Allow arbitrary negative levels (#350)

This allows logr to use high V() levels.

.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 +1,27 @@
+on: [push, pull_request]
+name: Test
+jobs:
+  test:
+    strategy:
+      matrix:
+        go-version: [1.15.x, 1.16.x]
+        os: [ubuntu-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
+    steps:
+    - name: Install Go
+      uses: actions/setup-go@v2
+      with:
+        go-version: ${{ matrix.go-version }}
+    - name: Checkout code
+      uses: actions/checkout@v2
+    - uses: actions/cache@v2
+      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 ./...
+

.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 ./...

CNAME

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

README.md

@@ -4,60 +4,311 @@
 
 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. As [suggested on reddit](https://www.reddit.com/r/golang/comments/6c9k7n/zerolog_is_now_faster_than_zap/), you may use tools like [humanlog](https://github.com/aybabtme/humanlog) to pretty print JSON on the console during development.
+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 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
 
-* Level logging
-* Sampling
-* Contextual fields
+* [Blazing fast](#benchmarks)
+* [Low to zero allocation](#benchmarks)
+* [Leveled logging](#leveled-logging)
+* [Sampling](#log-sampling)
+* [Hooks](#hooks)
+* [Contextual fields](#contextual-logging)
 * `context.Context` integration
-* `net/http` helpers
+* [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.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() {
+    // 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 *debug*
 
-NOTE: To import the global logger, import the `log` subpackage `github.com/rs/zerolog/log`.
+### 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.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.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: Using `Msgf` generates one allocation even when the logger is disabled.
+> 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)
 
-### Fields can be added to log messages
+### Leveled Logging
+
+#### Simple Leveled Logging Example
 
 ```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 (
+    "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"}
 ```
 
+> 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.
+
+**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
+package main
+
+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
@@ -72,28 +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
+### Pretty logging
+
+To log a human-friendly, colorized output, use `zerolog.ConsoleWriter`:
 
 ```go
-zerolog.SetGlobalLevel(zerolog.InfoLevel)
+log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr})
 
-log.Debug().Msg("filtered out message")
-log.Info().Msg("routed message")
+log.Info().Str("foo", "bar").Msg("Hello world")
 
-if e := log.Debug(); e.Enabled() {
-    // Compute log output only if enabled.
-    value := compute()
-    e.Str("foo": value).Msg("some debug message")
+// 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))
 }
 
-// Output: {"level":"info","time":1494567715,"message":"routed message"}
+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
@@ -103,7 +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"}
@@ -121,33 +391,84 @@ 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
+
+```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"}
+```
+
+
+### 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 follow:
+
+```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
-sampled := log.Sample(10)
+sampled := log.Sample(&zerolog.BasicSampler{N: 10})
 sampled.Info().Msg("will be logged every 10 messages")
 
-// Output: {"time":1494567715,"sample":10,"message":"will be logged every 10 messages"}
+// Output: {"time":1494567715,"level":"info","message":"will be logged every 10 messages"}
+```
+
+More advanced sampling:
+
+```go
+// Will let 5 debug messages per period of 1 second.
+// Over 5 debug message, 1 every 100 debug messages are logged.
+// Other levels are not sampled.
+sampled := log.Sample(zerolog.LevelSampler{
+    DebugSampler: &zerolog.BurstSampler{
+        Burst: 5,
+        Period: 1*time.Second,
+        NextSampler: &zerolog.BasicSampler{N: 100},
+    },
+})
+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")
 
@@ -188,7 +509,16 @@ 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).
+        Stringer("url", r.URL).
+        Int("status", status).
+        Int("size", size).
+        Dur("duration", duration).
+        Msg("")
+}))
 c = c.Append(hlog.RemoteAddrHandler("ip"))
 c = c.Append(hlog.UserAgentHandler("user_agent"))
 c = c.Append(hlog.RefererHandler("referer"))
@@ -213,23 +543,40 @@ 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:
 
 * `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.SampleFieldName`: Can be set to customize the field name added when sampling is enabled.
-* `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 formated 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.
 
 ## Field Types
 
@@ -243,26 +590,55 @@ 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.
 
-## Performance
+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](http://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/hn8/zerologr): Implementation of `logr.LogSink` interface using `zerolog`
+
+## Benchmarks
+
+See [logbench](http://hackemist.com/logbench/) 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
 ```
 
-Using Uber's zap [comparison benchmark](https://github.com/uber-go/zap#performance):
+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)
+
+Using Uber's zap comparison benchmark:
 
 Log a message and 10 fields:
 
@@ -304,3 +680,16 @@ 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
+
+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.

_config.yml

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

array.go

@@ -0,0 +1,233 @@
+package zerolog
+
+import (
+	"net"
+	"sync"
+	"time"
+)
+
+var arrayPool = &sync.Pool{
+	New: func() interface{} {
+		return &Array{
+			buf: make([]byte, 0, 500),
+		}
+	},
+}
+
+// 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)
+	a.buf = a.buf[:0]
+	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 {
+	dst = enc.AppendArrayStart(dst)
+	if len(a.buf) > 0 {
+		dst = append(append(dst, a.buf...))
+	}
+	dst = enc.AppendArrayEnd(dst)
+	putArray(a)
+	return dst
+}
+
+// Object marshals an object that implement the LogObjectMarshaler
+// interface and append append it to the array.
+func (a *Array) Object(obj LogObjectMarshaler) *Array {
+	e := Dict()
+	obj.MarshalZerologObject(e)
+	e.buf = enc.AppendEndMarker(e.buf)
+	a.buf = append(enc.AppendArrayDelim(a.buf), e.buf...)
+	putEvent(e)
+	return a
+}
+
+// Str append append the val as a string to the array.
+func (a *Array) Str(val string) *Array {
+	a.buf = enc.AppendString(enc.AppendArrayDelim(a.buf), val)
+	return a
+}
+
+// Bytes append append the val as a string to the array.
+func (a *Array) Bytes(val []byte) *Array {
+	a.buf = enc.AppendBytes(enc.AppendArrayDelim(a.buf), val)
+	return a
+}
+
+// Hex append append 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 {
+	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 append the val as a bool to the array.
+func (a *Array) Bool(b bool) *Array {
+	a.buf = enc.AppendBool(enc.AppendArrayDelim(a.buf), b)
+	return a
+}
+
+// Int append append i as a int to the array.
+func (a *Array) Int(i int) *Array {
+	a.buf = enc.AppendInt(enc.AppendArrayDelim(a.buf), i)
+	return a
+}
+
+// Int8 append append i as a int8 to the array.
+func (a *Array) Int8(i int8) *Array {
+	a.buf = enc.AppendInt8(enc.AppendArrayDelim(a.buf), i)
+	return a
+}
+
+// Int16 append append i as a int16 to the array.
+func (a *Array) Int16(i int16) *Array {
+	a.buf = enc.AppendInt16(enc.AppendArrayDelim(a.buf), i)
+	return a
+}
+
+// Int32 append append i as a int32 to the array.
+func (a *Array) Int32(i int32) *Array {
+	a.buf = enc.AppendInt32(enc.AppendArrayDelim(a.buf), i)
+	return a
+}
+
+// Int64 append append i as a int64 to the array.
+func (a *Array) Int64(i int64) *Array {
+	a.buf = enc.AppendInt64(enc.AppendArrayDelim(a.buf), i)
+	return a
+}
+
+// Uint append append i as a uint to the array.
+func (a *Array) Uint(i uint) *Array {
+	a.buf = enc.AppendUint(enc.AppendArrayDelim(a.buf), i)
+	return a
+}
+
+// Uint8 append append i as a uint8 to the array.
+func (a *Array) Uint8(i uint8) *Array {
+	a.buf = enc.AppendUint8(enc.AppendArrayDelim(a.buf), i)
+	return a
+}
+
+// Uint16 append append i as a uint16 to the array.
+func (a *Array) Uint16(i uint16) *Array {
+	a.buf = enc.AppendUint16(enc.AppendArrayDelim(a.buf), i)
+	return a
+}
+
+// Uint32 append append i as a uint32 to the array.
+func (a *Array) Uint32(i uint32) *Array {
+	a.buf = enc.AppendUint32(enc.AppendArrayDelim(a.buf), i)
+	return a
+}
+
+// Uint64 append append i as a uint64 to the array.
+func (a *Array) Uint64(i uint64) *Array {
+	a.buf = enc.AppendUint64(enc.AppendArrayDelim(a.buf), i)
+	return a
+}
+
+// Float32 append append f as a float32 to the array.
+func (a *Array) Float32(f float32) *Array {
+	a.buf = enc.AppendFloat32(enc.AppendArrayDelim(a.buf), f)
+	return a
+}
+
+// Float64 append append f as a float64 to the array.
+func (a *Array) Float64(f float64) *Array {
+	a.buf = enc.AppendFloat64(enc.AppendArrayDelim(a.buf), f)
+	return a
+}
+
+// Time append append t formated as string using zerolog.TimeFieldFormat.
+func (a *Array) Time(t time.Time) *Array {
+	a.buf = enc.AppendTime(enc.AppendArrayDelim(a.buf), t, TimeFieldFormat)
+	return a
+}
+
+// Dur append append d to the array.
+func (a *Array) Dur(d time.Duration) *Array {
+	a.buf = enc.AppendDuration(enc.AppendArrayDelim(a.buf), d, DurationFieldUnit, DurationFieldInteger)
+	return a
+}
+
+// Interface append append i marshaled using reflection.
+func (a *Array) Interface(i interface{}) *Array {
+	if obj, ok := i.(LogObjectMarshaler); ok {
+		return a.Object(obj)
+	}
+	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
+}

array_test.go

@@ -0,0 +1,35 @@
+package zerolog
+
+import (
+	"net"
+	"testing"
+	"time"
+)
+
+func TestArray(t *testing.T) {
+	a := Arr().
+		Bool(true).
+		Int(1).
+		Int8(2).
+		Int16(3).
+		Int32(4).
+		Int64(5).
+		Uint(6).
+		Uint8(7).
+		Uint16(8).
+		Uint32(9).
+		Uint64(10).
+		Float32(11.98122).
+		Float64(12.987654321).
+		Str("a").
+		Bytes([]byte("b")).
+		Hex([]byte{0x1f}).
+		RawJSON([]byte(`{"some":"json"}`)).
+		Time(time.Time{}).
+		IPAddr(net.IP{192, 168, 0, 10}).
+		Dur(0)
+	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]`
+	if got := decodeObjectToStr(a.write([]byte{})); got != want {
+		t.Errorf("Array.write()\ngot:  %s\nwant: %s", got, want)
+	}
+}

benchmark_test.go

@@ -3,6 +3,7 @@ package zerolog
 import (
 	"errors"
 	"io/ioutil"
+	"net"
 	"testing"
 	"time"
 )
@@ -57,6 +58,18 @@ func BenchmarkContextFields(b *testing.B) {
 	})
 }
 
+func BenchmarkContextAppend(b *testing.B) {
+	logger := New(ioutil.Discard).With().
+		Str("foo", "bar").
+		Logger()
+	b.ResetTimer()
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			logger.With().Str("bar", "baz")
+		}
+	})
+}
+
 func BenchmarkLogFields(b *testing.B) {
 	logger := New(ioutil.Discard)
 	b.ResetTimer()
@@ -71,3 +84,282 @@ func BenchmarkLogFields(b *testing.B) {
 		}
 	})
 }
+
+type obj struct {
+	Pub  string
+	Tag  string `json:"tag"`
+	priv int
+}
+
+func (o obj) MarshalZerologObject(e *Event) {
+	e.Str("Pub", o.Pub).
+		Str("Tag", o.Tag).
+		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(ioutil.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}
+	floats := []float64{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
+	strings := []string{"a", "b", "c", "d", "e", "f", "g", "h", "i", "j"}
+	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{
+		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},
+	}
+	errs := []error{errors.New("a"), errors.New("b"), errors.New("c"), errors.New("d"), errors.New("e")}
+	types := map[string]func(e *Event) *Event{
+		"Bool": func(e *Event) *Event {
+			return e.Bool("k", bools[0])
+		},
+		"Bools": func(e *Event) *Event {
+			return e.Bools("k", bools)
+		},
+		"Int": func(e *Event) *Event {
+			return e.Int("k", ints[0])
+		},
+		"Ints": func(e *Event) *Event {
+			return e.Ints("k", ints)
+		},
+		"Float": func(e *Event) *Event {
+			return e.Float64("k", floats[0])
+		},
+		"Floats": func(e *Event) *Event {
+			return e.Floats64("k", floats)
+		},
+		"Str": func(e *Event) *Event {
+			return e.Str("k", strings[0])
+		},
+		"Strs": func(e *Event) *Event {
+			return e.Strs("k", strings)
+		},
+		"Err": func(e *Event) *Event {
+			return e.Err(errs[0])
+		},
+		"Errs": func(e *Event) *Event {
+			return e.Errs("k", errs)
+		},
+		"Time": func(e *Event) *Event {
+			return e.Time("k", times[0])
+		},
+		"Times": func(e *Event) *Event {
+			return e.Times("k", times)
+		},
+		"Dur": func(e *Event) *Event {
+			return e.Dur("k", durations[0])
+		},
+		"Durs": func(e *Event) *Event {
+			return e.Durs("k", durations)
+		},
+		"Interface": func(e *Event) *Event {
+			return e.Interface("k", interfaces[0])
+		},
+		"Interfaces": func(e *Event) *Event {
+			return e.Interface("k", interfaces)
+		},
+		"Interface(Object)": func(e *Event) *Event {
+			return e.Interface("k", objects[0])
+		},
+		"Interface(Objects)": func(e *Event) *Event {
+			return e.Interface("k", objects)
+		},
+		"Object": func(e *Event) *Event {
+			return e.Object("k", objects[0])
+		},
+	}
+	logger := New(ioutil.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() {
+					f(logger.Info()).Msg("")
+				}
+			})
+		})
+	}
+}
+
+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{
+		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},
+	}
+	errs := []error{errors.New("a"), errors.New("b"), errors.New("c"), errors.New("d"), errors.New("e")}
+	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)
+		},
+		"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(ioutil.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 +1,512 @@
+// +build binary_log
+
+package zerolog
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+
+	//	"io/ioutil"
+	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 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"}
+}

