want: "0",
+	},
+	{
+		Name: "Smallest positive value",
+		Val:  math.SmallestNonzeroFloat64,
+		Want: "5e-324",
+	},
+	{
+		Name: "Largest positive value",
+		Val:  math.MaxFloat64,
+		Want: "1.7976931348623157e+308",
+	},
+	{
+		Name: "Smallest negative value",
+		Val:  -math.SmallestNonzeroFloat64,
+		Want: "-5e-324",
+	},
+	{
+		Name: "Largest negative value",
+		Val:  -math.MaxFloat64,
+		Want: "-1.7976931348623157e+308",
+	},
+	{
+		Name: "NaN",
+		Val:  math.NaN(),
+		Want: `"NaN"`,
+	},
+	{
+		Name: "+Inf",
+		Val:  math.Inf(1),
+		Want: `"+Inf"`,
+	},
+	{
+		Name: "-Inf",
+		Val:  math.Inf(-1),
+		Want: `"-Inf"`,
+	},
+	{
+		Name: "Clean up e-09 to e-9 case 1",
+		Val:  1e-9,
+		Want: "1e-9",
+	},
+	{
+		Name: "Clean up e-09 to e-9 case 2",
+		Val:  -2.236734e-9,
+		Want: "-2.236734e-9",
+	},
+}
+
+func TestEncoder_AppendFloat64(t *testing.T) {
+	for _, tc := range float64Tests {
+		t.Run(tc.Name, func(t *testing.T) {
+			var b []byte
+			b = (Encoder{}).AppendFloat64(b, tc.Val, -1)
+			if s := string(b); tc.Want != s {
+				t.Errorf("%q", s)
+			}
+		})
+	}
+}
+
+func FuzzEncoder_AppendFloat64(f *testing.F) {
+	for _, tc := range float64Tests {
+		f.Add(tc.Val)
+	}
+	f.Fuzz(func(t *testing.T, val float64) {
+		actual := (Encoder{}).AppendFloat64(nil, val, -1)
+		if len(actual) == 0 {
+			t.Fatal("empty buffer")
+		}
+
+		if actual[0] == '"' {
+			switch string(actual) {
+			case `"NaN"`:
+				if !math.IsNaN(val) {
+					t.Fatalf("expected %v got NaN", val)
+				}
+			case `"+Inf"`:
+				if !math.IsInf(val, 1) {
+					t.Fatalf("expected %v got +Inf", val)
+				}
+			case `"-Inf"`:
+				if !math.IsInf(val, -1) {
+					t.Fatalf("expected %v got -Inf", val)
+				}
+			default:
+				t.Fatalf("unexpected string: %s", actual)
+			}
+			return
+		}
+
+		if expected, err := json.Marshal(val); err != nil {
+			t.Error(err)
+		} else if string(actual) != string(expected) {
+			t.Errorf("expected %s, got %s", expected, actual)
+		}
+
+		var parsed float64
+		if err := json.Unmarshal(actual, &parsed); err != nil {
+			t.Fatal(err)
+		}
+
+		if parsed != val {
+			t.Fatalf("expected %v, got %v", val, parsed)
+		}
+	})
+}
+
+var float32Tests = []struct {
+	Name string
+	Val  float32
+	Want string
+}{
+	{
+		Name: "Positive integer",
+		Val:  1234.0,
+		Want: "1234",
+	},
+	{
+		Name: "Negative integer",
+		Val:  -5678.0,
+		Want: "-5678",
+	},
+	{
+		Name: "Positive decimal",
+		Val:  12.3456,
+		Want: "12.3456",
+	},
+	{
+		Name: "Negative decimal",
+		Val:  -78.9012,
+		Want: "-78.9012",
+	},
+	{
+		Name: "Large positive number",
+		Val:  123456789.0,
+		Want: "123456790",
+	},
+	{
+		Name: "Large negative number",
+		Val:  -987654321.0,
+		Want: "-987654340",
+	},
+	{
+		Name: "Zero",
+		Val:  0.0,
+		Want: "0",
+	},
+	{
+		Name: "Smallest positive value",
+		Val:  math.SmallestNonzeroFloat32,
+		Want: "1e-45",
+	},
+	{
+		Name: "Largest positive value",
+		Val:  math.MaxFloat32,
+		Want: "3.4028235e+38",
+	},
+	{
+		Name: "Smallest negative value",
+		Val:  -math.SmallestNonzeroFloat32,
+		Want: "-1e-45",
+	},
+	{
+		Name: "Largest negative value",
+		Val:  -math.MaxFloat32,
+		Want: "-3.4028235e+38",
+	},
+	{
+		Name: "NaN",
+		Val:  float32(math.NaN()),
+		Want: `"NaN"`,
+	},
+	{
+		Name: "+Inf",
+		Val:  float32(math.Inf(1)),
+		Want: `"+Inf"`,
+	},
+	{
+		Name: "-Inf",
+		Val:  float32(math.Inf(-1)),
+		Want: `"-Inf"`,
+	},
+	{
+		Name: "Clean up e-09 to e-9 case 1",
+		Val:  1e-9,
+		Want: "1e-9",
+	},
+	{
+		Name: "Clean up e-09 to e-9 case 2",
+		Val:  -2.236734e-9,
+		Want: "-2.236734e-9",
+	},
+}
+
+func TestEncoder_AppendFloat32(t *testing.T) {
+	for _, tc := range float32Tests {
+		t.Run(tc.Name, func(t *testing.T) {
+			var b []byte
+			b = (Encoder{}).AppendFloat32(b, tc.Val, -1)
+			if s := string(b); tc.Want != s {
+				t.Errorf("%q", s)
+			}
+		})
+	}
+}
+
+func FuzzEncoder_AppendFloat32(f *testing.F) {
+	for _, tc := range float32Tests {
+		f.Add(tc.Val)
+	}
+	f.Fuzz(func(t *testing.T, val float32) {
+		actual := (Encoder{}).AppendFloat32(nil, val, -1)
+		if len(actual) == 0 {
+			t.Fatal("empty buffer")
+		}
+
+		if actual[0] == '"' {
+			val := float64(val)
+			switch string(actual) {
+			case `"NaN"`:
+				if !math.IsNaN(val) {
+					t.Fatalf("expected %v got NaN", val)
+				}
+			case `"+Inf"`:
+				if !math.IsInf(val, 1) {
+					t.Fatalf("expected %v got +Inf", val)
+				}
+			case `"-Inf"`:
+				if !math.IsInf(val, -1) {
+					t.Fatalf("expected %v got -Inf", val)
+				}
+			default:
+				t.Fatalf("unexpected string: %s", actual)
+			}
+			return
+		}
+
+		if expected, err := json.Marshal(val); err != nil {
+			t.Error(err)
+		} else if string(actual) != string(expected) {
+			t.Errorf("expected %s, got %s", expected, actual)
+		}
+
+		var parsed float32
+		if err := json.Unmarshal(actual, &parsed); err != nil {
+			t.Fatal(err)
+		}
+
+		if parsed != val {
+			t.Fatalf("expected %v, got %v", val, parsed)
+		}
+	})
+}
+
+func generateFloat32s(n int) []float32 {
+	floats := make([]float32, n)
+	for i := 0; i < n; i++ {
+		floats[i] = rand.Float32()
+	}
+	return floats
+}
+
+func generateFloat64s(n int) []float64 {
+	floats := make([]float64, n)
+	for i := 0; i < n; i++ {
+		floats[i] = rand.Float64()
+	}
+	return floats
+}
+
+// this is really just for the memory allocation characteristics
+func BenchmarkEncoder_AppendFloat32(b *testing.B) {
+	floats := append(generateFloat32s(5000), float32(math.NaN()), float32(math.Inf(1)), float32(math.Inf(-1)))
+	dst := make([]byte, 0, 128)
+
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		for _, f := range floats {
+			dst = (Encoder{}).AppendFloat32(dst[:0], f, -1)
+		}
+	}
+}
+
+// this is really just for the memory allocation characteristics
+func BenchmarkEncoder_AppendFloat64(b *testing.B) {
+	floats := append(generateFloat64s(5000), math.NaN(), math.Inf(1), math.Inf(-1))
+	dst := make([]byte, 0, 128)
+
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		for _, f := range floats {
+			dst = (Encoder{}).AppendFloat64(dst[:0], f, -1)
+		}
+	}
+}

journald/journald.go

@@ -0,0 +1,121 @@
+//go:build !windows
+// +build !windows
+
+// Package journald provides a io.Writer to send the logs
+// to journalD component of systemd.
+
+package journald
+
+// This file provides a zerolog writer so that logs printed
+// using zerolog library can be sent to a journalD.
+
+// Zerolog's Top level key/Value Pairs are translated to
+// journald's args - all Values are sent to journald as strings.
+// And all key strings are converted to uppercase before sending
+// to journald (as required by journald).
+
+// In addition, entire log message (all Key Value Pairs), is also
+// sent to journald under the key "JSON".
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"strings"
+
+	"github.com/coreos/go-systemd/v22/journal"
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/internal/cbor"
+)
+
+const defaultJournalDPrio = journal.PriNotice
+
+// NewJournalDWriter returns a zerolog log destination
+// to be used as parameter to New() calls. Writing logs
+// to this writer will send the log messages to journalD
+// running in this system.
+func NewJournalDWriter() io.Writer {
+	return journalWriter{}
+}
+
+type journalWriter struct {
+}
+
+// levelToJPrio converts zerolog Level string into
+// journalD's priority values. JournalD has more
+// priorities than zerolog.
+func levelToJPrio(zLevel string) journal.Priority {
+	lvl, _ := zerolog.ParseLevel(zLevel)
+
+	switch lvl {
+	case zerolog.TraceLevel:
+		return journal.PriDebug
+	case zerolog.DebugLevel:
+		return journal.PriDebug
+	case zerolog.InfoLevel:
+		return journal.PriInfo
+	case zerolog.WarnLevel:
+		return journal.PriWarning
+	case zerolog.ErrorLevel:
+		return journal.PriErr
+	case zerolog.FatalLevel:
+		return journal.PriCrit
+	case zerolog.PanicLevel:
+		return journal.PriEmerg
+	case zerolog.NoLevel:
+		return journal.PriNotice
+	}
+	return defaultJournalDPrio
+}
+
+func (w journalWriter) Write(p []byte) (n int, err error) {
+	var event map[string]interface{}
+	origPLen := len(p)
+	p = cbor.DecodeIfBinaryToBytes(p)
+	d := json.NewDecoder(bytes.NewReader(p))
+	d.UseNumber()
+	err = d.Decode(&event)
+	jPrio := defaultJournalDPrio
+	args := make(map[string]string)
+	if err != nil {
+		return
+	}
+	if l, ok := event[zerolog.LevelFieldName].(string); ok {
+		jPrio = levelToJPrio(l)
+	}
+
+	msg := ""
+	for key, value := range event {
+		jKey := strings.ToUpper(key)
+		switch key {
+		case zerolog.LevelFieldName, zerolog.TimestampFieldName:
+			continue
+		case zerolog.MessageFieldName:
+			msg, _ = value.(string)
+			continue
+		}
+
+		switch v := value.(type) {
+		case string:
+			args[jKey] = v
+		case json.Number:
+			args[jKey] = fmt.Sprint(value)
+		default:
+			b, err := zerolog.InterfaceMarshalFunc(value)
+			if err != nil {
+				args[jKey] = fmt.Sprintf("[error: %v]", err)
+			} else {
+				args[jKey] = string(b)
+			}
+		}
+	}
+	args["JSON"] = string(p)
+	err = journal.Send(msg, jPrio, args)
+
+	if err == nil {
+		n = origPLen
+	}
+
+	return
+}

journald/journald_test.go

@@ -0,0 +1,86 @@
+// +build linux
+
+package journald_test
+
+import (
+	"bytes"
+	"io"
+	"testing"
+
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/journald"
+)
+
+func ExampleNewJournalDWriter() {
+	log := zerolog.New(journald.NewJournalDWriter())
+	log.Info().Str("foo", "bar").Uint64("small", 123).Float64("float", 3.14).Uint64("big", 1152921504606846976).Msg("Journal Test")
+	// Output:
+}
+
+/*
+
+There is no automated way to verify the output - since the output is sent
+to journald process and method to retrieve is journalctl. Will find a way
+to automate the process and fix this test.
+
+$ journalctl -o verbose -f
+
+Thu 2018-04-26 22:30:20.768136 PDT [s=3284d695bde946e4b5017c77a399237f;i=329f0;b=98c0dca0debc4b98a5b9534e910e7dd6;m=7a702e35dd4;t=56acdccd2ed0a;x=4690034cf0348614]
+    PRIORITY=6
+    _AUDIT_LOGINUID=1000
+    _BOOT_ID=98c0dca0debc4b98a5b9534e910e7dd6
+    _MACHINE_ID=926ed67eb4744580948de70fb474975e
+    _HOSTNAME=sprint
+    _UID=1000
+    _GID=1000
+    _CAP_EFFECTIVE=0
+    _SYSTEMD_SLICE=-.slice
+    _TRANSPORT=journal
+    _SYSTEMD_CGROUP=/
+    _AUDIT_SESSION=2945
+    MESSAGE=Journal Test
+    FOO=bar
+    BIG=1152921504606846976
+    _COMM=journald.test
+    SMALL=123
+    FLOAT=3.14
+    JSON={"level":"info","foo":"bar","small":123,"float":3.14,"big":1152921504606846976,"message":"Journal Test"}
+    _PID=27103
+    _SOURCE_REALTIME_TIMESTAMP=1524807020768136
+*/
+
+func TestWriteReturnsNoOfWrittenBytes(t *testing.T) {
+	input := []byte(`{"level":"info","time":1570912626,"message":"Starting..."}`)
+	wr := journald.NewJournalDWriter()
+	want := len(input)
+	got, err := wr.Write(input)
+
+	if err != nil {
+		t.Errorf("Unexpected error %v", err)
+	}
+
+	if want != got {
+		t.Errorf("Expected %d bytes to be written got %d", want, got)
+	}
+}
+
+func TestMultiWrite(t *testing.T) {
+	var (
+		w1 = new(bytes.Buffer)
+		w2 = new(bytes.Buffer)
+		w3 = journald.NewJournalDWriter()
+	)
+
+	zerolog.ErrorHandler = func(err error) {
+		if err == io.ErrShortWrite {
+			t.Errorf("Unexpected ShortWriteError")
+			t.FailNow()
+		}
+	}
+
+	log := zerolog.New(io.MultiWriter(w1, w2, w3)).With().Logger()
+
+	for i := 0; i < 10; i++ {
+		log.Info().Msg("Tick!")
+	}
+}

log.go

@@ -24,7 +24,7 @@
 //
 // Sub-loggers let you chain loggers with additional context:
 //
-//     sublogger := log.With().Str("component": "foo").Logger()
+//     sublogger := log.With().Str("component", "foo").Logger()
 //     sublogger.Info().Msg("hello world")
 //     // Output: {"time":1494567715,"level":"info","message":"hello world","component":"foo"}
 //
@@ -65,20 +65,66 @@
 //     sampled := log.Sample(&zerolog.BasicSampler{N: 10})
 //     sampled.Info().Msg("will be logged every 10 messages")
 //
+// Log with contextual hooks:
+//
+//     // Create the hook:
+//     type SeverityHook struct{}
+//
+//     func (h SeverityHook) Run(e *zerolog.Event, level zerolog.Level, msg string) {
+//          if level != zerolog.NoLevel {
+//              e.Str("severity", level.String())
+//          }
+//     }
+//
+//     // And use it:
+//     var h SeverityHook
+//     log := zerolog.New(os.Stdout).Hook(h)
+//     log.Warn().Msg("")
+//     // Output: {"level":"warn","severity":"warn"}
+//
+// # Caveats
+//
+// Field duplication:
+//
+// There is no fields deduplication out-of-the-box.
+// Using the same key multiple times creates new key in final JSON each time.
+//
+//     logger := zerolog.New(os.Stderr).With().Timestamp().Logger()
+//     logger.Info().
+//            Timestamp().
+//            Msg("dup")
+//     // Output: {"level":"info","time":1494567715,"time":1494567715,"message":"dup"}
+//
+// In this case, many consumers will take the last value,
+// but this is not guaranteed; check yours if in doubt.
+//
+// Concurrency safety:
+//
+// Be careful when calling UpdateContext. It is not concurrency safe. Use the With method to create a child logger:
+//
+//     func handler(w http.ResponseWriter, r *http.Request) {
+//         // Create a child logger for concurrency safety
+//         logger := log.Logger.With().Logger()
+//
+//         // Add context fields, for example User-Agent from HTTP headers
+//         logger.UpdateContext(func(c zerolog.Context) zerolog.Context {
+//             ...
+//         })
+//     }
 package zerolog
 
 import (
+	"context"
+	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
 	"strconv"
-
-	"github.com/rs/zerolog/internal/json"
+	"strings"
 )
 
