Embed the diode lib to avoid test dependencies

This commit introduces a breaking change in the diode API in order to
hide the diodes package interface. This removes a good number of
dependencies introduced by the test framework used by the diodes
package.

.travis.yml

@@ -1,10 +1,13 @@
 language: go
 go:
-- 1.7
-- 1.8
-- tip
+- "1.7"
+- "1.8"
+- "1.9"
+- "1.10"
+- "master"
 matrix:
   allow_failures:
-      - go: tip
+      - go: "master"
 script:
-    go test -v -race -cpu=1,2,4 ./...
+  - go test -v -race -cpu=1,2,4 -bench . -benchmem ./...
+  - go test -v -tags binary_log -race -cpu=1,2,4 -bench . -benchmem ./...

README.md

@@ -4,13 +4,17 @@
 
 The zerolog package provides a fast and simple logger dedicated to JSON output.
 
-Zerolog's API is designed to provide both a great developer experience and stunning [performance](#performance). Its unique chaining API allows zerolog to write JSON log events by avoiding allocations and reflection.
+Zerolog's API is designed to provide both a great developer experience and stunning [performance](#benchmarks). Its unique chaining API allows zerolog to write JSON (or CBOR) log events by avoiding allocations and reflection.
 
-The uber's [zap](https://godoc.org/go.uber.org/zap) library pioneered this approach. Zerolog is taking this concept to the next level with simpler to use API and even better performance.
+Uber's [zap](https://godoc.org/go.uber.org/zap) library pioneered this approach. Zerolog is taking this concept to the next level with a simpler to use API and even better performance.
 
-To keep the code base and the API simple, zerolog focuses on JSON logging only. Pretty logging on the console is made possible using the provided `zerolog.ConsoleWriter`.
+To keep the code base and the API simple, zerolog focuses on efficient structured logging only. Pretty logging on the console is made possible using the provided (but inefficient) `zerolog.ConsoleWriter`.
 
-![](pretty.png)
+![Pretty Logging Image](pretty.png)
+
+## Who uses zerolog
+
+Find out [who uses zerolog](https://github.com/rs/zerolog/wiki/Who-uses-zerolog) and add your company / project to the list.
 
 ## Features
 
@@ -18,50 +22,213 @@ To keep the code base and the API simple, zerolog focuses on JSON logging only.
 * Low to zero allocation
 * Level logging
 * Sampling
+* Hooks
 * Contextual fields
 * `context.Context` integration
 * `net/http` helpers
+* JSON and CBOR encoding formats
 * Pretty logging for development
 
-## Usage
+## Installation
 
 ```go
-import "github.com/rs/zerolog/log"
+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
+    // If you set zerolog.TimeFieldFormat to an empty string,
+    // logs will write with UNIX time
+    zerolog.TimeFieldFormat = ""
+
+    log.Print("hello world")
+}
+
+// Output: {"time":1516134303,"level":"debug","message":"hello world"}
 ```
 
-NOTE: To import the global logger, import the `log` subpackage `github.com/rs/zerolog/log`.
+> Note: The default log level for `log.Print` is *debug*
+
+### 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 = ""
+
+    log.Debug().
+        Str("Scale", "833 cents").
+        Float64("Interval", 833.09).
+        Msg("Fibonacci is everywhere")
+}
+
+// Output: {"time":1524104936,"level":"debug","Scale":"833 cents","Interval":833.09,"message":"Fibonacci is everywhere"}
 ```
 
-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 = ""
+
+    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)
+
+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 = ""
+    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 = ""
+
+    log.Log().
+        Str("foo", "bar").
+        Msg("")
+}
+
+// Output: {"time":1494567715,"foo":"bar"}
+```
+
+#### 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 = ""
+
+    log.Fatal().
+        Err(err).
+        Str("service", service).
+        Msgf("Cannot start %s", service)
+}
+
+// Output: {"time":1516133263,"level":"fatal","error":"A repo man spends his life getting into tense situations","service":"myservice","message":"Cannot start myservice"}
+//         exit status 1
+```
+
+> NOTE: Using `Msgf` generates one allocation even when the logger is disabled.
+
 ### Create logger instance to manage different outputs
 
 ```go
@@ -83,23 +250,6 @@ sublogger.Info().Msg("hello world")
 // Output: {"level":"info","time":1494567715,"message":"hello world","component":"foo"}
 ```
 
-### Level logging
-
-```go
-zerolog.SetGlobalLevel(zerolog.InfoLevel)
-
-log.Debug().Msg("filtered out message")
-log.Info().Msg("routed message")
-
-if e := log.Debug(); e.Enabled() {
-    // Compute log output only if enabled.
-    value := compute()
-    e.Str("foo": value).Msg("some debug message")
-}
-
-// Output: {"level":"info","time":1494567715,"message":"routed message"}
-```
-
 ### Pretty logging
 