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/lint/readme.md

@@ -0,0 +1,37 @@
+# Zerolog Lint
+
+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 dependecy 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.
+

console.go

@@ -0,0 +1,409 @@
+package zerolog
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"sort"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+)
+
+const (
+	colorBlack = iota + 30
+	colorRed
+	colorGreen
+	colorYellow
+	colorBlue
+	colorMagenta
+	colorCyan
+	colorWhite
+
+	colorBold     = 1
+	colorDarkGray = 90
+)
+
+var (
+	consoleBufPool = sync.Pool{
+		New: func() interface{} {
+			return bytes.NewBuffer(make([]byte, 0, 100))
+		},
+	}
+)
+
+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 is the output destination.
+	Out io.Writer
+
+	// NoColor disables the colorized output.
+	NoColor bool
+
+	// TimeFormat specifies the format for timestamp in output.
+	TimeFormat string
+
+	// PartsOrder defines the order of parts in output.
+	PartsOrder []string
+
+	// PartsExclude defines parts to not display in output.
+	PartsExclude []string
+
+	FormatTimestamp     Formatter
+	FormatLevel         Formatter
+	FormatCaller        Formatter
+	FormatMessage       Formatter
+	FormatFieldName     Formatter
+	FormatFieldValue    Formatter
+	FormatErrFieldName  Formatter
+	FormatErrFieldValue Formatter
+}
+
+// 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)
+	}
+
+	return w
+}
+
+// Write transforms the JSON input with formatters and appends to w.Out.
+func (w ConsoleWriter) Write(p []byte) (n int, err error) {
+	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 n, fmt.Errorf("cannot decode event: %s", err)
+	}
+
+	for _, p := range w.PartsOrder {
+		w.writePart(buf, evt, p)
+	}
+
+	w.writeFields(evt, buf)
+
+	err = buf.WriteByte('\n')
+	if err != nil {
+		return n, err
+	}
+	_, err = buf.WriteTo(w.Out)
+	return len(p), err
+}
+
+// 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 {
+		switch field {
+		case LevelFieldName, TimestampFieldName, MessageFieldName, CallerFieldName:
+			continue
+		}
+		fields = append(fields, field)
+	}
+	sort.Strings(fields)
+
+	if 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:
+			b, err := json.Marshal(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(' ')
+		}
+	}
+}
+
+// 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
+			}
+		}
+	}
+
+	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.NoColor)
+		} else {
+			f = w.FormatTimestamp
+		}
+	case MessageFieldName:
+		if w.FormatMessage == nil {
+			f = consoleDefaultFormatMessage
+		} else {
+			f = w.FormatMessage
+		}
+	case CallerFieldName:
+		if w.FormatCaller == nil {
+			f = consoleDefaultFormatCaller(w.NoColor)
+		} else {
+			f = w.FormatCaller
+		}
+	default:
+		if w.FormatFieldValue == nil {
+			f = consoleDefaultFormatFieldValue
+		} else {
+			f = w.FormatFieldValue
+		}
+	}
+
+	var s = f(evt[p])
+
+	if len(s) > 0 {
+		buf.WriteString(s)
+		if p != w.PartsOrder[len(w.PartsOrder)-1] { // Skip space for last part
+			buf.WriteByte(' ')
+		}
+	}
+}
+
+// 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] == '"' {
+			return true
+		}
+	}
+	return false
+}
+
+// colorize returns the string s wrapped in ANSI code c, unless disabled is true.
+func colorize(s interface{}, c int, disabled bool) string {
+	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, noColor bool) Formatter {
+	if timeFormat == "" {
+		timeFormat = consoleDefaultTimeFormat
+	}
+	return func(i interface{}) string {
+		t := "<nil>"
+		switch tt := i.(type) {
+		case string:
+			ts, err := time.Parse(TimeFieldFormat, tt)
+			if err != nil {
+				t = tt
+			} else {
+				t = ts.Format(timeFormat)
+			}
+		case json.Number:
+			i, err := tt.Int64()
+			if err != nil {
+				t = tt.String()
+			} else {
+				var sec, nsec int64 = i, 0
+				switch TimeFieldFormat {
+				case TimeFormatUnixMs:
+					nsec = int64(time.Duration(i) * time.Millisecond)
+					sec = 0
+				case TimeFormatUnixMicro:
+					nsec = int64(time.Duration(i) * time.Microsecond)
+					sec = 0
+				}
+				ts := time.Unix(sec, nsec).UTC()
+				t = ts.Format(timeFormat)
+			}
+		}
+		return colorize(t, colorDarkGray, noColor)
+	}
+}
+
+func consoleDefaultFormatLevel(noColor bool) Formatter {
+	return func(i interface{}) string {
+		var l string
+		if ll, ok := i.(string); ok {
+			switch ll {
+			case LevelTraceValue:
+				l = colorize("TRC", colorMagenta, noColor)
+			case LevelDebugValue:
+				l = colorize("DBG", colorYellow, noColor)
+			case LevelInfoValue:
+				l = colorize("INF", colorGreen, noColor)
+			case LevelWarnValue:
+				l = colorize("WRN", colorRed, noColor)
+			case LevelErrorValue:
+				l = colorize(colorize("ERR", colorRed, noColor), colorBold, noColor)
+			case LevelFatalValue:
+				l = colorize(colorize("FTL", colorRed, noColor), colorBold, noColor)
+			case LevelPanicValue:
+				l = colorize(colorize("PNC", colorRed, noColor), colorBold, noColor)
+			default:
+				l = colorize("???", colorBold, noColor)
+			}
+		} else {
+			if i == nil {
+				l = colorize("???", colorBold, noColor)
+			} else {
+				l = strings.ToUpper(fmt.Sprintf("%s", i))[0:3]
+			}
+		}
+		return l
+	}
+}
+
+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(i interface{}) string {
+	if i == nil {
+		return ""
+	}
+	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), colorRed, noColor)
+	}
+}
+
+func consoleDefaultFormatErrFieldValue(noColor bool) Formatter {
+	return func(i interface{}) string {
+		return colorize(fmt.Sprintf("%s", i), colorRed, noColor)
+	}
+}

console_test.go

@@ -0,0 +1,370 @@
+package zerolog_test
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"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[31mWRN\x1b[0m Foobar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("Write fields", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, NoColor: true}
+
+		d := time.Unix(0, 0).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 := "12:00AM 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 := "Jan  1 00:20:34.000 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 := "Jan  1 00:20:34.567 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 := "Jan  1 00:20:34.567891 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[31mWRN\x1b[0m Foobar \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}
+
+		d := time.Unix(0, 0).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 := "12:00AM 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)
+		}
+
+		d := time.Unix(0, 0).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 := "12:00AM 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)
+		}
+	})
+}
+
+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}
+
+		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 := "1970-01-01T00:00:00Z INF Foobar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	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)
+		}
+	})
+}
+
+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: ioutil.Discard, NoColor: false}
+
+	for i := 0; i < b.N; i++ {
+		w.Write(msg)
+	}
+}

context.go

@@ -1,6 +1,12 @@
 package zerolog
 
-import "time"
+import (
+	"fmt"
+	"io/ioutil"
+	"math"
+	"net"
+	"time"
+)
 
 // Context configures a new sub-logger with contextual fields.
 type Context struct {
@@ -12,136 +18,414 @@ 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)
+	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(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
+}
+
+// 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 (c Context) Array(key string, arr LogArrayMarshaler) Context {
+	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
+	}
+	var a *Array
+	if aa, ok := arr.(*Array); ok {
+		a = aa
+	} else {
+		a = Arr()
+		arr.MarshalZerologArray(a)
+	}
+	c.l.context = a.write(c.l.context)
+	return c
+}
+
+// Object marshals an object that implement the LogObjectMarshaler interface.
+func (c Context) Object(key string, obj LogObjectMarshaler) Context {
+	e := newEvent(levelWriterAdapter{ioutil.Discard}, 0)
+	e.Object(key, obj)
+	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{ioutil.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 = appendString(c.l.context, key, val)
+	c.l.context = enc.AppendString(enc.AppendKey(c.l.context, key), val)
 	return c
 }
 
-// AnErr adds the field key with err as a string to the logger context.
+// 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 = 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 = enc.AppendBytes(enc.AppendKey(c.l.context, key), val)
+	return c
+}
+
+// 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 {
-	c.l.context = appendErrorKey(c.l.context, key, err)
-	return c
+	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)
+	}
 }
 
-// Err adds the field "error" with err as a string to the logger context.
-// To customize the key name, change zerolog.ErrorFieldName.
+// 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 {
+	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 serialized err to the logger context.
 func (c Context) Err(err error) Context {
-	c.l.context = appendError(c.l.context, err)
+	return c.AnErr(ErrorFieldName, err)
+}
+
+// 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 = enc.AppendBool(enc.AppendKey(c.l.context, key), b)
 	return c
 }
 
-// Bool adds the field key with val as a Boolean to the logger context.
-func (c Context) Bool(key string, b bool) Context {
-	c.l.context = appendBool(c.l.context, key, b)
+// 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 = 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 = appendInt(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 = 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 = appendInt8(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 = 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 = appendInt16(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 = 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 = appendInt32(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 = 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 = appendInt64(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 = 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 = appendUint(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 = 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 = appendUint8(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 = 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 = appendUint16(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 = 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 = appendUint32(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 = 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 = appendUint64(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 = 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 = appendFloat32(c.l.context, key, f)
+	c.l.context = enc.AppendFloat32(enc.AppendKey(c.l.context, key), f)
+	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 = enc.AppendFloats32(enc.AppendKey(c.l.context, key), f)
 	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 = appendFloat64(c.l.context, key, f)
+	c.l.context = enc.AppendFloat64(enc.AppendKey(c.l.context, key), f)
 	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 = enc.AppendFloats64(enc.AppendKey(c.l.context, key), f)
+	return c
+}
+
+type timestampHook struct{}
+
+func (ts timestampHook) Run(e *Event, level Level, msg string) {
+	e.Timestamp()
+}
+
+var th = timestampHook{}
+
 // Timestamp adds the current local time as UNIX timestamp to the logger context with the "time" key.
 // To customize the key name, change zerolog.TimestampFieldName.
+//
+// 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.
 func (c Context) Time(key string, t time.Time) Context {
-	c.l.context = appendTime(c.l.context, key, t)
+	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.
+func (c Context) Times(key string, t []time.Time) Context {
+	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 = appendDuration(c.l.context, key, d)
+	c.l.context = enc.AppendDuration(enc.AppendKey(c.l.context, key), d, DurationFieldUnit, DurationFieldInteger)
+	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 = enc.AppendDurations(enc.AppendKey(c.l.context, key), d, DurationFieldUnit, DurationFieldInteger)
 	return c
 }
 
 // Interface adds the field key with obj marshaled using reflection.
 func (c Context) Interface(key string, i interface{}) Context {
-	c.l.context = appendInterface(c.l.context, key, i)
+	c.l.context = enc.AppendInterface(enc.AppendKey(c.l.context, key), i)
+	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

@@ -2,28 +2,50 @@ package zerolog
 
 import (
 	"context"
-	"io/ioutil"
 )
 
