Fix pretty logging and add a screenshot to the README

Add some utility functions to ease migration from other logger API.

README.md

@@ -8,16 +8,20 @@ Zerolog's API is designed to provide both a great developer experience and stunn
 
 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.
 
-To keep the code base and the API simple, zerolog focuses on JSON logging only. As [suggested on reddit](https://www.reddit.com/r/golang/comments/6c9k7n/zerolog_is_now_faster_than_zap/), you may use tools like [humanlog](https://github.com/aybabtme/humanlog) to pretty print JSON on the console during development.
+To keep the code base and the API simple, zerolog focuses on JSON logging only. Pretty logging on the console is made possible using the provided `zerolog.ConsoleWriter`.
 
+![](pretty.png)
 
 ## Features
 
+* Blazing fast
+* Low to zero allocation
 * Level logging
 * Sampling
 * Contextual fields
 * `context.Context` integration
 * `net/http` helpers
+* Pretty logging for development
 
 ## Usage
 
@@ -96,6 +100,18 @@ if e := log.Debug(); e.Enabled() {
 // Output: {"level":"info","time":1494567715,"message":"routed message"}
 ```
 
+### Pretty logging
+
+```go
+if isConsole {
+    log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr})
+}
+
+log.Info().Str("foo", "bar").Msg("Hello world")
+
+// Output: 1494567715 |INFO| Hello world foo=bar
+```
+
 ### Sub dictionary
 
 ```go
@@ -189,6 +205,15 @@ c = c.Append(hlog.NewHandler(log))
 
 // Install some provided extra handler to set some request's context fields.
 // Thanks to those handler, all our logs will come with some pre-populated fields.
+c = c.Append(hlog.AccessHandler(func(r *http.Request, status, size int, duration time.Duration) {
+    hlog.FromRequest(r).Info().
+        Str("method", r.Method).
+        Str("url", r.URL.String()).
+        Int("status", status).
+        Int("size", size).
+        Dur("duration", duration).
+        Msg("")
+}))
 c = c.Append(hlog.RemoteAddrHandler("ip"))
 c = c.Append(hlog.UserAgentHandler("user_agent"))
 c = c.Append(hlog.RefererHandler("referer"))
@@ -255,11 +280,11 @@ Some settings can be changed and will by applied to all loggers:
 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	    46.3 ns/op	   0 B/op       0 allocs/op
-BenchmarkContextFields-8   30000000	    47.1 ns/op	   0 B/op       0 allocs/op
-BenchmarkLogFields-8       10000000	   186 ns/op	   0 B/op       0 allocs/op
+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):

array.go

@@ -0,0 +1,169 @@
+package zerolog
+
+import (
+	"sync"
+	"time"
+
+	"github.com/rs/zerolog/internal/json"
+)
+
+var arrayPool = &sync.Pool{
+	New: func() interface{} {
+		return &Array{
+			buf: make([]byte, 0, 500),
+		}
+	},
+}
+
+type Array struct {
+	buf []byte
+}
+
+// Arr creates an array to be added to an Event or Context.
+func Arr() *Array {
+	a := arrayPool.Get().(*Array)
+	a.buf = a.buf[:0]
+	return a
+}
+
+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...), ']')
+	}
+	arrayPool.Put(a)
+	return dst
+}
+
+// Object marshals an object that implement the LogObjectMarshaler
+// interface and 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...)
+	return a
+}
+
+// Str append the val as a string to the array.
+func (a *Array) Str(val string) *Array {
+	a.buf = json.AppendString(append(a.buf, ','), val)
+	return a
+}
+
+// Bytes append the val as a string to the array.
+func (a *Array) Bytes(val []byte) *Array {
+	a.buf = json.AppendBytes(append(a.buf, ','), val)
+	return a
+}
+
+// Err append the err as a string to the array.
+func (a *Array) Err(err error) *Array {
+	a.buf = json.AppendError(append(a.buf, ','), err)
+	return a
+}
+
+// Bool append the val as a bool to the array.
+func (a *Array) Bool(b bool) *Array {
+	a.buf = json.AppendBool(append(a.buf, ','), b)
+	return a
+}
+
+// Int append i as a int to the array.
+func (a *Array) Int(i int) *Array {
+	a.buf = json.AppendInt(append(a.buf, ','), i)
+	return a
+}
+
+// Int8 append i as a int8 to the array.
+func (a *Array) Int8(i int8) *Array {
+	a.buf = json.AppendInt8(append(a.buf, ','), i)
+	return a
+}
+
+// Int16 append i as a int16 to the array.
+func (a *Array) Int16(i int16) *Array {
+	a.buf = json.AppendInt16(append(a.buf, ','), i)
+	return a
+}
+
+// Int32 append i as a int32 to the array.
+func (a *Array) Int32(i int32) *Array {
+	a.buf = json.AppendInt32(append(a.buf, ','), i)
+	return a
+}
+
+// Int64 append i as a int64 to the array.
+func (a *Array) Int64(i int64) *Array {
+	a.buf = json.AppendInt64(append(a.buf, ','), i)
+	return a
+}
+
+// Uint append i as a uint to the array.
+func (a *Array) Uint(i uint) *Array {
+	a.buf = json.AppendUint(append(a.buf, ','), i)
+	return a
+}
+
+// Uint8 append i as a uint8 to the array.
+func (a *Array) Uint8(i uint8) *Array {
+	a.buf = json.AppendUint8(append(a.buf, ','), i)
+	return a
+}
+
+// Uint16 append i as a uint16 to the array.
+func (a *Array) Uint16(i uint16) *Array {
+	a.buf = json.AppendUint16(append(a.buf, ','), i)
+	return a
+}
+
+// Uint32 append i as a uint32 to the array.
+func (a *Array) Uint32(i uint32) *Array {
+	a.buf = json.AppendUint32(append(a.buf, ','), i)
+	return a
+}
+
+// Uint64 append i as a uint64 to the array.
+func (a *Array) Uint64(i uint64) *Array {
+	a.buf = json.AppendUint64(append(a.buf, ','), i)
+	return a
+}
+
+// Float32 append f as a float32 to the array.
+func (a *Array) Float32(f float32) *Array {
+	a.buf = json.AppendFloat32(append(a.buf, ','), f)
+	return a
+}
+
+// Float64 append f as a float64 to the array.
+func (a *Array) Float64(f float64) *Array {
+	a.buf = json.AppendFloat64(append(a.buf, ','), f)
+	return a
+}
+
+// Time 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)
+	return a
+}
+
+// Dur append d to the array.
+func (a *Array) Dur(d time.Duration) *Array {
+	a.buf = json.AppendDuration(append(a.buf, ','), d, DurationFieldUnit, DurationFieldInteger)
+	return a
+}
+
+// Interface 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)
+	return a
+}

array_test.go

@@ -0,0 +1,30 @@
+package zerolog
+
+import (
+	"testing"
+	"time"
+)
+
+func TestArray(t *testing.T) {
+	a := Arr().
+		Bool(true).
+		Int(1).
+		Int8(2).
+		Int16(3).
+		Int32(4).
+		Int64(5).
+		Uint(6).
+		Uint8(7).
+		Uint16(8).
+		Uint32(9).
+		Uint64(10).
+		Float32(11).
+		Float64(12).
+		Str("a").
+		Time(time.Time{}).
+		Dur(0)
+	want := `[true,1,2,3,4,5,6,7,8,9,10,11,12,"a","0001-01-01T00:00:00Z",0]`
+	if got := string(a.write([]byte{})); got != want {
+		t.Errorf("Array.write()\ngot:  %s\nwant: %s", got, want)
+	}
+}