 // Level defines log levels.
-type Level uint8
+type Level int8
 
 const (
 	// DebugLevel defines debug log level.
@@ -93,33 +139,91 @@ const (
 	FatalLevel
 	// PanicLevel defines panic log level.
 	PanicLevel
+	// NoLevel defines an absent log level.
+	NoLevel
 	// Disabled disables the logger.
 	Disabled
+
+	// TraceLevel defines trace log level.
+	TraceLevel Level = -1
+	// Values less than TraceLevel are handled as numbers.
 )
 
 func (l Level) String() string {
 	switch l {
+	case TraceLevel:
+		return LevelTraceValue
 	case DebugLevel:
-		return "debug"
+		return LevelDebugValue
 	case InfoLevel:
-		return "info"
+		return LevelInfoValue
 	case WarnLevel:
-		return "warn"
+		return LevelWarnValue
 	case ErrorLevel:
-		return "error"
+		return LevelErrorValue
 	case FatalLevel:
-		return "fatal"
+		return LevelFatalValue
 	case PanicLevel:
-		return "panic"
+		return LevelPanicValue
+	case Disabled:
+		return "disabled"
+	case NoLevel:
+		return ""
 	}
-	return ""
+	return strconv.Itoa(int(l))
 }
 
-var disabledEvent = newEvent(levelWriterAdapter{ioutil.Discard}, 0, false)
+// ParseLevel converts a level string into a zerolog Level value.
+// returns an error if the input string does not match known values.
+func ParseLevel(levelStr string) (Level, error) {
+	switch {
+	case strings.EqualFold(levelStr, LevelFieldMarshalFunc(TraceLevel)):
+		return TraceLevel, nil
+	case strings.EqualFold(levelStr, LevelFieldMarshalFunc(DebugLevel)):
+		return DebugLevel, nil
+	case strings.EqualFold(levelStr, LevelFieldMarshalFunc(InfoLevel)):
+		return InfoLevel, nil
+	case strings.EqualFold(levelStr, LevelFieldMarshalFunc(WarnLevel)):
+		return WarnLevel, nil
+	case strings.EqualFold(levelStr, LevelFieldMarshalFunc(ErrorLevel)):
+		return ErrorLevel, nil
+	case strings.EqualFold(levelStr, LevelFieldMarshalFunc(FatalLevel)):
+		return FatalLevel, nil
+	case strings.EqualFold(levelStr, LevelFieldMarshalFunc(PanicLevel)):
+		return PanicLevel, nil
+	case strings.EqualFold(levelStr, LevelFieldMarshalFunc(Disabled)):
+		return Disabled, nil
+	case strings.EqualFold(levelStr, LevelFieldMarshalFunc(NoLevel)):
+		return NoLevel, nil
+	}
+	i, err := strconv.Atoi(levelStr)
+	if err != nil {
+		return NoLevel, fmt.Errorf("Unknown Level String: '%s', defaulting to NoLevel", levelStr)
+	}
+	if i > 127 || i < -128 {
+		return NoLevel, fmt.Errorf("Out-Of-Bounds Level: '%d', defaulting to NoLevel", i)
+	}
+	return Level(i), nil
+}
+
+// UnmarshalText implements encoding.TextUnmarshaler to allow for easy reading from toml/yaml/json formats
+func (l *Level) UnmarshalText(text []byte) error {
+	if l == nil {
+		return errors.New("can't unmarshal a nil *Level")
+	}
+	var err error
+	*l, err = ParseLevel(string(text))
+	return err
+}
+
+// MarshalText implements encoding.TextMarshaler to allow for easy writing into toml/yaml/json formats
+func (l Level) MarshalText() ([]byte, error) {
+	return []byte(LevelFieldMarshalFunc(l)), nil
+}
 
 // A Logger represents an active logging object that generates lines
 // of JSON output to an io.Writer. Each logging operation makes a single
-// call to the Writer's Write method. There is no guaranty on access
+// call to the Writer's Write method. There is no guarantee on access
 // serialization to the Writer. If your Writer is not thread safe,
 // you may consider a sync wrapper.
 type Logger struct {
@@ -127,6 +231,9 @@ type Logger struct {
 	level   Level
 	sampler Sampler
 	context []byte
+	hooks   []Hook
+	stack   bool
+	ctx     context.Context
 }
 
 // New creates a root logger with given output writer. If the output writer implements
@@ -134,17 +241,17 @@ type Logger struct {
 // one.
 //
 // Each logging operation makes a single call to the Writer's Write method. There is no
-// guaranty on access serialization to the Writer. If your Writer is not thread safe,
+// guarantee on access serialization to the Writer. If your Writer is not thread safe,
 // you may consider using sync wrapper.
 func New(w io.Writer) Logger {
 	if w == nil {
-		w = ioutil.Discard
+		w = io.Discard
 	}
 	lw, ok := w.(LevelWriter)
 	if !ok {
-		lw = levelWriterAdapter{w}
+		lw = LevelWriterAdapter{w}
 	}
-	return Logger{w: lw}
+	return Logger{w: lw, level: TraceLevel}
 }
 
 // Nop returns a disabled logger for which all operation are no-op.
@@ -157,8 +264,14 @@ func (l Logger) Output(w io.Writer) Logger {
 	l2 := New(w)
 	l2.level = l.level
 	l2.sampler = l.sampler
-	l2.context = make([]byte, len(l.context), cap(l.context))
-	copy(l2.context, l.context)
+	l2.stack = l.stack
+	if len(l.hooks) > 0 {
+		l2.hooks = append(l2.hooks, l.hooks...)
+	}
+	if l.context != nil {
+		l2.context = make([]byte, len(l.context), cap(l.context))
+		copy(l2.context, l.context)
+	}
 	return l2
 }
 
@@ -169,21 +282,26 @@ func (l Logger) With() Context {
 	if context != nil {
 		l.context = append(l.context, context...)
 	} else {
-		// first byte of context is presence of timestamp or not
-		l.context = append(l.context, 0)
+		// This is needed for AppendKey to not check len of input
+		// thus making it inlinable
+		l.context = enc.AppendBeginMarker(l.context)
 	}
 	return Context{l}
 }
 
 // UpdateContext updates the internal logger's context.
 //
-// Use this method with caution. If unsure, prefer the With method.
+// Caution: This method is not concurrency safe.
+// Use the With method to create a child logger before modifying the context from concurrent goroutines.
 func (l *Logger) UpdateContext(update func(c Context) Context) {
 	if l == disabledLogger {
 		return
 	}
 	if cap(l.context) == 0 {
-		l.context = make([]byte, 1, 500) // first byte is timestamp flag
+		l.context = make([]byte, 0, 500)
+	}
+	if len(l.context) == 0 {
+		l.context = enc.AppendBeginMarker(l.context)
 	}
 	c := update(Context{*l})
 	l.context = c.l.context
@@ -195,61 +313,107 @@ func (l Logger) Level(lvl Level) Logger {
 	return l
 }
 
+// GetLevel returns the current Level of l.
+func (l Logger) GetLevel() Level {
+	return l.level
+}
+
 // Sample returns a logger with the s sampler.
 func (l Logger) Sample(s Sampler) Logger {
 	l.sampler = s
 	return l
 }
 
+// Hook returns a logger with the h Hook.
+func (l Logger) Hook(hooks ...Hook) Logger {
+	if len(hooks) == 0 {
+		return l
+	}
+	newHooks := make([]Hook, len(l.hooks), len(l.hooks)+len(hooks))
+	copy(newHooks, l.hooks)
+	l.hooks = append(newHooks, hooks...)
+	return l
+}
+
+// Trace starts a new message with trace level.
+//
+// You must call Msg on the returned event in order to send the event.
+func (l *Logger) Trace() *Event {
+	return l.newEvent(TraceLevel, nil)
+}
+
 // Debug starts a new message with debug level.
 //
 // You must call Msg on the returned event in order to send the event.
-func (l Logger) Debug() *Event {
-	return l.newEvent(DebugLevel, true, nil)
+func (l *Logger) Debug() *Event {
+	return l.newEvent(DebugLevel, nil)
 }
 
 // Info starts a new message with info level.
 //
 // You must call Msg on the returned event in order to send the event.
-func (l Logger) Info() *Event {
-	return l.newEvent(InfoLevel, true, nil)
+func (l *Logger) Info() *Event {
+	return l.newEvent(InfoLevel, nil)
 }
 
 // Warn starts a new message with warn level.
 //
 // You must call Msg on the returned event in order to send the event.
-func (l Logger) Warn() *Event {
-	return l.newEvent(WarnLevel, true, nil)
+func (l *Logger) Warn() *Event {
+	return l.newEvent(WarnLevel, nil)
 }
 
 // Error starts a new message with error level.
 //
 // You must call Msg on the returned event in order to send the event.
-func (l Logger) Error() *Event {
-	return l.newEvent(ErrorLevel, true, nil)
+func (l *Logger) Error() *Event {
+	return l.newEvent(ErrorLevel, nil)
+}
+
+// Err starts a new message with error level with err as a field if not nil or
+// with info level if err is nil.
+//
+// You must call Msg on the returned event in order to send the event.
+func (l *Logger) Err(err error) *Event {
+	if err != nil {
+		return l.Error().Err(err)
+	}
+
+	return l.Info()
 }
 
 // Fatal starts a new message with fatal level. The os.Exit(1) function
-// is called by the Msg method.
+// is called by the Msg method, which terminates the program immediately.
 //
 // You must call Msg on the returned event in order to send the event.
-func (l Logger) Fatal() *Event {
-	return l.newEvent(FatalLevel, true, func(msg string) { os.Exit(1) })
+func (l *Logger) Fatal() *Event {
+	return l.newEvent(FatalLevel, func(msg string) {
+		if closer, ok := l.w.(io.Closer); ok {
+			// Close the writer to flush any buffered message. Otherwise the message
+			// will be lost as os.Exit() terminates the program immediately.
+			closer.Close()
+		}
+		os.Exit(1)
+	})
 }
 
-// Panic starts a new message with panic level. The message is also sent
-// to the panic function.
+// Panic starts a new message with panic level. The panic() function
+// is called by the Msg method, which stops the ordinary flow of a goroutine.
 //
 // You must call Msg on the returned event in order to send the event.
-func (l Logger) Panic() *Event {
-	return l.newEvent(PanicLevel, true, func(msg string) { panic(msg) })
+func (l *Logger) Panic() *Event {
+	return l.newEvent(PanicLevel, func(msg string) { panic(msg) })
 }
 
-// WithLevel starts a new message with level.
+// WithLevel starts a new message with level. Unlike Fatal and Panic
+// methods, WithLevel does not terminate the program or stop the ordinary
+// flow of a goroutine when used with their respective levels.
 //
 // You must call Msg on the returned event in order to send the event.
-func (l Logger) WithLevel(level Level) *Event {
+func (l *Logger) WithLevel(level Level) *Event {
 	switch level {
+	case TraceLevel:
+		return l.Trace()
 	case DebugLevel:
 		return l.Debug()
 	case InfoLevel:
@@ -259,13 +423,15 @@ func (l Logger) WithLevel(level Level) *Event {
 	case ErrorLevel:
 		return l.Error()
 	case FatalLevel:
-		return l.Fatal()
+		return l.newEvent(FatalLevel, nil)
 	case PanicLevel:
-		return l.Panic()
+		return l.newEvent(PanicLevel, nil)
+	case NoLevel:
+		return l.Log()
 	case Disabled:
-		return disabledEvent
+		return nil
 	default:
-		panic("zerolog: WithLevel(): invalid level: " + strconv.Itoa(int(level)))
+		return l.newEvent(level, nil)
 	}
 }
 
@@ -273,25 +439,31 @@ func (l Logger) WithLevel(level Level) *Event {
 // will still disable events produced by this method.
 //
 // You must call Msg on the returned event in order to send the event.
-func (l Logger) Log() *Event {
-	// We use panic level with addLevelField=false to make Log passthrough all
-	// levels except Disabled.
-	return l.newEvent(PanicLevel, false, nil)
+func (l *Logger) Log() *Event {
+	return l.newEvent(NoLevel, nil)
 }
 
 // Print sends a log event using debug level and no extra field.
 // Arguments are handled in the manner of fmt.Print.
-func (l Logger) Print(v ...interface{}) {
+func (l *Logger) Print(v ...interface{}) {
 	if e := l.Debug(); e.Enabled() {
-		e.Msg(fmt.Sprint(v...))
+		e.CallerSkipFrame(1).Msg(fmt.Sprint(v...))
 	}
 }
 
 // Printf sends a log event using debug level and no extra field.
 // Arguments are handled in the manner of fmt.Printf.
-func (l Logger) Printf(format string, v ...interface{}) {
+func (l *Logger) Printf(format string, v ...interface{}) {
 	if e := l.Debug(); e.Enabled() {
-		e.Msg(fmt.Sprintf(format, v...))
+		e.CallerSkipFrame(1).Msg(fmt.Sprintf(format, v...))
+	}
+}
+
+// Println sends a log event using debug level and no extra field.
+// Arguments are handled in the manner of fmt.Println.
+func (l *Logger) Println(v ...interface{}) {
+	if e := l.Debug(); e.Enabled() {
+		e.CallerSkipFrame(1).Msg(fmt.Sprintln(v...))
 	}
 }
 