-var disabledLogger = New(ioutil.Discard).Level(Disabled)
+var disabledLogger *Logger
+
+func init() {
+	SetGlobalLevel(TraceLevel)
+	l := Nop()
+	disabledLogger = &l
+}
 
 type ctxKey struct{}
 
-// WithContext returns a copy of ctx with l associated.
-func (l Logger) WithContext(ctx context.Context) context.Context {
+// WithContext returns a copy of ctx with l associated. If an instance of Logger
+// is already in the context, the context is not updated.
+//
+// For instance, to add a field to an existing logger in the context, use this
+// notation:
+//
+//     ctx := r.Context()
+//     l := zerolog.Ctx(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
+		if lp == l {
+			// Do not store same logger.
+			return ctx
+		}
+	} else if l.level == Disabled {
+		// Do not store disabled logger.
 		return ctx
 	}
-	return context.WithValue(ctx, ctxKey{}, &l)
+	return context.WithValue(ctx, ctxKey{}, l)
 }
 
 // Ctx returns the Logger associated with the ctx. If no logger
-// is associated, a disabled logger is returned.
-func Ctx(ctx context.Context) Logger {
+// 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
+		return l
+	} else if l = DefaultContextLogger; l != nil {
+		return l
 	}
 	return disabledLogger
 }

ctx_test.go

@@ -11,7 +11,7 @@ func TestCtx(t *testing.T) {
 	log := New(ioutil.Discard)
 	ctx := log.WithContext(context.Background())
 	log2 := Ctx(ctx)
-	if !reflect.DeepEqual(log, log2) {
+	if !reflect.DeepEqual(log, *log2) {
 		t.Error("Ctx did not return the expected logger")
 	}
 
@@ -19,12 +19,52 @@ func TestCtx(t *testing.T) {
 	log = log.Level(InfoLevel)
 	ctx = log.WithContext(ctx)
 	log2 = Ctx(ctx)
-	if !reflect.DeepEqual(log, log2) {
+	if !reflect.DeepEqual(log, *log2) {
 		t.Error("Ctx did not return the expected logger")
 	}
 
 	log2 = Ctx(context.Background())
-	if !reflect.DeepEqual(log2, disabledLogger) {
+	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) {
+	dl := New(ioutil.Discard).Level(Disabled)
+	ctx := dl.WithContext(context.Background())
+	if ctx != context.Background() {
+		t.Error("WithContext stored a disabled logger")
+	}
+
+	l := New(ioutil.Discard).With().Str("foo", "bar").Logger()
+	ctx = l.WithContext(ctx)
+	if Ctx(ctx) != &l {
+		t.Error("WithContext did not store logger")
+	}
+
+	l.UpdateContext(func(c Context) Context {
+		return c.Str("bar", "baz")
+	})
+	ctx = l.WithContext(ctx)
+	if Ctx(ctx) != &l {
+		t.Error("WithContext did not store updated logger")
+	}
+
+	l = l.Level(DebugLevel)
+	ctx = l.WithContext(ctx)
+	if Ctx(ctx) != &l {
+		t.Error("WithContext did not store copied logger")
+	}
+
+	ctx = dl.WithContext(ctx)
+	if Ctx(ctx) != &dl {
+		t.Error("WithContext did not overide logger with a disabled logger")
+	}
+}

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 +1,54 @@
+package diode_test
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"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 Benchmark(b *testing.B) {
+	log.SetOutput(ioutil.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(ioutil.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 optimzed 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 not 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 has 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 has 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 PollerConfigOption(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 PollerConfigOption(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 +1,83 @@
+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 WaiterConfigOption(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()
+		w.c.Broadcast()
+	}()
+
+	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) []byte
+	AppendDurations(dst []byte, vals []time.Duration, unit time.Duration, useInt bool) []byte
+	AppendEndMarker(dst []byte) []byte
+	AppendFloat32(dst []byte, val float32) []byte
+	AppendFloat64(dst []byte, val float64) []byte
+	AppendFloats32(dst []byte, vals []float32) []byte
+	AppendFloats64(dst []byte, vals []float64) []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 +1,42 @@
+// +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)
+}
+
+// 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 +1,39 @@
+// +build !binary_log
+
+package zerolog
+
+// encoder_json.go file contains bindings to generate
+// JSON encoded byte stream.
+
+import (
+	"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 decodeIfBinaryToString(in []byte) string {
+	return string(in)
+}
+
+func decodeObjectToStr(in []byte) string {
+	return string(in)
+}
+
+func decodeIfBinaryToBytes(in []byte) []byte {
+	return in
+}

event.go

@@ -2,8 +2,9 @@ package zerolog
 
 import (
 	"fmt"
-	"io/ioutil"
+	"net"
 	"os"
+	"runtime"
 	"sync"
 	"time"
 )
@@ -19,40 +20,81 @@ 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.
 }
 
-func newEvent(w LevelWriter, level Level, enabled bool) *Event {
-	if !enabled {
-		return &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
+// to be implemented by types used with Event/Context's Object methods.
+type LogObjectMarshaler interface {
+	MarshalZerologObject(e *Event)
+}
+
+// LogArrayMarshaler provides a strongly-typed and encoding-agnostic interface
+// to be implemented by types used with Event/Context's Array methods.
+type LogArrayMarshaler interface {
+	MarshalZerologArray(a *Array)
+}
+
+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.
@@ -60,48 +102,70 @@ 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
 	}
+	e.msg(msg)
+}
+
+// Send is equivalent to calling Msg("").
+//
+// NOTICE: once this method is called, the *Event should be disposed.
+func (e *Event) Send() {
+	if e == nil {
+		return
+	}
+	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) msg(msg string) {
+	for _, hook := range e.ch {
+		hook.Run(e, e.level, msg)
+	}
 	if msg != "" {
-		e.buf = appendString(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)
+		}
 	}
 }
 
-// Msgf sends the event with formated msg added as the message field if not empty.
-//
-// 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 {
-		return
-	}
-	msg := fmt.Sprintf(format, v...)
-	if msg != "" {
-		e.buf = appendString(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)
+// 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 == nil {
+		return e
 	}
+	e.buf = appendFields(e.buf, fields)
+	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(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
 }
 
@@ -109,172 +173,485 @@ 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 == nil {
+		return e
+	}
+	e.buf = enc.AppendKey(e.buf, key)
+	var a *Array
+	if aa, ok := arr.(*Array); ok {
+		a = aa
+	} else {
+		a = Arr()
+		arr.MarshalZerologArray(a)
+	}
+	e.buf = a.write(e.buf)
+	return e
+}
+
+func (e *Event) appendObject(obj LogObjectMarshaler) {
+	e.buf = enc.AppendBeginMarker(e.buf)
+	obj.MarshalZerologObject(e)
+	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 == nil {
+		return e
+	}
+	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 = appendString(e.buf, key, val)
+	e.buf = enc.AppendString(enc.AppendKey(e.buf, key), val)
 	return e
 }
 
-// AnErr adds the field key with err as a string to the *Event context.
+// 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 == nil {
+		return e
+	}
+	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
+	}
+
+	if val != nil {
+		e.buf = enc.AppendString(enc.AppendKey(e.buf, key), val.String())
+		return e
+	}
+
+	e.buf = enc.AppendInterface(enc.AppendKey(e.buf, key), nil)
+	return e
+}
+
+// Bytes adds the field key with val as a string to the *Event context.
+//
+// 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 == nil {
+		return e
+	}
+	e.buf = enc.AppendBytes(enc.AppendKey(e.buf, key), val)
+	return e
+}
+
+// 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
+}
+
+// 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
 	}
-	e.buf = appendErrorKey(e.buf, key, err)
-	return e
+	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)
+	}
 }
 
-// Err adds the field "error" with err as a string to the *Event context.
+// 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 == nil {
+		return e
+	}
+	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.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = appendError(e.buf, err)
+	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
 }
 
-// Bool adds the field key with val as a Boolean to the *Event context.
+// 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 = appendBool(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 == nil {
+		return e
+	}
+	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 = appendInt(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 == nil {
+		return e
+	}
+	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 = appendInt8(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 == nil {
+		return e
+	}
+	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 = appendInt16(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 == nil {
+		return e
+	}
+	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 = appendInt32(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 == nil {
+		return e
+	}
+	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 = appendInt64(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 == nil {
+		return e
+	}
+	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 = appendUint(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 == nil {
+		return e
+	}
+	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 = appendUint8(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 == nil {
+		return e
+	}
+	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 = appendUint16(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 == nil {
+		return e
+	}
+	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 = appendUint32(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 == nil {
+		return e
+	}
+	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 = appendUint64(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 == nil {
+		return e
+	}
+	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 = appendFloat32(e.buf, key, f)
+	e.buf = enc.AppendFloat32(enc.AppendKey(e.buf, key), f)
+	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 == nil {
+		return e
+	}
+	e.buf = enc.AppendFloats32(enc.AppendKey(e.buf, key), f)
 	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 = appendFloat64(e.buf, key, f)
+	e.buf = enc.AppendFloat64(enc.AppendKey(e.buf, key), f)
+	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 == nil {
+		return e
+	}
+	e.buf = enc.AppendFloats64(enc.AppendKey(e.buf, key), f)
 	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 = appendTimestamp(e.buf)
+	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.
 func (e *Event) Time(key string, t time.Time) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = appendTime(e.buf, key, t)
+	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.
+func (e *Event) Times(key string, t []time.Time) *Event {
+	if e == nil {
+		return e
+	}
+	e.buf = enc.AppendTimes(enc.AppendKey(e.buf, key), t, TimeFieldFormat)
 	return e
 }
 
@@ -282,10 +659,21 @@ func (e *Event) Time(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 = appendDuration(e.buf, key, d)
+	e.buf = enc.AppendDuration(enc.AppendKey(e.buf, key), d, DurationFieldUnit, DurationFieldInteger)
+	return e
+}
+
+// Durs adds the field key with duration d stored as zerolog.DurationFieldUnit.
+// 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 == nil {
+		return e
+	}
+	e.buf = enc.AppendDurations(enc.AppendKey(e.buf, key), d, DurationFieldUnit, DurationFieldInteger)
 	return e
 }
 
@@ -293,22 +681,85 @@ func (e *Event) Dur(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 = appendDuration(e.buf, key, d)
+	e.buf = enc.AppendDuration(enc.AppendKey(e.buf, key), d, DurationFieldUnit, DurationFieldInteger)
 	return e
 }
 
 // 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
 	}
-	e.buf = appendInterface(e.buf, key, i)
+	if obj, ok := i.(LogObjectMarshaler); ok {
+		return e.Object(key, obj)
+	}
+	e.buf = enc.AppendInterface(enc.AppendKey(e.buf, key), i)
+	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
+	}
+	_, file, line, ok := runtime.Caller(skip + e.skipFrame)
+	if !ok {
+		return e
+	}
+	e.buf = enc.AppendString(enc.AppendKey(e.buf, CallerFieldName), CallerMarshalFunc(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)
+	}
+}

field.go

@@ -1,109 +0,0 @@
-package zerolog
-
-import (
-	"encoding/json"
-	"fmt"
-	"strconv"
-	"time"
-)
-
-func appendKey(dst []byte, key string) []byte {
-	if len(dst) > 1 {
-		dst = append(dst, ',')
-	}
-	dst = appendJSONString(dst, key)
-	return append(dst, ':')
-}
-
-func appendString(dst []byte, key, val string) []byte {
-	return appendJSONString(appendKey(dst, key), val)
-}
-
-func appendErrorKey(dst []byte, key string, err error) []byte {
-	if err == nil {
-		return dst
-	}
-	return appendJSONString(appendKey(dst, key), err.Error())
-}
-
-func appendError(dst []byte, err error) []byte {
-	return appendErrorKey(dst, ErrorFieldName, err)
-}
-
-func appendBool(dst []byte, key string, val bool) []byte {
-	return strconv.AppendBool(appendKey(dst, key), val)
-}
-
-func appendInt(dst []byte, key string, val int) []byte {
-	return strconv.AppendInt(appendKey(dst, key), int64(val), 10)
-}
-
-func appendInt8(dst []byte, key string, val int8) []byte {
-	return strconv.AppendInt(appendKey(dst, key), int64(val), 10)
-}
-
-func appendInt16(dst []byte, key string, val int16) []byte {
-	return strconv.AppendInt(appendKey(dst, key), int64(val), 10)
-}
-
-func appendInt32(dst []byte, key string, val int32) []byte {
-	return strconv.AppendInt(appendKey(dst, key), int64(val), 10)
-}
-
-func appendInt64(dst []byte, key string, val int64) []byte {
-	return strconv.AppendInt(appendKey(dst, key), int64(val), 10)
-}
-
-func appendUint(dst []byte, key string, val uint) []byte {
-	return strconv.AppendUint(appendKey(dst, key), uint64(val), 10)
-}
-
-func appendUint8(dst []byte, key string, val uint8) []byte {
-	return strconv.AppendUint(appendKey(dst, key), uint64(val), 10)
-}
-
-func appendUint16(dst []byte, key string, val uint16) []byte {
-	return strconv.AppendUint(appendKey(dst, key), uint64(val), 10)
-}
-
-func appendUint32(dst []byte, key string, val uint32) []byte {
-	return strconv.AppendUint(appendKey(dst, key), uint64(val), 10)
-}
-
-func appendUint64(dst []byte, key string, val uint64) []byte {
-	return strconv.AppendUint(appendKey(dst, key), uint64(val), 10)
-}
-
-func appendFloat32(dst []byte, key string, val float32) []byte {
-	return strconv.AppendFloat(appendKey(dst, key), float64(val), 'f', -1, 32)
-}
-
-func appendFloat64(dst []byte, key string, val float64) []byte {
-	return strconv.AppendFloat(appendKey(dst, key), float64(val), 'f', -1, 32)
-}
-
-func appendTime(dst []byte, key string, t time.Time) []byte {
-	if TimeFieldFormat == "" {
-		return appendInt64(dst, key, t.Unix())
-	}
-	return append(t.AppendFormat(append(appendKey(dst, key), '"'), TimeFieldFormat), '"')
-}
-
-func appendTimestamp(dst []byte) []byte {
-	return appendTime(dst, TimestampFieldName, TimestampFunc())
-}
-
-func appendDuration(dst []byte, key string, d time.Duration) []byte {
-	if DurationFieldInteger {
-		return appendInt64(dst, key, int64(d/DurationFieldUnit))
-	}
-	return appendFloat64(dst, key, float64(d)/float64(DurationFieldUnit))
-}
-
-func appendInterface(dst []byte, key string, i interface{}) []byte {
-	marshaled, err := json.Marshal(i)
-	if err != nil {
-		return appendString(dst, key, fmt.Sprintf("marshaling error: %v", err))
-	}
-	return append(appendKey(dst, key), marshaled...)
-}