 ```go
@@ -119,7 +269,7 @@ 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"}
@@ -137,27 +287,69 @@ 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()
 ```
 
+### 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
+d := diodes.NewManyToOne(1000, diodes.AlertFunc(func(missed int) {
+    fmt.Printf("Dropped %d messages\n", missed)
+}))
+w := diode.NewWriter(os.Stdout, d, 10*time.Millisecond)
+log := zerolog.New(w)
+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
@@ -249,10 +441,9 @@ Some settings can be changed and will by applied to all loggers:
 * `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 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.
 
@@ -275,19 +466,39 @@ Some settings can be changed and will by applied to all loggers:
 * `Dict`: Adds a sub-key/value as a field of the event.
 * `Interface`: Uses reflection to marshal the type.
 
-## Performance
+## 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`
+
+## 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:
 
@@ -329,3 +540,16 @@ 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 de-duplication 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"}
+```
+
+However, it’s not a big deal as JSON accepts dup keys; the last one prevails.

array.go

@@ -1,10 +1,9 @@
 package zerolog
 
 import (
+	"net"
 	"sync"
 	"time"
-
-	"github.com/rs/zerolog/internal/json"
 )
 
 var arrayPool = &sync.Pool{
@@ -15,6 +14,8 @@ var arrayPool = &sync.Pool{
 	},
 }
 
+// Array is used to prepopulate an array of items
+// which can be re-used to add to log messages.
 type Array struct {
 	buf []byte
 }
@@ -26,144 +27,169 @@ func Arr() *Array {
 	return a
 }
 
+// MarshalZerologArray method here is no-op - since data is
+// already in the needed format.
 func (*Array) MarshalZerologArray(*Array) {
 }
 
 func (a *Array) write(dst []byte) []byte {
-	if len(a.buf) == 0 {
-		dst = append(dst, `[]`...)
-	} else {
-		a.buf[0] = '['
-		dst = append(append(dst, a.buf...), ']')
+	dst = enc.AppendArrayStart(dst)
+	if len(a.buf) > 0 {
+		dst = append(append(dst, a.buf...))
 	}
+	dst = enc.AppendArrayEnd(dst)
 	arrayPool.Put(a)
 	return dst
 }
 
 // Object marshals an object that implement the LogObjectMarshaler
-// interface and append it to the array.
+// interface and append append it to the array.
 func (a *Array) Object(obj LogObjectMarshaler) *Array {
-	a.buf = append(a.buf, ',')
 	e := Dict()
 	obj.MarshalZerologObject(e)
-	e.buf = append(e.buf, '}')
-	a.buf = append(a.buf, e.buf...)
+	e.buf = enc.AppendEndMarker(e.buf)
+	a.buf = append(enc.AppendArrayDelim(a.buf), e.buf...)
+	eventPool.Put(e)
 	return a
 }
 
-// Str append the val as a string to the array.
+// Str append append the val as a string to the array.
 func (a *Array) Str(val string) *Array {
-	a.buf = json.AppendString(append(a.buf, ','), val)
+	a.buf = enc.AppendString(enc.AppendArrayDelim(a.buf), val)
 	return a
 }
 
-// Bytes append the val as a string to the array.
+// Bytes append append the val as a string to the array.
 func (a *Array) Bytes(val []byte) *Array {
-	a.buf = json.AppendBytes(append(a.buf, ','), val)
+	a.buf = enc.AppendBytes(enc.AppendArrayDelim(a.buf), val)
 	return a
 }
 
-// Err append the err as a string to the array.
+// Hex 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
+}
+
+// Err append append the err as a string to the array.
 func (a *Array) Err(err error) *Array {
-	a.buf = json.AppendError(append(a.buf, ','), err)
+	a.buf = enc.AppendError(enc.AppendArrayDelim(a.buf), err)
 	return a
 }
 
-// Bool append the val as a bool to the array.
+// Bool append append the val as a bool to the array.
 func (a *Array) Bool(b bool) *Array {
-	a.buf = json.AppendBool(append(a.buf, ','), b)
+	a.buf = enc.AppendBool(enc.AppendArrayDelim(a.buf), b)
 	return a
 }
 
-// Int append i as a int to the array.
+// Int append append i as a int to the array.
 func (a *Array) Int(i int) *Array {
-	a.buf = json.AppendInt(append(a.buf, ','), i)
+	a.buf = enc.AppendInt(enc.AppendArrayDelim(a.buf), i)
 	return a
 }
 
-// Int8 append i as a int8 to the array.
+// Int8 append append i as a int8 to the array.
 func (a *Array) Int8(i int8) *Array {
-	a.buf = json.AppendInt8(append(a.buf, ','), i)
+	a.buf = enc.AppendInt8(enc.AppendArrayDelim(a.buf), i)
 	return a
 }
 
-// Int16 append i as a int16 to the array.
+// Int16 append append i as a int16 to the array.
 func (a *Array) Int16(i int16) *Array {
-	a.buf = json.AppendInt16(append(a.buf, ','), i)
+	a.buf = enc.AppendInt16(enc.AppendArrayDelim(a.buf), i)
 	return a
 }
 
-// Int32 append i as a int32 to the array.
+// Int32 append append i as a int32 to the array.
 func (a *Array) Int32(i int32) *Array {
-	a.buf = json.AppendInt32(append(a.buf, ','), i)
+	a.buf = enc.AppendInt32(enc.AppendArrayDelim(a.buf), i)
 	return a
 }
 
-// Int64 append i as a int64 to the array.
+// Int64 append append i as a int64 to the array.
 func (a *Array) Int64(i int64) *Array {
-	a.buf = json.AppendInt64(append(a.buf, ','), i)
+	a.buf = enc.AppendInt64(enc.AppendArrayDelim(a.buf), i)
 	return a
 }
 
-// Uint append i as a uint to the array.
+// Uint append append i as a uint to the array.
 func (a *Array) Uint(i uint) *Array {
-	a.buf = json.AppendUint(append(a.buf, ','), i)
+	a.buf = enc.AppendUint(enc.AppendArrayDelim(a.buf), i)
 	return a
 }
 
-// Uint8 append i as a uint8 to the array.
+// Uint8 append append i as a uint8 to the array.
 func (a *Array) Uint8(i uint8) *Array {
-	a.buf = json.AppendUint8(append(a.buf, ','), i)
+	a.buf = enc.AppendUint8(enc.AppendArrayDelim(a.buf), i)
 	return a
 }
 
-// Uint16 append i as a uint16 to the array.
+// Uint16 append append i as a uint16 to the array.
 func (a *Array) Uint16(i uint16) *Array {
-	a.buf = json.AppendUint16(append(a.buf, ','), i)
+	a.buf = enc.AppendUint16(enc.AppendArrayDelim(a.buf), i)
 	return a
 }
 
-// Uint32 append i as a uint32 to the array.
+// Uint32 append append i as a uint32 to the array.
 func (a *Array) Uint32(i uint32) *Array {
-	a.buf = json.AppendUint32(append(a.buf, ','), i)
+	a.buf = enc.AppendUint32(enc.AppendArrayDelim(a.buf), i)
 	return a
 }
 
-// Uint64 append i as a uint64 to the array.
+// Uint64 append append i as a uint64 to the array.
 func (a *Array) Uint64(i uint64) *Array {
-	a.buf = json.AppendUint64(append(a.buf, ','), i)
+	a.buf = enc.AppendUint64(enc.AppendArrayDelim(a.buf), i)
 	return a
 }
 
-// Float32 append f as a float32 to the array.
+// Float32 append append f as a float32 to the array.
 func (a *Array) Float32(f float32) *Array {
-	a.buf = json.AppendFloat32(append(a.buf, ','), f)
+	a.buf = enc.AppendFloat32(enc.AppendArrayDelim(a.buf), f)
 	return a
 }
 
-// Float64 append f as a float64 to the array.
+// Float64 append append f as a float64 to the array.
 func (a *Array) Float64(f float64) *Array {
-	a.buf = json.AppendFloat64(append(a.buf, ','), f)
+	a.buf = enc.AppendFloat64(enc.AppendArrayDelim(a.buf), f)
 	return a
 }
 
-// Time append t formated as string using zerolog.TimeFieldFormat.
+// Time append append t formated as string using zerolog.TimeFieldFormat.
 func (a *Array) Time(t time.Time) *Array {
-	a.buf = json.AppendTime(append(a.buf, ','), t, TimeFieldFormat)
+	a.buf = enc.AppendTime(enc.AppendArrayDelim(a.buf), t, TimeFieldFormat)
 	return a
 }
 
-// Dur append d to the array.
+// Dur append append d to the array.
 func (a *Array) Dur(d time.Duration) *Array {
-	a.buf = json.AppendDuration(append(a.buf, ','), d, DurationFieldUnit, DurationFieldInteger)
+	a.buf = enc.AppendDuration(enc.AppendArrayDelim(a.buf), d, DurationFieldUnit, DurationFieldInteger)
 	return a
 }
 
-// Interface append i marshaled using reflection.
+// 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 = json.AppendInterface(append(a.buf, ','), i)
+	a.buf = enc.AppendInterface(enc.AppendArrayDelim(a.buf), i)
+	return a
+}
+
+// IPAddr adds IPv4 or IPv6 address to the array
+func (a *Array) IPAddr(ip net.IP) *Array {
+	a.buf = enc.AppendIPAddr(enc.AppendArrayDelim(a.buf), ip)
+	return a
+}
+
+// IPPrefix adds IPv4 or IPv6 Prefix (IP + mask) to the array
+func (a *Array) IPPrefix(pfx net.IPNet) *Array {
+	a.buf = enc.AppendIPPrefix(enc.AppendArrayDelim(a.buf), pfx)
+	return a
+}
+
+// MACAddr adds a MAC (Ethernet) address to the array
+func (a *Array) MACAddr(ha net.HardwareAddr) *Array {
+	a.buf = enc.AppendMACAddr(enc.AppendArrayDelim(a.buf), ha)
 	return a
 }

array_test.go

@@ -1,6 +1,7 @@
 package zerolog
 
 import (
+	"net"
 	"testing"
 	"time"
 )
@@ -18,13 +19,16 @@ func TestArray(t *testing.T) {
 		Uint16(8).
 		Uint32(9).
 		Uint64(10).
-		Float32(11).
-		Float64(12).
+		Float32(11.98122).
+		Float64(12.987654321).
 		Str("a").
+		Bytes([]byte("b")).
+		Hex([]byte{0x1f}).
 		Time(time.Time{}).
+		IPAddr(net.IP{192, 168, 0, 10}).
 		Dur(0)
-	want := `[true,1,2,3,4,5,6,7,8,9,10,11,12,"a","0001-01-01T00:00:00Z",0]`
-	if got := string(a.write([]byte{})); got != want {
+	want := `[true,1,2,3,4,5,6,7,8,9,10,11.98122,12.987654321,"a","b","1f","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

@@ -57,6 +57,18 @@ 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()
@@ -84,6 +96,22 @@ func (o obj) MarshalZerologObject(e *Event) {
 		Int("priv", o.priv)
 }
 
+func BenchmarkLogArrayObject(b *testing.B) {
+	obj1 := obj{"a", "b", 2}
+	obj2 := obj{"c", "d", 3}
+	obj3 := obj{"e", "f", 4}
+	logger := New(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}
@@ -203,3 +231,130 @@ func BenchmarkLogFieldType(b *testing.B) {
 		})
 	}
 }
+
+func BenchmarkContextFieldType(b *testing.B) {
+	oldFormat := TimeFieldFormat
+	TimeFieldFormat = ""
+	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"}
+	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)
+		},
+		"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 +1,498 @@
+// +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 2"}
+	// {"level":"info","message":"message 4"}
+}
+
+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_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"}
+}

console.go

@@ -9,6 +9,7 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+	"time"
 )
 
 const (
@@ -39,7 +40,10 @@ type ConsoleWriter struct {
 
 func (w ConsoleWriter) Write(p []byte) (n int, err error) {
 	var event map[string]interface{}
-	err = json.Unmarshal(p, &event)
+	p = decodeIfBinaryToBytes(p)
+	d := json.NewDecoder(bytes.NewReader(p))
+	d.UseNumber()
+	err = d.Decode(&event)
 	if err != nil {
 		return
 	}
@@ -54,7 +58,7 @@ func (w ConsoleWriter) Write(p []byte) (n int, err error) {
 		level = strings.ToUpper(l)[0:4]
 	}
 	fmt.Fprintf(buf, "%s |%s| %s",
-		colorize(event[TimestampFieldName], cDarkGray, !w.NoColor),
+		colorize(formatTime(event[TimestampFieldName]), cDarkGray, !w.NoColor),
 		colorize(level, lvlColor, !w.NoColor),
 		colorize(event[MessageFieldName], cReset, !w.NoColor))
 	fields := make([]string, 0, len(event))
@@ -75,8 +79,15 @@ func (w ConsoleWriter) Write(p []byte) (n int, err error) {
 			} else {
 				buf.WriteString(value)
 			}
-		default:
+		case json.Number:
 			fmt.Fprint(buf, value)
+		default:
+			b, err := json.Marshal(value)
+			if err != nil {
+				fmt.Fprintf(buf, "[error: %v]", err)
+			} else {
+				fmt.Fprint(buf, string(b))
+			}
 		}
 	}
 	buf.WriteByte('\n')
@@ -85,6 +96,17 @@ func (w ConsoleWriter) Write(p []byte) (n int, err error) {
 	return
 }
 
+func formatTime(t interface{}) string {
+	switch t := t.(type) {
+	case string:
+		return t
+	case json.Number:
+		u, _ := t.Int64()
+		return time.Unix(u, 0).Format(time.RFC3339)
+	}
+	return "<nil>"
+}
+
 func colorize(s interface{}, color int, enabled bool) string {
 	if !enabled {
 		return fmt.Sprintf("%v", s)

console_test.go

@@ -0,0 +1,30 @@
+package zerolog_test
+
+import (
+	"bytes"
+	"os"
+	"strings"
+	"testing"
+
+	"github.com/rs/zerolog"
+)
+
+func ExampleConsoleWriter_Write() {
+	log := zerolog.New(zerolog.ConsoleWriter{Out: os.Stdout, NoColor: true})
+
+	log.Info().Msg("hello world")
+	// Output: <nil> |INFO| hello world
+}
+
+func TestConsoleWriterNumbers(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> |INFO| msg big=1152921504606846976 float=1.23 small=123"; got != want {
+		t.Errorf("\ngot:\n%s\nwant:\n%s", got, want)
+	}
+}

context.go

@@ -2,9 +2,8 @@ package zerolog
 
 import (
 	"io/ioutil"
+	"net"
 	"time"
-
-	"github.com/rs/zerolog/internal/json"
 )
 
 // Context configures a new sub-logger with contextual fields.
@@ -25,8 +24,8 @@ func (c Context) Fields(fields map[string]interface{}) Context {
 
 // Dict adds the field key with the dict to the logger context.
 func (c Context) Dict(key string, dict *Event) Context {
-	dict.buf = append(dict.buf, '}')
-	c.l.context = append(json.AppendKey(c.l.context, key), dict.buf...)
+	dict.buf = enc.AppendEndMarker(dict.buf)
+	c.l.context = append(enc.AppendKey(c.l.context, key), dict.buf...)
 	eventPool.Put(dict)
 	return c
 }
@@ -35,7 +34,7 @@ func (c Context) Dict(key string, dict *Event) Context {
 // Use zerolog.Arr() to create the array or pass a type that
 // implement the LogArrayMarshaler interface.
 func (c Context) Array(key string, arr LogArrayMarshaler) Context {
-	c.l.context = json.AppendKey(c.l.context, key)
+	c.l.context = enc.AppendKey(c.l.context, key)
 	if arr, ok := arr.(*Array); ok {
 		c.l.context = arr.write(c.l.context)
 		return c
@@ -53,43 +52,66 @@ func (c Context) Array(key string, arr LogArrayMarshaler) Context {
 
 // Object marshals an object that implement the LogObjectMarshaler interface.
 func (c Context) Object(key string, obj LogObjectMarshaler) Context {
-	e := newEvent(levelWriterAdapter{ioutil.Discard}, 0, true)
+	e := newEvent(levelWriterAdapter{ioutil.Discard}, 0)
 	e.Object(key, obj)
-	e.buf[0] = ',' // A new event starts as an object, we want to embed it.
-	c.l.context = append(c.l.context, e.buf...)
+	c.l.context = enc.AppendObjectData(c.l.context, e.buf)
+	eventPool.Put(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)
 	eventPool.Put(e)
 	return c
 }
 
 // Str adds the field key with val as a string to the logger context.
 func (c Context) Str(key, val string) Context {
-	c.l.context = json.AppendString(json.AppendKey(c.l.context, key), val)
+	c.l.context = enc.AppendString(enc.AppendKey(c.l.context, key), val)
 	return c
 }
 
 // Strs adds the field key with val as a string to the logger context.
 func (c Context) Strs(key string, vals []string) Context {
-	c.l.context = json.AppendStrings(json.AppendKey(c.l.context, key), vals)
+	c.l.context = enc.AppendStrings(enc.AppendKey(c.l.context, key), vals)
 	return c
 }
 
 // Bytes adds the field key with val as a []byte to the logger context.
 func (c Context) Bytes(key string, val []byte) Context {
-	c.l.context = json.AppendBytes(json.AppendKey(c.l.context, key), val)
+	c.l.context = enc.AppendBytes(enc.AppendKey(c.l.context, key), val)
+	return c
+}
+
+// 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 err as a string to the logger context.
 func (c Context) AnErr(key string, err error) Context {
 	if err != nil {
-		c.l.context = json.AppendError(json.AppendKey(c.l.context, key), err)
+		c.l.context = enc.AppendError(enc.AppendKey(c.l.context, key), err)
 	}
 	return c
 }
 
 // Errs adds the field key with errs as an array of strings to the logger context.
 func (c Context) Errs(key string, errs []error) Context {
-	c.l.context = json.AppendErrors(json.AppendKey(c.l.context, key), errs)
+	c.l.context = enc.AppendErrors(enc.AppendKey(c.l.context, key), errs)
 	return c
 }
 
@@ -97,204 +119,243 @@ func (c Context) Errs(key string, errs []error) Context {
 // To customize the key name, change zerolog.ErrorFieldName.
 func (c Context) Err(err error) Context {
 	if err != nil {
-		c.l.context = json.AppendError(json.AppendKey(c.l.context, ErrorFieldName), err)
+		c.l.context = enc.AppendError(enc.AppendKey(c.l.context, ErrorFieldName), err)
 	}
 	return c
 }
 
 // Bool adds the field key with val as a bool to the logger context.