benchmark_test.go

@@ -71,3 +71,135 @@ func BenchmarkLogFields(b *testing.B) {
 		}
 	})
 }
+
+type obj struct {
+	Pub  string
+	Tag  string `json:"tag"`
+	priv int
+}
+
+func (o obj) MarshalZerologObject(e *Event) {
+	e.Str("Pub", o.Pub).
+		Str("Tag", o.Tag).
+		Int("priv", o.priv)
+}
+
+func BenchmarkLogFieldType(b *testing.B) {
+	bools := []bool{true, false, true, false, true, false, true, false, true, false}
+	ints := []int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
+	floats := []float64{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
+	strings := []string{"a", "b", "c", "d", "e", "f", "g", "h", "i", "j"}
+	durations := []time.Duration{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
+	times := []time.Time{
+		time.Unix(0, 0),
+		time.Unix(1, 0),
+		time.Unix(2, 0),
+		time.Unix(3, 0),
+		time.Unix(4, 0),
+		time.Unix(5, 0),
+		time.Unix(6, 0),
+		time.Unix(7, 0),
+		time.Unix(8, 0),
+		time.Unix(9, 0),
+	}
+	interfaces := []struct {
+		Pub  string
+		Tag  string `json:"tag"`
+		priv int
+	}{
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+		{"a", "a", 0},
+	}
+	objects := []obj{
+		obj{"a", "a", 0},
+		obj{"a", "a", 0},
+		obj{"a", "a", 0},
+		obj{"a", "a", 0},
+		obj{"a", "a", 0},
+		obj{"a", "a", 0},
+		obj{"a", "a", 0},
+		obj{"a", "a", 0},
+		obj{"a", "a", 0},
+		obj{"a", "a", 0},
+	}
+	errs := []error{errors.New("a"), errors.New("b"), errors.New("c"), errors.New("d"), errors.New("e")}
+	types := map[string]func(e *Event) *Event{
+		"Bool": func(e *Event) *Event {
+			return e.Bool("k", bools[0])
+		},
+		"Bools": func(e *Event) *Event {
+			return e.Bools("k", bools)
+		},
+		"Int": func(e *Event) *Event {
+			return e.Int("k", ints[0])
+		},
+		"Ints": func(e *Event) *Event {
+			return e.Ints("k", ints)
+		},
+		"Float": func(e *Event) *Event {
+			return e.Float64("k", floats[0])
+		},
+		"Floats": func(e *Event) *Event {
+			return e.Floats64("k", floats)
+		},
+		"Str": func(e *Event) *Event {
+			return e.Str("k", strings[0])
+		},
+		"Strs": func(e *Event) *Event {
+			return e.Strs("k", strings)
+		},
+		"Err": func(e *Event) *Event {
+			return e.Err(errs[0])
+		},
+		"Errs": func(e *Event) *Event {
+			return e.Errs("k", errs)
+		},
+		"Time": func(e *Event) *Event {
+			return e.Time("k", times[0])
+		},
+		"Times": func(e *Event) *Event {
+			return e.Times("k", times)
+		},
+		"Dur": func(e *Event) *Event {
+			return e.Dur("k", durations[0])
+		},
+		"Durs": func(e *Event) *Event {
+			return e.Durs("k", durations)
+		},
+		"Interface": func(e *Event) *Event {
+			return e.Interface("k", interfaces[0])
+		},
+		"Interfaces": func(e *Event) *Event {
+			return e.Interface("k", interfaces)
+		},
+		"Interface(Object)": func(e *Event) *Event {
+			return e.Interface("k", objects[0])
+		},
+		"Interface(Objects)": func(e *Event) *Event {
+			return e.Interface("k", objects)
+		},
+		"Object": func(e *Event) *Event {
+			return e.Object("k", objects[0])
+		},
+	}
+	logger := New(ioutil.Discard)
+	b.ResetTimer()
+	for name := range types {
+		f := types[name]
+		b.Run(name, func(b *testing.B) {
+			b.RunParallel(func(pb *testing.PB) {
+				for pb.Next() {
+					f(logger.Info()).Msg("")
+				}
+			})
+		})
+	}
+}

console.go

@@ -0,0 +1,117 @@
+package zerolog
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"sort"
+	"strconv"
+	"strings"
+	"sync"
+)
+
+const (
+	cReset    = 0
+	cBold     = 1
+	cRed      = 31
+	cGreen    = 32
+	cYellow   = 33
+	cBlue     = 34
+	cMagenta  = 35
+	cCyan     = 36
+	cGray     = 37
+	cDarkGray = 90
+)
+
+var consoleBufPool = sync.Pool{
+	New: func() interface{} {
+		return bytes.NewBuffer(make([]byte, 0, 100))
+	},
+}
+
+// ConsoleWriter reads a JSON object per write operation and output an
+// optionally colored human readable version on the Out writer.
+type ConsoleWriter struct {
+	Out     io.Writer
+	NoColor bool
+}
+
+func (w ConsoleWriter) Write(p []byte) (n int, err error) {
+	var event map[string]interface{}
+	err = json.Unmarshal(p, &event)
+	if err != nil {
+		return
+	}
+	buf := consoleBufPool.Get().(*bytes.Buffer)
+	defer consoleBufPool.Put(buf)
+	lvlColor := cReset
+	level := "????"
+	if l, ok := event[LevelFieldName].(string); ok {
+		if !w.NoColor {
+			lvlColor = levelColor(l)
+		}
+		level = strings.ToUpper(l)[0:4]
+	}
+	fmt.Fprintf(buf, "%s |%s| %s",
+		colorize(event[TimestampFieldName], cDarkGray, !w.NoColor),
+		colorize(level, lvlColor, !w.NoColor),
+		colorize(event[MessageFieldName], cReset, !w.NoColor))
+	fields := make([]string, 0, len(event))
+	for field := range event {
+		switch field {
+		case LevelFieldName, TimestampFieldName, MessageFieldName:
+			continue
+		}
+		fields = append(fields, field)
+	}
+	sort.Strings(fields)
+	for _, field := range fields {
+		fmt.Fprintf(buf, " %s=", colorize(field, cCyan, !w.NoColor))
+		switch value := event[field].(type) {
+		case string:
+			if needsQuote(value) {
+				buf.WriteString(strconv.Quote(value))
+			} else {
+				buf.WriteString(value)
+			}
+		default:
+			fmt.Fprint(buf, value)
+		}
+	}
+	buf.WriteByte('\n')
+	buf.WriteTo(w.Out)
+	n = len(p)
+	return
+}
+
+func colorize(s interface{}, color int, enabled bool) string {
+	if !enabled {
+		return fmt.Sprintf("%v", s)
+	}
+	return fmt.Sprintf("\x1b[%dm%v\x1b[0m", color, s)
+}
+
+func levelColor(level string) int {
+	switch level {
+	case "debug":
+		return cMagenta
+	case "info":
+		return cGreen
+	case "warn":
+		return cYellow
+	case "error", "fatal", "panic":
+		return cRed
+	default:
+		return cReset
+	}
+}
+
+func needsQuote(s string) bool {
+	for i := range s {
+		if s[i] < 0x20 || s[i] > 0x7e || s[i] == ' ' || s[i] == '\\' || s[i] == '"' {
+			return true
+		}
+	}
+	return false
+}

context.go

@@ -1,6 +1,11 @@
 package zerolog
 
-import "time"
+import (
+	"io/ioutil"
+	"time"
+
+	"github.com/rs/zerolog/internal/json"
+)
 
 // Context configures a new sub-logger with contextual fields.
 type Context struct {
@@ -12,108 +17,244 @@ func (c Context) Logger() Logger {
 	return c.l
 }
 
+// Fields is a helper function to use a map to set fields using type assertion.
+func (c Context) Fields(fields map[string]interface{}) Context {
+	c.l.context = appendFields(c.l.context, fields)
+	return c
+}
+
 // Dict adds the field key with the dict to the logger context.
 func (c Context) Dict(key string, dict *Event) Context {
 	dict.buf = append(dict.buf, '}')
-	c.l.context = append(appendKey(c.l.context, key), dict.buf...)
+	c.l.context = append(json.AppendKey(c.l.context, key), dict.buf...)
 	eventPool.Put(dict)
 	return c
 }
 