fields.go

@@ -0,0 +1,256 @@
+package zerolog
+
+import (
+	"encoding/json"
+	"net"
+	"sort"
+	"time"
+	"unsafe"
+)
+
+func isNilValue(i interface{}) bool {
+	return (*[2]uintptr)(unsafe.Pointer(&i))[1] == 0
+}
+
+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 = enc.AppendKey(dst, key)
+		val := fields[key]
+		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)
+			}
+		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)
+		case float64:
+			dst = enc.AppendFloat64(dst, val)
+		case time.Time:
+			dst = enc.AppendTime(dst, val, TimeFieldFormat)
+		case time.Duration:
+			dst = enc.AppendDuration(dst, val, DurationFieldUnit, DurationFieldInteger)
+		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)
+			} else {
+				dst = enc.AppendNil(dst)
+			}
+		case *float64:
+			if val != nil {
+				dst = enc.AppendFloat64(dst, *val)
+			} 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)
+			} 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)
+		case []float64:
+			dst = enc.AppendFloats64(dst, val)
+		case []time.Time:
+			dst = enc.AppendTimes(dst, val, TimeFieldFormat)
+		case []time.Duration:
+			dst = enc.AppendDurations(dst, val, DurationFieldUnit, DurationFieldInteger)
+		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 +1,25 @@
 package zerolog
 
-import "time"
-import "sync/atomic"
+import (
+	"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"
+)
 
 var (
 	// TimestampFieldName is the field name used for the timestamp field.
@@ -10,18 +28,61 @@ 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"
 
-	// SampleFieldName is the name of the field used to report sampling.
-	SampleFieldName = "sample"
+	// CallerFieldName is the field name used for caller field.
+	CallerFieldName = "caller"
 
-	// 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.
+	// CallerSkipFrameCount is the number of stack frames to skip to find the caller.
+	CallerSkipFrameCount = 2
+
+	// CallerMarshalFunc allows customization of global caller marshaling
+	CallerMarshalFunc = func(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"
+	InterfaceMarshalFunc = json.Marshal
+
+	// TimeFieldFormat defines the time format of the Time field type. If set to
+	// TimeFormatUnix, TimeFormatUnixMs or TimeFormatUnixMicro, the time is formatted as an UNIX
+	// timestamp as integer.
 	TimeFieldFormat = time.RFC3339
 
 	// TimestampFunc defines the function called to generate a timestamp.
@@ -34,11 +95,20 @@ 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
 )
 
 var (
-	gLevel          = new(uint32)
-	disableSampling = new(uint32)
+	gLevel          = new(int32)
+	disableSampling = new(int32)
 )
 
 // SetGlobalLevel sets the global override for log level. If this
@@ -46,22 +116,23 @@ 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(gLevel) == 1
+	return atomic.LoadInt32(disableSampling) == 1
 }

go.mod

@@ -0,0 +1,10 @@
+module github.com/rs/zerolog
+
+go 1.15
+
+require (
+	github.com/coreos/go-systemd/v22 v22.3.2
+	github.com/pkg/errors v0.9.1
+	github.com/rs/xid v1.3.0
+	golang.org/x/tools v0.1.5
+)

go.sum

@@ -0,0 +1,34 @@
+github.com/coreos/go-systemd/v22 v22.3.2 h1:D9/bQk5vlXQFZ6Kwuu6zaiXJ9oTPe68++AzAJc1DzSI=
+github.com/coreos/go-systemd/v22 v22.3.2/go.mod h1:Y58oyj3AT4RCenI/lSvhwexgC+NSVTIJ3seZv2GcEnc=
+github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
+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 v1.3.0 h1:6NjYksEUlhurdVehpc7S7dk6DAmcKv8V9gG0FsVN2U4=
+github.com/rs/xid v1.3.0/go.mod h1:trrq9SKmegXys3aeAKXMUTdJsYXVwGY3RLcfgqegfbg=
+github.com/yuin/goldmark v1.3.5/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 v0.4.2 h1:Gz96sIWK3OalVv/I/qNygP42zyoKp3xptRVCWRFEBvo=
+golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
+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 v0.0.0-20210405180319-a5a99cb37ef4/go.mod h1:p54w0d4576C0XHj96bSt6lcn1PtDYWL6XObtHCRCNQM=
+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 v0.0.0-20210330210617-4fbd30eecc44/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210510120138-977fb7262007 h1:gG67DSER+11cZvqIMb8S8bt0vZtiN6xWYARwirrOSfE=
+golang.org/x/sys v0.0.0-20210510120138-977fb7262007/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 v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+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 v0.1.5 h1:ouewzE6p+/VEB31YYnTbEJdi8pFqKp4P4n85vwo3DHA=
+golang.org/x/tools v0.1.5/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
+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=

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

@@ -3,17 +3,18 @@ package hlog
 
 import (
 	"context"
-	"net"
 	"net/http"
+	"time"
 
 	"github.com/rs/xid"
 	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/hlog/internal/mutil"
 	"github.com/rs/zerolog/log"
 )
 
 // FromRequest gets the logger in the request's context.
 // This is a shortcut for log.Ctx(r.Context())
-func FromRequest(r *http.Request) zerolog.Logger {
+func FromRequest(r *http.Request) *zerolog.Logger {
 	return log.Ctx(r.Context())
 }
 
@@ -21,7 +22,10 @@ func FromRequest(r *http.Request) zerolog.Logger {
 func NewHandler(log zerolog.Logger) func(http.Handler) http.Handler {
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-			r = r.WithContext(log.WithContext(r.Context()))
+			// Create a copy of the logger (including internal context slice)
+			// to prevent data race when using UpdateContext.
+			l := log.With().Logger()
+			r = r.WithContext(l.WithContext(r.Context()))
 			next.ServeHTTP(w, r)
 		})
 	}
@@ -33,8 +37,9 @@ func URLHandler(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 = log.With().Str(fieldKey, r.URL.String()).Logger()
-			r = r.WithContext(log.WithContext(r.Context()))
+			log.UpdateContext(func(c zerolog.Context) zerolog.Context {
+				return c.Str(fieldKey, r.URL.String())
+			})
 			next.ServeHTTP(w, r)
 		})
 	}
@@ -46,8 +51,9 @@ func MethodHandler(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 = log.With().Str(fieldKey, r.Method).Logger()
-			r = r.WithContext(log.WithContext(r.Context()))
+			log.UpdateContext(func(c zerolog.Context) zerolog.Context {
+				return c.Str(fieldKey, r.Method)
+			})
 			next.ServeHTTP(w, r)
 		})
 	}
@@ -59,8 +65,9 @@ func RequestHandler(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 = log.With().Str(fieldKey, r.Method+" "+r.URL.String()).Logger()
-			r = r.WithContext(log.WithContext(r.Context()))
+			log.UpdateContext(func(c zerolog.Context) zerolog.Context {
+				return c.Str(fieldKey, r.Method+" "+r.URL.String())
+			})
 			next.ServeHTTP(w, r)
 		})
 	}
@@ -71,10 +78,11 @@ 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 = log.With().Str(fieldKey, host).Logger()
-				r = r.WithContext(log.WithContext(r.Context()))
+				log.UpdateContext(func(c zerolog.Context) zerolog.Context {
+					return c.Str(fieldKey, r.RemoteAddr)
+				})
 			}
 			next.ServeHTTP(w, r)
 		})
@@ -88,8 +96,9 @@ func UserAgentHandler(fieldKey string) func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			if ua := r.Header.Get("User-Agent"); ua != "" {
 				log := zerolog.Ctx(r.Context())
-				log = log.With().Str(fieldKey, ua).Logger()
-				r = r.WithContext(log.WithContext(r.Context()))
+				log.UpdateContext(func(c zerolog.Context) zerolog.Context {
+					return c.Str(fieldKey, ua)
+				})
 			}
 			next.ServeHTTP(w, r)
 		})
@@ -103,8 +112,9 @@ func RefererHandler(fieldKey string) func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			if ref := r.Header.Get("Referer"); ref != "" {
 				log := zerolog.Ctx(r.Context())
-				log = log.With().Str(fieldKey, ref).Logger()
-				r = r.WithContext(log.WithContext(r.Context()))
+				log.UpdateContext(func(c zerolog.Context) zerolog.Context {
+					return c.Str(fieldKey, ref)
+				})
 			}
 			next.ServeHTTP(w, r)
 		})
@@ -113,15 +123,25 @@ func RefererHandler(fieldKey string) func(next http.Handler) http.Handler {
 
 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
@@ -134,16 +154,18 @@ func IDFromRequest(r *http.Request) (id xid.ID, ok bool) {
 func RequestIDHandler(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) {
+			ctx := r.Context()
 			id, ok := IDFromRequest(r)
 			if !ok {
 				id = xid.New()
-				ctx := context.WithValue(r.Context(), idKey{}, id)
+				ctx = CtxWithID(ctx, id)
 				r = r.WithContext(ctx)
 			}
 			if fieldKey != "" {
-				log := zerolog.Ctx(r.Context())
-				log = log.With().Str(fieldKey, id.String()).Logger()
-				r = r.WithContext(log.WithContext(r.Context()))
+				log := zerolog.Ctx(ctx)
+				log.UpdateContext(func(c zerolog.Context) zerolog.Context {
+					return c.Str(fieldKey, id.String())
+				})
 			}
 			if headerName != "" {
 				w.Header().Set(headerName, id.String())
@@ -152,3 +174,31 @@ 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)
+		})
+	}
+}
+
+// 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)
+			next.ServeHTTP(lw, r)
+			f(r, lw.Status(), lw.BytesWritten(), time.Since(start))
+		})
+	}
+}

hlog/hlog_example_test.go

@@ -1,3 +1,5 @@
+// +build !binary_log
+
 package hlog_test
 
 import (
@@ -67,5 +69,5 @@ func Example_handler() {
 
 	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 happend"}
 }

hlog/hlog_test.go

@@ -4,18 +4,28 @@ package hlog
 
 import (
 	"bytes"
+	"context"
 	"fmt"
+	"io/ioutil"
 	"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").
@@ -23,7 +33,7 @@ func TestNewHandler(t *testing.T) {
 	lh := NewHandler(log)
 	h := lh(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		l := FromRequest(r)
-		if !reflect.DeepEqual(l, log) {
+		if !reflect.DeepEqual(*l, log) {
 			t.Fail()
 		}
 	}))
@@ -38,12 +48,12 @@ func TestURLHandler(t *testing.T) {
 	h := URLHandler("url")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		l := FromRequest(r)
 		l.Log().Msg("")
-		if want, got := `{"url":"/path?foo=bar"}`+"\n", out.String(); want != got {
-			t.Errorf("Invalid log output, got: %s, want: %s", got, want)
-		}
 	}))
 	h = NewHandler(zerolog.New(out))(h)
 	h.ServeHTTP(nil, r)
+	if want, got := `{"url":"/path?foo=bar"}`+"\n", decodeIfBinary(out); want != got {
+		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
+	}
 }
 