@@ -303,40 +475,40 @@ func (l Logger) Write(p []byte) (n int, err error) {
 		// Trim CR added by stdlog.
 		p = p[0 : n-1]
 	}
-	l.Log().Msg(string(p))
+	l.Log().CallerSkipFrame(1).Msg(string(p))
 	return
 }
 
-func (l Logger) newEvent(level Level, addLevelField bool, done func(string)) *Event {
+func (l *Logger) newEvent(level Level, done func(string)) *Event {
 	enabled := l.should(level)
 	if !enabled {
-		return disabledEvent
+		if done != nil {
+			done("")
+		}
+		return nil
 	}
-	lvl := InfoLevel
-	if addLevelField {
-		lvl = level
-	}
-	e := newEvent(l.w, lvl, true)
+	e := newEvent(l.w, level)
 	e.done = done
-	if l.context != nil && len(l.context) > 0 && l.context[0] > 0 {
-		// first byte of context is ts flag
-		e.buf = json.AppendTime(json.AppendKey(e.buf, TimestampFieldName), TimestampFunc(), TimeFieldFormat)
-	}
-	if addLevelField {
-		e.Str(LevelFieldName, level.String())
+	e.ch = l.hooks
+	e.ctx = l.ctx
+	if level != NoLevel && LevelFieldName != "" {
+		e.Str(LevelFieldName, LevelFieldMarshalFunc(level))
 	}
 	if l.context != nil && len(l.context) > 1 {
-		if len(e.buf) > 1 {
-			e.buf = append(e.buf, ',')
-		}
-		e.buf = append(e.buf, l.context[1:]...)
+		e.buf = enc.AppendObjectData(e.buf, l.context)
+	}
+	if l.stack {
+		e.Stack()
 	}
 	return e
 }
 
 // should returns true if the log event should be logged.
-func (l Logger) should(lvl Level) bool {
-	if lvl < l.level || lvl < globalLevel() {
+func (l *Logger) should(lvl Level) bool {
+	if l.w == nil {
+		return false
+	}
+	if lvl < l.level || lvl < GlobalLevel() {
 		return false
 	}
 	if l.sampler != nil && !samplingDisabled() {

log/log.go

@@ -3,6 +3,7 @@ package log
 
 import (
 	"context"
+	"fmt"
 	"io"
 	"os"
 
@@ -22,7 +23,7 @@ func With() zerolog.Context {
 	return Logger.With()
 }
 
-// Level crestes a child logger with the minium accepted level set to level.
+// Level creates a child logger with the minimum accepted level set to level.
 func Level(level zerolog.Level) zerolog.Logger {
 	return Logger.Level(level)
 }
@@ -32,6 +33,26 @@ func Sample(s zerolog.Sampler) zerolog.Logger {
 	return Logger.Sample(s)
 }
 
+// Hook returns a logger with the h Hook.
+func Hook(h zerolog.Hook) zerolog.Logger {
+	return Logger.Hook(h)
+}
+
+// Err starts a new message with error level with err as a field if not nil or
+// with info level if err is nil.
+//
+// You must call Msg on the returned event in order to send the event.
+func Err(err error) *zerolog.Event {
+	return Logger.Err(err)
+}
+
+// Trace starts a new message with trace level.
+//
+// You must call Msg on the returned event in order to send the event.
+func Trace() *zerolog.Event {
+	return Logger.Trace()
+}
+
 // Debug starts a new message with debug level.
 //
 // You must call Msg on the returned event in order to send the event.
@@ -76,8 +97,15 @@ func Panic() *zerolog.Event {
 	return Logger.Panic()
 }
 
+// WithLevel starts a new message with level.
+//
+// You must call Msg on the returned event in order to send the event.
+func WithLevel(level zerolog.Level) *zerolog.Event {
+	return Logger.WithLevel(level)
+}
+
 // Log starts a new message with no level. Setting zerolog.GlobalLevel to
-// zerlog.Disabled will still disable events produced by this method.
+// zerolog.Disabled will still disable events produced by this method.
 //
 // You must call Msg on the returned event in order to send the event.
 func Log() *zerolog.Event {
@@ -87,13 +115,13 @@ func Log() *zerolog.Event {
 // Print sends a log event using debug level and no extra field.
 // Arguments are handled in the manner of fmt.Print.
 func Print(v ...interface{}) {
-	Logger.Print(v...)
+	Logger.Debug().CallerSkipFrame(1).Msg(fmt.Sprint(v...))
 }
 
 // Printf sends a log event using debug level and no extra field.
 // Arguments are handled in the manner of fmt.Printf.
 func Printf(format string, v ...interface{}) {
-	Logger.Printf(format, v...)
+	Logger.Debug().CallerSkipFrame(1).Msgf(format, v...)
 }
 
 // Ctx returns the Logger associated with the ctx. If no logger

log/log_example_test.go

@@ -0,0 +1,162 @@
+// +build !binary_log
+
+package log_test
+
+import (
+	"errors"
+	"flag"
+	"os"
+	"time"
+
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/log"
+)
+
+// setup would normally be an init() function, however, there seems
+// to be something awry with the testing framework when we set the
+// global Logger from an init()
+func setup() {
+	// UNIX Time is faster and smaller than most timestamps
+	// If you set zerolog.TimeFieldFormat to an empty string,
+	// logs will write with UNIX time
+	zerolog.TimeFieldFormat = ""
+	// In order to always output a static time to stdout for these
+	// examples to pass, we need to override zerolog.TimestampFunc
+	// and log.Logger globals -- you would not normally need to do this
+	zerolog.TimestampFunc = func() time.Time {
+		return time.Date(2008, 1, 8, 17, 5, 05, 0, time.UTC)
+	}
+	log.Logger = zerolog.New(os.Stdout).With().Timestamp().Logger()
+}
+
+// Simple logging example using the Print function in the log package
+// Note that both Print and Printf are at the debug log level by default
+func ExamplePrint() {
+	setup()
+
+	log.Print("hello world")
+	// Output: {"level":"debug","time":1199811905,"message":"hello world"}
+}
+
+// Simple logging example using the Printf function in the log package
+func ExamplePrintf() {
+	setup()
+
+	log.Printf("hello %s", "world")
+	// Output: {"level":"debug","time":1199811905,"message":"hello world"}
+}
+
+// Example of a log with no particular "level"
+func ExampleLog() {
+	setup()
+	log.Log().Msg("hello world")
+
+	// Output: {"time":1199811905,"message":"hello world"}
+}
+
+// Example of a conditional level based on the presence of an error.
+func ExampleErr() {
+	setup()
+	err := errors.New("some error")
+	log.Err(err).Msg("hello world")
+	log.Err(nil).Msg("hello world")
+
+	// Output: {"level":"error","error":"some error","time":1199811905,"message":"hello world"}
+	// {"level":"info","time":1199811905,"message":"hello world"}
+}
+
+// Example of a log at a particular "level" (in this case, "trace")
+func ExampleTrace() {
+	setup()
+	log.Trace().Msg("hello world")
+
+	// Output: {"level":"trace","time":1199811905,"message":"hello world"}
+}
+
+// Example of a log at a particular "level" (in this case, "debug")
+func ExampleDebug() {
+	setup()
+	log.Debug().Msg("hello world")
+
+	// Output: {"level":"debug","time":1199811905,"message":"hello world"}
+}
+
+// Example of a log at a particular "level" (in this case, "info")
+func ExampleInfo() {
+	setup()
+	log.Info().Msg("hello world")
+
+	// Output: {"level":"info","time":1199811905,"message":"hello world"}
+}
+
+// Example of a log at a particular "level" (in this case, "warn")
+func ExampleWarn() {
+	setup()
+	log.Warn().Msg("hello world")
+
+	// Output: {"level":"warn","time":1199811905,"message":"hello world"}
+}
+
+// Example of a log at a particular "level" (in this case, "error")
+func ExampleError() {
+	setup()
+	log.Error().Msg("hello world")
+
+	// Output: {"level":"error","time":1199811905,"message":"hello world"}
+}
+
+// Example of a log at a particular "level" (in this case, "fatal")
+func ExampleFatal() {
+	setup()
+	err := errors.New("A repo man spends his life getting into tense situations")
+	service := "myservice"
+
+	log.Fatal().
+		Err(err).
+		Str("service", service).
+		Msgf("Cannot start %s", service)
+
+	// Outputs: {"level":"fatal","time":1199811905,"error":"A repo man spends his life getting into tense situations","service":"myservice","message":"Cannot start myservice"}
+}
+
+// TODO: Panic
+
+// This example uses command-line flags to demonstrate various outputs
+// depending on the chosen log level.
+func Example() {
+	setup()
+	debug := flag.Bool("debug", false, "sets log level to debug")
+
+	flag.Parse()
+
+	// Default level for this example is info, unless debug flag is present
+	zerolog.SetGlobalLevel(zerolog.InfoLevel)
+	if *debug {
+		zerolog.SetGlobalLevel(zerolog.DebugLevel)
+	}
+
+	log.Debug().Msg("This message appears only when log level set to Debug")
+	log.Info().Msg("This message appears when log level set to Debug or Info")
+
+	if e := log.Debug(); e.Enabled() {
+		// Compute log output only if enabled.
+		value := "bar"
+		e.Str("foo", value).Msg("some debug message")
+	}
+
+	// Output: {"level":"info","time":1199811905,"message":"This message appears when log level set to Debug or Info"}
+}
+
+// TODO: Output
+
+// TODO: With
+
+// TODO: Level
+
+// TODO: Sample
+
+// TODO: Hook
+
+// TODO: WithLevel
+
+// TODO: Ctx

log_example_test.go

@@ -1,8 +1,12 @@
+// +build !binary_log
+
 package zerolog_test
 
 import (
 	"errors"
+	"fmt"
 	stdlog "log"
+	"net"
 	"os"
 	"time"
 
@@ -13,7 +17,6 @@ func ExampleNew() {
 	log := zerolog.New(os.Stdout)
 
 	log.Info().Msg("hello world")
-
 	// Output: {"level":"info","message":"hello world"}
 }
 
@@ -45,8 +48,35 @@ func ExampleLogger_Sample() {
 	log.Info().Msg("message 3")
 	log.Info().Msg("message 4")
 
-	// Output: {"level":"info","message":"message 2"}
-	// {"level":"info","message":"message 4"}
+	// Output: {"level":"info","message":"message 1"}
+	// {"level":"info","message":"message 3"}
+}
+
+type LevelNameHook struct{}
+
+func (h LevelNameHook) Run(e *zerolog.Event, l zerolog.Level, msg string) {
+	if l != zerolog.NoLevel {
+		e.Str("level_name", l.String())
+	} else {
+		e.Str("level_name", "NoLevel")
+	}
+}
+
+type MessageHook string
+
+func (h MessageHook) Run(e *zerolog.Event, l zerolog.Level, msg string) {
+	e.Str("the_message", msg)
+}
+
+func ExampleLogger_Hook() {
+	var levelNameHook LevelNameHook
+	var messageHook MessageHook = "The message"
+
+	log := zerolog.New(os.Stdout).Hook(levelNameHook, messageHook)
+
+	log.Info().Msg("hello world")
+
+	// Output: {"level":"info","level_name":"info","the_message":"hello world","message":"hello world"}
 }
 
 func ExampleLogger_Print() {
@@ -65,6 +95,25 @@ func ExampleLogger_Printf() {
 	// Output: {"level":"debug","message":"hello world"}
 }
 
+func ExampleLogger_Println() {
+	log := zerolog.New(os.Stdout)
+
+	log.Println("hello world")
+
+	// Output: {"level":"debug","message":"hello world\n"}
+}
+
+func ExampleLogger_Trace() {
+	log := zerolog.New(os.Stdout)
+
+	log.Trace().
+		Str("foo", "bar").
+		Int("n", 123).
+		Msg("hello world")
+
+	// Output: {"level":"trace","foo":"bar","n":123,"message":"hello world"}
+}
+
 func ExampleLogger_Debug() {
 	log := zerolog.New(os.Stdout)
 
@@ -166,6 +215,22 @@ func (u User) MarshalZerologObject(e *zerolog.Event) {
 		Time("created", u.Created)
 }
 
+type Price struct {
+	val  uint64
+	prec int
+	unit string
+}
+
+func (p Price) MarshalZerologObject(e *zerolog.Event) {
+	denom := uint64(1)
+	for i := 0; i < p.prec; i++ {
+		denom *= 10
+	}
+	result := []byte(p.unit)
+	result = append(result, fmt.Sprintf("%d.%d", p.val/denom, p.val%denom)...)
+	e.Str("price", string(result))
+}
+
 type Users []User
 
 func (uu Users) MarshalZerologArray(a *zerolog.Array) {
@@ -181,11 +246,15 @@ func ExampleEvent_Array() {
 		Str("foo", "bar").
 		Array("array", zerolog.Arr().
 			Str("baz").
-			Int(1),
+			Int(1).
+			Dict(zerolog.Dict().
+				Str("bar", "baz").
+				Int("n", 1),
+			),
 		).
 		Msg("hello world")
 
-	// Output: {"foo":"bar","array":["baz",1],"message":"hello world"}
+	// Output: {"foo":"bar","array":["baz",1,{"bar":"baz","n":1}],"message":"hello world"}
 }
 
 func ExampleEvent_Array_object() {
@@ -219,6 +288,19 @@ func ExampleEvent_Object() {
 	// Output: {"foo":"bar","user":{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},"message":"hello world"}
 }
 
+func ExampleEvent_EmbedObject() {
+	log := zerolog.New(os.Stdout)
+
+	price := Price{val: 6449, prec: 2, unit: "$"}
+
+	log.Log().
+		Str("foo", "bar").
+		EmbedObject(price).
+		Msg("hello world")
+
+	// Output: {"foo":"bar","price":"$64.49","message":"hello world"}
+}
+
 func ExampleEvent_Interface() {
 	log := zerolog.New(os.Stdout)
 
@@ -237,7 +319,7 @@ func ExampleEvent_Interface() {
 }
 
 func ExampleEvent_Dur() {
-	d := time.Duration(10 * time.Second)
+	d := 10 * time.Second
 
 	log := zerolog.New(os.Stdout)
 
@@ -251,8 +333,8 @@ func ExampleEvent_Dur() {
 
 func ExampleEvent_Durs() {
 	d := []time.Duration{
-		time.Duration(10 * time.Second),
-		time.Duration(20 * time.Second),
+		10 * time.Second,
+		20 * time.Second,
 	}
 
 	log := zerolog.New(os.Stdout)
@@ -265,6 +347,38 @@ func ExampleEvent_Durs() {
 	// Output: {"foo":"bar","durs":[10000,20000],"message":"hello world"}
 }
 