 func (c Context) Bool(key string, b bool) Context {
-	c.l.context = json.AppendBool(json.AppendKey(c.l.context, key), b)
+	c.l.context = enc.AppendBool(enc.AppendKey(c.l.context, key), b)
 	return c
 }
 
 // Bools adds the field key with val as a []bool to the logger context.
 func (c Context) Bools(key string, b []bool) Context {
-	c.l.context = json.AppendBools(json.AppendKey(c.l.context, key), b)
+	c.l.context = enc.AppendBools(enc.AppendKey(c.l.context, key), b)
 	return c
 }
 
 // Int adds the field key with i as a int to the logger context.
 func (c Context) Int(key string, i int) Context {
-	c.l.context = json.AppendInt(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInt(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Ints adds the field key with i as a []int to the logger context.
 func (c Context) Ints(key string, i []int) Context {
-	c.l.context = json.AppendInts(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInts(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Int8 adds the field key with i as a int8 to the logger context.
 func (c Context) Int8(key string, i int8) Context {
-	c.l.context = json.AppendInt8(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInt8(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Ints8 adds the field key with i as a []int8 to the logger context.
 func (c Context) Ints8(key string, i []int8) Context {
-	c.l.context = json.AppendInts8(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInts8(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Int16 adds the field key with i as a int16 to the logger context.
 func (c Context) Int16(key string, i int16) Context {
-	c.l.context = json.AppendInt16(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInt16(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Ints16 adds the field key with i as a []int16 to the logger context.
 func (c Context) Ints16(key string, i []int16) Context {
-	c.l.context = json.AppendInts16(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInts16(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Int32 adds the field key with i as a int32 to the logger context.
 func (c Context) Int32(key string, i int32) Context {
-	c.l.context = json.AppendInt32(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInt32(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Ints32 adds the field key with i as a []int32 to the logger context.
 func (c Context) Ints32(key string, i []int32) Context {
-	c.l.context = json.AppendInts32(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInts32(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Int64 adds the field key with i as a int64 to the logger context.
 func (c Context) Int64(key string, i int64) Context {
-	c.l.context = json.AppendInt64(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInt64(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Ints64 adds the field key with i as a []int64 to the logger context.
 func (c Context) Ints64(key string, i []int64) Context {
-	c.l.context = json.AppendInts64(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInts64(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Uint adds the field key with i as a uint to the logger context.
 func (c Context) Uint(key string, i uint) Context {
-	c.l.context = json.AppendUint(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendUint(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Uints adds the field key with i as a []uint to the logger context.
 func (c Context) Uints(key string, i []uint) Context {
-	c.l.context = json.AppendUints(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendUints(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Uint8 adds the field key with i as a uint8 to the logger context.
 func (c Context) Uint8(key string, i uint8) Context {
-	c.l.context = json.AppendUint8(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendUint8(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Uints8 adds the field key with i as a []uint8 to the logger context.
 func (c Context) Uints8(key string, i []uint8) Context {
-	c.l.context = json.AppendUints8(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendUints8(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Uint16 adds the field key with i as a uint16 to the logger context.
 func (c Context) Uint16(key string, i uint16) Context {
-	c.l.context = json.AppendUint16(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendUint16(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Uints16 adds the field key with i as a []uint16 to the logger context.
 func (c Context) Uints16(key string, i []uint16) Context {
-	c.l.context = json.AppendUints16(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendUints16(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Uint32 adds the field key with i as a uint32 to the logger context.
 func (c Context) Uint32(key string, i uint32) Context {
-	c.l.context = json.AppendUint32(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendUint32(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Uints32 adds the field key with i as a []uint32 to the logger context.
 func (c Context) Uints32(key string, i []uint32) Context {
-	c.l.context = json.AppendUints32(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendUints32(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Uint64 adds the field key with i as a uint64 to the logger context.
 func (c Context) Uint64(key string, i uint64) Context {
-	c.l.context = json.AppendUint64(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendUint64(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Uints64 adds the field key with i as a []uint64 to the logger context.
 func (c Context) Uints64(key string, i []uint64) Context {
-	c.l.context = json.AppendUints64(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendUints64(enc.AppendKey(c.l.context, key), i)
 	return c
 }
 
 // Float32 adds the field key with f as a float32 to the logger context.
 func (c Context) Float32(key string, f float32) Context {
-	c.l.context = json.AppendFloat32(json.AppendKey(c.l.context, key), f)
+	c.l.context = enc.AppendFloat32(enc.AppendKey(c.l.context, key), f)
 	return c
 }
 
 // Floats32 adds the field key with f as a []float32 to the logger context.
 func (c Context) Floats32(key string, f []float32) Context {
-	c.l.context = json.AppendFloats32(json.AppendKey(c.l.context, key), f)
+	c.l.context = enc.AppendFloats32(enc.AppendKey(c.l.context, key), f)
 	return c
 }
 
 // Float64 adds the field key with f as a float64 to the logger context.
 func (c Context) Float64(key string, f float64) Context {
-	c.l.context = json.AppendFloat64(json.AppendKey(c.l.context, key), f)
+	c.l.context = enc.AppendFloat64(enc.AppendKey(c.l.context, key), f)
 	return c
 }
 
 // Floats64 adds the field key with f as a []float64 to the logger context.
 func (c Context) Floats64(key string, f []float64) Context {
-	c.l.context = json.AppendFloats64(json.AppendKey(c.l.context, key), f)
+	c.l.context = enc.AppendFloats64(enc.AppendKey(c.l.context, key), f)
 	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 = json.AppendTime(json.AppendKey(c.l.context, key), t, TimeFieldFormat)
+	c.l.context = enc.AppendTime(enc.AppendKey(c.l.context, key), t, TimeFieldFormat)
 	return c
 }
 
 // Times adds the field key with t formated as string using zerolog.TimeFieldFormat.
 func (c Context) Times(key string, t []time.Time) Context {
-	c.l.context = json.AppendTimes(json.AppendKey(c.l.context, key), t, TimeFieldFormat)
+	c.l.context = enc.AppendTimes(enc.AppendKey(c.l.context, key), t, TimeFieldFormat)
 	return c
 }
 
 // Dur adds the fields key with d divided by unit and stored as a float.
 func (c Context) Dur(key string, d time.Duration) Context {
-	c.l.context = json.AppendDuration(json.AppendKey(c.l.context, key), d, DurationFieldUnit, DurationFieldInteger)
+	c.l.context = enc.AppendDuration(enc.AppendKey(c.l.context, key), d, DurationFieldUnit, DurationFieldInteger)
 	return c
 }
 
 // Durs adds the fields key with d divided by unit and stored as a float.
 func (c Context) Durs(key string, d []time.Duration) Context {
-	c.l.context = json.AppendDurations(json.AppendKey(c.l.context, key), d, DurationFieldUnit, DurationFieldInteger)
+	c.l.context = enc.AppendDurations(enc.AppendKey(c.l.context, key), d, DurationFieldUnit, DurationFieldInteger)
 	return c
 }
 
 // Interface adds the field key with obj marshaled using reflection.
 func (c Context) Interface(key string, i interface{}) Context {
-	c.l.context = json.AppendInterface(json.AppendKey(c.l.context, key), i)
+	c.l.context = enc.AppendInterface(enc.AppendKey(c.l.context, key), i)
+	return c
+}
+
+type callerHook struct{}
+
+func (ch callerHook) Run(e *Event, level Level, msg string) {
+        //Two extra frames to skip (added by hook infra).
+	e.caller(CallerSkipFrameCount+2)
+}
+
+var ch = callerHook{}
+
+// 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
+}
+
+// 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

@@ -5,25 +5,42 @@ import (
 	"io/ioutil"
 )
 
-var disabledLogger = New(ioutil.Discard).Level(Disabled)
+var disabledLogger *Logger
+
+func init() {
+	l := New(ioutil.Discard).Level(Disabled)
+	disabledLogger = &l
+}
 
 type ctxKey struct{}
 
-// WithContext returns a copy of ctx with l associated.
+// WithContext returns a copy of ctx with l associated. If an instance of Logger
+// is already in the context, the pointer to this logger is updated with l.
+//
+// For instance, to add a field to an existing logger in the context, use this
+// notation:
+//
+//     ctx := r.Context()
+//     l := zerolog.Ctx(ctx)
+//     ctx = l.With().Str("foo", "bar").WithContext(ctx)
 func (l Logger) WithContext(ctx context.Context) context.Context {
 	if lp, ok := ctx.Value(ctxKey{}).(*Logger); ok {
 		// Update existing pointer.
 		*lp = l
 		return ctx
 	}
+	if l.level == Disabled {
+		// Do not store disabled logger.
+		return ctx
+	}
 	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 {
+func Ctx(ctx context.Context) *Logger {
 	if l, ok := ctx.Value(ctxKey{}).(*Logger); ok {
-		return *l
+		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 +19,29 @@ 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")
 	}
 }
+
+func TestCtxDisabled(t *testing.T) {
+	ctx := disabledLogger.WithContext(context.Background())
+	if ctx != context.Background() {
+		t.Error("WithContext stored a disabled logger")
+	}
+
+	ctx = New(ioutil.Discard).WithContext(ctx)
+	if reflect.DeepEqual(Ctx(ctx), disabledLogger) {
+		t.Error("WithContext did not store logger")
+	}
+
+	ctx = disabledLogger.WithContext(ctx)
+	if !reflect.DeepEqual(Ctx(ctx), disabledLogger) {
+		t.Error("WithContext did not update logger pointer with disabled logger")
+	}
+}

diode/diode.go

@@ -0,0 +1,90 @@
+// 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)
+
+// 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    *diodes.ManyToOne
+	p    *diodes.Poller
+	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
+//
+//     w := diode.NewWriter(w, 1000, 10 * time.Millisecond, func(missed int) {
+//         log.Printf("Dropped %d messages", missed)
+//     })
+//     log := zerolog.New(w)
+//
+// See code.cloudfoundry.org/go-diodes for more info on diode.
+func NewWriter(w io.Writer, size int, poolInterval time.Duration, f Alerter) Writer {
+	ctx, cancel := context.WithCancel(context.Background())
+	d := diodes.NewManyToOne(size, diodes.AlertFunc(f))
+	dw := Writer{
+		w: w,
+		d: d,
+		p: diodes.NewPoller(d,
+			diodes.WithPollingInterval(poolInterval),
+			diodes.WithPollingContext(ctx)),
+		c:    cancel,
+		done: make(chan struct{}),
+	}
+	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.p.Next()
+		if d == nil {
+			return
+		}
+		p := *(*[]byte)(d)
+		dw.w.Write(p)
+		bufPool.Put(p[:0])
+	}
+}

diode/diode_example_test.go

@@ -0,0 +1,24 @@
+// +build !binary_log
+
+package diode_test
+
+import (
+	"fmt"
+	"os"
+	"time"
+
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/diode"
+)
+
+func ExampleNewWriter() {
+	w := diode.NewWriter(os.Stdout, 1000, 10*time.Millisecond, 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 +1,47 @@
+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, 10*time.Millisecond, 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)
+	w := diode.NewWriter(ioutil.Discard, 100000, 10*time.Millisecond, 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 {
+	buffer     []unsafe.Pointer
+	writeIndex uint64
+	readIndex  uint64
+	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 {
+	buffer     []unsafe.Pointer
+	writeIndex uint64
+	readIndex  uint64
+	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 +1,58 @@
+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
+	AppendError(dst []byte, err error) []byte
+	AppendErrors(dst []byte, errs []error) []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 +1,35 @@
+// +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 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 +1,32 @@
+// +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 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

@@ -2,12 +2,12 @@ package zerolog
 
 import (
 	"fmt"
-	"io/ioutil"
+	"net"
 	"os"
+	"runtime"
+	"strconv"
 	"sync"
 	"time"
-
-	"github.com/rs/zerolog/internal/json"
 )
 
 var eventPool = &sync.Pool{
@@ -21,11 +21,12 @@ 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)
+	ch    []Hook // hooks from context
+	h     []Hook
 }
 
 // LogObjectMarshaler provides a strongly-typed and encoding-agnostic interface
@@ -40,25 +41,25 @@ type LogArrayMarshaler interface {
 	MarshalZerologArray(a *Array)
 }
 
-func newEvent(w LevelWriter, level Level, enabled bool) *Event {
-	if !enabled {
-		return &Event{}
-	}
+func newEvent(w LevelWriter, level Level) *Event {
 	e := eventPool.Get().(*Event)
-	e.buf = e.buf[:1]
-	e.buf[0] = '{'
+	e.buf = e.buf[:0]
+	e.h = e.h[:0]
+	e.buf = enc.AppendBeginMarker(e.buf)
 	e.w = w
 	e.level = level
-	e.enabled = true
 	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)
+	e.buf = enc.AppendEndMarker(e.buf)
+	e.buf = enc.AppendLineBreak(e.buf)
+	if e.w != nil {
+		_, err = e.w.WriteLevel(e.level, e.buf)
+	}
 	eventPool.Put(e)
 	return
 }
@@ -66,7 +67,7 @@ func (e *Event) write() (err error) {
 // 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
 }
 
 // Msg sends the *Event with msg added as the message field if not empty.
@@ -74,11 +75,27 @@ func (e *Event) Enabled() bool {
 // NOTICE: once this method is called, the *Event should be disposed.
 // Calling Msg twice can have unexpected result.
 func (e *Event) Msg(msg string) {
-	if !e.enabled {
+	if e == nil {
 		return
 	}
+	if len(e.ch) > 0 {
+		e.ch[0].Run(e, e.level, msg)
+		if len(e.ch) > 1 {
+			for _, hook := range e.ch[1:] {
+				hook.Run(e, e.level, msg)
+			}
+		}
+	}
+	if len(e.h) > 0 {
+		e.h[0].Run(e, e.level, msg)
+		if len(e.h) > 1 {
+			for _, hook := range e.h[1:] {
+				hook.Run(e, e.level, msg)
+			}
+		}
+	}
 	if msg != "" {
-		e.buf = json.AppendString(json.AppendKey(e.buf, MessageFieldName), msg)
+		e.buf = enc.AppendString(enc.AppendKey(e.buf, MessageFieldName), msg)
 	}
 	if e.done != nil {
 		defer e.done(msg)
@@ -93,24 +110,15 @@ func (e *Event) Msg(msg string) {
 // 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 {
+	if e == nil {
 		return
 	}
-	msg := fmt.Sprintf(format, v...)
-	if msg != "" {
-		e.buf = json.AppendString(json.AppendKey(e.buf, MessageFieldName), msg)
-	}
-	if e.done != nil {
-		defer e.done(msg)
-	}
-	if err := e.write(); err != nil {
-		fmt.Fprintf(os.Stderr, "zerolog: could not write event: %v", err)
-	}
+	e.Msg(fmt.Sprintf(format, v...))
 }
 
 // Fields is a helper function to use a map to set fields using type assertion.
 func (e *Event) Fields(fields map[string]interface{}) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