+// Array adds the field key with an array to the event context.
+// Use zerolog.Arr() to create the array or pass a type that
+// implement the LogArrayMarshaler interface.
+func (c Context) Array(key string, arr LogArrayMarshaler) Context {
+	c.l.context = json.AppendKey(c.l.context, key)
+	if arr, ok := arr.(*Array); ok {
+		c.l.context = arr.write(c.l.context)
+		return c
+	}
+	var a *Array
+	if aa, ok := arr.(*Array); ok {
+		a = aa
+	} else {
+		a = Arr()
+		arr.MarshalZerologArray(a)
+	}
+	c.l.context = a.write(c.l.context)
+	return c
+}
+
+// Object marshals an object that implement the LogObjectMarshaler interface.
+func (c Context) Object(key string, obj LogObjectMarshaler) Context {
+	e := newEvent(levelWriterAdapter{ioutil.Discard}, 0, true)
+	e.Object(key, obj)
+	e.buf[0] = ',' // A new event starts as an object, we want to embed it.
+	c.l.context = append(c.l.context, e.buf...)
+	eventPool.Put(e)
+	return c
+}
+
 // Str adds the field key with val as a string to the logger context.
 func (c Context) Str(key, val string) Context {
-	c.l.context = appendString(c.l.context, key, val)
+	c.l.context = json.AppendString(json.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)
+	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)
 	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 {
-	c.l.context = appendErrorKey(c.l.context, key, err)
+	if err != nil {
+		c.l.context = json.AppendError(json.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)
 	return c
 }
 
 // Err adds the field "error" with err as a string to the logger context.
 // To customize the key name, change zerolog.ErrorFieldName.
 func (c Context) Err(err error) Context {
-	c.l.context = appendError(c.l.context, err)
+	if err != nil {
+		c.l.context = json.AppendError(json.AppendKey(c.l.context, ErrorFieldName), err)
+	}
 	return c
 }
 
-// Bool adds the field key with val as a Boolean to the logger context.
+// 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 = appendBool(c.l.context, key, b)
+	c.l.context = json.AppendBool(json.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)
 	return c
 }
 
 // Int adds the field key with i as a int to the logger context.
 func (c Context) Int(key string, i int) Context {
-	c.l.context = appendInt(c.l.context, key, i)
+	c.l.context = json.AppendInt(json.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)
 	return c
 }
 
 // Int8 adds the field key with i as a int8 to the logger context.
 func (c Context) Int8(key string, i int8) Context {
-	c.l.context = appendInt8(c.l.context, key, i)
+	c.l.context = json.AppendInt8(json.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)
 	return c
 }
 
 // Int16 adds the field key with i as a int16 to the logger context.
 func (c Context) Int16(key string, i int16) Context {
-	c.l.context = appendInt16(c.l.context, key, i)
+	c.l.context = json.AppendInt16(json.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)
 	return c
 }
 
 // Int32 adds the field key with i as a int32 to the logger context.
 func (c Context) Int32(key string, i int32) Context {
-	c.l.context = appendInt32(c.l.context, key, i)
+	c.l.context = json.AppendInt32(json.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)
 	return c
 }
 
 // Int64 adds the field key with i as a int64 to the logger context.
 func (c Context) Int64(key string, i int64) Context {
-	c.l.context = appendInt64(c.l.context, key, i)
+	c.l.context = json.AppendInt64(json.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)
 	return c
 }
 
 // Uint adds the field key with i as a uint to the logger context.
 func (c Context) Uint(key string, i uint) Context {
-	c.l.context = appendUint(c.l.context, key, i)
+	c.l.context = json.AppendUint(json.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)
 	return c
 }
 
 // Uint8 adds the field key with i as a uint8 to the logger context.
 func (c Context) Uint8(key string, i uint8) Context {
-	c.l.context = appendUint8(c.l.context, key, i)
+	c.l.context = json.AppendUint8(json.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)
 	return c
 }
 
 // Uint16 adds the field key with i as a uint16 to the logger context.
 func (c Context) Uint16(key string, i uint16) Context {
-	c.l.context = appendUint16(c.l.context, key, i)
+	c.l.context = json.AppendUint16(json.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)
 	return c
 }
 
 // Uint32 adds the field key with i as a uint32 to the logger context.
 func (c Context) Uint32(key string, i uint32) Context {
-	c.l.context = appendUint32(c.l.context, key, i)
+	c.l.context = json.AppendUint32(json.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)
 	return c
 }
 
 // Uint64 adds the field key with i as a uint64 to the logger context.
 func (c Context) Uint64(key string, i uint64) Context {
-	c.l.context = appendUint64(c.l.context, key, i)
+	c.l.context = json.AppendUint64(json.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)
 	return c
 }
 
 // Float32 adds the field key with f as a float32 to the logger context.
 func (c Context) Float32(key string, f float32) Context {
-	c.l.context = appendFloat32(c.l.context, key, f)
+	c.l.context = json.AppendFloat32(json.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)
 	return c
 }
 
 // Float64 adds the field key with f as a float64 to the logger context.
 func (c Context) Float64(key string, f float64) Context {
-	c.l.context = appendFloat64(c.l.context, key, f)
+	c.l.context = json.AppendFloat64(json.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)
 	return c
 }
 
@@ -130,18 +271,30 @@ func (c Context) Timestamp() Context {
 
 // Time adds the field key with t formated as string using zerolog.TimeFieldFormat.
 func (c Context) Time(key string, t time.Time) Context {
-	c.l.context = appendTime(c.l.context, key, t)
+	c.l.context = json.AppendTime(json.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)
 	return c
 }
 
 // Dur adds the fields key with d divided by unit and stored as a float.
 func (c Context) Dur(key string, d time.Duration) Context {
-	c.l.context = appendDuration(c.l.context, key, d)
+	c.l.context = json.AppendDuration(json.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)
 	return c
 }
 
 // Interface adds the field key with obj marshaled using reflection.
 func (c Context) Interface(key string, i interface{}) Context {
-	c.l.context = appendInterface(c.l.context, key, i)
+	c.l.context = json.AppendInterface(json.AppendKey(c.l.context, key), i)
 	return c
 }

event.go

@@ -6,6 +6,8 @@ import (
 	"os"
 	"sync"
 	"time"
+
+	"github.com/rs/zerolog/internal/json"
 )
 
 var eventPool = &sync.Pool{
@@ -26,6 +28,18 @@ type Event struct {
 	done    func(msg string)
 }
 
+// LogObjectMarshaler provides a strongly-typed and encoding-agnostic interface
+// to be implemented by types used with Event/Context's Object methods.
+type LogObjectMarshaler interface {
+	MarshalZerologObject(e *Event)
+}
+
+// LogArrayMarshaler provides a strongly-typed and encoding-agnostic interface
+// to be implemented by types used with Event/Context's Array methods.
+type LogArrayMarshaler interface {
+	MarshalZerologArray(a *Array)
+}
+
 func newEvent(w LevelWriter, level Level, enabled bool) *Event {
 	if !enabled {
 		return &Event{}
@@ -64,7 +78,7 @@ func (e *Event) Msg(msg string) {
 		return
 	}
 	if msg != "" {
-		e.buf = appendString(e.buf, MessageFieldName, msg)
+		e.buf = json.AppendString(json.AppendKey(e.buf, MessageFieldName), msg)
 	}
 	if e.done != nil {
 		defer e.done(msg)
@@ -84,7 +98,7 @@ func (e *Event) Msgf(format string, v ...interface{}) {
 	}
 	msg := fmt.Sprintf(format, v...)
 	if msg != "" {
-		e.buf = appendString(e.buf, MessageFieldName, msg)
+		e.buf = json.AppendString(json.AppendKey(e.buf, MessageFieldName), msg)
 	}
 	if e.done != nil {
 		defer e.done(msg)
@@ -94,13 +108,22 @@ func (e *Event) Msgf(format string, v ...interface{}) {
 	}
 }
 