+func ExampleEvent_Fields_map() {
+	fields := map[string]interface{}{
+		"bar": "baz",
+		"n":   1,
+	}
+
+	log := zerolog.New(os.Stdout)
+
+	log.Log().
+		Str("foo", "bar").
+		Fields(fields).
+		Msg("hello world")
+
+	// Output: {"foo":"bar","bar":"baz","n":1,"message":"hello world"}
+}
+
+func ExampleEvent_Fields_slice() {
+	fields := []interface{}{
+		"bar", "baz",
+		"n", 1,
+	}
+
+	log := zerolog.New(os.Stdout)
+
+	log.Log().
+		Str("foo", "bar").
+		Fields(fields).
+		Msg("hello world")
+
+	// Output: {"foo":"bar","bar":"baz","n":1,"message":"hello world"}
+}
+
 func ExampleContext_Dict() {
 	log := zerolog.New(os.Stdout).With().
 		Str("foo", "bar").
@@ -322,6 +436,20 @@ func ExampleContext_Object() {
 	// Output: {"foo":"bar","user":{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},"message":"hello world"}
 }
 
+func ExampleContext_EmbedObject() {
+
+	price := Price{val: 6449, prec: 2, unit: "$"}
+
+	log := zerolog.New(os.Stdout).With().
+		Str("foo", "bar").
+		EmbedObject(price).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	// Output: {"foo":"bar","price":"$64.49","message":"hello world"}
+}
+
 func ExampleContext_Interface() {
 	obj := struct {
 		Name string `json:"name"`
@@ -340,7 +468,7 @@ func ExampleContext_Interface() {
 }
 
 func ExampleContext_Dur() {
-	d := time.Duration(10 * time.Second)
+	d := 10 * time.Second
 
 	log := zerolog.New(os.Stdout).With().
 		Str("foo", "bar").
@@ -354,8 +482,8 @@ func ExampleContext_Dur() {
 
 func ExampleContext_Durs() {
 	d := []time.Duration{
-		time.Duration(10 * time.Second),
-		time.Duration(20 * time.Second),
+		10 * time.Second,
+		20 * time.Second,
 	}
 
 	log := zerolog.New(os.Stdout).With().
@@ -367,3 +495,68 @@ func ExampleContext_Durs() {
 
 	// Output: {"foo":"bar","durs":[10000,20000],"message":"hello world"}
 }
+
+func ExampleContext_IPAddr() {
+	hostIP := net.IP{192, 168, 0, 100}
+	log := zerolog.New(os.Stdout).With().
+		IPAddr("HostIP", hostIP).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	// Output: {"HostIP":"192.168.0.100","message":"hello world"}
+}
+
+func ExampleContext_IPPrefix() {
+	route := net.IPNet{IP: net.IP{192, 168, 0, 0}, Mask: net.CIDRMask(24, 32)}
+	log := zerolog.New(os.Stdout).With().
+		IPPrefix("Route", route).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	// Output: {"Route":"192.168.0.0/24","message":"hello world"}
+}
+
+func ExampleContext_MACAddr() {
+	mac := net.HardwareAddr{0x00, 0x14, 0x22, 0x01, 0x23, 0x45}
+	log := zerolog.New(os.Stdout).With().
+		MACAddr("hostMAC", mac).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	// Output: {"hostMAC":"00:14:22:01:23:45","message":"hello world"}
+}
+
+func ExampleContext_Fields_map() {
+	fields := map[string]interface{}{
+		"bar": "baz",
+		"n":   1,
+	}
+
+	log := zerolog.New(os.Stdout).With().
+		Str("foo", "bar").
+		Fields(fields).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	// Output: {"foo":"bar","bar":"baz","n":1,"message":"hello world"}
+}
+
+func ExampleContext_Fields_slice() {
+	fields := []interface{}{
+		"bar", "baz",
+		"n", 1,
+	}
+
+	log := zerolog.New(os.Stdout).With().
+		Str("foo", "bar").
+		Fields(fields).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	// Output: {"foo":"bar","bar":"baz","n":1,"message":"hello world"}
+}

log_test.go

@@ -2,8 +2,14 @@ package zerolog
 
 import (
 	"bytes"
+	"context"
 	"errors"
+	"fmt"
+	"net"
 	"reflect"
+	"runtime"
+	"strconv"
+	"strings"
 	"testing"
 	"time"
 )
@@ -13,7 +19,7 @@ func TestLog(t *testing.T) {
 		out := &bytes.Buffer{}
 		log := New(out)
 		log.Log().Msg("")
-		if got, want := out.String(), "{}\n"; got != want {
+		if got, want := decodeIfBinaryToString(out.Bytes()), "{}\n"; got != want {
 			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
@@ -22,7 +28,7 @@ func TestLog(t *testing.T) {
 		out := &bytes.Buffer{}
 		log := New(out)
 		log.Log().Str("foo", "bar").Msg("")
-		if got, want := out.String(), `{"foo":"bar"}`+"\n"; got != want {
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"foo":"bar"}`+"\n"; got != want {
 			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
@@ -34,7 +40,7 @@ func TestLog(t *testing.T) {
 			Str("foo", "bar").
 			Int("n", 123).
 			Msg("")
-		if got, want := out.String(), `{"foo":"bar","n":123}`+"\n"; got != want {
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"foo":"bar","n":123}`+"\n"; got != want {
 			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
@@ -45,7 +51,7 @@ func TestInfo(t *testing.T) {
 		out := &bytes.Buffer{}
 		log := New(out)
 		log.Info().Msg("")
-		if got, want := out.String(), `{"level":"info"}`+"\n"; got != want {
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"info"}`+"\n"; got != want {
 			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
@@ -54,7 +60,7 @@ func TestInfo(t *testing.T) {
 		out := &bytes.Buffer{}
 		log := New(out)
 		log.Info().Str("foo", "bar").Msg("")
-		if got, want := out.String(), `{"level":"info","foo":"bar"}`+"\n"; got != want {
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"info","foo":"bar"}`+"\n"; got != want {
 			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
@@ -66,16 +72,39 @@ func TestInfo(t *testing.T) {
 			Str("foo", "bar").
 			Int("n", 123).
 			Msg("")
-		if got, want := out.String(), `{"level":"info","foo":"bar","n":123}`+"\n"; got != want {
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"info","foo":"bar","n":123}`+"\n"; got != want {
 			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
 }
 