 	e.buf = appendFields(e.buf, fields)
@@ -120,10 +128,11 @@ func (e *Event) Fields(fields map[string]interface{}) *Event {
 // Dict adds the field key with a dict to the event context.
 // Use zerolog.Dict() to create the dictionary.
 func (e *Event) Dict(key string, dict *Event) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = append(append(json.AppendKey(e.buf, key), dict.buf...), '}')
+	dict.buf = enc.AppendEndMarker(dict.buf)
+	e.buf = append(enc.AppendKey(e.buf, key), dict.buf...)
 	eventPool.Put(dict)
 	return e
 }
@@ -132,17 +141,17 @@ func (e *Event) Dict(key string, dict *Event) *Event {
 // Call usual field methods like Str, Int etc to add fields to this
 // event and give it as argument the *Event.Dict method.
 func Dict() *Event {
-	return newEvent(levelWriterAdapter{ioutil.Discard}, 0, true)
+	return newEvent(nil, 0)
 }
 
 // Array adds the field key with an array to the event context.
 // Use zerolog.Arr() to create the array or pass a type that
 // implement the LogArrayMarshaler interface.
 func (e *Event) Array(key string, arr LogArrayMarshaler) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendKey(e.buf, key)
+	e.buf = enc.AppendKey(e.buf, key)
 	var a *Array
 	if aa, ok := arr.(*Array); ok {
 		a = aa
@@ -155,44 +164,45 @@ func (e *Event) Array(key string, arr LogArrayMarshaler) *Event {
 }
 
 func (e *Event) appendObject(obj LogObjectMarshaler) {
-	pos := len(e.buf)
+	e.buf = enc.AppendBeginMarker(e.buf)
 	obj.MarshalZerologObject(e)
-	if pos < len(e.buf) {
-		// As MarshalZerologObject will use event API, the first field will be
-		// preceded by a comma. If at least one field has been added (buf grew),
-		// we replace this coma by the opening bracket.
-		e.buf[pos] = '{'
-	} else {
-		e.buf = append(e.buf, '{')
-	}
-	e.buf = append(e.buf, '}')
+	e.buf = enc.AppendEndMarker(e.buf)
 }
 
 // Object marshals an object that implement the LogObjectMarshaler interface.
 func (e *Event) Object(key string, obj LogObjectMarshaler) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendKey(e.buf, key)
+	e.buf = enc.AppendKey(e.buf, key)
 	e.appendObject(obj)
 	return e
 }
 
+// Object marshals an object that implement the LogObjectMarshaler interface.
+func (e *Event) EmbedObject(obj LogObjectMarshaler) *Event {
+	if e == nil {
+		return e
+	}
+	obj.MarshalZerologObject(e)
+	return e
+}
+
 // Str adds the field key with val as a string to the *Event context.
 func (e *Event) Str(key, val string) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendString(json.AppendKey(e.buf, key), val)
+	e.buf = enc.AppendString(enc.AppendKey(e.buf, key), val)
 	return e
 }
 
 // Strs adds the field key with vals as a []string to the *Event context.
 func (e *Event) Strs(key string, vals []string) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendStrings(json.AppendKey(e.buf, key), vals)
+	e.buf = enc.AppendStrings(enc.AppendKey(e.buf, key), vals)
 	return e
 }
 
@@ -201,21 +211,42 @@ func (e *Event) Strs(key string, vals []string) *Event {
 // Runes outside of normal ASCII ranges will be hex-encoded in the resulting
 // JSON.
 func (e *Event) Bytes(key string, val []byte) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendBytes(json.AppendKey(e.buf, key), val)
+	e.buf = enc.AppendBytes(enc.AppendKey(e.buf, key), val)
+	return e
+}
+
+// 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 err as a string to the *Event context.
 // If err is nil, no field is added.
 func (e *Event) AnErr(key string, err error) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
 	if err != nil {
-		e.buf = json.AppendError(json.AppendKey(e.buf, key), err)
+		e.buf = enc.AppendError(enc.AppendKey(e.buf, key), err)
 	}
 	return e
 }
@@ -223,10 +254,10 @@ func (e *Event) AnErr(key string, err error) *Event {
 // Errs adds the field key with errs as an array of strings to the *Event context.
 // If err is nil, no field is added.
 func (e *Event) Errs(key string, errs []error) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendErrors(json.AppendKey(e.buf, key), errs)
+	e.buf = enc.AppendErrors(enc.AppendKey(e.buf, key), errs)
 	return e
 }
 
@@ -234,274 +265,277 @@ func (e *Event) Errs(key string, errs []error) *Event {
 // If err is nil, no field is added.
 // To customize the key name, change zerolog.ErrorFieldName.
 func (e *Event) Err(err error) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
 	if err != nil {
-		e.buf = json.AppendError(json.AppendKey(e.buf, ErrorFieldName), err)
+		e.buf = enc.AppendError(enc.AppendKey(e.buf, ErrorFieldName), err)
 	}
 	return e
 }
 
 // Bool adds the field key with val as a bool to the *Event context.
 func (e *Event) Bool(key string, b bool) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendBool(json.AppendKey(e.buf, key), b)
+	e.buf = enc.AppendBool(enc.AppendKey(e.buf, key), b)
 	return e
 }
 
 // Bools adds the field key with val as a []bool to the *Event context.
 func (e *Event) Bools(key string, b []bool) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendBools(json.AppendKey(e.buf, key), b)
+	e.buf = enc.AppendBools(enc.AppendKey(e.buf, key), b)
 	return e
 }
 
 // Int adds the field key with i as a int to the *Event context.
 func (e *Event) Int(key string, i int) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendInt(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInt(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Ints adds the field key with i as a []int to the *Event context.
 func (e *Event) Ints(key string, i []int) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendInts(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInts(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Int8 adds the field key with i as a int8 to the *Event context.
 func (e *Event) Int8(key string, i int8) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendInt8(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInt8(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Ints8 adds the field key with i as a []int8 to the *Event context.
 func (e *Event) Ints8(key string, i []int8) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendInts8(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInts8(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Int16 adds the field key with i as a int16 to the *Event context.
 func (e *Event) Int16(key string, i int16) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendInt16(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInt16(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Ints16 adds the field key with i as a []int16 to the *Event context.
 func (e *Event) Ints16(key string, i []int16) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendInts16(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInts16(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Int32 adds the field key with i as a int32 to the *Event context.
 func (e *Event) Int32(key string, i int32) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendInt32(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInt32(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Ints32 adds the field key with i as a []int32 to the *Event context.
 func (e *Event) Ints32(key string, i []int32) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendInts32(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInts32(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Int64 adds the field key with i as a int64 to the *Event context.
 func (e *Event) Int64(key string, i int64) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendInt64(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInt64(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Ints64 adds the field key with i as a []int64 to the *Event context.
 func (e *Event) Ints64(key string, i []int64) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendInts64(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInts64(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Uint adds the field key with i as a uint to the *Event context.
 func (e *Event) Uint(key string, i uint) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendUint(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendUint(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Uints adds the field key with i as a []int to the *Event context.
 func (e *Event) Uints(key string, i []uint) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendUints(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendUints(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Uint8 adds the field key with i as a uint8 to the *Event context.
 func (e *Event) Uint8(key string, i uint8) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendUint8(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendUint8(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Uints8 adds the field key with i as a []int8 to the *Event context.
 func (e *Event) Uints8(key string, i []uint8) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendUints8(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendUints8(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Uint16 adds the field key with i as a uint16 to the *Event context.
 func (e *Event) Uint16(key string, i uint16) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendUint16(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendUint16(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Uints16 adds the field key with i as a []int16 to the *Event context.
 func (e *Event) Uints16(key string, i []uint16) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendUints16(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendUints16(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Uint32 adds the field key with i as a uint32 to the *Event context.
 func (e *Event) Uint32(key string, i uint32) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendUint32(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendUint32(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Uints32 adds the field key with i as a []int32 to the *Event context.
 func (e *Event) Uints32(key string, i []uint32) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendUints32(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendUints32(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Uint64 adds the field key with i as a uint64 to the *Event context.
 func (e *Event) Uint64(key string, i uint64) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendUint64(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendUint64(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Uints64 adds the field key with i as a []int64 to the *Event context.
 func (e *Event) Uints64(key string, i []uint64) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendUints64(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendUints64(enc.AppendKey(e.buf, key), i)
 	return e
 }
 
 // Float32 adds the field key with f as a float32 to the *Event context.
 func (e *Event) Float32(key string, f float32) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendFloat32(json.AppendKey(e.buf, key), f)
+	e.buf = enc.AppendFloat32(enc.AppendKey(e.buf, key), f)
 	return e
 }
 
 // Floats32 adds the field key with f as a []float32 to the *Event context.
 func (e *Event) Floats32(key string, f []float32) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendFloats32(json.AppendKey(e.buf, key), f)
+	e.buf = enc.AppendFloats32(enc.AppendKey(e.buf, key), f)
 	return e
 }
 
 // Float64 adds the field key with f as a float64 to the *Event context.
 func (e *Event) Float64(key string, f float64) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendFloat64(json.AppendKey(e.buf, key), f)
+	e.buf = enc.AppendFloat64(enc.AppendKey(e.buf, key), f)
 	return e
 }
 
 // Floats64 adds the field key with f as a []float64 to the *Event context.
 func (e *Event) Floats64(key string, f []float64) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendFloats64(json.AppendKey(e.buf, key), f)
+	e.buf = enc.AppendFloats64(enc.AppendKey(e.buf, key), f)
 	return e
 }
 
 // Timestamp adds the current local time as UNIX timestamp to the *Event context with the "time" key.
 // To customize the key name, change zerolog.TimestampFieldName.
+//
+// NOTE: It won't dedupe the "time" key if the *Event (or *Context) has one
+// already.
 func (e *Event) Timestamp() *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendTime(json.AppendKey(e.buf, TimestampFieldName), TimestampFunc(), TimeFieldFormat)
+	e.buf = enc.AppendTime(enc.AppendKey(e.buf, TimestampFieldName), TimestampFunc(), TimeFieldFormat)
 	return e
 }
 
 // Time adds the field key with t formated as string using zerolog.TimeFieldFormat.
 func (e *Event) Time(key string, t time.Time) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendTime(json.AppendKey(e.buf, key), t, TimeFieldFormat)
+	e.buf = enc.AppendTime(enc.AppendKey(e.buf, key), t, TimeFieldFormat)
 	return e
 }
 
 // Times adds the field key with t formated as string using zerolog.TimeFieldFormat.
 func (e *Event) Times(key string, t []time.Time) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendTimes(json.AppendKey(e.buf, key), t, TimeFieldFormat)
+	e.buf = enc.AppendTimes(enc.AppendKey(e.buf, key), t, TimeFieldFormat)
 	return e
 }
 
@@ -509,10 +543,10 @@ func (e *Event) Times(key string, t []time.Time) *Event {
 // If zerolog.DurationFieldInteger is true, durations are rendered as integer
 // instead of float.
 func (e *Event) Dur(key string, d time.Duration) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendDuration(json.AppendKey(e.buf, key), d, DurationFieldUnit, DurationFieldInteger)
+	e.buf = enc.AppendDuration(enc.AppendKey(e.buf, key), d, DurationFieldUnit, DurationFieldInteger)
 	return e
 }
 
@@ -520,10 +554,10 @@ func (e *Event) Dur(key string, d time.Duration) *Event {
 // If zerolog.DurationFieldInteger is true, durations are rendered as integer
 // instead of float.
 func (e *Event) Durs(key string, d []time.Duration) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
-	e.buf = json.AppendDurations(json.AppendKey(e.buf, key), d, DurationFieldUnit, DurationFieldInteger)
+	e.buf = enc.AppendDurations(enc.AppendKey(e.buf, key), d, DurationFieldUnit, DurationFieldInteger)
 	return e
 }
 
@@ -531,25 +565,69 @@ func (e *Event) Durs(key string, d []time.Duration) *Event {
 // If time t is not greater than start, duration will be 0.
 // Duration format follows the same principle as Dur().
 func (e *Event) TimeDiff(key string, t time.Time, start time.Time) *Event {
-	if !e.enabled {
+	if e == nil {
 		return e
 	}
 	var d time.Duration
 	if t.After(start) {
 		d = t.Sub(start)
 	}
-	e.buf = json.AppendDuration(json.AppendKey(e.buf, key), d, DurationFieldUnit, DurationFieldInteger)
+	e.buf = enc.AppendDuration(enc.AppendKey(e.buf, key), d, DurationFieldUnit, DurationFieldInteger)
 	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
 	}
 	if obj, ok := i.(LogObjectMarshaler); ok {
 		return e.Object(key, obj)
 	}
-	e.buf = json.AppendInterface(json.AppendKey(e.buf, key), i)
+	e.buf = enc.AppendInterface(enc.AppendKey(e.buf, key), i)
+	return e
+}
+
+// Caller adds the file:line of the caller with the zerolog.CallerFieldName key.
+func (e *Event) Caller() *Event {
+	return e.caller(CallerSkipFrameCount)
+}
+
+func (e *Event) caller(skip int) *Event {
+	if e == nil {
+		return e
+	}
+	_, file, line, ok := runtime.Caller(skip)
+	if !ok {
+		return e
+	}
+	e.buf = enc.AppendString(enc.AppendKey(e.buf, CallerFieldName), file+":"+strconv.Itoa(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
 }

fields.go

@@ -1,10 +1,9 @@
 package zerolog
 
 import (
+	"net"
 	"sort"
 	"time"
-
-	"github.com/rs/zerolog/internal/json"
 )
 
 func appendFields(dst []byte, fields map[string]interface{}) []byte {
@@ -14,82 +13,129 @@ func appendFields(dst []byte, fields map[string]interface{}) []byte {
 	}
 	sort.Strings(keys)