+// 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 {
+		return e
+	}
+	e.buf = appendFields(e.buf, fields)
+	return e
+}
+
 // Dict adds the field key with a dict to the event context.
 // Use zerolog.Dict() to create the dictionary.
 func (e *Event) Dict(key string, dict *Event) *Event {
 	if !e.enabled {
 		return e
 	}
-	e.buf = append(append(appendKey(e.buf, key), dict.buf...), '}')
+	e.buf = append(append(json.AppendKey(e.buf, key), dict.buf...), '}')
 	eventPool.Put(dict)
 	return e
 }
@@ -112,12 +135,76 @@ func Dict() *Event {
 	return newEvent(levelWriterAdapter{ioutil.Discard}, 0, true)
 }
 
+// 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 {
+		return e
+	}
+	e.buf = json.AppendKey(e.buf, key)
+	var a *Array
+	if aa, ok := arr.(*Array); ok {
+		a = aa
+	} else {
+		a = Arr()
+		arr.MarshalZerologArray(a)
+	}
+	e.buf = a.write(e.buf)
+	return e
+}
+
+func (e *Event) appendObject(obj LogObjectMarshaler) {
+	pos := len(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, '}')
+}
+
+// Object marshals an object that implement the LogObjectMarshaler interface.
+func (e *Event) Object(key string, obj LogObjectMarshaler) *Event {
+	if !e.enabled {
+		return e
+	}
+	e.buf = json.AppendKey(e.buf, key)
+	e.appendObject(obj)
+	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 {
 		return e
 	}
-	e.buf = appendString(e.buf, key, val)
+	e.buf = json.AppendString(json.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 {
+		return e
+	}
+	e.buf = json.AppendStrings(json.AppendKey(e.buf, key), vals)
+	return e
+}
+
+// Bytes adds the field key with val as a string to the *Event context.
+//
+// Runes outside of normal ASCII ranges will be hex-encoded in the resulting
+// JSON.
+func (e *Event) Bytes(key string, val []byte) *Event {
+	if !e.enabled {
+		return e
+	}
+	e.buf = json.AppendBytes(json.AppendKey(e.buf, key), val)
 	return e
 }
 
@@ -127,7 +214,19 @@ func (e *Event) AnErr(key string, err error) *Event {
 	if !e.enabled {
 		return e
 	}
-	e.buf = appendErrorKey(e.buf, key, err)
+	if err != nil {
+		e.buf = json.AppendError(json.AppendKey(e.buf, key), err)
+	}
+	return e
+}
+
+// Errs adds the field key with errs as an array of strings to the *Event context.
+// If err is nil, no field is added.
+func (e *Event) Errs(key string, errs []error) *Event {
+	if !e.enabled {
+		return e
+	}
+	e.buf = json.AppendErrors(json.AppendKey(e.buf, key), errs)
 	return e
 }
 
@@ -138,16 +237,27 @@ func (e *Event) Err(err error) *Event {
 	if !e.enabled {
 		return e
 	}
-	e.buf = appendError(e.buf, err)
+	if err != nil {
+		e.buf = json.AppendError(json.AppendKey(e.buf, ErrorFieldName), err)
+	}
 	return e
 }
 
-// Bool adds the field key with val as a Boolean to the *Event context.
+// Bool adds the field key with val as a bool to the *Event context.
 func (e *Event) Bool(key string, b bool) *Event {
 	if !e.enabled {
 		return e
 	}
-	e.buf = appendBool(e.buf, key, b)
+	e.buf = json.AppendBool(json.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 {
+		return e
+	}
+	e.buf = json.AppendBools(json.AppendKey(e.buf, key), b)
 	return e
 }
 
@@ -156,7 +266,16 @@ func (e *Event) Int(key string, i int) *Event {
 	if !e.enabled {
 		return e
 	}
-	e.buf = appendInt(e.buf, key, i)
+	e.buf = json.AppendInt(json.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 {
+		return e
+	}
+	e.buf = json.AppendInts(json.AppendKey(e.buf, key), i)
 	return e
 }
 
@@ -165,7 +284,16 @@ func (e *Event) Int8(key string, i int8) *Event {
 	if !e.enabled {
 		return e
 	}
-	e.buf = appendInt8(e.buf, key, i)
+	e.buf = json.AppendInt8(json.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 {
+		return e
+	}
+	e.buf = json.AppendInts8(json.AppendKey(e.buf, key), i)
 	return e
 }
 
@@ -174,7 +302,16 @@ func (e *Event) Int16(key string, i int16) *Event {
 	if !e.enabled {
 		return e
 	}
-	e.buf = appendInt16(e.buf, key, i)
+	e.buf = json.AppendInt16(json.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 {
+		return e
+	}
+	e.buf = json.AppendInts16(json.AppendKey(e.buf, key), i)
 	return e
 }
 
@@ -183,7 +320,16 @@ func (e *Event) Int32(key string, i int32) *Event {
 	if !e.enabled {
 		return e
 	}
-	e.buf = appendInt32(e.buf, key, i)
+	e.buf = json.AppendInt32(json.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 {
+		return e
+	}
+	e.buf = json.AppendInts32(json.AppendKey(e.buf, key), i)
 	return e
 }
 
@@ -192,7 +338,16 @@ func (e *Event) Int64(key string, i int64) *Event {
 	if !e.enabled {
 		return e
 	}
-	e.buf = appendInt64(e.buf, key, i)
+	e.buf = json.AppendInt64(json.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 {
+		return e
+	}
+	e.buf = json.AppendInts64(json.AppendKey(e.buf, key), i)
 	return e
 }
 
@@ -201,7 +356,16 @@ func (e *Event) Uint(key string, i uint) *Event {
 	if !e.enabled {
 		return e
 	}
-	e.buf = appendUint(e.buf, key, i)
+	e.buf = json.AppendUint(json.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 {
+		return e
+	}
+	e.buf = json.AppendUints(json.AppendKey(e.buf, key), i)
 	return e
 }
 
@@ -210,7 +374,16 @@ func (e *Event) Uint8(key string, i uint8) *Event {
 	if !e.enabled {
 		return e
 	}
-	e.buf = appendUint8(e.buf, key, i)
+	e.buf = json.AppendUint8(json.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 {
+		return e
+	}
+	e.buf = json.AppendUints8(json.AppendKey(e.buf, key), i)
 	return e
 }
 
@@ -219,7 +392,16 @@ func (e *Event) Uint16(key string, i uint16) *Event {
 	if !e.enabled {
 		return e
 	}
-	e.buf = appendUint16(e.buf, key, i)
+	e.buf = json.AppendUint16(json.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 {
+		return e
+	}
+	e.buf = json.AppendUints16(json.AppendKey(e.buf, key), i)
 	return e
 }
 
@@ -228,7 +410,16 @@ func (e *Event) Uint32(key string, i uint32) *Event {
 	if !e.enabled {
 		return e
 	}
-	e.buf = appendUint32(e.buf, key, i)
+	e.buf = json.AppendUint32(json.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 {
+		return e
+	}
+	e.buf = json.AppendUints32(json.AppendKey(e.buf, key), i)
 	return e
 }
 
@@ -237,7 +428,16 @@ func (e *Event) Uint64(key string, i uint64) *Event {
 	if !e.enabled {
 		return e
 	}
-	e.buf = appendUint64(e.buf, key, i)
+	e.buf = json.AppendUint64(json.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 {
+		return e
+	}
+	e.buf = json.AppendUints64(json.AppendKey(e.buf, key), i)
 	return e
 }
 