+func TestEmptyLevelFieldName(t *testing.T) {
+	fieldName := LevelFieldName
+	LevelFieldName = ""
+
+	t.Run("empty setting", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out)
+		log.Info().
+			Str("foo", "bar").
+			Int("n", 123).
+			Msg("")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"foo":"bar","n":123}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+	LevelFieldName = fieldName
+}
+
 func TestWith(t *testing.T) {
 	out := &bytes.Buffer{}
-	log := New(out).With().
-		Str("foo", "bar").
+	ctx := New(out).With().
+		Str("string", "foo").
+		Stringer("stringer", net.IP{127, 0, 0, 1}).
+		Stringer("stringer_nil", nil).
+		Bytes("bytes", []byte("bar")).
+		Hex("hex", []byte{0x12, 0xef}).
+		RawJSON("json", []byte(`{"some":"json"}`)).
 		AnErr("some_err", nil).
 		Err(errors.New("some error")).
 		Bool("bool", true).
@@ -89,12 +118,48 @@ func TestWith(t *testing.T) {
 		Uint16("uint16", 8).
 		Uint32("uint32", 9).
 		Uint64("uint64", 10).
-		Float32("float32", 11).
-		Float64("float64", 12).
+		Float32("float32", 11.101).
+		Float64("float64", 12.30303).
 		Time("time", time.Time{}).
-		Logger()
+		Ctx(context.Background())
+	_, file, line, _ := runtime.Caller(0)
+	caller := fmt.Sprintf("%s:%d", file, line+3)
+	log := ctx.Caller().Logger()
 	log.Log().Msg("")
-	if got, want := out.String(), `{"foo":"bar","error":"some error","bool":true,"int":1,"int8":2,"int16":3,"int32":4,"int64":5,"uint":6,"uint8":7,"uint16":8,"uint32":9,"uint64":10,"float32":11,"float64":12,"time":"0001-01-01T00:00:00Z"}`+"\n"; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"string":"foo","stringer":"127.0.0.1","stringer_nil":null,"bytes":"bar","hex":"12ef","json":{"some":"json"},"error":"some error","bool":true,"int":1,"int8":2,"int16":3,"int32":4,"int64":5,"uint":6,"uint8":7,"uint16":8,"uint32":9,"uint64":10,"float32":11.101,"float64":12.30303,"time":"0001-01-01T00:00:00Z","caller":"`+caller+`"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+
+	// Validate CallerWithSkipFrameCount.
+	out.Reset()
+	_, file, line, _ = runtime.Caller(0)
+	caller = fmt.Sprintf("%s:%d", file, line+5)
+	log = ctx.CallerWithSkipFrameCount(3).Logger()
+	func() {
+		log.Log().Msg("")
+	}()
+	// The above line is a little contrived, but the line above should be the line due
+	// to the extra frame skip.
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"string":"foo","stringer":"127.0.0.1","stringer_nil":null,"bytes":"bar","hex":"12ef","json":{"some":"json"},"error":"some error","bool":true,"int":1,"int8":2,"int16":3,"int32":4,"int64":5,"uint":6,"uint8":7,"uint16":8,"uint32":9,"uint64":10,"float32":11.101,"float64":12.30303,"time":"0001-01-01T00:00:00Z","caller":"`+caller+`"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestWithReset(t *testing.T) {
+	out := &bytes.Buffer{}
+	ctx := New(out).With().
+		Str("string", "foo").
+		Stringer("stringer", net.IP{127, 0, 0, 1}).
+		Stringer("stringer_nil", nil).
+		Reset().
+		Bytes("bytes", []byte("bar")).
+		Hex("hex", []byte{0x12, 0xef}).
+		Uint64("uint64", 10).
+		Float64("float64", 12.30303).
+		Ctx(context.Background())
+	log := ctx.Logger()
+	log.Log().Msg("")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"bytes":"bar","hex":"12ef","uint64":10,"float64":12.30303}`+"\n"; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
@@ -120,10 +185,144 @@ func TestFieldsMap(t *testing.T) {
 		"uint64":  uint64(10),
 		"float32": float32(11),
 		"float64": float64(12),
+		"ipv6":    net.IP{0x20, 0x01, 0x0d, 0xb8, 0x85, 0xa3, 0x00, 0x00, 0x00, 0x00, 0x8a, 0x2e, 0x03, 0x70, 0x73, 0x34},
 		"dur":     1 * time.Second,
 		"time":    time.Time{},
+		"obj":     obj{"a", "b", 1},
 	}).Msg("")
-	if got, want := out.String(), `{"bool":true,"bytes":"bar","dur":1000,"error":"some error","float32":11,"float64":12,"int":1,"int16":3,"int32":4,"int64":5,"int8":2,"nil":null,"string":"foo","time":"0001-01-01T00:00:00Z","uint":6,"uint16":8,"uint32":9,"uint64":10,"uint8":7}`+"\n"; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"bool":true,"bytes":"bar","dur":1000,"error":"some error","float32":11,"float64":12,"int":1,"int16":3,"int32":4,"int64":5,"int8":2,"ipv6":"2001:db8:85a3::8a2e:370:7334","nil":null,"obj":{"Pub":"a","Tag":"b","priv":1},"string":"foo","time":"0001-01-01T00:00:00Z","uint":6,"uint16":8,"uint32":9,"uint64":10,"uint8":7}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestFieldsMapPnt(t *testing.T) {
+	out := &bytes.Buffer{}
+	log := New(out)
+	log.Log().Fields(map[string]interface{}{
+		"string":  new(string),
+		"bool":    new(bool),
+		"int":     new(int),
+		"int8":    new(int8),
+		"int16":   new(int16),
+		"int32":   new(int32),
+		"int64":   new(int64),
+		"uint":    new(uint),
+		"uint8":   new(uint8),
+		"uint16":  new(uint16),
+		"uint32":  new(uint32),
+		"uint64":  new(uint64),
+		"float32": new(float32),
+		"float64": new(float64),
+		"dur":     new(time.Duration),
+		"time":    new(time.Time),
+	}).Msg("")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"bool":false,"dur":0,"float32":0,"float64":0,"int":0,"int16":0,"int32":0,"int64":0,"int8":0,"string":"","time":"0001-01-01T00:00:00Z","uint":0,"uint16":0,"uint32":0,"uint64":0,"uint8":0}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestFieldsMapNilPnt(t *testing.T) {
+	var (
+		stringPnt  *string
+		boolPnt    *bool
+		intPnt     *int
+		int8Pnt    *int8
+		int16Pnt   *int16
+		int32Pnt   *int32
+		int64Pnt   *int64
+		uintPnt    *uint
+		uint8Pnt   *uint8
+		uint16Pnt  *uint16
+		uint32Pnt  *uint32
+		uint64Pnt  *uint64
+		float32Pnt *float32
+		float64Pnt *float64
+		durPnt     *time.Duration
+		timePnt    *time.Time
+	)
+	out := &bytes.Buffer{}
+	log := New(out)
+	fields := map[string]interface{}{
+		"string":  stringPnt,
+		"bool":    boolPnt,
+		"int":     intPnt,
+		"int8":    int8Pnt,
+		"int16":   int16Pnt,
+		"int32":   int32Pnt,
+		"int64":   int64Pnt,
+		"uint":    uintPnt,
+		"uint8":   uint8Pnt,
+		"uint16":  uint16Pnt,
+		"uint32":  uint32Pnt,
+		"uint64":  uint64Pnt,
+		"float32": float32Pnt,
+		"float64": float64Pnt,
+		"dur":     durPnt,
+		"time":    timePnt,
+	}
+
+	log.Log().Fields(fields).Msg("")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"bool":null,"dur":null,"float32":null,"float64":null,"int":null,"int16":null,"int32":null,"int64":null,"int8":null,"string":null,"time":null,"uint":null,"uint16":null,"uint32":null,"uint64":null,"uint8":null}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestFieldsSlice(t *testing.T) {
+	out := &bytes.Buffer{}
+	log := New(out)
+	log.Log().Fields([]interface{}{
+		"nil", nil,
+		"string", "foo",
+		"bytes", []byte("bar"),
+		"error", errors.New("some error"),
+		"bool", true,
+		"int", int(1),
+		"int8", int8(2),
+		"int16", int16(3),
+		"int32", int32(4),
+		"int64", int64(5),
+		"uint", uint(6),
+		"uint8", uint8(7),
+		"uint16", uint16(8),
+		"uint32", uint32(9),
+		"uint64", uint64(10),
+		"float32", float32(11),
+		"float64", float64(12),
+		"ipv6", net.IP{0x20, 0x01, 0x0d, 0xb8, 0x85, 0xa3, 0x00, 0x00, 0x00, 0x00, 0x8a, 0x2e, 0x03, 0x70, 0x73, 0x34},
+		"dur", 1 * time.Second,
+		"time", time.Time{},
+		"obj", obj{"a", "b", 1},
+	}).Msg("")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"nil":null,"string":"foo","bytes":"bar","error":"some error","bool":true,"int":1,"int8":2,"int16":3,"int32":4,"int64":5,"uint":6,"uint8":7,"uint16":8,"uint32":9,"uint64":10,"float32":11,"float64":12,"ipv6":"2001:db8:85a3::8a2e:370:7334","dur":1000,"time":"0001-01-01T00:00:00Z","obj":{"Pub":"a","Tag":"b","priv":1}}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestFieldsSliceExtraneous(t *testing.T) {
+	out := &bytes.Buffer{}
+	log := New(out)
+	log.Log().Fields([]interface{}{
+		"string", "foo",
+		"error", errors.New("some error"),
+		32, "valueForNonStringKey",
+		"bool", true,
+		"int", int(1),
+		"keyWithoutValue",
+	}).Msg("")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"string":"foo","error":"some error","bool":true,"int":1}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestFieldsNotMapSlice(t *testing.T) {
+	out := &bytes.Buffer{}
+	log := New(out)
+	log.Log().
+		Fields(obj{"a", "b", 1}).
+		Fields("string").
+		Fields(1).
+		Msg("")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{}`+"\n"; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
@@ -132,9 +331,18 @@ func TestFields(t *testing.T) {
 	out := &bytes.Buffer{}
 	log := New(out)
 	now := time.Now()
+	_, file, line, _ := runtime.Caller(0)
+	caller := fmt.Sprintf("%s:%d", file, line+3)
 	log.Log().
+		Caller().
 		Str("string", "foo").
+		Stringer("stringer", net.IP{127, 0, 0, 1}).
+		Stringer("stringer_nil", nil).
 		Bytes("bytes", []byte("bar")).
+		Hex("hex", []byte{0x12, 0xef}).
+		RawJSON("json", []byte(`{"some":"json"}`)).
+		RawCBOR("cbor", []byte{0x83, 0x01, 0x82, 0x02, 0x03, 0x82, 0x04, 0x05}).
+		Func(func(e *Event) { e.Str("func", "func_output") }).
 		AnErr("some_err", nil).
 		Err(errors.New("some error")).
 		Bool("bool", true).
@@ -148,13 +356,18 @@ func TestFields(t *testing.T) {
 		Uint16("uint16", 8).
 		Uint32("uint32", 9).
 		Uint64("uint64", 10).
-		Float32("float32", 11).
-		Float64("float64", 12).
+		IPAddr("IPv4", net.IP{192, 168, 0, 100}).
+		IPAddr("IPv6", net.IP{0x20, 0x01, 0x0d, 0xb8, 0x85, 0xa3, 0x00, 0x00, 0x00, 0x00, 0x8a, 0x2e, 0x03, 0x70, 0x73, 0x34}).
+		MACAddr("Mac", net.HardwareAddr{0x00, 0x14, 0x22, 0x01, 0x23, 0x45}).
+		IPPrefix("Prefix", net.IPNet{IP: net.IP{192, 168, 0, 100}, Mask: net.CIDRMask(24, 32)}).
+		Float32("float32", 11.1234).
+		Float64("float64", 12.321321321).
 		Dur("dur", 1*time.Second).
 		Time("time", time.Time{}).
 		TimeDiff("diff", now, now.Add(-10*time.Second)).
+		Ctx(context.Background()).
 		Msg("")
-	if got, want := out.String(), `{"string":"foo","bytes":"bar","error":"some error","bool":true,"int":1,"int8":2,"int16":3,"int32":4,"int64":5,"uint":6,"uint8":7,"uint16":8,"uint32":9,"uint64":10,"float32":11,"float64":12,"dur":1000,"time":"0001-01-01T00:00:00Z","diff":10000}`+"\n"; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"caller":"`+caller+`","string":"foo","stringer":"127.0.0.1","stringer_nil":null,"bytes":"bar","hex":"12ef","json":{"some":"json"},"cbor":"data:application/cbor;base64,gwGCAgOCBAU=","func":"func_output","error":"some error","bool":true,"int":1,"int8":2,"int16":3,"int32":4,"int64":5,"uint":6,"uint8":7,"uint16":8,"uint32":9,"uint64":10,"IPv4":"192.168.0.100","IPv6":"2001:db8:85a3::8a2e:370:7334","Mac":"00:14:22:01:23:45","Prefix":"192.168.0.100/24","float32":11.1234,"float64":12.321321321,"dur":1000,"time":"0001-01-01T00:00:00Z","diff":10000}`+"\n"; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
@@ -164,6 +377,7 @@ func TestFieldsArrayEmpty(t *testing.T) {
 	log := New(out)
 	log.Log().
 		Strs("string", []string{}).
+		Stringers("stringer", []fmt.Stringer{}).
 		Errs("err", []error{}).
 		Bools("bool", []bool{}).
 		Ints("int", []int{}).
@@ -181,7 +395,7 @@ func TestFieldsArrayEmpty(t *testing.T) {
 		Durs("dur", []time.Duration{}).
 		Times("time", []time.Time{}).
 		Msg("")
-	if got, want := out.String(), `{"string":[],"err":[],"bool":[],"int":[],"int8":[],"int16":[],"int32":[],"int64":[],"uint":[],"uint8":[],"uint16":[],"uint32":[],"uint64":[],"float32":[],"float64":[],"dur":[],"time":[]}`+"\n"; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"string":[],"stringer":[],"err":[],"bool":[],"int":[],"int8":[],"int16":[],"int32":[],"int64":[],"uint":[],"uint8":[],"uint16":[],"uint32":[],"uint64":[],"float32":[],"float64":[],"dur":[],"time":[]}`+"\n"; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
@@ -191,6 +405,7 @@ func TestFieldsArraySingleElement(t *testing.T) {
 	log := New(out)
 	log.Log().
 		Strs("string", []string{"foo"}).
+		Stringers("stringer", []fmt.Stringer{net.IP{127, 0, 0, 1}}).
 		Errs("err", []error{errors.New("some error")}).
 		Bools("bool", []bool{true}).
 		Ints("int", []int{1}).
@@ -206,9 +421,9 @@ func TestFieldsArraySingleElement(t *testing.T) {
 		Floats32("float32", []float32{11}).
 		Floats64("float64", []float64{12}).
 		Durs("dur", []time.Duration{1 * time.Second}).
-		Times("time", []time.Time{time.Time{}}).
+		Times("time", []time.Time{{}}).
 		Msg("")
-	if got, want := out.String(), `{"string":["foo"],"err":["some error"],"bool":[true],"int":[1],"int8":[2],"int16":[3],"int32":[4],"int64":[5],"uint":[6],"uint8":[7],"uint16":[8],"uint32":[9],"uint64":[10],"float32":[11],"float64":[12],"dur":[1000],"time":["0001-01-01T00:00:00Z"]}`+"\n"; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"string":["foo"],"stringer":["127.0.0.1"],"err":["some error"],"bool":[true],"int":[1],"int8":[2],"int16":[3],"int32":[4],"int64":[5],"uint":[6],"uint8":[7],"uint16":[8],"uint32":[9],"uint64":[10],"float32":[11],"float64":[12],"dur":[1000],"time":["0001-01-01T00:00:00Z"]}`+"\n"; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
@@ -218,6 +433,7 @@ func TestFieldsArrayMultipleElement(t *testing.T) {
 	log := New(out)
 	log.Log().
 		Strs("string", []string{"foo", "bar"}).
+		Stringers("stringer", []fmt.Stringer{nil, net.IP{127, 0, 0, 1}}).
 		Errs("err", []error{errors.New("some error"), nil}).
 		Bools("bool", []bool{true, false}).
 		Ints("int", []int{1, 0}).
@@ -233,9 +449,9 @@ func TestFieldsArrayMultipleElement(t *testing.T) {
 		Floats32("float32", []float32{11, 0}).
 		Floats64("float64", []float64{12, 0}).
 		Durs("dur", []time.Duration{1 * time.Second, 0}).
-		Times("time", []time.Time{time.Time{}, time.Time{}}).
+		Times("time", []time.Time{{}, {}}).
 		Msg("")
-	if got, want := out.String(), `{"string":["foo","bar"],"err":["some error",null],"bool":[true,false],"int":[1,0],"int8":[2,0],"int16":[3,0],"int32":[4,0],"int64":[5,0],"uint":[6,0],"uint8":[7,0],"uint16":[8,0],"uint32":[9,0],"uint64":[10,0],"float32":[11,0],"float64":[12,0],"dur":[1000,0],"time":["0001-01-01T00:00:00Z","0001-01-01T00:00:00Z"]}`+"\n"; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"string":["foo","bar"],"stringer":[null,"127.0.0.1"],"err":["some error",null],"bool":[true,false],"int":[1,0],"int8":[2,0],"int16":[3,0],"int32":[4,0],"int64":[5,0],"uint":[6,0],"uint8":[7,0],"uint16":[8,0],"uint32":[9,0],"uint64":[10,0],"float32":[11,0],"float64":[12,0],"dur":[1000,0],"time":["0001-01-01T00:00:00Z","0001-01-01T00:00:00Z"]}`+"\n"; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
@@ -246,9 +462,12 @@ func TestFieldsDisabled(t *testing.T) {
 	now := time.Now()
 	log.Debug().
 		Str("string", "foo").
+		Stringer("stringer", net.IP{127, 0, 0, 1}).
 		Bytes("bytes", []byte("bar")).
+		Hex("hex", []byte{0x12, 0xef}).
 		AnErr("some_err", nil).
 		Err(errors.New("some error")).
+		Func(func(e *Event) { e.Str("func", "func_output") }).
 		Bool("bool", true).
 		Int("int", 1).
 		Int8("int8", 2).
@@ -265,16 +484,18 @@ func TestFieldsDisabled(t *testing.T) {
 		Dur("dur", 1*time.Second).
 		Time("time", time.Time{}).
 		TimeDiff("diff", now, now.Add(-10*time.Second)).
+		Ctx(context.Background()).
 		Msg("")
-	if got, want := out.String(), ""; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), ""; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
 
 func TestMsgf(t *testing.T) {
 	out := &bytes.Buffer{}
-	New(out).Log().Msgf("one %s %.1f %d %v", "two", 3.4, 5, errors.New("six"))
-	if got, want := out.String(), `{"message":"one two 3.4 5 six"}`+"\n"; got != want {
+	log := New(out)
+	log.Log().Msgf("one %s %.1f %d %v", "two", 3.4, 5, errors.New("six"))
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"message":"one two 3.4 5 six"}`+"\n"; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
@@ -283,7 +504,7 @@ func TestWithAndFieldsCombined(t *testing.T) {
 	out := &bytes.Buffer{}
 	log := New(out).With().Str("f1", "val").Str("f2", "val").Logger()
 	log.Log().Str("f3", "val").Msg("")
-	if got, want := out.String(), `{"f1":"val","f2":"val","f3":"val"}`+"\n"; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"f1":"val","f2":"val","f3":"val"}`+"\n"; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
@@ -293,7 +514,43 @@ func TestLevel(t *testing.T) {
 		out := &bytes.Buffer{}
 		log := New(out).Level(Disabled)
 		log.Info().Msg("test")
-		if got, want := out.String(), ""; got != want {
+		if got, want := decodeIfBinaryToString(out.Bytes()), ""; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+
+	t.Run("NoLevel/Disabled", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).Level(Disabled)
+		log.Log().Msg("test")
+		if got, want := decodeIfBinaryToString(out.Bytes()), ""; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+
+	t.Run("NoLevel/Info", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).Level(InfoLevel)
+		log.Log().Msg("test")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"message":"test"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+
+	t.Run("NoLevel/Panic", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).Level(PanicLevel)
+		log.Log().Msg("test")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"message":"test"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+
+	t.Run("NoLevel/WithLevel", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).Level(InfoLevel)
+		log.WithLevel(NoLevel).Msg("test")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"message":"test"}`+"\n"; got != want {
 			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
@@ -302,12 +559,30 @@ func TestLevel(t *testing.T) {
 		out := &bytes.Buffer{}
 		log := New(out).Level(InfoLevel)
 		log.Info().Msg("test")
-		if got, want := out.String(), `{"level":"info","message":"test"}`+"\n"; got != want {
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"info","message":"test"}`+"\n"; got != want {
 			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
 }
 
+func TestGetLevel(t *testing.T) {
+	levels := []Level{
+		DebugLevel,
+		InfoLevel,
+		WarnLevel,
+		ErrorLevel,
+		FatalLevel,
+		PanicLevel,
+		NoLevel,
+		Disabled,
+	}
+	for _, level := range levels {
+		if got, want := New(nil).Level(level).GetLevel(), level; got != want {
+			t.Errorf("GetLevel() = %v, want: %v", got, want)
+		}
+	}
+}
+
 func TestSampling(t *testing.T) {
 	out := &bytes.Buffer{}
 	log := New(out).Sample(&BasicSampler{N: 2})
@@ -315,7 +590,22 @@ func TestSampling(t *testing.T) {
 	log.Log().Int("i", 2).Msg("")
 	log.Log().Int("i", 3).Msg("")
 	log.Log().Int("i", 4).Msg("")
-	if got, want := out.String(), "{\"i\":2}\n{\"i\":4}\n"; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), "{\"i\":1}\n{\"i\":3}\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestDiscard(t *testing.T) {
+	out := &bytes.Buffer{}
+	log := New(out)
+	log.Log().Discard().Str("a", "b").Msgf("one %s %.1f %d %v", "two", 3.4, 5, errors.New("six"))
+	if got, want := decodeIfBinaryToString(out.Bytes()), ""; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+
+	// Double call
+	log.Log().Discard().Discard().Str("a", "b").Msgf("one %s %.1f %d %v", "two", 3.4, 5, errors.New("six"))
+	if got, want := decodeIfBinaryToString(out.Bytes()), ""; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
@@ -332,6 +622,7 @@ func (lw *levelWriter) Write(p []byte) (int, error) {
 }
 
 func (lw *levelWriter) WriteLevel(lvl Level, p []byte) (int, error) {
+	p = decodeIfBinaryToBytes(p)
 	lw.ops = append(lw.ops, struct {
 		l Level
 		p string
@@ -346,28 +637,45 @@ func TestLevelWriter(t *testing.T) {
 			p string
 		}{},
 	}
-	log := New(lw)
+
+	// Allow extra-verbose logs.
+	SetGlobalLevel(TraceLevel - 1)
+	log := New(lw).Level(TraceLevel - 1)
+
+	log.Trace().Msg("0")
 	log.Debug().Msg("1")
 	log.Info().Msg("2")
 	log.Warn().Msg("3")
 	log.Error().Msg("4")
-	log.WithLevel(DebugLevel).Msg("5")
-	log.WithLevel(InfoLevel).Msg("6")
-	log.WithLevel(WarnLevel).Msg("7")
-	log.WithLevel(ErrorLevel).Msg("8")
+	log.Log().Msg("nolevel-1")
+	log.WithLevel(TraceLevel).Msg("5")
+	log.WithLevel(DebugLevel).Msg("6")
+	log.WithLevel(InfoLevel).Msg("7")
+	log.WithLevel(WarnLevel).Msg("8")
+	log.WithLevel(ErrorLevel).Msg("9")
+	log.WithLevel(NoLevel).Msg("nolevel-2")
+	log.WithLevel(-1).Msg("-1") // Same as TraceLevel
+	log.WithLevel(-2).Msg("-2") // Will log
+	log.WithLevel(-3).Msg("-3") // Will not log
 