 	for _, key := range keys {
-		dst = json.AppendKey(dst, key)
-		switch val := fields[key].(type) {
+		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...)
+			eventPool.Put(e)
+			continue
+		}
+		switch val := val.(type) {
 		case string:
-			dst = json.AppendString(dst, val)
+			dst = enc.AppendString(dst, val)
 		case []byte:
-			dst = json.AppendBytes(dst, val)
+			dst = enc.AppendBytes(dst, val)
 		case error:
-			dst = json.AppendError(dst, val)
+			dst = enc.AppendError(dst, val)
 		case []error:
-			dst = json.AppendErrors(dst, val)
+			dst = enc.AppendErrors(dst, val)
 		case bool:
-			dst = json.AppendBool(dst, val)
+			dst = enc.AppendBool(dst, val)
 		case int:
-			dst = json.AppendInt(dst, val)
+			dst = enc.AppendInt(dst, val)
 		case int8:
-			dst = json.AppendInt8(dst, val)
+			dst = enc.AppendInt8(dst, val)
 		case int16:
-			dst = json.AppendInt16(dst, val)
+			dst = enc.AppendInt16(dst, val)
 		case int32:
-			dst = json.AppendInt32(dst, val)
+			dst = enc.AppendInt32(dst, val)
 		case int64:
-			dst = json.AppendInt64(dst, val)
+			dst = enc.AppendInt64(dst, val)
 		case uint:
-			dst = json.AppendUint(dst, val)
+			dst = enc.AppendUint(dst, val)
 		case uint8:
-			dst = json.AppendUint8(dst, val)
+			dst = enc.AppendUint8(dst, val)
 		case uint16:
-			dst = json.AppendUint16(dst, val)
+			dst = enc.AppendUint16(dst, val)
 		case uint32:
-			dst = json.AppendUint32(dst, val)
+			dst = enc.AppendUint32(dst, val)
 		case uint64:
-			dst = json.AppendUint64(dst, val)
+			dst = enc.AppendUint64(dst, val)
 		case float32:
-			dst = json.AppendFloat32(dst, val)
+			dst = enc.AppendFloat32(dst, val)
 		case float64:
-			dst = json.AppendFloat64(dst, val)
+			dst = enc.AppendFloat64(dst, val)
 		case time.Time:
-			dst = json.AppendTime(dst, val, TimeFieldFormat)
+			dst = enc.AppendTime(dst, val, TimeFieldFormat)
 		case time.Duration:
-			dst = json.AppendDuration(dst, val, DurationFieldUnit, DurationFieldInteger)
+			dst = enc.AppendDuration(dst, val, DurationFieldUnit, DurationFieldInteger)
+		case *string:
+			dst = enc.AppendString(dst, *val)
+		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:
-			dst = json.AppendStrings(dst, val)
+			dst = enc.AppendStrings(dst, val)
 		case []bool:
-			dst = json.AppendBools(dst, val)
+			dst = enc.AppendBools(dst, val)
 		case []int:
-			dst = json.AppendInts(dst, val)
+			dst = enc.AppendInts(dst, val)
 		case []int8:
-			dst = json.AppendInts8(dst, val)
+			dst = enc.AppendInts8(dst, val)
 		case []int16:
-			dst = json.AppendInts16(dst, val)
+			dst = enc.AppendInts16(dst, val)
 		case []int32:
-			dst = json.AppendInts32(dst, val)
+			dst = enc.AppendInts32(dst, val)
 		case []int64:
-			dst = json.AppendInts64(dst, val)
+			dst = enc.AppendInts64(dst, val)
 		case []uint:
-			dst = json.AppendUints(dst, val)
+			dst = enc.AppendUints(dst, val)
 		// case []uint8:
-		// 	dst = appendUints8(dst, val)
+		// 	dst = enc.AppendUints8(dst, val)
 		case []uint16:
-			dst = json.AppendUints16(dst, val)
+			dst = enc.AppendUints16(dst, val)
 		case []uint32:
-			dst = json.AppendUints32(dst, val)
+			dst = enc.AppendUints32(dst, val)
 		case []uint64:
-			dst = json.AppendUints64(dst, val)
+			dst = enc.AppendUints64(dst, val)
 		case []float32:
-			dst = json.AppendFloats32(dst, val)
+			dst = enc.AppendFloats32(dst, val)
 		case []float64:
-			dst = json.AppendFloats64(dst, val)
+			dst = enc.AppendFloats64(dst, val)
 		case []time.Time:
-			dst = json.AppendTimes(dst, val, TimeFieldFormat)
+			dst = enc.AppendTimes(dst, val, TimeFieldFormat)
 		case []time.Duration:
-			dst = json.AppendDurations(dst, val, DurationFieldUnit, DurationFieldInteger)
+			dst = enc.AppendDurations(dst, val, DurationFieldUnit, DurationFieldInteger)
 		case nil:
-			dst = append(dst, "null"...)
+			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)
 		default:
-			dst = json.AppendInterface(dst, val)
+			dst = enc.AppendInterface(dst, val)
 		}
 	}
 	return dst

globals.go

@@ -16,8 +16,11 @@ var (
 	// 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"
+
+	// CallerSkipFrameCount is the number of stack frames to skip to find the caller.
+	CallerSkipFrameCount = 2
 
 	// TimeFieldFormat defines the time format of the Time field type.
 	// If set to an empty string, the time is formatted as an UNIX timestamp
@@ -49,7 +52,8 @@ func SetGlobalLevel(l Level) {
 	atomic.StoreUint32(gLevel, uint32(l))
 }
 
-func globalLevel() Level {
+// GlobalLevel returns the current global log level
+func GlobalLevel() Level {
 	return Level(atomic.LoadUint32(gLevel))
 }
 

go.mod

@@ -0,0 +1 @@
+module github.com/rs/zerolog

hlog/hlog.go

@@ -15,7 +15,7 @@ import (
 
 // 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())
 }
 
@@ -23,7 +23,10 @@ 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)
 		})
 	}
@@ -35,8 +38,9 @@ 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)
 		})
 	}
@@ -48,8 +52,9 @@ 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)
 		})
 	}
@@ -61,8 +66,9 @@ 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)
 		})
 	}
@@ -75,8 +81,9 @@ func RemoteAddrHandler(fieldKey string) 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 {
 				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, host)
+				})
 			}
 			next.ServeHTTP(w, r)
 		})
@@ -90,8 +97,9 @@ 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)
 		})
@@ -105,8 +113,9 @@ 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)
 		})
@@ -115,7 +124,7 @@ 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
@@ -136,16 +145,18 @@ 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 = context.WithValue(ctx, idKey{}, 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())

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

@@ -5,6 +5,7 @@ package hlog
 import (
 	"bytes"
 	"fmt"
+	"io/ioutil"
 	"net/http"
 	"net/url"
 	"testing"
@@ -14,8 +15,17 @@ import (
 	"net/http/httptest"
 
 	"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"}`+"\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"}`+"\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 +174,73 @@ 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 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{})
+		}
+	})
+}

hook.go

@@ -0,0 +1,51 @@
+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)
+}
+
+// LevelHook applies a different hook for each level.
+type LevelHook struct {
+	NoLevelHook, 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 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 +1,236 @@
+package zerolog
+
+import (
+	"bytes"
+	"io/ioutil"
+	"testing"
+)
+
+type LevelNameHook struct{}
+
+func (h LevelNameHook) Run(e *Event, level Level, msg string) {
+	levelName := level.String()
+	if level == NoLevel {
+		levelName = "nolevel"
+	}
+	e.Str("level_name", levelName)
+}
+
+type SimpleHook struct{}
+
+func (h SimpleHook) Run(e *Event, level Level, msg string) {
+	e.Bool("has_level", level != NoLevel)
+	e.Str("test", "logged")
+}
+
+type CopyHook struct{}
+
+func (h CopyHook) Run(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)
+}
+
+type NopHook struct{}
+
+func (h NopHook) Run(e *Event, level Level, msg string) {
+}
+
+var (
+	levelNameHook LevelNameHook
+	simpleHook    SimpleHook
+	copyHook      CopyHook
+	nopHook       NopHook
+)
+
+func TestHook(t *testing.T) {
+	t.Run("Message", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).Hook(levelNameHook)
+		log.Log().Msg("test message")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level_name":"nolevel","message":"test message"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+	t.Run("NoLevel", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).Hook(levelNameHook)
+		log.Log().Msg("")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level_name":"nolevel"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+	t.Run("Print", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).Hook(levelNameHook)
+		log.Print("")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"debug","level_name":"debug"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+	t.Run("Error", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).Hook(levelNameHook)
+		log.Error().Msg("")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"error","level_name":"error"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+	t.Run("Copy/1", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).Hook(copyHook)
+		log.Log().Msg("")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"copy_has_level":false,"copy_msg":""}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+	t.Run("Copy/2", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).Hook(copyHook)
+		log.Info().Msg("a message")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"info","copy_has_level":true,"copy_level":"info","copy_msg":"a message","message":"a message"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+	t.Run("Multi", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).Hook(levelNameHook).Hook(simpleHook)
+		log.Error().Msg("")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"error","level_name":"error","has_level":true,"test":"logged"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+	t.Run("Multi/Message", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).Hook(levelNameHook).Hook(simpleHook)
+		log.Error().Msg("a message")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"error","level_name":"error","has_level":true,"test":"logged","message":"a message"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+	t.Run("Output/single/pre", func(t *testing.T) {
+		ignored := &bytes.Buffer{}
+		out := &bytes.Buffer{}
+		log := New(ignored).Hook(levelNameHook).Output(out)
+		log.Error().Msg("")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"error","level_name":"error"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+	t.Run("Output/single/post", func(t *testing.T) {
+		ignored := &bytes.Buffer{}
+		out := &bytes.Buffer{}
+		log := New(ignored).Output(out).Hook(levelNameHook)
+		log.Error().Msg("")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"error","level_name":"error"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+	t.Run("Output/multi/pre", func(t *testing.T) {
+		ignored := &bytes.Buffer{}
+		out := &bytes.Buffer{}
+		log := New(ignored).Hook(levelNameHook).Hook(simpleHook).Output(out)
+		log.Error().Msg("")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"error","level_name":"error","has_level":true,"test":"logged"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+	t.Run("Output/multi/post", func(t *testing.T) {
+		ignored := &bytes.Buffer{}
+		out := &bytes.Buffer{}
+		log := New(ignored).Output(out).Hook(levelNameHook).Hook(simpleHook)
+		log.Error().Msg("")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"error","level_name":"error","has_level":true,"test":"logged"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+	t.Run("Output/mixed", func(t *testing.T) {
+		ignored := &bytes.Buffer{}
+		out := &bytes.Buffer{}
+		log := New(ignored).Hook(levelNameHook).Output(out).Hook(simpleHook)
+		log.Error().Msg("")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"error","level_name":"error","has_level":true,"test":"logged"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+	t.Run("With/single/pre", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).Hook(levelNameHook).With().Str("with", "pre").Logger()
+		log.Error().Msg("")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"error","with":"pre","level_name":"error"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+	t.Run("With/single/post", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).With().Str("with", "post").Logger().Hook(levelNameHook)
+		log.Error().Msg("")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"error","with":"post","level_name":"error"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+	t.Run("With/multi/pre", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).Hook(levelNameHook).Hook(simpleHook).With().Str("with", "pre").Logger()
+		log.Error().Msg("")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"error","with":"pre","level_name":"error","has_level":true,"test":"logged"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+	t.Run("With/multi/post", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).With().Str("with", "post").Logger().Hook(levelNameHook).Hook(simpleHook)
+		log.Error().Msg("")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"error","with":"post","level_name":"error","has_level":true,"test":"logged"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+	t.Run("With/mixed", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).Hook(levelNameHook).With().Str("with", "mixed").Logger().Hook(simpleHook)
+		log.Error().Msg("")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"error","with":"mixed","level_name":"error","has_level":true,"test":"logged"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+	t.Run("None", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out)
+		log.Error().Msg("")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"error"}`+"\n"; 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 +1,45 @@
+package cbor
+
+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)
+}
+
+// AppendError adds the Error to the log message if error is NOT nil
+func (e Encoder) AppendError(dst []byte, err error) []byte {
+	if err == nil {
+		return append(dst, `null`...)
+	}
+	return e.AppendString(dst, err.Error())
+}
+
+// AppendErrors when given an array of errors,
+// adds them to the log message if a specific error is nil, then
+// Nil is added, or else the error string is added.
+func (e Encoder) AppendErrors(dst []byte, errs []error) []byte {
+	if len(errs) == 0 {
+		return e.AppendArrayEnd(e.AppendArrayStart(dst))
+	}
+	dst = e.AppendArrayStart(dst)
+	if errs[0] != nil {
+		dst = e.AppendString(dst, errs[0].Error())
+	} else {
+		dst = e.AppendNil(dst)
+	}
+	if len(errs) > 1 {
+		for _, err := range errs[1:] {
+			if err == nil {
+				dst = e.AppendNil(dst)
+				continue
+			}
+			dst = e.AppendString(dst, err.Error())
+		}
+	}
+	dst = e.AppendArrayEnd(dst)
+	return dst
+}

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 +1,478 @@
+package cbor
+
+import (
+	"encoding/json"
+	"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 := json.Marshal(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_test.go

@@ -0,0 +1,322 @@
+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"},
+	{0xFFFFFFFE, "\x1a\xff\xff\xff\xfe"},
+	{1000000, "\x1a\x00\x0f\x42\x40"},
+	// Value in 8 bytes.
+	{0xabcd100000000, "\x1b\x00\x0a\xbc\xd1\x00\x00\x00\x00"},
+	{1000000000000, "\x1b\x00\x00\x00\xe8\xd4\xa5\x10\x00"},
+	// 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"},
+	{-0xFFFFFFFE, "\x3a\xff\xff\xff\xfd"},
+	{-1000000, "\x3a\x00\x0f\x42\x3f"},
+	// 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(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

@@ -1,27 +1,34 @@
 package json
 
-func AppendKey(dst []byte, key string) []byte {
-	if len(dst) > 1 {
+type Encoder struct{}
+
+// AppendKey appends a new key to the output JSON.
+func (e Encoder) AppendKey(dst []byte, key string) []byte {
+	if len(dst) > 1 && dst[len(dst)-1] != '{' {
 		dst = append(dst, ',')
 	}
-	dst = AppendString(dst, key)
+	dst = e.AppendString(dst, key)
 	return append(dst, ':')
 }
 
-func AppendError(dst []byte, err error) []byte {
+// AppendError encodes the error string to json and appends
+// the encoded string to the input byte slice.
+func (e Encoder) AppendError(dst []byte, err error) []byte {
 	if err == nil {
 		return append(dst, `null`...)
 	}
-	return AppendString(dst, err.Error())
+	return e.AppendString(dst, err.Error())
 }
 
-func AppendErrors(dst []byte, errs []error) []byte {
+// AppendErrors encodes the error strings to json and
+// appends the encoded string list to the input byte slice.