 func TestMethodHandler(t *testing.T) {
@@ -54,12 +64,12 @@ func TestMethodHandler(t *testing.T) {
 	h := MethodHandler("method")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		l := FromRequest(r)
 		l.Log().Msg("")
-		if want, got := `{"method":"POST"}`+"\n", out.String(); want != got {
-			t.Errorf("Invalid log output, got: %s, want: %s", got, want)
-		}
 	}))
 	h = NewHandler(zerolog.New(out))(h)
 	h.ServeHTTP(nil, r)
+	if want, got := `{"method":"POST"}`+"\n", decodeIfBinary(out); want != got {
+		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
+	}
 }
 
 func TestRequestHandler(t *testing.T) {
@@ -71,12 +81,12 @@ func TestRequestHandler(t *testing.T) {
 	h := RequestHandler("request")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		l := FromRequest(r)
 		l.Log().Msg("")
-		if want, got := `{"request":"POST /path?foo=bar"}`+"\n", out.String(); want != got {
-			t.Errorf("Invalid log output, got: %s, want: %s", got, want)
-		}
 	}))
 	h = NewHandler(zerolog.New(out))(h)
 	h.ServeHTTP(nil, r)
+	if want, got := `{"request":"POST /path?foo=bar"}`+"\n", decodeIfBinary(out); want != got {
+		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
+	}
 }
 
 func TestRemoteAddrHandler(t *testing.T) {
@@ -87,12 +97,12 @@ func TestRemoteAddrHandler(t *testing.T) {
 	h := RemoteAddrHandler("ip")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		l := FromRequest(r)
 		l.Log().Msg("")
-		if want, got := `{"ip":"1.2.3.4"}`+"\n", out.String(); want != got {
-			t.Errorf("Invalid log output, got: %s, want: %s", got, want)
-		}
 	}))
 	h = NewHandler(zerolog.New(out))(h)
 	h.ServeHTTP(nil, r)
+	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)
+	}
 }
 
 func TestRemoteAddrHandlerIPv6(t *testing.T) {
@@ -103,12 +113,12 @@ func TestRemoteAddrHandlerIPv6(t *testing.T) {
 	h := RemoteAddrHandler("ip")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		l := FromRequest(r)
 		l.Log().Msg("")
-		if want, got := `{"ip":"2001:db8:a0b:12f0::1"}`+"\n", out.String(); want != got {
-			t.Errorf("Invalid log output, got: %s, want: %s", got, want)
-		}
 	}))
 	h = NewHandler(zerolog.New(out))(h)
 	h.ServeHTTP(nil, r)
+	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 TestUserAgentHandler(t *testing.T) {
@@ -121,12 +131,12 @@ func TestUserAgentHandler(t *testing.T) {
 	h := UserAgentHandler("ua")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		l := FromRequest(r)
 		l.Log().Msg("")
-		if want, got := `{"ua":"some user agent string"}`+"\n", out.String(); want != got {
-			t.Errorf("Invalid log output, got: %s, want: %s", got, want)
-		}
 	}))
 	h = NewHandler(zerolog.New(out))(h)
 	h.ServeHTTP(nil, r)
+	if want, got := `{"ua":"some user agent string"}`+"\n", decodeIfBinary(out); want != got {
+		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
+	}
 }
 
 func TestRefererHandler(t *testing.T) {
@@ -139,12 +149,12 @@ func TestRefererHandler(t *testing.T) {
 	h := RefererHandler("referer")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		l := FromRequest(r)
 		l.Log().Msg("")
-		if want, got := `{"referer":"http://foo.com/bar"}`+"\n", out.String(); want != got {
-			t.Errorf("Invalid log output, got: %s, want: %s", got, want)
-		}
 	}))
 	h = NewHandler(zerolog.New(out))(h)
 	h.ServeHTTP(nil, r)
+	if want, got := `{"referer":"http://foo.com/bar"}`+"\n", decodeIfBinary(out); want != got {
+		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
+	}
 }
 
 func TestRequestIDHandler(t *testing.T) {
@@ -164,10 +174,104 @@ 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)
 		}
 	}))
 	h = NewHandler(zerolog.New(out))(h)
 	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 TestCombinedHandlers(t *testing.T) {
+	out := &bytes.Buffer{}
+	r := &http.Request{
+		Method: "POST",
+		URL:    &url.URL{Path: "/path", RawQuery: "foo=bar"},
+	}
+	h := MethodHandler("method")(RequestHandler("request")(URLHandler("url")(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 := `{"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)
+	}
+}
+
+func BenchmarkHandlers(b *testing.B) {
+	r := &http.Request{
+		Method: "POST",
+		URL:    &url.URL{Path: "/path", RawQuery: "foo=bar"},
+	}
+	h1 := URLHandler("url")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		l := FromRequest(r)
+		l.Log().Msg("")
+	}))
+	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),
+	}
+	for name := range handlers {
+		h := handlers[name]
+		b.Run(name, func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				h.ServeHTTP(nil, r)
+			}
+		})
+	}
+}
+
+func BenchmarkDataRace(b *testing.B) {
+	log := zerolog.New(nil).With().
+		Str("foo", "bar").
+		Logger()
+	lh := NewHandler(log)
+	h := lh(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		l := FromRequest(r)
+		l.UpdateContext(func(c zerolog.Context) zerolog.Context {
+			return c.Str("bar", "baz")
+		})
+		l.Log().Msg("")
+	}))
+
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			h.ServeHTTP(nil, &http.Request{})
+		}
+	})
+}
+
+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)
+	}
+}

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 +1,167 @@
+package zerolog
+
+import (
+	"bytes"
+	"io/ioutil"
+	"testing"
+)
+
+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()
+	})
+)
+
+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")
+		}},
+		{"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(ioutil.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 +1,100 @@
+// 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
+
+	// 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 nano seconds).
+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, byte(major|minor))
+	byteCount--
+	for ; byteCount >= 0; byteCount-- {
+		dst = append(dst, byte(number>>(uint(byteCount)*8)))
+	}
+	return dst
+}

internal/cbor/decode_stream.go

@@ -0,0 +1,614 @@
+package cbor
+
+// This file contains code to decode a stream of CBOR Data into JSON.
+
+import (
+	"bufio"
+	"bytes"
+	"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 decodeIntAdditonalType(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 := decodeIntAdditonalType(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 suppported 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 := decodeIntAdditonalType(src, minor)
+	len := int(length)
+	pbs := readNBytes(src, len)
+	result = append(result, pbs...)
+	if noQuotes {
+		return result
+	}
+	return append(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 := decodeIntAdditonalType(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 an 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 := decodeIntAdditonalType(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] == byte(majorTypeSimpleAndFloat|additionalTypeBreak) {
+				readByte(src)
+				break
+			}
+		}
+		cbor2JsonOneObject(src, dst)
+		if unSpecifiedCount {
+			pb, e := src.Peek(1)
+			if e != nil {
+				panic(e)
+			}
+			if pb[0] == byte(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 := decodeIntAdditonalType(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] == byte(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] == byte(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)
+
+	// Tag value is larger than 256 (so uint16).
+	case additionalTypeIntUint16:
+		val := decodeIntAdditonalType(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 != byte(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 +1,68 @@
+package cbor
+
+// 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, byte(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, byte(major|lb))
+	} else {
+		dst = appendCborTypePrefix(dst, majorTypeUtf8String, uint64(l))
+	}
+	return append(dst, s...)
+}
+
+// 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, byte(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, byte(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, byte(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, byte(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, uint64(val))
+	return dst
+}
+
+func (e Encoder) appendFloatTimestamp(dst []byte, t time.Time) []byte {
+	major := majorTypeTags
+	minor := additionalTypeTimestamp
+	dst = append(dst, byte(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)
+}
+
+// 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, byte(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) []byte {
+	if useInt {
+		return e.AppendInt64(dst, int64(d/unit))
+	}
+	return e.AppendFloat64(dst, float64(d)/float64(unit))
+}
+
+// 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) []byte {
+	major := majorTypeArray
+	l := len(vals)
+	if l == 0 {
+		return e.AppendArrayEnd(e.AppendArrayStart(dst))
+	}
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, byte(major|lb))
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	for _, d := range vals {
+		dst = e.AppendDuration(dst, d, unit, useInt)
+	}
+	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 +1,477 @@
+package cbor
+
+import (
+	"fmt"
+	"math"
+	"net"
+)
+
+// AppendNil inserts a 'Nil' object into the dst byte array.
+func (Encoder) AppendNil(dst []byte) []byte {
+	return append(dst, byte(majorTypeSimpleAndFloat|additionalTypeNull))
+}
+
+// AppendBeginMarker inserts a map start into the dst byte array.
+func (Encoder) AppendBeginMarker(dst []byte) []byte {
+	return append(dst, byte(majorTypeMap|additionalTypeInfiniteCount))
+}
+
+// AppendEndMarker inserts a map end into the dst byte array.
+func (Encoder) AppendEndMarker(dst []byte) []byte {
+	return append(dst, byte(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, byte(majorTypeArray|additionalTypeInfiniteCount))
+}
+
+// AppendArrayEnd adds markers to indicate the end of an array.
+func (Encoder) AppendArrayEnd(dst []byte) []byte {
+	return append(dst, byte(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, byte(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, byte(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, byte(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, byte(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, byte(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, byte(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, byte(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, byte(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, byte(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, byte(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, byte(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, byte(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, byte(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, byte(major|lb))
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(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, byte(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) []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, byte(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) []byte {
+	major := majorTypeArray
+	l := len(vals)
+	if l == 0 {
+		return e.AppendArrayEnd(e.AppendArrayStart(dst))
+	}
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, byte(major|lb))
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	for _, v := range vals {
+		dst = e.AppendFloat32(dst, v)
+	}
+	return dst
+}
+
+// AppendFloat64 encodes and inserts a double precision float value into the dst byte array.
+func (Encoder) AppendFloat64(dst []byte, val float64) []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, byte(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) []byte {
+	major := majorTypeArray
+	l := len(vals)
+	if l == 0 {
+		return e.AppendArrayEnd(e.AppendArrayStart(dst))
+	}
+	if l <= additionalMax {
+		lb := byte(l)
+		dst = append(dst, byte(major|lb))
+	} else {
+		dst = appendCborTypePrefix(dst, major, uint64(l))
+	}
+	for _, v := range vals {
+		dst = e.AppendFloat64(dst, v)
+	}
+	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)
+}
+
+// AppendIPAddr encodes and inserts an IP Address (IPv4 or IPv6).
+func (e Encoder) AppendIPAddr(dst []byte, ip net.IP) []byte {
+	dst = append(dst, byte(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, byte(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, byte(majorTypeMap|0x1))
+	dst = e.AppendBytes(dst, pfx.IP)
+	maskLen, _ := pfx.Mask.Size()
+	return e.AppendUint8(dst, uint8(maskLen))
+}
+
+// AppendMACAddr encodes and inserts an Hardware (MAC) address.
+func (e Encoder) AppendMACAddr(dst []byte, ha net.HardwareAddr) []byte {
+	dst = append(dst, byte(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, byte(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 +1,317 @@
+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)
+		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))
+				case 8:
+					_ = enc.AppendFloat64(buf, str.val)
+				}
+			}
+		})
+	}
+}

internal/json/base.go

@@ -0,0 +1,19 @@
+package json
+
+// 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, ',')
+	}
+	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

@@ -1,10 +1,35 @@
-package zerolog
+package json
 
 import "unicode/utf8"
 
 const hex = "0123456789abcdef"
 
-// appendJSONString encodes the input string to json and appends
+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 = e.AppendString(dst, vals[0])
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = e.AppendString(append(dst, ','), val)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+// AppendString encodes the input string to json and appends
 // the encoded string to the input byte slice.
 //
 // The operation loops though each byte in the string looking
@@ -13,7 +38,7 @@ const hex = "0123456789abcdef"
 // 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 appendJSONString(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.
@@ -21,10 +46,10 @@ func appendJSONString(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 = appendJSONStringComplex(dst, s, i)
+			dst = appendStringComplex(dst, s, i)
 			return append(dst, '"')
 		}
 	}
@@ -35,10 +60,10 @@ func appendJSONString(dst []byte, s string) []byte {
 	return append(dst, '"')
 }
 