 	want := []struct {
 		l Level
 		p string
 	}{
+		{TraceLevel, `{"level":"trace","message":"0"}` + "\n"},
 		{DebugLevel, `{"level":"debug","message":"1"}` + "\n"},
 		{InfoLevel, `{"level":"info","message":"2"}` + "\n"},
 		{WarnLevel, `{"level":"warn","message":"3"}` + "\n"},
 		{ErrorLevel, `{"level":"error","message":"4"}` + "\n"},
-		{DebugLevel, `{"level":"debug","message":"5"}` + "\n"},
-		{InfoLevel, `{"level":"info","message":"6"}` + "\n"},
-		{WarnLevel, `{"level":"warn","message":"7"}` + "\n"},
-		{ErrorLevel, `{"level":"error","message":"8"}` + "\n"},
+		{NoLevel, `{"message":"nolevel-1"}` + "\n"},
+		{TraceLevel, `{"level":"trace","message":"5"}` + "\n"},
+		{DebugLevel, `{"level":"debug","message":"6"}` + "\n"},
+		{InfoLevel, `{"level":"info","message":"7"}` + "\n"},
+		{WarnLevel, `{"level":"warn","message":"8"}` + "\n"},
+		{ErrorLevel, `{"level":"error","message":"9"}` + "\n"},
+		{NoLevel, `{"message":"nolevel-2"}` + "\n"},
+		{Level(-1), `{"level":"trace","message":"-1"}` + "\n"},
+		{Level(-2), `{"level":"-2","message":"-2"}` + "\n"},
 	}
 	if got := lw.ops; !reflect.DeepEqual(got, want) {
 		t.Errorf("invalid ops:\ngot:\n%v\nwant:\n%v", got, want)
@@ -385,7 +693,7 @@ func TestContextTimestamp(t *testing.T) {
 	log := New(out).With().Timestamp().Str("foo", "bar").Logger()
 	log.Log().Msg("hello world")
 
-	if got, want := out.String(), `{"time":"2001-02-03T04:05:06Z","foo":"bar","message":"hello world"}`+"\n"; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"foo":"bar","time":"2001-02-03T04:05:06Z","message":"hello world"}`+"\n"; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
@@ -401,7 +709,335 @@ func TestEventTimestamp(t *testing.T) {
 	log := New(out).With().Str("foo", "bar").Logger()
 	log.Log().Timestamp().Msg("hello world")
 
-	if got, want := out.String(), `{"foo":"bar","time":"2001-02-03T04:05:06Z","message":"hello world"}`+"\n"; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"foo":"bar","time":"2001-02-03T04:05:06Z","message":"hello world"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestOutputWithoutTimestamp(t *testing.T) {
+	ignoredOut := &bytes.Buffer{}
+	out := &bytes.Buffer{}
+	log := New(ignoredOut).Output(out).With().Str("foo", "bar").Logger()
+	log.Log().Msg("hello world")
+
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"foo":"bar","message":"hello world"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestOutputWithTimestamp(t *testing.T) {
+	TimestampFunc = func() time.Time {
+		return time.Date(2001, time.February, 3, 4, 5, 6, 7, time.UTC)
+	}
+	defer func() {
+		TimestampFunc = time.Now
+	}()
+	ignoredOut := &bytes.Buffer{}
+	out := &bytes.Buffer{}
+	log := New(ignoredOut).Output(out).With().Timestamp().Str("foo", "bar").Logger()
+	log.Log().Msg("hello world")
+
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"foo":"bar","time":"2001-02-03T04:05:06Z","message":"hello world"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+type loggableError struct {
+	error
+}
+
+func (l loggableError) MarshalZerologObject(e *Event) {
+	e.Str("message", l.error.Error()+": loggableError")
+}
+
+func TestErrorMarshalFunc(t *testing.T) {
+	out := &bytes.Buffer{}
+	log := New(out)
+
+	// test default behaviour
+	log.Log().Err(errors.New("err")).Msg("msg")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"error":"err","message":"msg"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+	out.Reset()
+
+	log.Log().Err(loggableError{errors.New("err")}).Msg("msg")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"error":{"message":"err: loggableError"},"message":"msg"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+	out.Reset()
+
+	// test overriding the ErrorMarshalFunc
+	originalErrorMarshalFunc := ErrorMarshalFunc
+	defer func() {
+		ErrorMarshalFunc = originalErrorMarshalFunc
+	}()
+
+	ErrorMarshalFunc = func(err error) interface{} {
+		return err.Error() + ": marshaled string"
+	}
+	log.Log().Err(errors.New("err")).Msg("msg")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"error":"err: marshaled string","message":"msg"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+
+	out.Reset()
+	ErrorMarshalFunc = func(err error) interface{} {
+		return errors.New(err.Error() + ": new error")
+	}
+	log.Log().Err(errors.New("err")).Msg("msg")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"error":"err: new error","message":"msg"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+
+	out.Reset()
+	ErrorMarshalFunc = func(err error) interface{} {
+		return loggableError{err}
+	}
+	log.Log().Err(errors.New("err")).Msg("msg")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"error":{"message":"err: loggableError"},"message":"msg"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestCallerMarshalFunc(t *testing.T) {
+	out := &bytes.Buffer{}
+	log := New(out)
+
+	// test default behaviour this is really brittle due to the line numbers
+	// actually mattering for validation
+	pc, file, line, _ := runtime.Caller(0)
+	caller := fmt.Sprintf("%s:%d", file, line+2)
+	log.Log().Caller().Msg("msg")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"caller":"`+caller+`","message":"msg"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+	out.Reset()
+
+	// test custom behavior. In this case we'll take just the last directory
+	origCallerMarshalFunc := CallerMarshalFunc
+	defer func() { CallerMarshalFunc = origCallerMarshalFunc }()
+	CallerMarshalFunc = func(pc uintptr, file string, line int) string {
+		parts := strings.Split(file, "/")
+		if len(parts) > 1 {
+			return strings.Join(parts[len(parts)-2:], "/") + ":" + strconv.Itoa(line)
+		}
+
+		return runtime.FuncForPC(pc).Name() + ":" + file + ":" + strconv.Itoa(line)
+	}
+	pc, file, line, _ = runtime.Caller(0)
+	caller = CallerMarshalFunc(pc, file, line+2)
+	log.Log().Caller().Msg("msg")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"caller":"`+caller+`","message":"msg"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestLevelFieldMarshalFunc(t *testing.T) {
+	origLevelFieldMarshalFunc := LevelFieldMarshalFunc
+	LevelFieldMarshalFunc = func(l Level) string {
+		return strings.ToUpper(l.String())
+	}
+	defer func() {
+		LevelFieldMarshalFunc = origLevelFieldMarshalFunc
+	}()
+	out := &bytes.Buffer{}
+	log := New(out)
+
+	log.Debug().Msg("test")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"DEBUG","message":"test"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+	out.Reset()
+
+	log.Info().Msg("test")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"INFO","message":"test"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+	out.Reset()
+
+	log.Warn().Msg("test")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"WARN","message":"test"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+	out.Reset()
+
+	log.Error().Msg("test")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"ERROR","message":"test"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+	out.Reset()
+}
+
+type errWriter struct {
+	error
+}
+
+func (w errWriter) Write(p []byte) (n int, err error) {
+	return 0, w.error
+}
+
+func TestErrorHandler(t *testing.T) {
+	var got error
+	want := errors.New("write error")
+	ErrorHandler = func(err error) {
+		got = err
+	}
+	log := New(errWriter{want})
+	log.Log().Msg("test")
+	if got != want {
+		t.Errorf("ErrorHandler err = %#v, want %#v", got, want)
+	}
+}
+
+func TestUpdateEmptyContext(t *testing.T) {
+	var buf bytes.Buffer
+	log := New(&buf)
+
+	log.UpdateContext(func(c Context) Context {
+		return c.Str("foo", "bar")
+	})
+	log.Info().Msg("no panic")
+
+	want := `{"level":"info","foo":"bar","message":"no panic"}` + "\n"
+
+	if got := decodeIfBinaryToString(buf.Bytes()); got != want {
+		t.Errorf("invalid log output:\ngot:  %q\nwant: %q", got, want)
+	}
+}
+
+func TestLevel_String(t *testing.T) {
+	tests := []struct {
+		name string
+		l    Level
+		want string
+	}{
+		{"trace", TraceLevel, "trace"},
+		{"debug", DebugLevel, "debug"},
+		{"info", InfoLevel, "info"},
+		{"warn", WarnLevel, "warn"},
+		{"error", ErrorLevel, "error"},
+		{"fatal", FatalLevel, "fatal"},
+		{"panic", PanicLevel, "panic"},
+		{"disabled", Disabled, "disabled"},
+		{"nolevel", NoLevel, ""},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := tt.l.String(); got != tt.want {
+				t.Errorf("String() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestLevel_MarshalText(t *testing.T) {
+	tests := []struct {
+		name string
+		l    Level
+		want string
+	}{
+		{"trace", TraceLevel, "trace"},
+		{"debug", DebugLevel, "debug"},
+		{"info", InfoLevel, "info"},
+		{"warn", WarnLevel, "warn"},
+		{"error", ErrorLevel, "error"},
+		{"fatal", FatalLevel, "fatal"},
+		{"panic", PanicLevel, "panic"},
+		{"disabled", Disabled, "disabled"},
+		{"nolevel", NoLevel, ""},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got, err := tt.l.MarshalText(); err != nil {
+				t.Errorf("MarshalText couldn't marshal: %v", tt.l)
+			} else if string(got) != tt.want {
+				t.Errorf("String() = %v, want %v", string(got), tt.want)
+			}
+		})
+	}
+}
+
+func TestParseLevel(t *testing.T) {
+	type args struct {
+		levelStr string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    Level
+		wantErr bool
+	}{
+		{"trace", args{"trace"}, TraceLevel, false},
+		{"debug", args{"debug"}, DebugLevel, false},
+		{"info", args{"info"}, InfoLevel, false},
+		{"warn", args{"warn"}, WarnLevel, false},
+		{"error", args{"error"}, ErrorLevel, false},
+		{"fatal", args{"fatal"}, FatalLevel, false},
+		{"panic", args{"panic"}, PanicLevel, false},
+		{"disabled", args{"disabled"}, Disabled, false},
+		{"nolevel", args{""}, NoLevel, false},
+		{"-1", args{"-1"}, TraceLevel, false},
+		{"-2", args{"-2"}, Level(-2), false},
+		{"-3", args{"-3"}, Level(-3), false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := ParseLevel(tt.args.levelStr)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("ParseLevel() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if got != tt.want {
+				t.Errorf("ParseLevel() got = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestUnmarshalTextLevel(t *testing.T) {
+	type args struct {
+		levelStr string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    Level
+		wantErr bool
+	}{
+		{"trace", args{"trace"}, TraceLevel, false},
+		{"debug", args{"debug"}, DebugLevel, false},
+		{"info", args{"info"}, InfoLevel, false},
+		{"warn", args{"warn"}, WarnLevel, false},
+		{"error", args{"error"}, ErrorLevel, false},
+		{"fatal", args{"fatal"}, FatalLevel, false},
+		{"panic", args{"panic"}, PanicLevel, false},
+		{"disabled", args{"disabled"}, Disabled, false},
+		{"nolevel", args{""}, NoLevel, false},
+		{"-1", args{"-1"}, TraceLevel, false},
+		{"-2", args{"-2"}, Level(-2), false},
+		{"-3", args{"-3"}, Level(-3), false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var l Level
+			err := l.UnmarshalText([]byte(tt.args.levelStr))
+			if (err != nil) != tt.wantErr {
+				t.Errorf("UnmarshalText() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if l != tt.want {
+				t.Errorf("UnmarshalText() got = %v, want %v", l, tt.want)
+			}
+		})
+	}
+}
+
+func TestHTMLNoEscaping(t *testing.T) {
+	out := &bytes.Buffer{}
+	log := New(out)
+	log.Log().Interface("head", "<test>").Send()
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"head":"<test>"}`+"\n"; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }

not_go112.go

@@ -0,0 +1,5 @@
+// +build !go1.12
+
+package zerolog
+
+const contextCallerSkipFrameCount = 3

pkgerrors/stacktrace.go

@@ -0,0 +1,82 @@
+package pkgerrors
+
+import (
+	"github.com/pkg/errors"
+)
+
+var (
+	StackSourceFileName     = "source"
+	StackSourceLineName     = "line"
+	StackSourceFunctionName = "func"
+)
+
+type state struct {
+	b []byte
+}
+
+// Write implement fmt.Formatter interface.
+func (s *state) Write(b []byte) (n int, err error) {
+	s.b = b
+	return len(b), nil
+}
+
+// Width implement fmt.Formatter interface.
+func (s *state) Width() (wid int, ok bool) {
+	return 0, false
+}
+
+// Precision implement fmt.Formatter interface.
+func (s *state) Precision() (prec int, ok bool) {
+	return 0, false
+}
+
+// Flag implement fmt.Formatter interface.
+func (s *state) Flag(c int) bool {
+	return false
+}
+
+func frameField(f errors.Frame, s *state, c rune) string {
+	f.Format(s, c)
+	return string(s.b)
+}
+
+// MarshalStack implements pkg/errors stack trace marshaling.
+//
+// zerolog.ErrorStackMarshaler = MarshalStack
+func MarshalStack(err error) interface{} {
+	type stackTracer interface {
+		StackTrace() errors.StackTrace
+	}
+	var sterr stackTracer
+	var ok bool
+	for err != nil {
+		sterr, ok = err.(stackTracer)
+		if ok {
+			break
+		}
+
+		u, ok := err.(interface {
+			Unwrap() error
+		})
+		if !ok {
+			return nil
+		}
+
+		err = u.Unwrap()
+	}
+	if sterr == nil {
+		return nil
+	}
+
+	st := sterr.StackTrace()
+	s := &state{}
+	out := make([]map[string]string, 0, len(st))
+	for _, frame := range st {
+		out = append(out, map[string]string{
+			StackSourceFileName:     frameField(frame, s, 's'),
+			StackSourceLineName:     frameField(frame, s, 'd'),
+			StackSourceFunctionName: frameField(frame, s, 'n'),
+		})
+	}
+	return out
+}