+func (e Encoder) AppendErrors(dst []byte, errs []error) []byte {
 	if len(errs) == 0 {
 		return append(dst, '[', ']')
 	}
 	dst = append(dst, '[')
 	if errs[0] != nil {
-		dst = AppendString(dst, errs[0].Error())
+		dst = e.AppendString(dst, errs[0].Error())
 	} else {
 		dst = append(dst, "null"...)
 	}
@@ -31,7 +38,7 @@ func AppendErrors(dst []byte, errs []error) []byte {
 				dst = append(dst, ",null"...)
 				continue
 			}
-			dst = AppendString(append(dst, ','), err.Error())
+			dst = e.AppendString(append(dst, ','), err.Error())
 		}
 	}
 	dst = append(dst, ']')

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

@@ -4,15 +4,25 @@ import "unicode/utf8"
 
 const hex = "0123456789abcdef"
 
-func AppendStrings(dst []byte, vals []string) []byte {
+var noEscapeTable = [256]bool{}
+
+func init() {
+	for i := 0; i <= 0x7e; i++ {
+		noEscapeTable[i] = i >= 0x20 && i != '\\' && i != '"'
+	}
+}
+
+// AppendStrings encodes the input strings to json and
+// appends the encoded string list to the input byte slice.
+func (e Encoder) AppendStrings(dst []byte, vals []string) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
 	dst = append(dst, '[')
-	dst = AppendString(dst, vals[0])
+	dst = e.AppendString(dst, vals[0])
 	if len(vals) > 1 {
 		for _, val := range vals[1:] {
-			dst = AppendString(append(dst, ','), val)
+			dst = e.AppendString(append(dst, ','), val)
 		}
 	}
 	dst = append(dst, ']')
@@ -28,7 +38,7 @@ func AppendStrings(dst []byte, vals []string) []byte {
 // entirety to the byte slice.
 // If we encounter a byte that does need encoding, switch up
 // the operation and perform a byte-by-byte read-encode-append.
-func AppendString(dst []byte, s string) []byte {
+func (Encoder) AppendString(dst []byte, s string) []byte {
 	// Start with a double quote.
 	dst = append(dst, '"')
 	// Loop through each character in the string.
@@ -36,7 +46,7 @@ func AppendString(dst []byte, s string) []byte {
 		// Check if the character needs encoding. Control characters, slashes,
 		// and the double quote need json encoding. Bytes above the ascii
 		// boundary needs utf8 encoding.
-		if s[i] < 0x20 || s[i] > 0x7e || s[i] == '\\' || s[i] == '"' {
+		if !noEscapeTable[s[i]] {
 			// We encountered a character that needs to be encoded. Switch
 			// to complex version of the algorithm.
 			dst = appendStringComplex(dst, s, i)
@@ -74,76 +84,7 @@ func appendStringComplex(dst []byte, s string, i int) []byte {
 			i += size
 			continue
 		}
-		if b >= 0x20 && b <= 0x7e && b != '\\' && b != '"' {
-			i++
-			continue
-		}
-		// We encountered a character that needs to be encoded.
-		// Let's append the previous simple characters to the byte slice
-		// and switch our operation to read and encode the remainder
-		// characters byte-by-byte.
-		if start < i {
-			dst = append(dst, s[start:i]...)
-		}
-		switch b {
-		case '"', '\\':
-			dst = append(dst, '\\', b)
-		case '\b':
-			dst = append(dst, '\\', 'b')
-		case '\f':
-			dst = append(dst, '\\', 'f')
-		case '\n':
-			dst = append(dst, '\\', 'n')
-		case '\r':
-			dst = append(dst, '\\', 'r')
-		case '\t':
-			dst = append(dst, '\\', 't')
-		default:
-			dst = append(dst, '\\', 'u', '0', '0', hex[b>>4], hex[b&0xF])
-		}
-		i++
-		start = i
-	}
-	if start < len(s) {
-		dst = append(dst, s[start:]...)
-	}
-	return dst
-}
-
-// AppendBytes is a mirror of appendString with []byte arg
-func AppendBytes(dst, s []byte) []byte {
-	dst = append(dst, '"')
-	for i := 0; i < len(s); i++ {
-		if s[i] < 0x20 || s[i] > 0x7e || s[i] == '\\' || s[i] == '"' {
-			dst = appendBytesComplex(dst, s, i)
-			return append(dst, '"')
-		}
-	}
-	dst = append(dst, s...)
-	return append(dst, '"')
-}
-
-// appendBytesComplex is a mirror of the appendStringComplex
-// with []byte arg
-func appendBytesComplex(dst, s []byte, i int) []byte {
-	start := 0
-	for i < len(s) {
-		b := s[i]
-		if b >= utf8.RuneSelf {
-			r, size := utf8.DecodeRune(s[i:])
-			if r == utf8.RuneError && size == 1 {
-				if start < i {
-					dst = append(dst, s[start:i]...)
-				}
-				dst = append(dst, `\ufffd`...)
-				i += size
-				start = i
-				continue
-			}
-			i += size
-			continue
-		}
-		if b >= 0x20 && b <= 0x7e && b != '\\' && b != '"' {
+		if noEscapeTable[b] {
 			i++
 			continue
 		}

internal/json/string_test.go

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

internal/json/time.go

@@ -5,14 +5,18 @@ import (
 	"time"
 )
 
-func AppendTime(dst []byte, t time.Time, format string) []byte {
+// 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 {
 	if format == "" {
-		return AppendInt64(dst, t.Unix())
+		return e.AppendInt64(dst, t.Unix())
 	}
 	return append(t.AppendFormat(append(dst, '"'), format), '"')
 }
 
-func AppendTimes(dst []byte, vals []time.Time, format string) []byte {
+// 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 {
 	if format == "" {
 		return appendUnixTimes(dst, vals)
 	}
@@ -38,29 +42,33 @@ func appendUnixTimes(dst []byte, vals []time.Time) []byte {
 	dst = strconv.AppendInt(dst, vals[0].Unix(), 10)
 	if len(vals) > 1 {
 		for _, t := range vals[1:] {
-			dst = strconv.AppendInt(dst, t.Unix(), 10)
+			dst = strconv.AppendInt(append(dst, ','), t.Unix(), 10)
 		}
 	}
 	dst = append(dst, ']')
 	return dst
 }
 
-func AppendDuration(dst []byte, d time.Duration, unit time.Duration, useInt bool) []byte {
+// 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 AppendFloat64(dst, float64(d)/float64(unit))
+	return e.AppendFloat64(dst, float64(d)/float64(unit))
 }
 
-func AppendDurations(dst []byte, vals []time.Duration, unit time.Duration, useInt bool) []byte {
+// 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 = AppendDuration(dst, vals[0], unit, useInt)
+	dst = e.AppendDuration(dst, vals[0], unit, useInt)
 	if len(vals) > 1 {
 		for _, d := range vals[1:] {
-			dst = AppendDuration(append(dst, ','), d, unit, useInt)
+			dst = e.AppendDuration(append(dst, ','), d, unit, useInt)
 		}
 	}
 	dst = append(dst, ']')

internal/json/types.go

@@ -4,14 +4,57 @@ import (
 	"encoding/json"
 	"fmt"
 	"math"
+	"net"
 	"strconv"
 )
 
-func AppendBool(dst []byte, val bool) []byte {
+// AppendNil inserts a 'Nil' object into the dst byte array.
+func (Encoder) AppendNil(dst []byte) []byte {
+	return append(dst, "null"...)
+}
+
+// AppendBeginMarker inserts a map start into the dst byte array.
+func (Encoder) AppendBeginMarker(dst []byte) []byte {
+	return append(dst, '{')
+}
+
+// AppendEndMarker inserts a map end into the dst byte array.
+func (Encoder) AppendEndMarker(dst []byte) []byte {
+	return append(dst, '}')
+}
+
+// AppendLineBreak appends a line break.
+func (Encoder) AppendLineBreak(dst []byte) []byte {
+	return append(dst, '\n')
+}
+
+// AppendArrayStart adds markers to indicate the start of an array.
+func (Encoder) AppendArrayStart(dst []byte) []byte {
+	return append(dst, '[')
+}
+
+// AppendArrayEnd adds markers to indicate the end of an array.
+func (Encoder) AppendArrayEnd(dst []byte) []byte {
+	return append(dst, ']')
+}
+
+// AppendArrayDelim adds markers to indicate end of a particular array element.
+func (Encoder) AppendArrayDelim(dst []byte) []byte {
+	if len(dst) > 0 {
+		return append(dst, ',')
+	}
+	return dst
+}
+
+// AppendBool converts the input bool to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendBool(dst []byte, val bool) []byte {
 	return strconv.AppendBool(dst, val)
 }
 
-func AppendBools(dst []byte, vals []bool) []byte {
+// AppendBools encodes the input bools to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendBools(dst []byte, vals []bool) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -26,11 +69,15 @@ func AppendBools(dst []byte, vals []bool) []byte {
 	return dst
 }
 
-func AppendInt(dst []byte, val int) []byte {
+// AppendInt converts the input int to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendInt(dst []byte, val int) []byte {
 	return strconv.AppendInt(dst, int64(val), 10)
 }
 
-func AppendInts(dst []byte, vals []int) []byte {
+// AppendInts encodes the input ints to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendInts(dst []byte, vals []int) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -45,11 +92,15 @@ func AppendInts(dst []byte, vals []int) []byte {
 	return dst
 }
 
-func AppendInt8(dst []byte, val int8) []byte {
+// AppendInt8 converts the input []int8 to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendInt8(dst []byte, val int8) []byte {
 	return strconv.AppendInt(dst, int64(val), 10)
 }
 
-func AppendInts8(dst []byte, vals []int8) []byte {
+// AppendInts8 encodes the input int8s to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendInts8(dst []byte, vals []int8) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -64,11 +115,15 @@ func AppendInts8(dst []byte, vals []int8) []byte {
 	return dst
 }
 
-func AppendInt16(dst []byte, val int16) []byte {
+// AppendInt16 converts the input int16 to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendInt16(dst []byte, val int16) []byte {
 	return strconv.AppendInt(dst, int64(val), 10)
 }
 
-func AppendInts16(dst []byte, vals []int16) []byte {
+// AppendInts16 encodes the input int16s to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendInts16(dst []byte, vals []int16) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -83,11 +138,15 @@ func AppendInts16(dst []byte, vals []int16) []byte {
 	return dst
 }
 
-func AppendInt32(dst []byte, val int32) []byte {
+// AppendInt32 converts the input int32 to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendInt32(dst []byte, val int32) []byte {
 	return strconv.AppendInt(dst, int64(val), 10)
 }
 
-func AppendInts32(dst []byte, vals []int32) []byte {
+// AppendInts32 encodes the input int32s to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendInts32(dst []byte, vals []int32) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -102,11 +161,15 @@ func AppendInts32(dst []byte, vals []int32) []byte {
 	return dst
 }
 
-func AppendInt64(dst []byte, val int64) []byte {
+// AppendInt64 converts the input int64 to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendInt64(dst []byte, val int64) []byte {
 	return strconv.AppendInt(dst, val, 10)
 }
 
-func AppendInts64(dst []byte, vals []int64) []byte {
+// AppendInts64 encodes the input int64s to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendInts64(dst []byte, vals []int64) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -121,11 +184,15 @@ func AppendInts64(dst []byte, vals []int64) []byte {
 	return dst
 }
 
-func AppendUint(dst []byte, val uint) []byte {
+// AppendUint converts the input uint to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendUint(dst []byte, val uint) []byte {
 	return strconv.AppendUint(dst, uint64(val), 10)
 }
 
-func AppendUints(dst []byte, vals []uint) []byte {
+// AppendUints encodes the input uints to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendUints(dst []byte, vals []uint) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -140,11 +207,15 @@ func AppendUints(dst []byte, vals []uint) []byte {
 	return dst
 }
 
-func AppendUint8(dst []byte, val uint8) []byte {
+// AppendUint8 converts the input uint8 to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendUint8(dst []byte, val uint8) []byte {
 	return strconv.AppendUint(dst, uint64(val), 10)
 }
 
-func AppendUints8(dst []byte, vals []uint8) []byte {
+// AppendUints8 encodes the input uint8s to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendUints8(dst []byte, vals []uint8) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -159,11 +230,15 @@ func AppendUints8(dst []byte, vals []uint8) []byte {
 	return dst
 }
 
-func AppendUint16(dst []byte, val uint16) []byte {
+// AppendUint16 converts the input uint16 to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendUint16(dst []byte, val uint16) []byte {
 	return strconv.AppendUint(dst, uint64(val), 10)
 }
 
-func AppendUints16(dst []byte, vals []uint16) []byte {
+// AppendUints16 encodes the input uint16s to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendUints16(dst []byte, vals []uint16) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -178,11 +253,15 @@ func AppendUints16(dst []byte, vals []uint16) []byte {
 	return dst
 }
 
-func AppendUint32(dst []byte, val uint32) []byte {
+// AppendUint32 converts the input uint32 to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendUint32(dst []byte, val uint32) []byte {
 	return strconv.AppendUint(dst, uint64(val), 10)
 }
 
-func AppendUints32(dst []byte, vals []uint32) []byte {
+// AppendUints32 encodes the input uint32s to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendUints32(dst []byte, vals []uint32) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -197,11 +276,15 @@ func AppendUints32(dst []byte, vals []uint32) []byte {
 	return dst
 }
 
-func AppendUint64(dst []byte, val uint64) []byte {
+// 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)
 }
 
-func AppendUints64(dst []byte, vals []uint64) []byte {
+// AppendUints64 encodes the input uint64s to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendUints64(dst []byte, vals []uint64) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
@@ -216,7 +299,7 @@ func AppendUints64(dst []byte, vals []uint64) []byte {
 	return dst
 }
 
-func AppendFloat(dst []byte, val float64, bitSize int) []byte {
+func appendFloat(dst []byte, val float64, bitSize 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.
@@ -231,48 +314,89 @@ func AppendFloat(dst []byte, val float64, bitSize int) []byte {
 	return strconv.AppendFloat(dst, val, 'f', -1, bitSize)
 }
 
-func AppendFloat32(dst []byte, val float32) []byte {
-	return AppendFloat(dst, float64(val), 32)
+// AppendFloat32 converts the input float32 to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendFloat32(dst []byte, val float32) []byte {
+	return appendFloat(dst, float64(val), 32)
 }
 
-func AppendFloats32(dst []byte, vals []float32) []byte {
+// AppendFloats32 encodes the input float32s to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendFloats32(dst []byte, vals []float32) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
 	dst = append(dst, '[')
-	dst = AppendFloat(dst, float64(vals[0]), 32)
+	dst = appendFloat(dst, float64(vals[0]), 32)
 	if len(vals) > 1 {
 		for _, val := range vals[1:] {
-			dst = AppendFloat(append(dst, ','), float64(val), 32)
+			dst = appendFloat(append(dst, ','), float64(val), 32)
 		}
 	}
 	dst = append(dst, ']')
 	return dst
 }
 
-func AppendFloat64(dst []byte, val float64) []byte {
-	return AppendFloat(dst, val, 64)
+// AppendFloat64 converts the input float64 to a string and
+// appends the encoded string to the input byte slice.
+func (Encoder) AppendFloat64(dst []byte, val float64) []byte {
+	return appendFloat(dst, val, 64)
 }
 
-func AppendFloats64(dst []byte, vals []float64) []byte {
+// AppendFloats64 encodes the input float64s to json and
+// appends the encoded string list to the input byte slice.
+func (Encoder) AppendFloats64(dst []byte, vals []float64) []byte {
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
 	}
 	dst = append(dst, '[')
-	dst = AppendFloat(dst, vals[0], 32)
+	dst = appendFloat(dst, vals[0], 32)
 	if len(vals) > 1 {
 		for _, val := range vals[1:] {
-			dst = AppendFloat(append(dst, ','), val, 64)
+			dst = appendFloat(append(dst, ','), val, 64)
 		}
 	}
 	dst = append(dst, ']')
 	return dst
 }
 
-func AppendInterface(dst []byte, i interface{}) []byte {
+// 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 := json.Marshal(i)
 	if err != nil {
-		return AppendString(dst, fmt.Sprintf("marshaling error: %v", err))
+		return e.AppendString(dst, fmt.Sprintf("marshaling error: %v", err))
 	}
 	return append(dst, marshaled...)
 }
+
+// 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 {
+	// Two conditions we want to put a ',' between existing content and
+	// new content:
+	// 1. new content starts with '{' - which shd be dropped   OR
+	// 2. existing content has already other fields
+	if o[0] == '{' {
+		o[0] = ','
+	} 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

@@ -2,31 +2,165 @@ package json
 
 import (
 	"math"
+	"net"
 	"reflect"
 	"testing"
 )
 
-func Test_appendFloat64(t *testing.T) {
+func TestAppendType(t *testing.T) {
+	w := map[string]func(interface{}) []byte{
+		"AppendInt":     func(v interface{}) []byte { return enc.AppendInt([]byte{}, v.(int)) },
+		"AppendInt8":    func(v interface{}) []byte { return enc.AppendInt8([]byte{}, v.(int8)) },
+		"AppendInt16":   func(v interface{}) []byte { return enc.AppendInt16([]byte{}, v.(int16)) },
+		"AppendInt32":   func(v interface{}) []byte { return enc.AppendInt32([]byte{}, v.(int32)) },
+		"AppendInt64":   func(v interface{}) []byte { return enc.AppendInt64([]byte{}, v.(int64)) },
+		"AppendUint":    func(v interface{}) []byte { return enc.AppendUint([]byte{}, v.(uint)) },
+		"AppendUint8":   func(v interface{}) []byte { return enc.AppendUint8([]byte{}, v.(uint8)) },
+		"AppendUint16":  func(v interface{}) []byte { return enc.AppendUint16([]byte{}, v.(uint16)) },
+		"AppendUint32":  func(v interface{}) []byte { return enc.AppendUint32([]byte{}, v.(uint32)) },
+		"AppendUint64":  func(v interface{}) []byte { return enc.AppendUint64([]byte{}, v.(uint64)) },
+		"AppendFloat32": func(v interface{}) []byte { return enc.AppendFloat32([]byte{}, v.(float32)) },
+		"AppendFloat64": func(v interface{}) []byte { return enc.AppendFloat64([]byte{}, v.(float64)) },
+	}
 	tests := []struct {
 		name  string
-		input float64
+		fn    string
+		input interface{}
 		want  []byte
 	}{
-		{"-Inf", math.Inf(-1), []byte(`"-Inf"`)},
-		{"+Inf", math.Inf(1), []byte(`"+Inf"`)},
-		{"NaN", math.NaN(), []byte(`"NaN"`)},
-		{"0", 0, []byte(`0`)},
-		{"-1.1", -1.1, []byte(`-1.1`)},
-		{"1e20", 1e20, []byte(`100000000000000000000`)},
-		{"1e21", 1e21, []byte(`1000000000000000000000`)},
+		{"AppendInt8(math.MaxInt8)", "AppendInt8", int8(math.MaxInt8), []byte("127")},
+		{"AppendInt16(math.MaxInt16)", "AppendInt16", int16(math.MaxInt16), []byte("32767")},
+		{"AppendInt32(math.MaxInt32)", "AppendInt32", int32(math.MaxInt32), []byte("2147483647")},
+		{"AppendInt64(math.MaxInt64)", "AppendInt64", int64(math.MaxInt64), []byte("9223372036854775807")},
+
+		{"AppendUint8(math.MaxUint8)", "AppendUint8", uint8(math.MaxUint8), []byte("255")},
+		{"AppendUint16(math.MaxUint16)", "AppendUint16", uint16(math.MaxUint16), []byte("65535")},
+		{"AppendUint32(math.MaxUint32)", "AppendUint32", uint32(math.MaxUint32), []byte("4294967295")},
+		{"AppendUint64(math.MaxUint64)", "AppendUint64", uint64(math.MaxUint64), []byte("18446744073709551615")},
+
+		{"AppendFloat32(-Inf)", "AppendFloat32", float32(math.Inf(-1)), []byte(`"-Inf"`)},
+		{"AppendFloat32(+Inf)", "AppendFloat32", float32(math.Inf(1)), []byte(`"+Inf"`)},
+		{"AppendFloat32(NaN)", "AppendFloat32", float32(math.NaN()), []byte(`"NaN"`)},
+		{"AppendFloat32(0)", "AppendFloat32", float32(0), []byte(`0`)},
+		{"AppendFloat32(-1.1)", "AppendFloat32", float32(-1.1), []byte(`-1.1`)},
+		{"AppendFloat32(1e20)", "AppendFloat32", float32(1e20), []byte(`100000000000000000000`)},
+		{"AppendFloat32(1e21)", "AppendFloat32", float32(1e21), []byte(`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 := AppendFloat32([]byte{}, float32(tt.input)); !reflect.DeepEqual(got, tt.want) {
-				t.Errorf("appendFloat32() = %s, want %s", got, tt.want)
-			}
-			if got := AppendFloat64([]byte{}, tt.input); !reflect.DeepEqual(got, tt.want) {
-				t.Errorf("appendFloat32() = %s, want %s", got, tt.want)
+			if got := w[tt.fn](tt.input); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("got %s, want %s", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_appendMAC(t *testing.T) {
+	MACtests := []struct {
+		input string
+		want  []byte
+	}{
+		{"01:23:45:67:89:ab", []byte(`"01:23:45:67:89:ab"`)},
+		{"cd:ef:11:22:33:44", []byte(`"cd:ef:11:22:33:44"`)},
+	}
+	for _, tt := range MACtests {
+		t.Run("MAC", func(t *testing.T) {
+			ha, _ := net.ParseMAC(tt.input)
+			if got := enc.AppendMACAddr([]byte{}, ha); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("appendMACAddr() = %s, want %s", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_appendIP(t *testing.T) {
+	IPv4tests := []struct {
+		input net.IP
+		want  []byte
+	}{
+		{net.IP{0, 0, 0, 0}, []byte(`"0.0.0.0"`)},
+		{net.IP{192, 0, 2, 200}, []byte(`"192.0.2.200"`)},
+	}
+
+	for _, tt := range IPv4tests {
+		t.Run("IPv4", func(t *testing.T) {
+			if got := enc.AppendIPAddr([]byte{}, tt.input); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("appendIPAddr() = %s, want %s", got, tt.want)
+			}
+		})
+	}
+	IPv6tests := []struct {
+		input net.IP
+		want  []byte
+	}{
+		{net.IPv6zero, []byte(`"::"`)},
+		{net.IPv6linklocalallnodes, []byte(`"ff02::1"`)},
+		{net.IP{0x20, 0x01, 0x0d, 0xb8, 0x85, 0xa3, 0x00, 0x00, 0x00, 0x00, 0x8a, 0x2e, 0x03, 0x70, 0x73, 0x34}, []byte(`"2001:db8:85a3::8a2e:370:7334"`)},
+	}
+	for _, tt := range IPv6tests {
+		t.Run("IPv6", func(t *testing.T) {
+			if got := enc.AppendIPAddr([]byte{}, tt.input); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("appendIPAddr() = %s, want %s", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_appendIPPrefix(t *testing.T) {
+	IPv4Prefixtests := []struct {
+		input net.IPNet
+		want  []byte
+	}{
+		{net.IPNet{IP: net.IP{0, 0, 0, 0}, Mask: net.IPv4Mask(0, 0, 0, 0)}, []byte(`"0.0.0.0/0"`)},
+		{net.IPNet{IP: net.IP{192, 0, 2, 200}, Mask: net.IPv4Mask(255, 255, 255, 0)}, []byte(`"192.0.2.200/24"`)},
+	}
+	for _, tt := range IPv4Prefixtests {
+		t.Run("IPv4", func(t *testing.T) {
+			if got := enc.AppendIPPrefix([]byte{}, tt.input); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("appendIPPrefix() = %s, want %s", got, tt.want)
+			}
+		})
+	}
+	IPv6Prefixtests := []struct {
+		input net.IPNet
+		want  []byte
+	}{
+		{net.IPNet{IP: net.IPv6zero, Mask: net.CIDRMask(0, 128)}, []byte(`"::/0"`)},
+		{net.IPNet{IP: net.IPv6linklocalallnodes, Mask: net.CIDRMask(128, 128)}, []byte(`"ff02::1/128"`)},
+		{net.IPNet{IP: net.IP{0x20, 0x01, 0x0d, 0xb8, 0x85, 0xa3, 0x00, 0x00, 0x00, 0x00, 0x8a, 0x2e, 0x03, 0x70, 0x73, 0x34},
+			Mask: net.CIDRMask(64, 128)},
+			[]byte(`"2001:db8:85a3::8a2e:370:7334/64"`)},
+	}
+	for _, tt := range IPv6Prefixtests {
+		t.Run("IPv6", func(t *testing.T) {
+			if got := enc.AppendIPPrefix([]byte{}, tt.input); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("appendIPPrefix() = %s, want %s", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_appendMac(t *testing.T) {
+	MACtests := []struct {
+		input net.HardwareAddr
+		want  []byte
+	}{
+		{net.HardwareAddr{0x12, 0x34, 0x56, 0x78, 0x90, 0xab}, []byte(`"12:34:56:78:90:ab"`)},
+		{net.HardwareAddr{0x12, 0x34, 0x00, 0x00, 0x90, 0xab}, []byte(`"12:34:00:00:90:ab"`)},
+	}
+
+	for _, tt := range MACtests {
+		t.Run("MAC", func(t *testing.T) {
+			if got := enc.AppendMACAddr([]byte{}, tt.input); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("appendMAC() = %s, want %s", got, tt.want)
 			}
 		})
 	}

journald/journald.go

@@ -0,0 +1,115 @@
+// +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"
+	"github.com/coreos/go-systemd/journal"
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/internal/cbor"
+	"io"
+	"strings"
+)
+
+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.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{}
+	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)
+	return
+}

journald/journald_test.go

@@ -0,0 +1,44 @@
+// +build !windows
+
+package journald_test
+
+import "github.com/rs/zerolog"
+import "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
+*/

log.go

@@ -62,19 +62,48 @@
 //
 // 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"}
+//
+// However, it’s not a big deal though as JSON accepts dup keys,
+// the last one prevails.
 package zerolog
 
 import (
+	"fmt"
 	"io"
 	"io/ioutil"
 	"os"
 	"strconv"
-	"sync/atomic"
-
-	"github.com/rs/zerolog/internal/json"
 )
 
 // Level defines log levels.
@@ -93,6 +122,8 @@ const (
 	FatalLevel
 	// PanicLevel defines panic log level.
 	PanicLevel
+	// NoLevel defines an absent log level.
+	NoLevel
 	// Disabled disables the logger.
 	Disabled
 )
@@ -111,20 +142,33 @@ func (l Level) String() string {
 		return "fatal"
 	case PanicLevel:
 		return "panic"
+	case NoLevel:
+		return ""
 	}
 	return ""
 }
 
-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 DebugLevel.String():
+		return DebugLevel, nil
+	case InfoLevel.String():
+		return InfoLevel, nil
+	case WarnLevel.String():
+		return WarnLevel, nil
+	case ErrorLevel.String():
+		return ErrorLevel, nil
+	case FatalLevel.String():
+		return FatalLevel, nil
+	case PanicLevel.String():
+		return PanicLevel, nil
+	case NoLevel.String():
+		return NoLevel, nil
+	}
+	return NoLevel, fmt.Errorf("Unknown Level String: '%s', defaulting to NoLevel", levelStr)
+}
 
 // A Logger represents an active logging object that generates lines
 // of JSON output to an io.Writer. Each logging operation makes a single
@@ -134,9 +178,9 @@ var disabledEvent = newEvent(levelWriterAdapter{ioutil.Discard}, 0, false)
 type Logger struct {
 	w       LevelWriter
 	level   Level
-	sample  uint32
-	counter *uint32
+	sampler Sampler
 	context []byte
+	hooks   []Hook
 }
 
 // New creates a root logger with given output writer. If the output writer implements
@@ -166,9 +210,14 @@ func Nop() Logger {
 func (l Logger) Output(w io.Writer) Logger {
 	l2 := New(w)
 	l2.level = l.level
-	l2.sample = l.sample
-	l2.context = make([]byte, len(l.context))
-	copy(l2.context, l.context)
+	l2.sampler = l.sampler
+	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
 }
 
@@ -178,91 +227,90 @@ func (l Logger) With() Context {
 	l.context = make([]byte, 0, 500)
 	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)
 	}
 	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)
+	}
+	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
+}
+
+// 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
 }
 
 // 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)
 }
 
 // Fatal starts a new message with fatal level. The os.Exit(1) function
 // is called by the Msg method.
 //
 // 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.
 //
 // 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.
 //
 // You must call Msg on the returned event in order to send the event.
-func (l Logger) WithLevel(level Level) *Event {
+func (l *Logger) WithLevel(level Level) *Event {
 	switch level {
 	case DebugLevel:
 		return l.Debug()
@@ -276,8 +324,10 @@ func (l Logger) WithLevel(level Level) *Event {
 		return l.Fatal()
 	case PanicLevel:
 		return l.Panic()
+	case NoLevel:
+		return l.Log()
 	case Disabled:
-		return disabledEvent
+		return nil
 	default:
 		panic("zerolog: WithLevel(): invalid level: " + strconv.Itoa(int(level)))
 	}
@@ -287,10 +337,24 @@ func (l Logger) WithLevel(level Level) *Event {
 // will still disable events produced by this method.
 //
 // You must call Msg on the returned event in order to send the event.
-func (l Logger) Log() *Event {
-	// We use panic level with addLevelField=false to make Log passthrough all
-	// levels except Disabled.
-	return l.newEvent(PanicLevel, false, nil)
+func (l *Logger) Log() *Event {
+	return l.newEvent(NoLevel, nil)
+}
+
+// Print sends a log event using debug level and no extra field.
+// Arguments are handled in the manner of fmt.Print.
+func (l *Logger) Print(v ...interface{}) {
+	if e := l.Debug(); e.Enabled() {
+		e.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.Msg(fmt.Sprintf(format, v...))
+	}
 }
 
 // Write implements the io.Writer interface. This is useful to set as a writer
@@ -305,44 +369,30 @@ func (l Logger) Write(p []byte) (n int, err error) {
 	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 = json.AppendTime(json.AppendKey(e.buf, TimestampFieldName), TimestampFunc(), TimeFieldFormat)
-	}
-	if addLevelField {
+	e.ch = l.hooks
+	if level != NoLevel {
 		e.Str(LevelFieldName, level.String())
 	}
-	if l.sample > 0 && SampleFieldName != "" {
-		e.Uint32(SampleFieldName, l.sample)
-	}
-	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:]...)
+	if l.context != nil && len(l.context) > 0 {
+		e.buf = enc.AppendObjectData(e.buf, l.context)
 	}
 	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

@@ -22,14 +22,19 @@ 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)
 }
 
 // Debug starts a new message with debug level.
@@ -76,16 +81,35 @@ 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.Print(v...)
+}
+
+// Printf sends a log event using debug level and no extra field.
+// Arguments are handled in the manner of fmt.Printf.
+func Printf(format string, v ...interface{}) {
+	Logger.Printf(format, v...)
+}
+
 // 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 +1,143 @@
+// +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 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 +41,58 @@ 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 2"}
+	// {"level":"info","message":"message 4"}
+}
+
+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_Debug() {
@@ -150,6 +196,22 @@ func (u User) MarshalZerologObject(e *zerolog.Event) {
 		Time("created", u.Created)
 }
 
+type Price struct {
+	val  uint64
+	prec int
+	unit string
+}
+
+func (p Price) MarshalZerologObject(e *zerolog.Event) {
+	denom := uint64(1)
+	for i := 0; i < p.prec; i++ {
+		denom *= 10
+	}
+	result := []byte(p.unit)
+	result = append(result, fmt.Sprintf("%d.%d", p.val/denom, p.val%denom)...)
+	e.Str("price", string(result))
+}
+
 type Users []User
 
 func (uu Users) MarshalZerologArray(a *zerolog.Array) {
@@ -203,6 +265,19 @@ func ExampleEvent_Object() {
 	// Output: {"foo":"bar","user":{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},"message":"hello world"}
 }
 
+func ExampleEvent_EmbedObject() {
+	log := zerolog.New(os.Stdout)
+
+	price := Price{val: 6449, prec: 2, unit: "$"}
+
+	log.Log().
+		Str("foo", "bar").
+		EmbedObject(price).
+		Msg("hello world")
+
+	// Output: {"foo":"bar","price":"$64.49","message":"hello world"}
+}
+
 func ExampleEvent_Interface() {
 	log := zerolog.New(os.Stdout)
 
@@ -306,6 +381,20 @@ func ExampleContext_Object() {
 	// Output: {"foo":"bar","user":{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},"message":"hello world"}
 }
 
+func ExampleContext_EmbedObject() {
+
+	price := Price{val: 6449, prec: 2, unit: "$"}
+
+	log := zerolog.New(os.Stdout).With().
+		Str("foo", "bar").
+		EmbedObject(price).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	// Output: {"foo":"bar","price":"$64.49","message":"hello world"}
+}
+
 func ExampleContext_Interface() {
 	obj := struct {
 		Name string `json:"name"`
@@ -351,3 +440,36 @@ func ExampleContext_Durs() {
 
 	// Output: {"foo":"bar","durs":[10000,20000],"message":"hello world"}
 }
+
+func ExampleContext_IPAddr() {
+	hostIP := net.IP{192, 168, 0, 100}
+	log := zerolog.New(os.Stdout).With().
+		IPAddr("HostIP", hostIP).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	// Output: {"HostIP":"192.168.0.100","message":"hello world"}
+}
+
+func ExampleContext_IPPrefix() {
+	route := net.IPNet{IP: net.IP{192, 168, 0, 0}, Mask: net.CIDRMask(24, 32)}
+	log := zerolog.New(os.Stdout).With().
+		IPPrefix("Route", route).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	// Output: {"Route":"192.168.0.0/24","message":"hello world"}
+}
+
+func ExampleContext_MacAddr() {
+	mac := net.HardwareAddr{0x00, 0x14, 0x22, 0x01, 0x23, 0x45}
+	log := zerolog.New(os.Stdout).With().
+		MACAddr("hostMAC", mac).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	// Output: {"hostMAC":"00:14:22:01:23:45","message":"hello world"}
+}

log_test.go

@@ -3,7 +3,10 @@ package zerolog
 import (
 	"bytes"
 	"errors"
+	"fmt"
+	"net"
 	"reflect"
+	"runtime"
 	"testing"
 	"time"
 )