-// appendJSONStringComplex is used by appendJSONString to take over an in
+// appendStringComplex is used by appendString to take over an in
 // progress JSON string encoding that encountered a character that needs
 // to be encoded.
-func appendJSONStringComplex(dst []byte, s string, i int) []byte {
+func appendStringComplex(dst []byte, s string, i int) []byte {
 	start := 0
 	for i < len(s) {
 		b := s[i]
@@ -59,7 +84,7 @@ func appendJSONStringComplex(dst []byte, s string, i int) []byte {
 			i += size
 			continue
 		}
-		if b >= 0x20 && b <= 0x7e && b != '\\' && b != '"' {
+		if noEscapeTable[b] {
 			i++
 			continue
 		}

internal/json/string_test.go

@@ -0,0 +1,93 @@
+package json
+
+import (
+	"testing"
+)
+
+var encodeStringTests = []struct {
+	in  string
+	out string
+}{
+	{"", `""`},
+	{"\\", `"\\"`},
+	{"\x00", `"\u0000"`},
+	{"\x01", `"\u0001"`},
+	{"\x02", `"\u0002"`},
+	{"\x03", `"\u0003"`},
+	{"\x04", `"\u0004"`},
+	{"\x05", `"\u0005"`},
+	{"\x06", `"\u0006"`},
+	{"\x07", `"\u0007"`},
+	{"\x08", `"\b"`},
+	{"\x09", `"\t"`},
+	{"\x0a", `"\n"`},
+	{"\x0b", `"\u000b"`},
+	{"\x0c", `"\f"`},
+	{"\x0d", `"\r"`},
+	{"\x0e", `"\u000e"`},
+	{"\x0f", `"\u000f"`},
+	{"\x10", `"\u0010"`},
+	{"\x11", `"\u0011"`},
+	{"\x12", `"\u0012"`},
+	{"\x13", `"\u0013"`},
+	{"\x14", `"\u0014"`},
+	{"\x15", `"\u0015"`},
+	{"\x16", `"\u0016"`},
+	{"\x17", `"\u0017"`},
+	{"\x18", `"\u0018"`},
+	{"\x19", `"\u0019"`},
+	{"\x1a", `"\u001a"`},
+	{"\x1b", `"\u001b"`},
+	{"\x1c", `"\u001c"`},
+	{"\x1d", `"\u001d"`},
+	{"\x1e", `"\u001e"`},
+	{"\x1f", `"\u001f"`},
+	{"✭", `"✭"`},
+	{"foo\xc2\x7fbar", `"foo\ufffd\u007fbar"`}, // invalid sequence
+	{"ascii", `"ascii"`},
+	{"\"a", `"\"a"`},
+	{"\x1fa", `"\u001fa"`},
+	{"foo\"bar\"baz", `"foo\"bar\"baz"`},
+	{"\x1ffoo\x1fbar\x1fbaz", `"\u001ffoo\u001fbar\u001fbaz"`},
+	{"emoji \u2764\ufe0f!", `"emoji ❤️!"`},
+}
+
+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 := 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 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, 100)
+			for i := 0; i < b.N; i++ {
+				_ = enc.AppendString(buf, str)
+			}
+		})
+	}
+}

internal/json/time.go

@@ -0,0 +1,106 @@
+package json
+
+import (
+	"strconv"
+	"time"
+)
+
+const (
+	// Import from zerolog/global.go
+	timeFormatUnix   = ""
+	timeFormatUnixMs = "UNIXMS"
+	timeFormatUnixMicro = "UNIXMICRO"
+)
+
+// 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)
+	}
+	return append(t.AppendFormat(append(dst, '"'), 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 appendUnixMsTimes(dst, vals)
+	}
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = append(vals[0].AppendFormat(append(dst, '"'), format), '"')
+	if len(vals) > 1 {
+		for _, t := range vals[1:] {
+			dst = append(t.AppendFormat(append(dst, ',', '"'), format), '"')
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+func appendUnixTimes(dst []byte, vals []time.Time) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendInt(dst, vals[0].Unix(), 10)
+	if len(vals) > 1 {
+		for _, t := range vals[1:] {
+			dst = strconv.AppendInt(append(dst, ','), t.Unix(), 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+func appendUnixMsTimes(dst []byte, vals []time.Time) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendInt(dst, vals[0].UnixNano()/1000000, 10)
+	if len(vals) > 1 {
+		for _, t := range vals[1:] {
+			dst = strconv.AppendInt(append(dst, ','), t.UnixNano()/1000000, 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) []byte {
+	if useInt {
+		return strconv.AppendInt(dst, int64(d/unit), 10)
+	}
+	return e.AppendFloat64(dst, float64(d)/float64(unit))
+}
+
+// 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) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = e.AppendDuration(dst, vals[0], unit, useInt)
+	if len(vals) > 1 {
+		for _, d := range vals[1:] {
+			dst = e.AppendDuration(append(dst, ','), d, unit, useInt)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}

internal/json/types.go

@@ -0,0 +1,405 @@
+package json
+
+import (
+	"fmt"
+	"math"
+	"net"
+	"strconv"
+)
+
+// 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)
+}
+
+// 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, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendBool(dst, vals[0])
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendBool(append(dst, ','), val)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+// 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)
+}
+
+// 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, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendInt(dst, int64(vals[0]), 10)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendInt(append(dst, ','), int64(val), 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+// 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)
+}
+
+// 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, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendInt(dst, int64(vals[0]), 10)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendInt(append(dst, ','), int64(val), 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+// 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)
+}
+
+// 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, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendInt(dst, int64(vals[0]), 10)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendInt(append(dst, ','), int64(val), 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+// 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)
+}
+
+// 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, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendInt(dst, int64(vals[0]), 10)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendInt(append(dst, ','), int64(val), 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+// 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)
+}
+
+// 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, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendInt(dst, vals[0], 10)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendInt(append(dst, ','), val, 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+// 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)
+}
+
+// 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, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendUint(dst, uint64(vals[0]), 10)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendUint(append(dst, ','), uint64(val), 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+// 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)
+}
+
+// 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, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendUint(dst, uint64(vals[0]), 10)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendUint(append(dst, ','), uint64(val), 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+// 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)
+}
+
+// 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, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendUint(dst, uint64(vals[0]), 10)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendUint(append(dst, ','), uint64(val), 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+// 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)
+}
+
+// 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, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendUint(dst, uint64(vals[0]), 10)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendUint(append(dst, ','), uint64(val), 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+// 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, uint64(val), 10)
+}
+
+// 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, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendUint(dst, vals[0], 10)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendUint(append(dst, ','), val, 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+func appendFloat(dst []byte, val float64, bitSize 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
+	// make a tradeoff and store those types as string.
+	switch {
+	case math.IsNaN(val):
+		return append(dst, `"NaN"`...)
+	case math.IsInf(val, 1):
+		return append(dst, `"+Inf"`...)
+	case math.IsInf(val, -1):
+		return append(dst, `"-Inf"`...)
+	}
+	return strconv.AppendFloat(dst, val, 'f', -1, bitSize)
+}
+
+// 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) []byte {
+	return appendFloat(dst, float64(val), 32)
+}
+
+// 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) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = appendFloat(dst, float64(vals[0]), 32)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = appendFloat(append(dst, ','), float64(val), 32)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+// 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) []byte {
+	return appendFloat(dst, val, 64)
+}
+
+// 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) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = appendFloat(dst, vals[0], 64)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = appendFloat(append(dst, ','), val, 64)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+// 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 e.AppendString(dst, fmt.Sprintf("marshaling error: %v", err))
+	}
+	return append(dst, marshaled...)
+}
+
+// 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

@@ -0,0 +1,187 @@
+package json
+
+import (
+	"math"
+	"net"
+	"reflect"
+	"testing"
+)
+
+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)) },
+		"AppendFloat64": func(v interface{}) []byte { return enc.AppendFloat64([]byte{}, v.(float64)) },
+	}
+	tests := []struct {
+		name  string
+		fn    string
+		input interface{}
+		want  []byte
+	}{
+		{"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(`1000000000000000000000`)},
+
+		{"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(`1000000000000000000000`)},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			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_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)
+			}
+		})
+	}
+}

journald/journald.go

@@ -0,0 +1,125 @@
+// +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) {
+	if !journal.Enabled() {
+		err = fmt.Errorf("cannot connect to journalD")
+		return
+	}
+
+	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, 0)
+	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 value.(type) {
+		case string:
+			args[jKey], _ = value.(string)
+		case json.Number:
+			args[jKey] = fmt.Sprint(value)
+		default:
+			b, err := json.Marshal(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!")
+	}
+}

json_test.go

@@ -1,82 +0,0 @@
-package zerolog
-
-import (
-	"testing"
-)
-
-func TestAppendJSONString(t *testing.T) {
-	encodeStringTests := []struct {
-		in  string
-		out string
-	}{
-		{"", `""`},
-		{"\\", `"\\"`},
-		{"\x00", `"\u0000"`},
-		{"\x01", `"\u0001"`},
-		{"\x02", `"\u0002"`},
-		{"\x03", `"\u0003"`},
-		{"\x04", `"\u0004"`},
-		{"\x05", `"\u0005"`},
-		{"\x06", `"\u0006"`},
-		{"\x07", `"\u0007"`},
-		{"\x08", `"\b"`},
-		{"\x09", `"\t"`},
-		{"\x0a", `"\n"`},
-		{"\x0b", `"\u000b"`},
-		{"\x0c", `"\f"`},
-		{"\x0d", `"\r"`},
-		{"\x0e", `"\u000e"`},
-		{"\x0f", `"\u000f"`},
-		{"\x10", `"\u0010"`},
-		{"\x11", `"\u0011"`},
-		{"\x12", `"\u0012"`},
-		{"\x13", `"\u0013"`},
-		{"\x14", `"\u0014"`},
-		{"\x15", `"\u0015"`},
-		{"\x16", `"\u0016"`},
-		{"\x17", `"\u0017"`},
-		{"\x18", `"\u0018"`},
-		{"\x19", `"\u0019"`},
-		{"\x1a", `"\u001a"`},
-		{"\x1b", `"\u001b"`},
-		{"\x1c", `"\u001c"`},
-		{"\x1d", `"\u001d"`},
-		{"\x1e", `"\u001e"`},
-		{"\x1f", `"\u001f"`},
-		{"✭", `"✭"`},
-		{"foo\xc2\x7fbar", `"foo\ufffd\u007fbar"`}, // invalid sequence
-		{"ascii", `"ascii"`},
-		{"\"a", `"\"a"`},
-		{"\x1fa", `"\u001fa"`},
-		{"foo\"bar\"baz", `"foo\"bar\"baz"`},
-		{"\x1ffoo\x1fbar\x1fbaz", `"\u001ffoo\u001fbar\u001fbaz"`},
-		{"emoji \u2764\ufe0f!", `"emoji ❤️!"`},
-	}
-
-	for _, tt := range encodeStringTests {
-		b := appendJSONString([]byte{}, tt.in)
-		if got, want := string(b), tt.out; got != want {
-			t.Errorf("appendJSONString(%q) = %#q, want %#q", tt.in, got, want)
-		}
-	}
-}
-
-func BenchmarkAppendJSONString(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, 100)
-			for i := 0; i < b.N; i++ {
-				_ = appendJSONString(buf, str)
-			}
-		})
-	}
-}

log.go

@@ -62,20 +62,52 @@
 //
 // Sample logs:
 //
-//     sampled := log.Sample(10)
+//     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
+//
+// 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.
 package zerolog
 
 import (
+	"fmt"
 	"io"
 	"io/ioutil"
 	"os"
-	"sync/atomic"
+	"strconv"
 )
 
 // Level defines log levels.
-type Level uint8
+type Level int8
 
 const (
 	// DebugLevel defines debug log level.
@@ -90,50 +122,85 @@ 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))
 }
 
-const (
-	// Often samples log every 10 events.
-	Often = 10
-	// Sometimes samples log every 100 events.
-	Sometimes = 100
-	// Rarely samples log every 1000 events.
-	Rarely = 1000
-)
-
-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 levelStr {
+	case LevelFieldMarshalFunc(TraceLevel):
+		return TraceLevel, nil
+	case LevelFieldMarshalFunc(DebugLevel):
+		return DebugLevel, nil
+	case LevelFieldMarshalFunc(InfoLevel):
+		return InfoLevel, nil
+	case LevelFieldMarshalFunc(WarnLevel):
+		return WarnLevel, nil
+	case LevelFieldMarshalFunc(ErrorLevel):
+		return ErrorLevel, nil
+	case LevelFieldMarshalFunc(FatalLevel):
+		return FatalLevel, nil
+	case LevelFieldMarshalFunc(PanicLevel):
+		return PanicLevel, nil
+	case LevelFieldMarshalFunc(Disabled):
+		return Disabled, nil
+	case 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
+}
 
 // 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 {
 	w       LevelWriter
 	level   Level
-	sample  uint32
-	counter *uint32
+	sampler Sampler
 	context []byte
+	hooks   []Hook
+	stack   bool
 }
 
 // New creates a root logger with given output writer. If the output writer implements
@@ -141,7 +208,7 @@ 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 {
@@ -151,7 +218,7 @@ func New(w io.Writer) Logger {
 	if !ok {
 		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.
@@ -159,6 +226,22 @@ func Nop() Logger {
 	return New(nil).Level(Disabled)
 }
 