@@ -246,7 +446,16 @@ func (e *Event) Float32(key string, f float32) *Event {
 	if !e.enabled {
 		return e
 	}
-	e.buf = appendFloat32(e.buf, key, f)
+	e.buf = json.AppendFloat32(json.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 {
+		return e
+	}
+	e.buf = json.AppendFloats32(json.AppendKey(e.buf, key), f)
 	return e
 }
 
@@ -255,7 +464,16 @@ func (e *Event) Float64(key string, f float64) *Event {
 	if !e.enabled {
 		return e
 	}
-	e.buf = appendFloat64(e.buf, key, f)
+	e.buf = json.AppendFloat64(json.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 {
+		return e
+	}
+	e.buf = json.AppendFloats64(json.AppendKey(e.buf, key), f)
 	return e
 }
 
@@ -265,7 +483,7 @@ func (e *Event) Timestamp() *Event {
 	if !e.enabled {
 		return e
 	}
-	e.buf = appendTimestamp(e.buf)
+	e.buf = json.AppendTime(json.AppendKey(e.buf, TimestampFieldName), TimestampFunc(), TimeFieldFormat)
 	return e
 }
 
@@ -274,7 +492,16 @@ func (e *Event) Time(key string, t time.Time) *Event {
 	if !e.enabled {
 		return e
 	}
-	e.buf = appendTime(e.buf, key, t)
+	e.buf = json.AppendTime(json.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 {
+		return e
+	}
+	e.buf = json.AppendTimes(json.AppendKey(e.buf, key), t, TimeFieldFormat)
 	return e
 }
 
@@ -285,7 +512,18 @@ func (e *Event) Dur(key string, d time.Duration) *Event {
 	if !e.enabled {
 		return e
 	}
-	e.buf = appendDuration(e.buf, key, d)
+	e.buf = json.AppendDuration(json.AppendKey(e.buf, key), d, DurationFieldUnit, DurationFieldInteger)
+	return e
+}
+
+// Durs adds the field key with duration d stored as zerolog.DurationFieldUnit.
+// If zerolog.DurationFieldInteger is true, durations are rendered as integer
+// instead of float.
+func (e *Event) Durs(key string, d []time.Duration) *Event {
+	if !e.enabled {
+		return e
+	}
+	e.buf = json.AppendDurations(json.AppendKey(e.buf, key), d, DurationFieldUnit, DurationFieldInteger)
 	return e
 }
 
@@ -300,7 +538,7 @@ func (e *Event) TimeDiff(key string, t time.Time, start time.Time) *Event {
 	if t.After(start) {
 		d = t.Sub(start)
 	}
-	e.buf = appendDuration(e.buf, key, d)
+	e.buf = json.AppendDuration(json.AppendKey(e.buf, key), d, DurationFieldUnit, DurationFieldInteger)
 	return e
 }
 
@@ -309,6 +547,9 @@ func (e *Event) Interface(key string, i interface{}) *Event {
 	if !e.enabled {
 		return e
 	}
-	e.buf = appendInterface(e.buf, key, i)
+	if obj, ok := i.(LogObjectMarshaler); ok {
+		return e.Object(key, obj)
+	}
+	e.buf = json.AppendInterface(json.AppendKey(e.buf, key), i)
 	return e
 }

field.go

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

fields.go

@@ -0,0 +1,96 @@
+package zerolog
+
+import (
+	"sort"
+	"time"
+
+	"github.com/rs/zerolog/internal/json"
+)
+
+func appendFields(dst []byte, fields map[string]interface{}) []byte {
+	keys := make([]string, 0, len(fields))
+	for key := range fields {
+		keys = append(keys, key)
+	}
+	sort.Strings(keys)
+	for _, key := range keys {
+		dst = json.AppendKey(dst, key)
+		switch val := fields[key].(type) {
+		case string:
+			dst = json.AppendString(dst, val)
+		case []byte:
+			dst = json.AppendBytes(dst, val)
+		case error:
+			dst = json.AppendError(dst, val)
+		case []error:
+			dst = json.AppendErrors(dst, val)
+		case bool:
+			dst = json.AppendBool(dst, val)
+		case int:
+			dst = json.AppendInt(dst, val)
+		case int8:
+			dst = json.AppendInt8(dst, val)
+		case int16:
+			dst = json.AppendInt16(dst, val)
+		case int32:
+			dst = json.AppendInt32(dst, val)
+		case int64:
+			dst = json.AppendInt64(dst, val)
+		case uint:
+			dst = json.AppendUint(dst, val)
+		case uint8:
+			dst = json.AppendUint8(dst, val)
+		case uint16:
+			dst = json.AppendUint16(dst, val)
+		case uint32:
+			dst = json.AppendUint32(dst, val)
+		case uint64:
+			dst = json.AppendUint64(dst, val)
+		case float32:
+			dst = json.AppendFloat32(dst, val)
+		case float64:
+			dst = json.AppendFloat64(dst, val)
+		case time.Time:
+			dst = json.AppendTime(dst, val, TimeFieldFormat)
+		case time.Duration:
+			dst = json.AppendDuration(dst, val, DurationFieldUnit, DurationFieldInteger)
+		case []string:
+			dst = json.AppendStrings(dst, val)
+		case []bool:
+			dst = json.AppendBools(dst, val)
+		case []int:
+			dst = json.AppendInts(dst, val)
+		case []int8:
+			dst = json.AppendInts8(dst, val)
+		case []int16:
+			dst = json.AppendInts16(dst, val)
+		case []int32:
+			dst = json.AppendInts32(dst, val)
+		case []int64:
+			dst = json.AppendInts64(dst, val)
+		case []uint:
+			dst = json.AppendUints(dst, val)
+		// case []uint8:
+		// 	dst = appendUints8(dst, val)
+		case []uint16:
+			dst = json.AppendUints16(dst, val)
+		case []uint32:
+			dst = json.AppendUints32(dst, val)
+		case []uint64:
+			dst = json.AppendUints64(dst, val)
+		case []float32:
+			dst = json.AppendFloats32(dst, val)
+		case []float64:
+			dst = json.AppendFloats64(dst, val)
+		case []time.Time:
+			dst = json.AppendTimes(dst, val, TimeFieldFormat)
+		case []time.Duration:
+			dst = json.AppendDurations(dst, val, DurationFieldUnit, DurationFieldInteger)
+		case nil:
+			dst = append(dst, "null"...)
+		default:
+			dst = json.AppendInterface(dst, val)
+		}
+	}
+	return dst
+}

globals.go

@@ -63,5 +63,5 @@ func DisableSampling(v bool) {
 }
 
 func samplingDisabled() bool {
-	return atomic.LoadUint32(gLevel) == 1
+	return atomic.LoadUint32(disableSampling) == 1
 }

hlog/hlog.go

@@ -5,10 +5,12 @@ import (
 	"context"
 	"net"
 	"net/http"
+	"time"
 
 	"github.com/rs/xid"
 	"github.com/rs/zerolog"
 	"github.com/rs/zerolog/log"
+	"github.com/zenazn/goji/web/mutil"
 )
 