pkgerrors/stacktrace_test.go

@@ -0,0 +1,90 @@
+// +build !binary_log
+
+package pkgerrors
+
+import (
+	"bytes"
+	"fmt"
+	"regexp"
+	"testing"
+
+	"github.com/pkg/errors"
+	"github.com/rs/zerolog"
+)
+
+func TestLogStack(t *testing.T) {
+	zerolog.ErrorStackMarshaler = MarshalStack
+
+	out := &bytes.Buffer{}
+	log := zerolog.New(out)
+
+	err := fmt.Errorf("from error: %w", errors.New("error message"))
+	log.Log().Stack().Err(err).Msg("")
+
+	got := out.String()
+	want := `\{"stack":\[\{"func":"TestLogStack","line":"21","source":"stacktrace_test.go"\},.*\],"error":"from error: error message"\}\n`
+	if ok, _ := regexp.MatchString(want, got); !ok {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestLogStackFields(t *testing.T) {
+	zerolog.ErrorStackMarshaler = MarshalStack
+
+	out := &bytes.Buffer{}
+	log := zerolog.New(out)
+
+	err := fmt.Errorf("from error: %w", errors.New("error message"))
+	log.Log().Stack().Fields([]interface{}{"error", err}).Msg("")
+
+	got := out.String()
+	want := `\{"error":"from error: error message","stack":\[\{"func":"TestLogStackFields","line":"37","source":"stacktrace_test.go"\},.*\]\}\n`
+	if ok, _ := regexp.MatchString(want, got); !ok {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestLogStackFromContext(t *testing.T) {
+	zerolog.ErrorStackMarshaler = MarshalStack
+
+	out := &bytes.Buffer{}
+	log := zerolog.New(out).With().Stack().Logger() // calling Stack() on log context instead of event
+
+	err := fmt.Errorf("from error: %w", errors.New("error message"))
+	log.Log().Err(err).Msg("") // not explicitly calling Stack()
+
+	got := out.String()
+	want := `\{"stack":\[\{"func":"TestLogStackFromContext","line":"53","source":"stacktrace_test.go"\},.*\],"error":"from error: error message"\}\n`
+	if ok, _ := regexp.MatchString(want, got); !ok {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestLogStackFromContextWith(t *testing.T) {
+	zerolog.ErrorStackMarshaler = MarshalStack
+
+	err := fmt.Errorf("from error: %w", errors.New("error message"))
+	out := &bytes.Buffer{}
+	log := zerolog.New(out).With().Stack().Err(err).Logger() // calling Stack() on log context instead of event
+
+	log.Error().Msg("")
+
+	got := out.String()
+	want := `\{"level":"error","stack":\[\{"func":"TestLogStackFromContextWith","line":"66","source":"stacktrace_test.go"\},.*\],"error":"from error: error message"\}\n`
+	if ok, _ := regexp.MatchString(want, got); !ok {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func BenchmarkLogStack(b *testing.B) {
+	zerolog.ErrorStackMarshaler = MarshalStack
+	out := &bytes.Buffer{}
+	log := zerolog.New(out)
+	err := errors.Wrap(errors.New("error message"), "from error")
+	b.ReportAllocs()
+
+	for i := 0; i < b.N; i++ {
+		log.Log().Stack().Err(err).Msg("")
+		out.Reset()
+	}
+}

sampler.go

@@ -31,16 +31,14 @@ func (s RandomSampler) Sample(lvl Level) bool {
 	if s <= 0 {
 		return false
 	}
-	if s > 0 {
-		if rand.Intn(int(s)) != 0 {
-			return false
-		}
+	if rand.Intn(int(s)) != 0 {
+		return false
 	}
 	return true
 }
 
 // BasicSampler is a sampler that will send every Nth events, regardless of
-// there level.
+// their level.
 type BasicSampler struct {
 	N       uint32
 	counter uint32
@@ -48,8 +46,12 @@ type BasicSampler struct {
 
 // Sample implements the Sampler interface.
 func (s *BasicSampler) Sample(lvl Level) bool {
+	n := s.N
+	if n == 1 {
+		return true
+	}
 	c := atomic.AddUint32(&s.counter, 1)
-	return c%s.N == 0
+	return c%n == 1
 }
 
 // BurstSampler lets Burst events pass per Period then pass the decision to
@@ -70,7 +72,7 @@ type BurstSampler struct {
 
 // Sample implements the Sampler interface.
 func (s *BurstSampler) Sample(lvl Level) bool {
-	if s.Burst > 9 && s.Period > 0 {
+	if s.Burst > 0 && s.Period > 0 {
 		if s.inc() <= s.Burst {
 			return true
 		}
@@ -82,7 +84,7 @@ func (s *BurstSampler) Sample(lvl Level) bool {
 }
 
 func (s *BurstSampler) inc() uint32 {
-	now := time.Now().UnixNano()
+	now := TimestampFunc().UnixNano()
 	resetAt := atomic.LoadInt64(&s.resetAt)
 	var c uint32
 	if now > resetAt {
@@ -102,11 +104,15 @@ func (s *BurstSampler) inc() uint32 {
 
 // LevelSampler applies a different sampler for each level.
 type LevelSampler struct {
-	DebugSampler, InfoSampler, WarnSampler, ErrorSampler Sampler
+	TraceSampler, DebugSampler, InfoSampler, WarnSampler, ErrorSampler Sampler
 }
 
 func (s LevelSampler) Sample(lvl Level) bool {
 	switch lvl {
+	case TraceLevel:
+		if s.TraceSampler != nil {
+			return s.TraceSampler.Sample(lvl)
+		}
 	case DebugLevel:
 		if s.DebugSampler != nil {
 			return s.DebugSampler.Sample(lvl)

sampler_test.go

@@ -1,3 +1,5 @@
+// +build !binary_log
+
 package zerolog
 
 import (
@@ -13,7 +15,14 @@ var samplers = []struct {
 	wantMax int
 }{
 	{
-		"BasicSampler",
+		"BasicSampler_1",
+		func() Sampler {
+			return &BasicSampler{N: 1}
+		},
+		100, 100, 100,
+	},
+	{
+		"BasicSampler_5",
 		func() Sampler {
 			return &BasicSampler{N: 5}
 		},

syslog.go

@@ -1,8 +1,15 @@
 // +build !windows
+// +build !binary_log
 
 package zerolog
 
-import "io"
+import (
+	"io"
+)
+
+// See http://cee.mitre.org/language/1.0-beta1/clt.html#syslog
+// or https://www.rsyslog.com/json-elasticsearch/
+const ceePrefix = "@cee:"
 
 // SyslogWriter is an interface matching a syslog.Writer struct.
 type SyslogWriter interface {
@@ -16,37 +23,67 @@ type SyslogWriter interface {
 }
 
 type syslogWriter struct {
-	w SyslogWriter
+	w      SyslogWriter
+	prefix string
 }
 
 // SyslogLevelWriter wraps a SyslogWriter and call the right syslog level
 // method matching the zerolog level.
 func SyslogLevelWriter(w SyslogWriter) LevelWriter {
-	return syslogWriter{w}
+	return syslogWriter{w, ""}
+}
+
+// SyslogCEEWriter wraps a SyslogWriter with a SyslogLevelWriter that adds a
+// MITRE CEE prefix for JSON syslog entries, compatible with rsyslog 
+// and syslog-ng JSON logging support. 
+// See https://www.rsyslog.com/json-elasticsearch/
+func SyslogCEEWriter(w SyslogWriter) LevelWriter {
+	return syslogWriter{w, ceePrefix}
 }
 
 func (sw syslogWriter) Write(p []byte) (n int, err error) {
-	return sw.w.Write(p)
+	var pn int
+	if sw.prefix != "" {
+		pn, err = sw.w.Write([]byte(sw.prefix))
+		if err != nil {
+			return pn, err
+		}
+	}
+	n, err = sw.w.Write(p)
+	return pn + n, err
 }
 
 // WriteLevel implements LevelWriter interface.
 func (sw syslogWriter) WriteLevel(level Level, p []byte) (n int, err error) {
 	switch level {
+	case TraceLevel:
 	case DebugLevel:
-		err = sw.w.Debug(string(p))
+		err = sw.w.Debug(sw.prefix + string(p))
 	case InfoLevel:
-		err = sw.w.Info(string(p))
+		err = sw.w.Info(sw.prefix + string(p))
 	case WarnLevel:
-		err = sw.w.Warning(string(p))
+		err = sw.w.Warning(sw.prefix + string(p))
 	case ErrorLevel:
-		err = sw.w.Err(string(p))
+		err = sw.w.Err(sw.prefix + string(p))
 	case FatalLevel:
-		err = sw.w.Emerg(string(p))
+		err = sw.w.Emerg(sw.prefix + string(p))
 	case PanicLevel:
-		err = sw.w.Crit(string(p))
+		err = sw.w.Crit(sw.prefix + string(p))
+	case NoLevel:
+		err = sw.w.Info(sw.prefix + string(p))
 	default:
 		panic("invalid level")
 	}
+	// Any CEE prefix is not part of the message, so we don't include its length
 	n = len(p)
 	return
 }
+
+// Call the underlying writer's Close method if it is an io.Closer. Otherwise
+// does nothing.
+func (sw syslogWriter) Close() error {
+	if c, ok := sw.w.(io.Closer); ok {
+		return c.Close()
+	}
+	return nil
+}

syslog_test.go

@@ -1,7 +1,14 @@
+// +build !binary_log
+// +build !windows
+
 package zerolog
 
-import "testing"
-import "reflect"
+import (
+	"bytes"
+	"reflect"
+	"strings"
+	"testing"
+)
 
 type syslogEvent struct {
 	level string
@@ -14,6 +21,10 @@ type syslogTestWriter struct {
 func (w *syslogTestWriter) Write(p []byte) (int, error) {
 	return 0, nil
 }
+func (w *syslogTestWriter) Trace(m string) error {
+	w.events = append(w.events, syslogEvent{"Trace", m})
+	return nil
+}
 func (w *syslogTestWriter) Debug(m string) error {
 	w.events = append(w.events, syslogEvent{"Debug", m})
 	return nil
@@ -42,17 +53,56 @@ func (w *syslogTestWriter) Crit(m string) error {
 func TestSyslogWriter(t *testing.T) {
 	sw := &syslogTestWriter{}
 	log := New(SyslogLevelWriter(sw))
+	log.Trace().Msg("trace")
 	log.Debug().Msg("debug")
 	log.Info().Msg("info")
 	log.Warn().Msg("warn")
 	log.Error().Msg("error")
+	log.Log().Msg("nolevel")
 	want := []syslogEvent{
 		{"Debug", `{"level":"debug","message":"debug"}` + "\n"},
 		{"Info", `{"level":"info","message":"info"}` + "\n"},
 		{"Warning", `{"level":"warn","message":"warn"}` + "\n"},
 		{"Err", `{"level":"error","message":"error"}` + "\n"},
+		{"Info", `{"message":"nolevel"}` + "\n"},
 	}
 	if got := sw.events; !reflect.DeepEqual(got, want) {
 		t.Errorf("Invalid syslog message routing: want %v, got %v", want, got)
 	}
 }
+
+type testCEEwriter struct {
+	buf *bytes.Buffer
+}
+
+// Only implement one method as we're just testing the prefixing
+func (c testCEEwriter) Debug(m string) error { return nil }
+
+func (c testCEEwriter) Info(m string) error {
+	_, err := c.buf.Write([]byte(m))
+	return err
+}
+
+func (c testCEEwriter) Warning(m string) error { return nil }
+
+func (c testCEEwriter) Err(m string) error { return nil }
+
+func (c testCEEwriter) Emerg(m string) error { return nil }
+
+func (c testCEEwriter) Crit(m string) error { return nil }
+
+func (c testCEEwriter) Write(b []byte) (int, error) {
+	return c.buf.Write(b)
+}
+
+func TestSyslogWriter_WithCEE(t *testing.T) {
+	var buf bytes.Buffer
+	sw := testCEEwriter{&buf}
+	log := New(SyslogCEEWriter(sw))
+	log.Info().Str("key", "value").Msg("message string")
+	got := buf.String()
+	want := "@cee:{"
+	if !strings.HasPrefix(got, want) {
+		t.Errorf("Bad CEE message start: want %v, got %v", want, got)
+	}
+}

writer.go

@@ -1,7 +1,12 @@
 package zerolog
 
 import (
+	"bytes"
 	"io"
+	"path"
+	"runtime"
+	"strconv"
+	"strings"
 	"sync"
 )
 
@@ -12,30 +17,39 @@ type LevelWriter interface {
 	WriteLevel(level Level, p []byte) (n int, err error)
 }
 
-type levelWriterAdapter struct {
+// LevelWriterAdapter adapts an io.Writer to support the LevelWriter interface.
+type LevelWriterAdapter struct {
 	io.Writer
 }
 
-func (lw levelWriterAdapter) WriteLevel(l Level, p []byte) (n int, err error) {
+// WriteLevel simply writes everything to the adapted writer, ignoring the level.
+func (lw LevelWriterAdapter) WriteLevel(l Level, p []byte) (n int, err error) {
 	return lw.Write(p)
 }
 
+// Call the underlying writer's Close method if it is an io.Closer. Otherwise
+// does nothing.
+func (lw LevelWriterAdapter) Close() error {
+	if closer, ok := lw.Writer.(io.Closer); ok {
+		return closer.Close()
+	}
+	return nil
+}
+
 type syncWriter struct {
 	mu sync.Mutex
 	lw LevelWriter
 }
 
 // SyncWriter wraps w so that each call to Write is synchronized with a mutex.
-// This syncer can be the call to writer's Write method is not thread safe.
-// Note that os.File Write operation is using write() syscall which is supposed
-// to be thread-safe on POSIX systems. So there is no need to use this with
-// os.File on such systems as zerolog guaranties to issue a single Write call
-// per log event.
+// This syncer can be used to wrap the call to writer's Write method if it is
+// not thread safe. Note that you do not need this wrapper for os.File Write
+// operations on POSIX and Windows systems as they are already thread-safe.
 func SyncWriter(w io.Writer) io.Writer {
 	if lw, ok := w.(LevelWriter); ok {
 		return &syncWriter{lw: lw}
 	}
-	return &syncWriter{lw: levelWriterAdapter{w}}
+	return &syncWriter{lw: LevelWriterAdapter{w}}
 }
 
 // Write implements the io.Writer interface.
@@ -52,36 +66,59 @@ func (s *syncWriter) WriteLevel(l Level, p []byte) (n int, err error) {
 	return s.lw.WriteLevel(l, p)
 }
 