+// Output duplicates the current logger and sets w as its output.
+func (l Logger) Output(w io.Writer) Logger {
+	l2 := New(w)
+	l2.level = l.level
+	l2.sampler = l.sampler
+	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
+}
+
 // With creates a child logger with the field added to its context.
 func (l Logger) With() Context {
 	context := l.context
@@ -166,94 +249,168 @@ 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}
 }
 
-// Level creates a child logger with the minimum accepted level set to level.
-func (l Logger) Level(lvl Level) Logger {
-	return Logger{
-		w:       l.w,
-		level:   lvl,
-		sample:  l.sample,
-		counter: l.counter,
-		context: l.context,
+// UpdateContext updates the internal logger's context.
+//
+// Use this method with caution. If unsure, prefer the With method.
+func (l *Logger) UpdateContext(update func(c Context) Context) {
+	if l == disabledLogger {
+		return
 	}
+	if cap(l.context) == 0 {
+		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
 }
 
-// Sample returns a logger that only let one message out of every to pass thru.
-func (l Logger) Sample(every int) Logger {
-	if every == 0 {
-		// Create a child with no sampling.
-		return Logger{
-			w:       l.w,
-			level:   l.level,
-			context: l.context,
-		}
-	}
-	return Logger{
-		w:       l.w,
-		level:   l.level,
-		sample:  uint32(every),
-		counter: new(uint32),
-		context: l.context,
-	}
+// Level creates a child logger with the minimum accepted level set to level.
+func (l Logger) Level(lvl Level) Logger {
+	l.level = lvl
+	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(h Hook) Logger {
+	l.hooks = append(l.hooks, h)
+	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) { 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. Unlike Fatal and Panic
+// methods, WithLevel does not terminate the program or stop the ordinary
+// flow of a gourotine 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 {
+	switch level {
+	case TraceLevel:
+		return l.Trace()
+	case DebugLevel:
+		return l.Debug()
+	case InfoLevel:
+		return l.Info()
+	case WarnLevel:
+		return l.Warn()
+	case ErrorLevel:
+		return l.Error()
+	case FatalLevel:
+		return l.newEvent(FatalLevel, nil)
+	case PanicLevel:
+		return l.newEvent(PanicLevel, nil)
+	case NoLevel:
+		return l.Log()
+	case Disabled:
+		return nil
+	default:
+		return l.newEvent(level, nil)
+	}
 }
 
 // Log starts a new message with no level. Setting GlobalLevel to Disabled
 // 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{}) {
+	if e := l.Debug(); e.Enabled() {
+		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{}) {
+	if e := l.Debug(); e.Enabled() {
+		e.CallerSkipFrame(1).Msg(fmt.Sprintf(format, v...))
+	}
 }
 
 // Write implements the io.Writer interface. This is useful to set as a writer
@@ -264,48 +421,37 @@ 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
+		return nil
 	}
-	lvl := InfoLevel
-	if addLevelField {
-		lvl = level
-	}
-	e := newEvent(l.w, lvl, enabled)
+	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 = appendTimestamp(e.buf)
-	}
-	if addLevelField {
-		e.Str(LevelFieldName, level.String())
-	}
-	if l.sample > 0 && SampleFieldName != "" {
-		e.Uint32(SampleFieldName, l.sample)
+	e.ch = l.hooks
+	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 lvl < l.level || lvl < GlobalLevel() {
 		return false
 	}
-	if l.sample > 0 && l.counter != nil && !samplingDisabled() {
-		c := atomic.AddUint32(l.counter, 1)
-		return c%l.sample == 0
+	if l.sampler != nil && !samplingDisabled() {
+		return l.sampler.Sample(lvl)
 	}
 	return true
 }

log/log.go

@@ -3,6 +3,8 @@ package log
 
 import (
 	"context"
+	"fmt"
+	"io"
 	"os"
 
 	"github.com/rs/zerolog"
@@ -11,19 +13,44 @@ import (
 // Logger is the global logger.
 var Logger = zerolog.New(os.Stderr).With().Timestamp().Logger()
 
+// Output duplicates the global logger and sets w as its output.
+func Output(w io.Writer) zerolog.Logger {
+	return Logger.Output(w)
+}
+
 // With creates a child logger with the field added to its context.
 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)
 }
 
-// Sample returns a logger that only let one message out of every to pass thru.
-func Sample(every int) zerolog.Logger {
-	return Logger.Sample(every)
+// Sample returns a logger with the s sampler.
+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.
@@ -70,16 +97,35 @@ 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 {
 	return Logger.Log()
 }
 
+// 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.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.Debug().CallerSkipFrame(1).Msgf(format, v...)
+}
+
 // Ctx returns the Logger associated with the ctx. If no logger
 // is associated, a disabled logger is returned.
-func Ctx(ctx context.Context) zerolog.Logger {
+func Ctx(ctx context.Context) *zerolog.Logger {
 	return zerolog.Ctx(ctx)
 }

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"}
 }
 
@@ -38,15 +41,69 @@ func ExampleLogger_Level() {
 }
 
 func ExampleLogger_Sample() {
-	log := zerolog.New(os.Stdout).Sample(2)
+	log := zerolog.New(os.Stdout).Sample(&zerolog.BasicSampler{N: 2})
 
 	log.Info().Msg("message 1")
 	log.Info().Msg("message 2")
 	log.Info().Msg("message 3")
 	log.Info().Msg("message 4")
 
-	// Output: {"level":"info","sample":2,"message":"message 2"}
-	// {"level":"info","sample":2,"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).Hook(messageHook)
+
+	log.Info().Msg("hello world")
+
+	// Output: {"level":"info","level_name":"info","the_message":"hello world","message":"hello world"}
+}
+
+func ExampleLogger_Print() {
+	log := zerolog.New(os.Stdout)
+
+	log.Print("hello world")
+
+	// Output: {"level":"debug","message":"hello world"}
+}
+
+func ExampleLogger_Printf() {
+	log := zerolog.New(os.Stdout)
+
+	log.Printf("hello %s", "world")
+
+	// Output: {"level":"debug","message":"hello world"}
+}
+
+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() {
@@ -91,6 +148,15 @@ func ExampleLogger_Error() {
 	// Output: {"level":"error","error":"some error","message":"error doing something"}
 }
 
+func ExampleLogger_WithLevel() {
+	log := zerolog.New(os.Stdout)
+
+	log.WithLevel(zerolog.InfoLevel).
+		Msg("hello world")
+
+	// Output: {"level":"info","message":"hello world"}
+}
+
 func ExampleLogger_Write() {
 	log := zerolog.New(os.Stdout).With().
 		Str("foo", "bar").
@@ -129,6 +195,100 @@ func ExampleEvent_Dict() {
 	// 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 *zerolog.Event) {
+	e.Str("name", u.Name).
+		Int("age", u.Age).
+		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) {
+	for _, u := range uu {
+		a.Object(u)
+	}
+}
+
+func ExampleEvent_Array() {
+	log := zerolog.New(os.Stdout)
+
+	log.Log().
+		Str("foo", "bar").
+		Array("array", zerolog.Arr().
+			Str("baz").
+			Int(1),
+		).
+		Msg("hello world")
+
+	// Output: {"foo":"bar","array":["baz",1],"message":"hello world"}
+}
+
+func ExampleEvent_Array_object() {
+	log := zerolog.New(os.Stdout)
+
+	// Users implements zerolog.LogArrayMarshaler
+	u := Users{
+		User{"John", 35, time.Time{}},
+		User{"Bob", 55, time.Time{}},
+	}
+
+	log.Log().
+		Str("foo", "bar").
+		Array("users", u).
+		Msg("hello world")
+
+	// 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() {
+	log := zerolog.New(os.Stdout)
+
+	// User implements zerolog.LogObjectMarshaler
+	u := User{"John", 35, time.Time{}}
+
+	log.Log().
+		Str("foo", "bar").
+		Object("user", u).
+		Msg("hello world")
+
+	// 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)
 
@@ -159,6 +319,22 @@ func ExampleEvent_Dur() {
 	// Output: {"foo":"bar","dur":10000,"message":"hello world"}
 }
 
+func ExampleEvent_Durs() {
+	d := []time.Duration{
+		time.Duration(10 * time.Second),
+		time.Duration(20 * time.Second),
+	}
+
+	log := zerolog.New(os.Stdout)
+
+	log.Log().
+		Str("foo", "bar").
+		Durs("durs", d).
+		Msg("hello world")
+
+	// Output: {"foo":"bar","durs":[10000,20000],"message":"hello world"}
+}
+
 func ExampleContext_Dict() {
 	log := zerolog.New(os.Stdout).With().
 		Str("foo", "bar").
@@ -172,6 +348,64 @@ func ExampleContext_Dict() {
 	// Output: {"foo":"bar","dict":{"bar":"baz","n":1},"message":"hello world"}
 }
 
+func ExampleContext_Array() {
+	log := zerolog.New(os.Stdout).With().
+		Str("foo", "bar").
+		Array("array", zerolog.Arr().
+			Str("baz").
+			Int(1),
+		).Logger()
+
+	log.Log().Msg("hello world")
+
+	// Output: {"foo":"bar","array":["baz",1],"message":"hello world"}
+}
+
+func ExampleContext_Array_object() {
+	// Users implements zerolog.LogArrayMarshaler
+	u := Users{
+		User{"John", 35, time.Time{}},
+		User{"Bob", 55, time.Time{}},
+	}
+
+	log := zerolog.New(os.Stdout).With().
+		Str("foo", "bar").
+		Array("users", u).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	// 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 ExampleContext_Object() {
+	// User implements zerolog.LogObjectMarshaler
+	u := User{"John", 35, time.Time{}}
+
+	log := zerolog.New(os.Stdout).With().
+		Str("foo", "bar").
+		Object("user", u).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	// 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"`
@@ -201,3 +435,52 @@ func ExampleContext_Dur() {
 
 	// Output: {"foo":"bar","dur":10000,"message":"hello world"}
 }
+
+func ExampleContext_Durs() {
+	d := []time.Duration{
+		time.Duration(10 * time.Second),
+		time.Duration(20 * time.Second),
+	}
+
+	log := zerolog.New(os.Stdout).With().
+		Str("foo", "bar").
+		Durs("durs", d).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	// 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"}
+}

log_test.go

@@ -3,7 +3,12 @@ package zerolog
 import (
 	"bytes"
 	"errors"
+	"fmt"
+	"net"
 	"reflect"
+	"runtime"
+	"strconv"
+	"strings"
 	"testing"
 	"time"
 )
@@ -13,8 +18,8 @@ func TestLog(t *testing.T) {
 		out := &bytes.Buffer{}
 		log := New(out)
 		log.Log().Msg("")
-		if got, want := out.String(), "{}\n"; got != want {
-			t.Errorf("invalid log output: got %q, want %q", got, want)
+		if got, want := decodeIfBinaryToString(out.Bytes()), "{}\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
 
@@ -22,8 +27,8 @@ 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 {
-			t.Errorf("invalid log output: got %q, want %q", got, want)
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"foo":"bar"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
 
@@ -34,8 +39,8 @@ func TestLog(t *testing.T) {
 			Str("foo", "bar").
 			Int("n", 123).
 			Msg("")
-		if got, want := out.String(), `{"foo":"bar","n":123}`+"\n"; got != want {
-			t.Errorf("invalid log output: got %q, want %q", 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)
 		}
 	})
 }
@@ -45,8 +50,8 @@ func TestInfo(t *testing.T) {
 		out := &bytes.Buffer{}
 		log := New(out)
 		log.Info().Msg("")
-		if got, want := out.String(), `{"level":"info"}`+"\n"; got != want {
-			t.Errorf("invalid log output: got %q, want %q", got, want)
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"info"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
 