 // FromRequest gets the logger in the request's context.
@@ -152,3 +154,15 @@ func RequestIDHandler(fieldKey, headerName string) func(next http.Handler) http.
 		})
 	}
 }
+
+// AccessHandler returns a handler that call f after each request.
+func AccessHandler(f func(r *http.Request, status, size int, duration time.Duration)) func(next http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			start := time.Now()
+			lw := mutil.WrapWriter(w)
+			next.ServeHTTP(lw, r)
+			f(r, lw.Status(), lw.BytesWritten(), time.Since(start))
+		})
+	}
+}

internal/json/base.go

@@ -0,0 +1,39 @@
+package json
+
+func AppendKey(dst []byte, key string) []byte {
+	if len(dst) > 1 {
+		dst = append(dst, ',')
+	}
+	dst = AppendString(dst, key)
+	return append(dst, ':')
+}
+
+func AppendError(dst []byte, err error) []byte {
+	if err == nil {
+		return append(dst, `null`...)
+	}
+	return AppendString(dst, err.Error())
+}
+
+func AppendErrors(dst []byte, errs []error) []byte {
+	if len(errs) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	if errs[0] != nil {
+		dst = AppendString(dst, errs[0].Error())
+	} else {
+		dst = append(dst, "null"...)
+	}
+	if len(errs) > 1 {
+		for _, err := range errs[1:] {
+			if err == nil {
+				dst = append(dst, ",null"...)
+				continue
+			}
+			dst = AppendString(append(dst, ','), err.Error())
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}

internal/json/string.go

@@ -0,0 +1,180 @@
+package json
+
+import "unicode/utf8"
+
+const hex = "0123456789abcdef"
+
+func AppendStrings(dst []byte, vals []string) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = AppendString(dst, vals[0])
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = AppendString(append(dst, ','), val)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+// AppendString encodes the input string to json and appends
+// the encoded string to the input byte slice.
+//
+// The operation loops though each byte in the string looking
+// for characters that need json or utf8 encoding. If the string
+// does not need encoding, then the string is appended in it's
+// 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 {
+	// Start with a double quote.
+	dst = append(dst, '"')
+	// Loop through each character in the string.
+	for i := 0; i < len(s); 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 s[i] < 0x20 || s[i] > 0x7e || s[i] == '\\' || s[i] == '"' {
+			// We encountered a character that needs to be encoded. Switch
+			// to complex version of the algorithm.
+			dst = appendStringComplex(dst, s, i)
+			return append(dst, '"')
+		}
+	}
+	// The string has no need for encoding an therefore is directly
+	// appended to the byte slice.
+	dst = append(dst, s...)
+	// End with a double quote
+	return append(dst, '"')
+}
+
+// appendStringComplex is used by appendString to take over an in
+// progress JSON string encoding that encountered a character that needs
+// to be encoded.
+func appendStringComplex(dst []byte, s string, i int) []byte {
+	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 remplacement 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', 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 != '"' {
+			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/string_test.go

@@ -0,0 +1,150 @@
+package json
+
+import (
+	"testing"
+	"unicode"
+)
+
+var encodeStringTests = []struct {
+	in  string
+	out string
+}{
+	{"", `""`},
+	{"\\", `"\\"`},
+	{"\x00", `"\u0000"`},
+	{"\x01", `"\u0001"`},
+	{"\x02", `"\u0002"`},
+	{"\x03", `"\u0003"`},
+	{"\x04", `"\u0004"`},
+	{"\x05", `"\u0005"`},
+	{"\x06", `"\u0006"`},
+	{"\x07", `"\u0007"`},
+	{"\x08", `"\b"`},
+	{"\x09", `"\t"`},
+	{"\x0a", `"\n"`},
+	{"\x0b", `"\u000b"`},
+	{"\x0c", `"\f"`},
+	{"\x0d", `"\r"`},
+	{"\x0e", `"\u000e"`},
+	{"\x0f", `"\u000f"`},
+	{"\x10", `"\u0010"`},
+	{"\x11", `"\u0011"`},
+	{"\x12", `"\u0012"`},
+	{"\x13", `"\u0013"`},
+	{"\x14", `"\u0014"`},
+	{"\x15", `"\u0015"`},
+	{"\x16", `"\u0016"`},
+	{"\x17", `"\u0017"`},
+	{"\x18", `"\u0018"`},
+	{"\x19", `"\u0019"`},
+	{"\x1a", `"\u001a"`},
+	{"\x1b", `"\u001b"`},
+	{"\x1c", `"\u001c"`},
+	{"\x1d", `"\u001d"`},
+	{"\x1e", `"\u001e"`},
+	{"\x1f", `"\u001f"`},
+	{"✭", `"✭"`},
+	{"foo\xc2\x7fbar", `"foo\ufffd\u007fbar"`}, // invalid sequence
+	{"ascii", `"ascii"`},
+	{"\"a", `"\"a"`},
+	{"\x1fa", `"\u001fa"`},
+	{"foo\"bar\"baz", `"foo\"bar\"baz"`},
+	{"\x1ffoo\x1fbar\x1fbaz", `"\u001ffoo\u001fbar\u001fbaz"`},
+	{"emoji \u2764\ufe0f!", `"emoji ❤️!"`},
+}
+
+func TestappendString(t *testing.T) {
+	for _, tt := range encodeStringTests {
+		b := 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) {
+	tests := map[string]string{
+		"NoEncoding":       `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,
+		"EncodingFirst":    `"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,
+		"EncodingMiddle":   `aaaaaaaaaaaaaaaaaaaaaaaaa"aaaaaaaaaaaaaaaaaaaaaaaa`,
+		"EncodingLast":     `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"`,
+		"MultiBytesFirst":  `❤️aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,
+		"MultiBytesMiddle": `aaaaaaaaaaaaaaaaaaaaaaaaa❤️aaaaaaaaaaaaaaaaaaaaaaaa`,
+		"MultiBytesLast":   `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa❤️`,
+	}
+	for name, str := range tests {
+		b.Run(name, func(b *testing.B) {
+			buf := make([]byte, 0, 100)
+			for i := 0; i < b.N; i++ {
+				_ = 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)
+			}
+		})
+	}
+}

internal/json/time.go

@@ -0,0 +1,68 @@
+package json
+
+import (
+	"strconv"
+	"time"
+)
+
+func AppendTime(dst []byte, t time.Time, format string) []byte {
+	if format == "" {
+		return AppendInt64(dst, t.Unix())
+	}
+	return append(t.AppendFormat(append(dst, '"'), format), '"')
+}
+
+func AppendTimes(dst []byte, vals []time.Time, format string) []byte {
+	if format == "" {
+		return appendUnixTimes(dst, vals)
+	}
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = append(vals[0].AppendFormat(append(dst, '"'), format), '"')
+	if len(vals) > 1 {
+		for _, t := range vals[1:] {
+			dst = append(t.AppendFormat(append(dst, ',', '"'), format), '"')
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+func appendUnixTimes(dst []byte, vals []time.Time) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendInt(dst, vals[0].Unix(), 10)
+	if len(vals) > 1 {
+		for _, t := range vals[1:] {
+			dst = strconv.AppendInt(dst, t.Unix(), 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+func AppendDuration(dst []byte, d time.Duration, unit time.Duration, useInt bool) []byte {
+	if useInt {
+		return strconv.AppendInt(dst, int64(d/unit), 10)
+	}
+	return AppendFloat64(dst, float64(d)/float64(unit))
+}
+
+func AppendDurations(dst []byte, vals []time.Duration, unit time.Duration, useInt bool) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = AppendDuration(dst, vals[0], unit, useInt)
+	if len(vals) > 1 {
+		for _, d := range vals[1:] {
+			dst = AppendDuration(append(dst, ','), d, unit, useInt)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}