+func (s *syncWriter) Close() error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if closer, ok := s.lw.(io.Closer); ok {
+		return closer.Close()
+	}
+	return nil
+}
+
 type multiLevelWriter struct {
 	writers []LevelWriter
 }
 
 func (t multiLevelWriter) Write(p []byte) (n int, err error) {
 	for _, w := range t.writers {
-		n, err = w.Write(p)
-		if err != nil {
-			return
-		}
-		if n != len(p) {
-			err = io.ErrShortWrite
-			return
+		if _n, _err := w.Write(p); err == nil {
+			n = _n
+			if _err != nil {
+				err = _err
+			} else if _n != len(p) {
+				err = io.ErrShortWrite
+			}
 		}
 	}
-	return len(p), nil
+	return n, err
 }
 
 func (t multiLevelWriter) WriteLevel(l Level, p []byte) (n int, err error) {
 	for _, w := range t.writers {
-		n, err = w.WriteLevel(l, p)
-		if err != nil {
-			return
-		}
-		if n != len(p) {
-			err = io.ErrShortWrite
-			return
+		if _n, _err := w.WriteLevel(l, p); err == nil {
+			n = _n
+			if _err != nil {
+				err = _err
+			} else if _n != len(p) {
+				err = io.ErrShortWrite
+			}
 		}
 	}
-	return len(p), nil
+	return n, err
+}
+
+// Calls close on all the underlying writers that are io.Closers. If any of the
+// Close methods return an error, the remainder of the closers are not closed
+// and the error is returned.
+func (t multiLevelWriter) Close() error {
+	for _, w := range t.writers {
+		if closer, ok := w.(io.Closer); ok {
+			if err := closer.Close(); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
 }
 
 // MultiLevelWriter creates a writer that duplicates its writes to all the
@@ -93,8 +130,217 @@ func MultiLevelWriter(writers ...io.Writer) LevelWriter {
 		if lw, ok := w.(LevelWriter); ok {
 			lwriters = append(lwriters, lw)
 		} else {
-			lwriters = append(lwriters, levelWriterAdapter{w})
+			lwriters = append(lwriters, LevelWriterAdapter{w})
 		}
 	}
 	return multiLevelWriter{lwriters}
 }
+
+// TestingLog is the logging interface of testing.TB.
+type TestingLog interface {
+	Log(args ...interface{})
+	Logf(format string, args ...interface{})
+	Helper()
+}
+
+// TestWriter is a writer that writes to testing.TB.
+type TestWriter struct {
+	T TestingLog
+
+	// Frame skips caller frames to capture the original file and line numbers.
+	Frame int
+}
+
+// NewTestWriter creates a writer that logs to the testing.TB.
+func NewTestWriter(t TestingLog) TestWriter {
+	return TestWriter{T: t}
+}
+
+// Write to testing.TB.
+func (t TestWriter) Write(p []byte) (n int, err error) {
+	t.T.Helper()
+
+	n = len(p)
+
+	// Strip trailing newline because t.Log always adds one.
+	p = bytes.TrimRight(p, "\n")
+
+	// Try to correct the log file and line number to the caller.
+	if t.Frame > 0 {
+		_, origFile, origLine, _ := runtime.Caller(1)
+		_, frameFile, frameLine, ok := runtime.Caller(1 + t.Frame)
+		if ok {
+			erase := strings.Repeat("\b", len(path.Base(origFile))+len(strconv.Itoa(origLine))+3)
+			t.T.Logf("%s%s:%d: %s", erase, path.Base(frameFile), frameLine, p)
+			return n, err
+		}
+	}
+	t.T.Log(string(p))
+
+	return n, err
+}
+
+// ConsoleTestWriter creates an option that correctly sets the file frame depth for testing.TB log.
+func ConsoleTestWriter(t TestingLog) func(w *ConsoleWriter) {
+	return func(w *ConsoleWriter) {
+		w.Out = TestWriter{T: t, Frame: 6}
+	}
+}
+
+// FilteredLevelWriter writes only logs at Level or above to Writer.
+//
+// It should be used only in combination with MultiLevelWriter when you
+// want to write to multiple destinations at different levels. Otherwise
+// you should just set the level on the logger and filter events early.
+// When using MultiLevelWriter then you set the level on the logger to
+// the lowest of the levels you use for writers.
+type FilteredLevelWriter struct {
+	Writer LevelWriter
+	Level  Level
+}
+
+// Write writes to the underlying Writer.
+func (w *FilteredLevelWriter) Write(p []byte) (int, error) {
+	return w.Writer.Write(p)
+}
+
+// WriteLevel calls WriteLevel of the underlying Writer only if the level is equal
+// or above the Level.
+func (w *FilteredLevelWriter) WriteLevel(level Level, p []byte) (int, error) {
+	if level >= w.Level {
+		return w.Writer.WriteLevel(level, p)
+	}
+	return len(p), nil
+}
+
+var triggerWriterPool = &sync.Pool{
+	New: func() interface{} {
+		return bytes.NewBuffer(make([]byte, 0, 1024))
+	},
+}
+
+// TriggerLevelWriter buffers log lines at the ConditionalLevel or below
+// until a trigger level (or higher) line is emitted. Log lines with level
+// higher than ConditionalLevel are always written out to the destination
+// writer. If trigger never happens, buffered log lines are never written out.
+//
+// It can be used to configure "log level per request".
+type TriggerLevelWriter struct {
+	// Destination writer. If LevelWriter is provided (usually), its WriteLevel is used
+	// instead of Write.
+	io.Writer
+
+	// ConditionalLevel is the level (and below) at which lines are buffered until
+	// a trigger level (or higher) line is emitted. Usually this is set to DebugLevel.
+	ConditionalLevel Level
+
+	// TriggerLevel is the lowest level that triggers the sending of the conditional
+	// level lines. Usually this is set to ErrorLevel.
+	TriggerLevel Level
+
+	buf       *bytes.Buffer
+	triggered bool
+	mu        sync.Mutex
+}
+
+func (w *TriggerLevelWriter) WriteLevel(l Level, p []byte) (n int, err error) {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+
+	// At first trigger level or above log line, we flush the buffer and change the
+	// trigger state to triggered.
+	if !w.triggered && l >= w.TriggerLevel {
+		err := w.trigger()
+		if err != nil {
+			return 0, err
+		}
+	}
+
+	// Unless triggered, we buffer everything at and below ConditionalLevel.
+	if !w.triggered && l <= w.ConditionalLevel {
+		if w.buf == nil {
+			w.buf = triggerWriterPool.Get().(*bytes.Buffer)
+		}
+
+		// We prefix each log line with a byte with the level.
+		// Hopefully we will never have a level value which equals a newline
+		// (which could interfere with reconstruction of log lines in the trigger method).
+		w.buf.WriteByte(byte(l))
+		w.buf.Write(p)
+		return len(p), nil
+	}
+
+	// Anything above ConditionalLevel is always passed through.
+	// Once triggered, everything is passed through.
+	if lw, ok := w.Writer.(LevelWriter); ok {
+		return lw.WriteLevel(l, p)
+	}
+	return w.Write(p)
+}
+
+// trigger expects lock to be held.
+func (w *TriggerLevelWriter) trigger() error {
+	if w.triggered {
+		return nil
+	}
+	w.triggered = true
+
+	if w.buf == nil {
+		return nil
+	}
+
+	p := w.buf.Bytes()
+	for len(p) > 0 {
+		// We do not use bufio.Scanner here because we already have full buffer
+		// in the memory and we do not want extra copying from the buffer to
+		// scanner's token slice, nor we want to hit scanner's token size limit,
+		// and we also want to preserve newlines.
+		i := bytes.IndexByte(p, '\n')
+		line := p[0 : i+1]
+		p = p[i+1:]
+		// We prefixed each log line with a byte with the level.
+		level := Level(line[0])
+		line = line[1:]
+		var err error
+		if lw, ok := w.Writer.(LevelWriter); ok {
+			_, err = lw.WriteLevel(level, line)
+		} else {
+			_, err = w.Write(line)
+		}
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// Trigger forces flushing the buffer and change the trigger state to
+// triggered, if the writer has not already been triggered before.
+func (w *TriggerLevelWriter) Trigger() error {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+
+	return w.trigger()
+}
+
+// Close closes the writer and returns the buffer to the pool.
+func (w *TriggerLevelWriter) Close() error {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+
+	if w.buf == nil {
+		return nil
+	}
+
+	// We return the buffer only if it has not grown above the limit.
+	// This prevents accumulation of large buffers in the pool just
+	// because occasionally a large buffer might be needed.
+	if w.buf.Cap() <= TriggerLevelWriterBufferReuseLimit {
+		w.buf.Reset()
+		triggerWriterPool.Put(w.buf)
+	}
+	w.buf = nil
+
+	return nil
+}

writer_test.go

@@ -1,6 +1,13 @@
+//go:build !binary_log && !windows
+// +build !binary_log,!windows
+
 package zerolog
 
 import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
 	"reflect"
 	"testing"
 )
@@ -12,13 +19,234 @@ func TestMultiSyslogWriter(t *testing.T) {
 	log.Info().Msg("info")
 	log.Warn().Msg("warn")
 	log.Error().Msg("error")
+	log.Log().Msg("nolevel")
 	want := []syslogEvent{
 		{"Debug", `{"level":"debug","message":"debug"}` + "\n"},
 		{"Info", `{"level":"info","message":"info"}` + "\n"},
 		{"Warning", `{"level":"warn","message":"warn"}` + "\n"},
 		{"Err", `{"level":"error","message":"error"}` + "\n"},
+		{"Info", `{"message":"nolevel"}` + "\n"},
 	}
 	if got := sw.events; !reflect.DeepEqual(got, want) {
 		t.Errorf("Invalid syslog message routing: want %v, got %v", want, got)
 	}
 }
+
+var writeCalls int
+
+type mockedWriter struct {
+	wantErr bool
+}
+
+func (c mockedWriter) Write(p []byte) (int, error) {
+	writeCalls++
+
+	if c.wantErr {
+		return -1, errors.New("Expected error")
+	}
+
+	return len(p), nil
+}
+
+// Tests that a new writer is only used if it actually works.
+func TestResilientMultiWriter(t *testing.T) {
+	tests := []struct {
+		name    string
+		writers []io.Writer
+	}{
+		{
+			name: "All valid writers",
+			writers: []io.Writer{
+				mockedWriter{
+					wantErr: false,
+				},
+				mockedWriter{
+					wantErr: false,
+				},
+			},
+		},
+		{
+			name: "All invalid writers",
+			writers: []io.Writer{
+				mockedWriter{
+					wantErr: true,
+				},
+				mockedWriter{
+					wantErr: true,
+				},
+			},
+		},
+		{
+			name: "First invalid writer",
+			writers: []io.Writer{
+				mockedWriter{
+					wantErr: true,
+				},
+				mockedWriter{
+					wantErr: false,
+				},
+			},
+		},
+		{
+			name: "First valid writer",
+			writers: []io.Writer{
+				mockedWriter{
+					wantErr: false,
+				},
+				mockedWriter{
+					wantErr: true,
+				},
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		writers := tt.writers
+		multiWriter := MultiLevelWriter(writers...)
+
+		logger := New(multiWriter).With().Timestamp().Logger().Level(InfoLevel)
+		logger.Info().Msg("Test msg")
+
+		if len(writers) != writeCalls {
+			t.Errorf("Expected %d writers to have been called but only %d were.", len(writers), writeCalls)
+		}
+		writeCalls = 0
+	}
+}
+
+type testingLog struct {
+	testing.TB
+	buf bytes.Buffer
+}
+
+func (t *testingLog) Log(args ...interface{}) {
+	if _, err := t.buf.WriteString(fmt.Sprint(args...)); err != nil {
+		t.Error(err)
+	}
+}
+
+func (t *testingLog) Logf(format string, args ...interface{}) {
+	if _, err := t.buf.WriteString(fmt.Sprintf(format, args...)); err != nil {
+		t.Error(err)
+	}
+}
+
+func TestTestWriter(t *testing.T) {
+	tests := []struct {
+		name  string
+		write []byte
+		want  []byte
+	}{{
+		name:  "newline",
+		write: []byte("newline\n"),
+		want:  []byte("newline"),
+	}, {
+		name:  "oneline",
+		write: []byte("oneline"),
+		want:  []byte("oneline"),
+	}, {
+		name:  "twoline",
+		write: []byte("twoline\n\n"),
+		want:  []byte("twoline"),
+	}}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tb := &testingLog{TB: t} // Capture TB log buffer.
+			w := TestWriter{T: tb}
+
+			n, err := w.Write(tt.write)
+			if err != nil {
+				t.Error(err)
+			}
+			if n != len(tt.write) {
+				t.Errorf("Expected %d write length but got %d", len(tt.write), n)
+			}
+			p := tb.buf.Bytes()
+			if !bytes.Equal(tt.want, p) {
+				t.Errorf("Expected %q, got %q.", tt.want, p)
+			}
+
+			log := New(NewConsoleWriter(ConsoleTestWriter(t)))
+			log.Info().Str("name", tt.name).Msg("Success!")
+
+			tb.buf.Reset()
+		})
+	}
+
+}
+
+func TestFilteredLevelWriter(t *testing.T) {
+	buf := bytes.Buffer{}
+	writer := FilteredLevelWriter{
+		Writer: LevelWriterAdapter{&buf},
+		Level:  InfoLevel,
+	}
+	_, err := writer.WriteLevel(DebugLevel, []byte("no"))
+	if err != nil {
+		t.Error(err)
+	}
+	_, err = writer.WriteLevel(InfoLevel, []byte("yes"))
+	if err != nil {
+		t.Error(err)
+	}
+	p := buf.Bytes()
+	if want := "yes"; !bytes.Equal([]byte(want), p) {
+		t.Errorf("Expected %q, got %q.", want, p)
+	}
+}
+
+type testWrite struct {
+	Level
+	Line []byte
+}
+
+func TestTriggerLevelWriter(t *testing.T) {
+	tests := []struct {
+		write []testWrite
+		want  []byte
+		all   []byte
+	}{{
+		[]testWrite{
+			{DebugLevel, []byte("no\n")},
+			{InfoLevel, []byte("yes\n")},
+		},
+		[]byte("yes\n"),
+		[]byte("yes\nno\n"),
+	}, {
+		[]testWrite{
+			{DebugLevel, []byte("yes1\n")},
+			{InfoLevel, []byte("yes2\n")},
+			{ErrorLevel, []byte("yes3\n")},
+			{DebugLevel, []byte("yes4\n")},
+		},
+		[]byte("yes2\nyes1\nyes3\nyes4\n"),
+		[]byte("yes2\nyes1\nyes3\nyes4\n"),
+	}}
+
+	for k, tt := range tests {
+		t.Run(fmt.Sprintf("case=%d", k), func(t *testing.T) {
+			buf := bytes.Buffer{}
+			writer := TriggerLevelWriter{Writer: LevelWriterAdapter{&buf}, ConditionalLevel: DebugLevel, TriggerLevel: ErrorLevel}
+			t.Cleanup(func() { writer.Close() })
+			for _, w := range tt.write {
+				_, err := writer.WriteLevel(w.Level, w.Line)
+				if err != nil {
+					t.Error(err)
+				}
+			}
+			p := buf.Bytes()
+			if want := tt.want; !bytes.Equal([]byte(want), p) {
+				t.Errorf("Expected %q, got %q.", want, p)
+			}
+			err := writer.Trigger()
+			if err != nil {
+				t.Error(err)
+			}
+			p = buf.Bytes()
+			if want := tt.all; !bytes.Equal([]byte(want), p) {
+				t.Errorf("Expected %q, got %q.", want, p)
+			}
+		})
+	}
+}