@@ -13,7 +16,7 @@ func TestLog(t *testing.T) {
 		out := &bytes.Buffer{}
 		log := New(out)
 		log.Log().Msg("")
-		if got, want := out.String(), "{}\n"; got != want {
+		if got, want := decodeIfBinaryToString(out.Bytes()), "{}\n"; got != want {
 			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
@@ -22,7 +25,7 @@ func TestLog(t *testing.T) {
 		out := &bytes.Buffer{}
 		log := New(out)
 		log.Log().Str("foo", "bar").Msg("")
-		if got, want := out.String(), `{"foo":"bar"}`+"\n"; got != want {
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"foo":"bar"}`+"\n"; got != want {
 			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
@@ -34,7 +37,7 @@ func TestLog(t *testing.T) {
 			Str("foo", "bar").
 			Int("n", 123).
 			Msg("")
-		if got, want := out.String(), `{"foo":"bar","n":123}`+"\n"; got != want {
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"foo":"bar","n":123}`+"\n"; got != want {
 			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
@@ -45,7 +48,7 @@ func TestInfo(t *testing.T) {
 		out := &bytes.Buffer{}
 		log := New(out)
 		log.Info().Msg("")
-		if got, want := out.String(), `{"level":"info"}`+"\n"; got != want {
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"info"}`+"\n"; got != want {
 			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
@@ -54,7 +57,7 @@ func TestInfo(t *testing.T) {
 		out := &bytes.Buffer{}
 		log := New(out)
 		log.Info().Str("foo", "bar").Msg("")
-		if got, want := out.String(), `{"level":"info","foo":"bar"}`+"\n"; got != want {
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"info","foo":"bar"}`+"\n"; got != want {
 			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
@@ -66,7 +69,7 @@ func TestInfo(t *testing.T) {
 			Str("foo", "bar").
 			Int("n", 123).
 			Msg("")
-		if got, want := out.String(), `{"level":"info","foo":"bar","n":123}`+"\n"; got != want {
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"info","foo":"bar","n":123}`+"\n"; got != want {
 			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
@@ -74,8 +77,11 @@ func TestInfo(t *testing.T) {
 
 func TestWith(t *testing.T) {
 	out := &bytes.Buffer{}
-	log := New(out).With().
-		Str("foo", "bar").
+	ctx := New(out).With().
+		Str("string", "foo").
+		Bytes("bytes", []byte("bar")).
+		Hex("hex", []byte{0x12, 0xef}).
+		RawJSON("json", []byte(`{"some":"json"}`)).
 		AnErr("some_err", nil).
 		Err(errors.New("some error")).
 		Bool("bool", true).
@@ -89,12 +95,14 @@ 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 {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"string":"foo","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)
 	}
 }
@@ -120,10 +128,38 @@ func TestFieldsMap(t *testing.T) {
 		"uint64":  uint64(10),
 		"float32": float32(11),
 		"float64": float64(12),
+		"ipv6":    net.IP{0x20, 0x01, 0x0d, 0xb8, 0x85, 0xa3, 0x00, 0x00, 0x00, 0x00, 0x8a, 0x2e, 0x03, 0x70, 0x73, 0x34},
 		"dur":     1 * time.Second,
 		"time":    time.Time{},
+		"obj":     obj{"a", "b", 1},
 	}).Msg("")
-	if got, want := out.String(), `{"bool":true,"bytes":"bar","dur":1000,"error":"some error","float32":11,"float64":12,"int":1,"int16":3,"int32":4,"int64":5,"int8":2,"nil":null,"string":"foo","time":"0001-01-01T00:00:00Z","uint":6,"uint16":8,"uint32":9,"uint64":10,"uint8":7}`+"\n"; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"bool":true,"bytes":"bar","dur":1000,"error":"some error","float32":11,"float64":12,"int":1,"int16":3,"int32":4,"int64":5,"int8":2,"ipv6":"2001:db8:85a3::8a2e:370:7334","nil":null,"obj":{"Pub":"a","Tag":"b","priv":1},"string":"foo","time":"0001-01-01T00:00:00Z","uint":6,"uint16":8,"uint32":9,"uint64":10,"uint8":7}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestFieldsMapPnt(t *testing.T) {
+	out := &bytes.Buffer{}
+	log := New(out)
+	log.Log().Fields(map[string]interface{}{
+		"string":  new(string),
+		"bool":    new(bool),
+		"int":     new(int),
+		"int8":    new(int8),
+		"int16":   new(int16),
+		"int32":   new(int32),
+		"int64":   new(int64),
+		"uint":    new(uint),
+		"uint8":   new(uint8),
+		"uint16":  new(uint16),
+		"uint32":  new(uint32),
+		"uint64":  new(uint64),
+		"float32": new(float32),
+		"float64": new(float64),
+		"dur":     new(time.Duration),
+		"time":    new(time.Time),
+	}).Msg("")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"bool":false,"dur":0,"float32":0,"float64":0,"int":0,"int16":0,"int32":0,"int64":0,"int8":0,"string":"","time":"0001-01-01T00:00:00Z","uint":0,"uint16":0,"uint32":0,"uint64":0,"uint8":0}`+"\n"; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
@@ -132,9 +168,14 @@ func TestFields(t *testing.T) {
 	out := &bytes.Buffer{}
 	log := New(out)
 	now := time.Now()
+	_, file, line, _ := runtime.Caller(0)
+	caller := fmt.Sprintf("%s:%d", file, line+3)
 	log.Log().
+		Caller().
 		Str("string", "foo").
 		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).
@@ -148,13 +189,17 @@ func TestFields(t *testing.T) {
 		Uint16("uint16", 8).
 		Uint32("uint32", 9).
 		Uint64("uint64", 10).
-		Float32("float32", 11).
-		Float64("float64", 12).
+		IPAddr("IPv4", net.IP{192, 168, 0, 100}).
+		IPAddr("IPv6", net.IP{0x20, 0x01, 0x0d, 0xb8, 0x85, 0xa3, 0x00, 0x00, 0x00, 0x00, 0x8a, 0x2e, 0x03, 0x70, 0x73, 0x34}).
+		MACAddr("Mac", net.HardwareAddr{0x00, 0x14, 0x22, 0x01, 0x23, 0x45}).
+		IPPrefix("Prefix", net.IPNet{IP: net.IP{192, 168, 0, 100}, Mask: net.CIDRMask(24, 32)}).
+		Float32("float32", 11.1234).
+		Float64("float64", 12.321321321).
 		Dur("dur", 1*time.Second).
 		Time("time", time.Time{}).
 		TimeDiff("diff", now, now.Add(-10*time.Second)).
 		Msg("")
-	if got, want := out.String(), `{"string":"foo","bytes":"bar","error":"some error","bool":true,"int":1,"int8":2,"int16":3,"int32":4,"int64":5,"uint":6,"uint8":7,"uint16":8,"uint32":9,"uint64":10,"float32":11,"float64":12,"dur":1000,"time":"0001-01-01T00:00:00Z","diff":10000}`+"\n"; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"caller":"`+caller+`","string":"foo","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,"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)
 	}
 }
@@ -181,7 +226,7 @@ func TestFieldsArrayEmpty(t *testing.T) {
 		Durs("dur", []time.Duration{}).
 		Times("time", []time.Time{}).
 		Msg("")
-	if got, want := out.String(), `{"string":[],"err":[],"bool":[],"int":[],"int8":[],"int16":[],"int32":[],"int64":[],"uint":[],"uint8":[],"uint16":[],"uint32":[],"uint64":[],"float32":[],"float64":[],"dur":[],"time":[]}`+"\n"; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"string":[],"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)
 	}
 }
@@ -208,7 +253,7 @@ func TestFieldsArraySingleElement(t *testing.T) {
 		Durs("dur", []time.Duration{1 * time.Second}).
 		Times("time", []time.Time{time.Time{}}).
 		Msg("")
-	if got, want := out.String(), `{"string":["foo"],"err":["some error"],"bool":[true],"int":[1],"int8":[2],"int16":[3],"int32":[4],"int64":[5],"uint":[6],"uint8":[7],"uint16":[8],"uint32":[9],"uint64":[10],"float32":[11],"float64":[12],"dur":[1000],"time":["0001-01-01T00:00:00Z"]}`+"\n"; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"string":["foo"],"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)
 	}
 }
@@ -235,7 +280,7 @@ func TestFieldsArrayMultipleElement(t *testing.T) {
 		Durs("dur", []time.Duration{1 * time.Second, 0}).
 		Times("time", []time.Time{time.Time{}, time.Time{}}).
 		Msg("")
-	if got, want := out.String(), `{"string":["foo","bar"],"err":["some error",null],"bool":[true,false],"int":[1,0],"int8":[2,0],"int16":[3,0],"int32":[4,0],"int64":[5,0],"uint":[6,0],"uint8":[7,0],"uint16":[8,0],"uint32":[9,0],"uint64":[10,0],"float32":[11,0],"float64":[12,0],"dur":[1000,0],"time":["0001-01-01T00:00:00Z","0001-01-01T00:00:00Z"]}`+"\n"; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"string":["foo","bar"],"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)
 	}
 }
@@ -247,6 +292,7 @@ func TestFieldsDisabled(t *testing.T) {
 	log.Debug().
 		Str("string", "foo").
 		Bytes("bytes", []byte("bar")).
+		Hex("hex", []byte{0x12, 0xef}).
 		AnErr("some_err", nil).
 		Err(errors.New("some error")).
 		Bool("bool", true).
@@ -266,15 +312,16 @@ func TestFieldsDisabled(t *testing.T) {
 		Time("time", time.Time{}).
 		TimeDiff("diff", now, now.Add(-10*time.Second)).
 		Msg("")
-	if got, want := out.String(), ""; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), ""; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
 
 func TestMsgf(t *testing.T) {
 	out := &bytes.Buffer{}
-	New(out).Log().Msgf("one %s %.1f %d %v", "two", 3.4, 5, errors.New("six"))
-	if got, want := out.String(), `{"message":"one two 3.4 5 six"}`+"\n"; got != want {
+	log := New(out)
+	log.Log().Msgf("one %s %.1f %d %v", "two", 3.4, 5, errors.New("six"))
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"message":"one two 3.4 5 six"}`+"\n"; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
@@ -283,7 +330,7 @@ func TestWithAndFieldsCombined(t *testing.T) {
 	out := &bytes.Buffer{}
 	log := New(out).With().Str("f1", "val").Str("f2", "val").Logger()
 	log.Log().Str("f3", "val").Msg("")
-	if got, want := out.String(), `{"f1":"val","f2":"val","f3":"val"}`+"\n"; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"f1":"val","f2":"val","f3":"val"}`+"\n"; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
@@ -293,7 +340,43 @@ func TestLevel(t *testing.T) {
 		out := &bytes.Buffer{}
 		log := New(out).Level(Disabled)
 		log.Info().Msg("test")
-		if got, want := out.String(), ""; got != want {
+		if got, want := decodeIfBinaryToString(out.Bytes()), ""; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+
+	t.Run("NoLevel/Disabled", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).Level(Disabled)
+		log.Log().Msg("test")
+		if got, want := decodeIfBinaryToString(out.Bytes()), ""; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+
+	t.Run("NoLevel/Info", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).Level(InfoLevel)
+		log.Log().Msg("test")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"message":"test"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+
+	t.Run("NoLevel/Panic", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).Level(PanicLevel)
+		log.Log().Msg("test")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"message":"test"}`+"\n"; got != want {
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+		}
+	})
+
+	t.Run("NoLevel/WithLevel", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		log := New(out).Level(InfoLevel)
+		log.WithLevel(NoLevel).Msg("test")
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"message":"test"}`+"\n"; got != want {
 			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
@@ -302,7 +385,7 @@ func TestLevel(t *testing.T) {
 		out := &bytes.Buffer{}
 		log := New(out).Level(InfoLevel)
 		log.Info().Msg("test")
-		if got, want := out.String(), `{"level":"info","message":"test"}`+"\n"; got != want {
+		if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"info","message":"test"}`+"\n"; got != want {
 			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
@@ -310,12 +393,12 @@ func TestLevel(t *testing.T) {
 
 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 {
+	if got, want := decodeIfBinaryToString(out.Bytes()), "{\"i\":2}\n{\"i\":4}\n"; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
@@ -332,6 +415,7 @@ 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
@@ -351,10 +435,12 @@ func TestLevelWriter(t *testing.T) {
 	log.Info().Msg("2")
 	log.Warn().Msg("3")
 	log.Error().Msg("4")
+	log.Log().Msg("nolevel-1")
 	log.WithLevel(DebugLevel).Msg("5")
 	log.WithLevel(InfoLevel).Msg("6")
 	log.WithLevel(WarnLevel).Msg("7")
 	log.WithLevel(ErrorLevel).Msg("8")
+	log.WithLevel(NoLevel).Msg("nolevel-2")
 
 	want := []struct {
 		l Level
@@ -364,10 +450,12 @@ func TestLevelWriter(t *testing.T) {
 		{InfoLevel, `{"level":"info","message":"2"}` + "\n"},
 		{WarnLevel, `{"level":"warn","message":"3"}` + "\n"},
 		{ErrorLevel, `{"level":"error","message":"4"}` + "\n"},
+		{NoLevel, `{"message":"nolevel-1"}` + "\n"},
 		{DebugLevel, `{"level":"debug","message":"5"}` + "\n"},
 		{InfoLevel, `{"level":"info","message":"6"}` + "\n"},
 		{WarnLevel, `{"level":"warn","message":"7"}` + "\n"},
 		{ErrorLevel, `{"level":"error","message":"8"}` + "\n"},
+		{NoLevel, `{"message":"nolevel-2"}` + "\n"},
 	}
 	if got := lw.ops; !reflect.DeepEqual(got, want) {
 		t.Errorf("invalid ops:\ngot:\n%v\nwant:\n%v", got, want)
@@ -385,7 +473,7 @@ func TestContextTimestamp(t *testing.T) {
 	log := New(out).With().Timestamp().Str("foo", "bar").Logger()
 	log.Log().Msg("hello world")
 
-	if got, want := out.String(), `{"time":"2001-02-03T04:05:06Z","foo":"bar","message":"hello world"}`+"\n"; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"foo":"bar","time":"2001-02-03T04:05:06Z","message":"hello world"}`+"\n"; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
@@ -401,7 +489,35 @@ func TestEventTimestamp(t *testing.T) {
 	log := New(out).With().Str("foo", "bar").Logger()
 	log.Log().Timestamp().Msg("hello world")
 
-	if got, want := out.String(), `{"foo":"bar","time":"2001-02-03T04:05:06Z","message":"hello world"}`+"\n"; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"foo":"bar","time":"2001-02-03T04:05:06Z","message":"hello world"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestOutputWithoutTimestamp(t *testing.T) {
+	ignoredOut := &bytes.Buffer{}
+	out := &bytes.Buffer{}
+	log := New(ignoredOut).Output(out).With().Str("foo", "bar").Logger()
+	log.Log().Msg("hello world")
+
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"foo":"bar","message":"hello world"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestOutputWithTimestamp(t *testing.T) {
+	TimestampFunc = func() time.Time {
+		return time.Date(2001, time.February, 3, 4, 5, 6, 7, time.UTC)
+	}
+	defer func() {
+		TimestampFunc = time.Now
+	}()
+	ignoredOut := &bytes.Buffer{}
+	out := &bytes.Buffer{}
+	log := New(ignoredOut).Output(out).With().Timestamp().Str("foo", "bar").Logger()
+	log.Log().Msg("hello world")
+
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"foo":"bar","time":"2001-02-03T04:05:06Z","message":"hello world"}`+"\n"; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }

sampler.go

@@ -0,0 +1,126 @@
+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
+// there level.
+type BasicSampler struct {
+	N       uint32
+	counter uint32
+}
+
+// Sample implements the Sampler interface.
+func (s *BasicSampler) Sample(lvl Level) bool {
+	c := atomic.AddUint32(&s.counter, 1)
+	return c%s.N == 0
+}
+
+// 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 {
+	DebugSampler, InfoSampler, WarnSampler, ErrorSampler Sampler
+}
+
+func (s LevelSampler) Sample(lvl Level) bool {
+	switch 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 +1,77 @@
+// +build !binary_log
+
+package zerolog
+
+import (
+	"testing"
+	"time"
+)
+
+var samplers = []struct {
+	name    string
+	sampler func() Sampler
+	total   int
+	wantMin int
+	wantMax int
+}{
+	{
+		"BasicSampler",
+		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 +1,11 @@
 // +build !windows
+// +build !binary_log
 
 package zerolog
 
-import "io"
+import (
+	"io"
+)
 
 // SyslogWriter is an interface matching a syslog.Writer struct.
 type SyslogWriter interface {
@@ -44,6 +47,8 @@ func (sw syslogWriter) WriteLevel(level Level, p []byte) (n int, err error) {
 		err = sw.w.Emerg(string(p))
 	case PanicLevel:
 		err = sw.w.Crit(string(p))
+	case NoLevel:
+		err = sw.w.Info(string(p))
 	default:
 		panic("invalid level")
 	}

syslog_test.go

@@ -1,3 +1,6 @@
+// +build !binary_log
+// +build !windows
+
 package zerolog
 
 import "testing"
@@ -46,11 +49,13 @@ func TestSyslogWriter(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)

writer_test.go

@@ -1,3 +1,6 @@
+// +build !binary_log
+// +build !windows
+
 package zerolog
 
 import (
@@ -12,11 +15,13 @@ 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)