internal/json/types.go

@@ -0,0 +1,278 @@
+package json
+
+import (
+	"encoding/json"
+	"fmt"
+	"math"
+	"strconv"
+)
+
+func AppendBool(dst []byte, val bool) []byte {
+	return strconv.AppendBool(dst, val)
+}
+
+func AppendBools(dst []byte, vals []bool) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendBool(dst, vals[0])
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendBool(append(dst, ','), val)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+func AppendInt(dst []byte, val int) []byte {
+	return strconv.AppendInt(dst, int64(val), 10)
+}
+
+func AppendInts(dst []byte, vals []int) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendInt(dst, int64(vals[0]), 10)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendInt(append(dst, ','), int64(val), 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+func AppendInt8(dst []byte, val int8) []byte {
+	return strconv.AppendInt(dst, int64(val), 10)
+}
+
+func AppendInts8(dst []byte, vals []int8) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendInt(dst, int64(vals[0]), 10)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendInt(append(dst, ','), int64(val), 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+func AppendInt16(dst []byte, val int16) []byte {
+	return strconv.AppendInt(dst, int64(val), 10)
+}
+
+func AppendInts16(dst []byte, vals []int16) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendInt(dst, int64(vals[0]), 10)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendInt(append(dst, ','), int64(val), 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+func AppendInt32(dst []byte, val int32) []byte {
+	return strconv.AppendInt(dst, int64(val), 10)
+}
+
+func AppendInts32(dst []byte, vals []int32) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendInt(dst, int64(vals[0]), 10)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendInt(append(dst, ','), int64(val), 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+func AppendInt64(dst []byte, val int64) []byte {
+	return strconv.AppendInt(dst, val, 10)
+}
+
+func AppendInts64(dst []byte, vals []int64) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendInt(dst, vals[0], 10)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendInt(append(dst, ','), val, 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+func AppendUint(dst []byte, val uint) []byte {
+	return strconv.AppendUint(dst, uint64(val), 10)
+}
+
+func AppendUints(dst []byte, vals []uint) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendUint(dst, uint64(vals[0]), 10)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendUint(append(dst, ','), uint64(val), 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+func AppendUint8(dst []byte, val uint8) []byte {
+	return strconv.AppendUint(dst, uint64(val), 10)
+}
+
+func AppendUints8(dst []byte, vals []uint8) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendUint(dst, uint64(vals[0]), 10)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendUint(append(dst, ','), uint64(val), 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+func AppendUint16(dst []byte, val uint16) []byte {
+	return strconv.AppendUint(dst, uint64(val), 10)
+}
+
+func AppendUints16(dst []byte, vals []uint16) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendUint(dst, uint64(vals[0]), 10)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendUint(append(dst, ','), uint64(val), 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+func AppendUint32(dst []byte, val uint32) []byte {
+	return strconv.AppendUint(dst, uint64(val), 10)
+}
+
+func AppendUints32(dst []byte, vals []uint32) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendUint(dst, uint64(vals[0]), 10)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendUint(append(dst, ','), uint64(val), 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+func AppendUint64(dst []byte, val uint64) []byte {
+	return strconv.AppendUint(dst, uint64(val), 10)
+}
+
+func AppendUints64(dst []byte, vals []uint64) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendUint(dst, vals[0], 10)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = strconv.AppendUint(append(dst, ','), val, 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+func AppendFloat(dst []byte, val float64, bitSize int) []byte {
+	// JSON does not permit NaN or Infinity. A typical JSON encoder would fail
+	// with an error, but a logging library wants the data to get thru so we
+	// make a tradeoff and store those types as string.
+	switch {
+	case math.IsNaN(val):
+		return append(dst, `"NaN"`...)
+	case math.IsInf(val, 1):
+		return append(dst, `"+Inf"`...)
+	case math.IsInf(val, -1):
+		return append(dst, `"-Inf"`...)
+	}
+	return strconv.AppendFloat(dst, val, 'f', -1, bitSize)
+}
+
+func AppendFloat32(dst []byte, val float32) []byte {
+	return AppendFloat(dst, float64(val), 32)
+}
+
+func AppendFloats32(dst []byte, vals []float32) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = AppendFloat(dst, float64(vals[0]), 32)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = AppendFloat(append(dst, ','), float64(val), 32)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+func AppendFloat64(dst []byte, val float64) []byte {
+	return AppendFloat(dst, val, 64)
+}
+
+func AppendFloats64(dst []byte, vals []float64) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = AppendFloat(dst, vals[0], 32)
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = AppendFloat(append(dst, ','), val, 64)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+func AppendInterface(dst []byte, i interface{}) []byte {
+	marshaled, err := json.Marshal(i)
+	if err != nil {
+		return AppendString(dst, fmt.Sprintf("marshaling error: %v", err))
+	}
+	return append(dst, marshaled...)
+}

internal/json/types_test.go

@@ -0,0 +1,33 @@
+package json
+
+import (
+	"math"
+	"reflect"
+	"testing"
+)
+
+func Test_appendFloat64(t *testing.T) {
+	tests := []struct {
+		name  string
+		input float64
+		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`)},
+	}
+	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)
+			}
+		})
+	}
+}

json.go

@@ -1,74 +0,0 @@
-package zerolog
-
-import "unicode/utf8"
-
-const hex = "0123456789abcdef"
-
-// appendJSONString encodes the input string to json and appends
-// the encoded string to the input byte slice.
-//
-// The operation loops though each byte in the string looking
-// for characters that need json or utf8 encoding. If the string
-// does not need encoding, then the string is appended in it's
-// entirety to the byte slice.
-// If we encounter a byte that does need encoding, switch up
-// the operation and perform a byte-by-byte read-encode-append.
-func appendJSONString(dst []byte, s string) []byte {
-	// Start with a double quote.
-	dst = append(dst, '"')
-	// Loop through each character in the string.
-	for i := 0; i < len(s); 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 s[i] < ' ' || s[i] == '\\' || s[i] == '"' || s[i] > 126 {
-			// 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.
-			dst = append(dst, s[:i]...)
-			for i < len(s) {
-				if b := s[i]; b < utf8.RuneSelf {
-					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:
-						if b >= 0x20 {
-							dst = append(dst, b)
-						} else {
-							dst = append(dst, '\\', 'u', '0', '0',
-								hex[b>>4], hex[b&0xF])
-						}
-					}
-					i++
-					continue
-				}
-				r, size := utf8.DecodeRuneInString(s[i:])
-				if r == utf8.RuneError && size == 1 {
-					dst = append(dst, `\ufffd`...)
-					i++
-					continue
-				}
-				dst = append(dst, s[i:i+size]...)
-				i += size
-			}
-			// End with a double quote
-			return append(dst, '"')
-		}
-	}
-	// The string has no need for encoding an therefore is directly
-	// appended to the byte slice.
-	dst = append(dst, s...)
-	// End with a double quote
-	return append(dst, '"')
-}

json_test.go

@@ -1,53 +0,0 @@
-package zerolog
-
-import "testing"
-
-func TestAppendJSONString(t *testing.T) {
-	encodeStringTests := []struct {
-		in  string
-		out string
-	}{
-		{"\\", `"\\"`},
-		{"\x00", `"\u0000"`},
-		{"\x01", `"\u0001"`},
-		{"\x02", `"\u0002"`},
-		{"\x03", `"\u0003"`},
-		{"\x04", `"\u0004"`},
-		{"\x05", `"\u0005"`},
-		{"\x06", `"\u0006"`},
-		{"\x07", `"\u0007"`},
-		{"\x08", `"\b"`},
-		{"\x09", `"\t"`},
-		{"\x0a", `"\n"`},
-		{"\x0b", `"\u000b"`},
-		{"\x0c", `"\f"`},
-		{"\x0d", `"\r"`},
-		{"\x0e", `"\u000e"`},
-		{"\x0f", `"\u000f"`},
-		{"\x10", `"\u0010"`},
-		{"\x11", `"\u0011"`},
-		{"\x12", `"\u0012"`},
-		{"\x13", `"\u0013"`},
-		{"\x14", `"\u0014"`},
-		{"\x15", `"\u0015"`},
-		{"\x16", `"\u0016"`},
-		{"\x17", `"\u0017"`},
-		{"\x18", `"\u0018"`},
-		{"\x19", `"\u0019"`},
-		{"\x1a", `"\u001a"`},
-		{"\x1b", `"\u001b"`},
-		{"\x1c", `"\u001c"`},
-		{"\x1d", `"\u001d"`},
-		{"\x1e", `"\u001e"`},
-		{"\x1f", `"\u001f"`},
-		{"ascii", `"ascii"`},
-		{"emoji \u2764\ufe0f!", `"emoji ❤️!"`},
-	}
-
-	for _, tt := range encodeStringTests {
-		b := appendJSONString([]byte{}, tt.in)
-		if got, want := string(b), tt.out; got != want {
-			t.Errorf("appendJSONString(%q) = %#q, want %#q", tt.in, got, want)
-		}
-	}
-}

log.go

@@ -71,7 +71,10 @@ import (
 	"io"
 	"io/ioutil"
 	"os"
+	"strconv"
 	"sync/atomic"
+
+	"github.com/rs/zerolog/internal/json"
 )
 