@@ -54,8 +59,8 @@ 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 {
-			t.Errorf("invalid log output: got %q, want %q", 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 +71,39 @@ 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 {
-			t.Errorf("invalid log output: got %q, want %q", 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).
@@ -89,21 +117,150 @@ func TestWith(t *testing.T) {
 		Uint16("uint16", 8).
 		Uint32("uint32", 9).
 		Uint64("uint64", 10).
-		Float32("float32", 11).
-		Float64("float64", 12).
-		Time("time", time.Time{}).
-		Logger()
+		Float32("float32", 11.101).
+		Float64("float64", 12.30303).
+		Time("time", time.Time{})
+	_, 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 {
-		t.Errorf("invalid log output: got %q, want %q", 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 TestFieldsMap(t *testing.T) {
+	out := &bytes.Buffer{}
+	log := New(out)
+	log.Log().Fields(map[string]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()), `{"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 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().
-		Str("foo", "bar").
+		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"}`)).
+		Func(func(e *Event) { e.Str("func", "func_output") }).
 		AnErr("some_err", nil).
 		Err(errors.New("some error")).
 		Bool("bool", true).
@@ -117,24 +274,113 @@ 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", time.Now(), time.Now().Add(-10*time.Second)).
+		TimeDiff("diff", now, now.Add(-10*time.Second)).
 		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,"dur":1000,"time":"0001-01-01T00:00:00Z","diff":10000}`+"\n"; got != want {
-		t.Errorf("invalid log output: got %q, want %q", 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"},"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)
+	}
+}
+
+func TestFieldsArrayEmpty(t *testing.T) {
+	out := &bytes.Buffer{}
+	log := New(out)
+	log.Log().
+		Strs("string", []string{}).
+		Errs("err", []error{}).
+		Bools("bool", []bool{}).
+		Ints("int", []int{}).
+		Ints8("int8", []int8{}).
+		Ints16("int16", []int16{}).
+		Ints32("int32", []int32{}).
+		Ints64("int64", []int64{}).
+		Uints("uint", []uint{}).
+		Uints8("uint8", []uint8{}).
+		Uints16("uint16", []uint16{}).
+		Uints32("uint32", []uint32{}).
+		Uints64("uint64", []uint64{}).
+		Floats32("float32", []float32{}).
+		Floats64("float64", []float64{}).
+		Durs("dur", []time.Duration{}).
+		Times("time", []time.Time{}).
+		Msg("")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"string":[],"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)
+	}
+}
+
+func TestFieldsArraySingleElement(t *testing.T) {
+	out := &bytes.Buffer{}
+	log := New(out)
+	log.Log().
+		Strs("string", []string{"foo"}).
+		Errs("err", []error{errors.New("some error")}).
+		Bools("bool", []bool{true}).
+		Ints("int", []int{1}).
+		Ints8("int8", []int8{2}).
+		Ints16("int16", []int16{3}).
+		Ints32("int32", []int32{4}).
+		Ints64("int64", []int64{5}).
+		Uints("uint", []uint{6}).
+		Uints8("uint8", []uint8{7}).
+		Uints16("uint16", []uint16{8}).
+		Uints32("uint32", []uint32{9}).
+		Uints64("uint64", []uint64{10}).
+		Floats32("float32", []float32{11}).
+		Floats64("float64", []float64{12}).
+		Durs("dur", []time.Duration{1 * time.Second}).
+		Times("time", []time.Time{time.Time{}}).
+		Msg("")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"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 {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestFieldsArrayMultipleElement(t *testing.T) {
+	out := &bytes.Buffer{}
+	log := New(out)
+	log.Log().
+		Strs("string", []string{"foo", "bar"}).
+		Errs("err", []error{errors.New("some error"), nil}).
+		Bools("bool", []bool{true, false}).
+		Ints("int", []int{1, 0}).
+		Ints8("int8", []int8{2, 0}).
+		Ints16("int16", []int16{3, 0}).
+		Ints32("int32", []int32{4, 0}).
+		Ints64("int64", []int64{5, 0}).
+		Uints("uint", []uint{6, 0}).
+		Uints8("uint8", []uint8{7, 0}).
+		Uints16("uint16", []uint16{8, 0}).
+		Uints32("uint32", []uint32{9, 0}).
+		Uints64("uint64", []uint64{10, 0}).
+		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{}}).
+		Msg("")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"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 {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
 
 func TestFieldsDisabled(t *testing.T) {
 	out := &bytes.Buffer{}
 	log := New(out).Level(InfoLevel)
+	now := time.Now()
 	log.Debug().
-		Str("foo", "bar").
+		Str("string", "foo").
+		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).
@@ -150,18 +396,19 @@ func TestFieldsDisabled(t *testing.T) {
 		Float64("float64", 12).
 		Dur("dur", 1*time.Second).
 		Time("time", time.Time{}).
-		TimeDiff("diff", time.Now(), time.Now().Add(-10*time.Second)).
+		TimeDiff("diff", now, now.Add(-10*time.Second)).
 		Msg("")
-	if got, want := out.String(), ""; got != want {
-		t.Errorf("invalid log output: got %q, want %q", 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 {
-		t.Errorf("invalid log output: got %q, want %q", 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)
 	}
 }
 
@@ -169,8 +416,8 @@ 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 {
-		t.Errorf("invalid log output: got %q, want %q", 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)
 	}
 }
 
@@ -179,8 +426,44 @@ func TestLevel(t *testing.T) {
 		out := &bytes.Buffer{}
 		log := New(out).Level(Disabled)
 		log.Info().Msg("test")
-		if got, want := out.String(), ""; got != want {
-			t.Errorf("invalid log output: got %q, want %q", 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)
 		}
 	})
 
@@ -188,21 +471,54 @@ 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 {
-			t.Errorf("invalid log output: got %q, want %q", 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(2)
+	log := New(out).Sample(&BasicSampler{N: 2})
 	log.Log().Int("i", 1).Msg("")
 	log.Log().Int("i", 2).Msg("")
 	log.Log().Int("i", 3).Msg("")
 	log.Log().Int("i", 4).Msg("")
-	if got, want := out.String(), "{\"sample\":2,\"i\":2}\n{\"sample\":2,\"i\":4}\n"; got != want {
-		t.Errorf("invalid log output: got %q, want %q", 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)
 	}
 }
 
@@ -218,6 +534,7 @@ 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
@@ -232,19 +549,45 @@ 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.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"},
+		{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)
@@ -262,8 +605,8 @@ 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 {
-		t.Errorf("invalid log output: got %q, want %q", 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)
 	}
 }
 
@@ -278,7 +621,261 @@ 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 {
-		t.Errorf("invalid log output: got %q, want %q", 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
+	_, 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(file string, line int) string {
+		parts := strings.Split(file, "/")
+		if len(parts) > 1 {
+			return strings.Join(parts[len(parts)-2:], "/") + ":" + strconv.Itoa(line)
+		}
+
+		return file + ":" + strconv.Itoa(line)
+	}
+	_, file, line, _ = runtime.Caller(0)
+	caller = CallerMarshalFunc(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 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)
+			}
+		})
 	}
 }

not_go112.go

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

pkgerrors/stacktrace.go

@@ -0,0 +1,65 @@
+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
+	}
+	sterr, ok := err.(stackTracer)
+	if !ok {
+		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 +1,57 @@
+// +build !binary_log
+
+package pkgerrors
+
+import (
+	"bytes"
+	"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 := errors.Wrap(errors.New("error message"), "from error")
+	log.Log().Stack().Err(err).Msg("")
+
+	got := out.String()
+	want := `\{"stack":\[\{"func":"TestLogStack","line":"20","source":"stacktrace_test.go"\},.*\],"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 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 := errors.Wrap(errors.New("error message"), "from error")
+	log.Log().Err(err).Msg("") // not explicitly calling Stack()
+
+	got := out.String()
+	want := `\{"stack":\[\{"func":"TestLogStackFromContext","line":"36","source":"stacktrace_test.go"\},.*\],"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

@@ -0,0 +1,134 @@
+package zerolog
+
+import (
+	"math/rand"
+	"sync/atomic"
+	"time"
+)
+
+var (
+	// Often samples log every ~ 10 events.
+	Often = RandomSampler(10)
+	// Sometimes samples log every ~ 100 events.
+	Sometimes = RandomSampler(100)
+	// Rarely samples log every ~ 1000 events.
+	Rarely = RandomSampler(1000)
+)
+
+// Sampler defines an interface to a log sampler.
+type Sampler interface {
+	// Sample returns true if the event should be part of the sample, false if
+	// the event should be dropped.
+	Sample(lvl Level) bool
+}
+
+// RandomSampler use a PRNG to randomly sample an event out of N events,
+// regardless of their level.
+type RandomSampler uint32
+
+// Sample implements the Sampler interface.
+func (s RandomSampler) Sample(lvl Level) bool {
+	if 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
+// their level.
+type BasicSampler struct {
+	N       uint32
+	counter uint32
+}
+
+// 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%n == 1
+}
+
+// BurstSampler lets Burst events pass per Period then pass the decision to
+// NextSampler. If Sampler is not set, all subsequent events are rejected.
+type BurstSampler struct {
+	// Burst is the maximum number of event per period allowed before calling
+	// NextSampler.
+	Burst uint32
+	// Period defines the burst period. If 0, NextSampler is always called.
+	Period time.Duration
+	// NextSampler is the sampler used after the burst is reached. If nil,
+	// events are always rejected after the burst.
+	NextSampler Sampler
+
+	counter uint32
+	resetAt int64
+}
+
+// Sample implements the Sampler interface.
+func (s *BurstSampler) Sample(lvl Level) bool {
+	if s.Burst > 0 && s.Period > 0 {
+		if s.inc() <= s.Burst {
+			return true
+		}
+	}
+	if s.NextSampler == nil {
+		return false
+	}
+	return s.NextSampler.Sample(lvl)
+}
+
+func (s *BurstSampler) inc() uint32 {
+	now := time.Now().UnixNano()
+	resetAt := atomic.LoadInt64(&s.resetAt)
+	var c uint32
+	if now > resetAt {
+		c = 1
+		atomic.StoreUint32(&s.counter, c)
+		newResetAt := now + s.Period.Nanoseconds()
+		reset := atomic.CompareAndSwapInt64(&s.resetAt, resetAt, newResetAt)
+		if !reset {
+			// Lost the race with another goroutine trying to reset.
+			c = atomic.AddUint32(&s.counter, 1)
+		}
+	} else {
+		c = atomic.AddUint32(&s.counter, 1)
+	}
+	return c
+}
+
+// LevelSampler applies a different sampler for each level.
+type LevelSampler struct {
+	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)
+		}
+	case InfoLevel:
+		if s.InfoSampler != nil {
+			return s.InfoSampler.Sample(lvl)
+		}
+	case WarnLevel:
+		if s.WarnSampler != nil {
+			return s.WarnSampler.Sample(lvl)
+		}
+	case ErrorLevel:
+		if s.ErrorSampler != nil {
+			return s.ErrorSampler.Sample(lvl)
+		}
+	}
+	return true
+}

sampler_test.go

@@ -0,0 +1,84 @@
+// +build !binary_log
+
+package zerolog
+
+import (
+	"testing"
+	"time"
+)
+
+var samplers = []struct {
+	name    string
+	sampler func() Sampler
+	total   int
+	wantMin int
+	wantMax int
+}{
+	{
+		"BasicSampler_1",
+		func() Sampler {
+			return &BasicSampler{N: 1}
+		},
+		100, 100, 100,
+	},
+	{
+		"BasicSampler_5",
+		func() Sampler {
+			return &BasicSampler{N: 5}
+		},
+		100, 20, 20,
+	},
+	{
+		"RandomSampler",
+		func() Sampler {
+			return RandomSampler(5)
+		},
+		100, 10, 30,
+	},
+	{
+		"BurstSampler",
+		func() Sampler {
+			return &BurstSampler{Burst: 20, Period: time.Second}
+		},
+		100, 20, 20,
+	},
+	{
+		"BurstSamplerNext",
+		func() Sampler {
+			return &BurstSampler{Burst: 20, Period: time.Second, NextSampler: &BasicSampler{N: 5}}
+		},
+		120, 40, 40,
+	},
+}
+
+func TestSamplers(t *testing.T) {
+	for i := range samplers {
+		s := samplers[i]
+		t.Run(s.name, func(t *testing.T) {
+			sampler := s.sampler()
+			got := 0
+			for t := s.total; t > 0; t-- {
+				if sampler.Sample(0) {
+					got++
+				}
+			}
+			if got < s.wantMin || got > s.wantMax {
+				t.Errorf("%s.Sample(0) == true %d on %d, want [%d, %d]", s.name, got, s.total, s.wantMin, s.wantMax)
+			}
+		})
+	}
+}
+
+func BenchmarkSamplers(b *testing.B) {
+	for i := range samplers {
+		s := samplers[i]
+		b.Run(s.name, func(b *testing.B) {
+			sampler := s.sampler()
+			b.RunParallel(func(pb *testing.PB) {
+				for pb.Next() {
+					sampler.Sample(0)
+				}
+			})
+		})
+	}
+}

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 +23,58 @@ 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
 }

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 := string(buf.Bytes())
+	want := "@cee:{"
+	if !strings.HasPrefix(got, want) {
+		t.Errorf("Bad CEE message start: want %v, got %v", want, got)
+	}
+}

writer.go

@@ -26,11 +26,9 @@ type syncWriter struct {
 }
 
 // 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}
@@ -58,30 +56,30 @@ type multiLevelWriter struct {
 
 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
 }
 
 // MultiLevelWriter creates a writer that duplicates its writes to all the

writer_test.go

@@ -1,6 +1,11 @@
+// +build !binary_log
+// +build !windows
+
 package zerolog
 
 import (
+	"errors"
+	"io"
 	"reflect"
 	"testing"
 )
@@ -12,13 +17,97 @@ 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
+	}
+}