 // Level defines log levels.
@@ -159,6 +162,16 @@ func Nop() Logger {
 	return New(nil).Level(Disabled)
 }
 
+// Output duplicates the current logger and sets w as its output.
+func (l Logger) Output(w io.Writer) Logger {
+	l2 := New(w)
+	l2.level = l.level
+	l2.sample = l.sample
+	l2.context = make([]byte, len(l.context))
+	copy(l2.context, l.context)
+	return l2
+}
+
 // With creates a child logger with the field added to its context.
 func (l Logger) With() Context {
 	context := l.context
@@ -246,6 +259,30 @@ func (l Logger) Panic() *Event {
 	return l.newEvent(PanicLevel, true, 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 {
+	switch level {
+	case DebugLevel:
+		return l.Debug()
+	case InfoLevel:
+		return l.Info()
+	case WarnLevel:
+		return l.Warn()
+	case ErrorLevel:
+		return l.Error()
+	case FatalLevel:
+		return l.Fatal()
+	case PanicLevel:
+		return l.Panic()
+	case Disabled:
+		return disabledEvent
+	default:
+		panic("zerolog: WithLevel(): invalid level: " + strconv.Itoa(int(level)))
+	}
+}
+
 // Log starts a new message with no level. Setting GlobalLevel to Disabled
 // will still disable events produced by this method.
 //
@@ -281,7 +318,7 @@ func (l Logger) newEvent(level Level, addLevelField bool, done func(string)) *Ev
 	e.done = done
 	if l.context != nil && len(l.context) > 0 && l.context[0] > 0 {
 		// first byte of context is ts flag
-		e.buf = appendTimestamp(e.buf)
+		e.buf = json.AppendTime(json.AppendKey(e.buf, TimestampFieldName), TimestampFunc(), TimeFieldFormat)
 	}
 	if addLevelField {
 		e.Str(LevelFieldName, level.String())

log/log.go

@@ -3,6 +3,7 @@ package log
 
 import (
 	"context"
+	"io"
 	"os"
 
 	"github.com/rs/zerolog"
@@ -11,6 +12,11 @@ import (
 // Logger is the global logger.
 var Logger = zerolog.New(os.Stderr).With().Timestamp().Logger()
 
+// Output duplicates the global logger and sets w as its output.
+func Output(w io.Writer) zerolog.Logger {
+	return Logger.Output(w)
+}
+
 // With creates a child logger with the field added to its context.
 func With() zerolog.Context {
 	return Logger.With()

log_example_test.go

@@ -91,6 +91,15 @@ func ExampleLogger_Error() {
 	// Output: {"level":"error","error":"some error","message":"error doing something"}
 }
 
+func ExampleLogger_WithLevel() {
+	log := zerolog.New(os.Stdout)
+
+	log.WithLevel(zerolog.InfoLevel).
+		Msg("hello world")
+
+	// Output: {"level":"info","message":"hello world"}
+}
+
 func ExampleLogger_Write() {
 	log := zerolog.New(os.Stdout).With().
 		Str("foo", "bar").
@@ -129,6 +138,71 @@ func ExampleEvent_Dict() {
 	// Output: {"foo":"bar","dict":{"bar":"baz","n":1},"message":"hello world"}
 }
 
+type User struct {
+	Name    string
+	Age     int
+	Created time.Time
+}
+
+func (u User) MarshalZerologObject(e *zerolog.Event) {
+	e.Str("name", u.Name).
+		Int("age", u.Age).
+		Time("created", u.Created)
+}
+
+type Users []User
+
+func (uu Users) MarshalZerologArray(a *zerolog.Array) {
+	for _, u := range uu {
+		a.Object(u)
+	}
+}
+
+func ExampleEvent_Array() {
+	log := zerolog.New(os.Stdout)
+
+	log.Log().
+		Str("foo", "bar").
+		Array("array", zerolog.Arr().
+			Str("baz").
+			Int(1),
+		).
+		Msg("hello world")
+
+	// Output: {"foo":"bar","array":["baz",1],"message":"hello world"}
+}
+
+func ExampleEvent_Array_object() {
+	log := zerolog.New(os.Stdout)
+
+	// Users implements zerolog.LogArrayMarshaler
+	u := Users{
+		User{"John", 35, time.Time{}},
+		User{"Bob", 55, time.Time{}},
+	}
+
+	log.Log().
+		Str("foo", "bar").
+		Array("users", u).
+		Msg("hello world")
+
+	// Output: {"foo":"bar","users":[{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},{"name":"Bob","age":55,"created":"0001-01-01T00:00:00Z"}],"message":"hello world"}
+}
+
+func ExampleEvent_Object() {
+	log := zerolog.New(os.Stdout)
+
+	// User implements zerolog.LogObjectMarshaler
+	u := User{"John", 35, time.Time{}}
+
+	log.Log().
+		Str("foo", "bar").
+		Object("user", u).
+		Msg("hello world")
+
+	// Output: {"foo":"bar","user":{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},"message":"hello world"}
+}
+
 func ExampleEvent_Interface() {
 	log := zerolog.New(os.Stdout)
 
@@ -159,6 +233,22 @@ func ExampleEvent_Dur() {
 	// Output: {"foo":"bar","dur":10000,"message":"hello world"}
 }
 
+func ExampleEvent_Durs() {
+	d := []time.Duration{
+		time.Duration(10 * time.Second),
+		time.Duration(20 * time.Second),
+	}
+
+	log := zerolog.New(os.Stdout)
+
+	log.Log().
+		Str("foo", "bar").
+		Durs("durs", d).
+		Msg("hello world")
+
+	// Output: {"foo":"bar","durs":[10000,20000],"message":"hello world"}
+}
+
 func ExampleContext_Dict() {
 	log := zerolog.New(os.Stdout).With().
 		Str("foo", "bar").
@@ -172,6 +262,50 @@ func ExampleContext_Dict() {
 	// Output: {"foo":"bar","dict":{"bar":"baz","n":1},"message":"hello world"}
 }
 
+func ExampleContext_Array() {
+	log := zerolog.New(os.Stdout).With().
+		Str("foo", "bar").
+		Array("array", zerolog.Arr().
+			Str("baz").
+			Int(1),
+		).Logger()
+
+	log.Log().Msg("hello world")
+
+	// Output: {"foo":"bar","array":["baz",1],"message":"hello world"}
+}
+
+func ExampleContext_Array_object() {
+	// Users implements zerolog.LogArrayMarshaler
+	u := Users{
+		User{"John", 35, time.Time{}},
+		User{"Bob", 55, time.Time{}},
+	}
+
+	log := zerolog.New(os.Stdout).With().
+		Str("foo", "bar").
+		Array("users", u).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	// Output: {"foo":"bar","users":[{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},{"name":"Bob","age":55,"created":"0001-01-01T00:00:00Z"}],"message":"hello world"}
+}
+
+func ExampleContext_Object() {
+	// User implements zerolog.LogObjectMarshaler
+	u := User{"John", 35, time.Time{}}
+
+	log := zerolog.New(os.Stdout).With().
+		Str("foo", "bar").
+		Object("user", u).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	// Output: {"foo":"bar","user":{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},"message":"hello world"}
+}
+
 func ExampleContext_Interface() {
 	obj := struct {
 		Name string `json:"name"`
@@ -201,3 +335,19 @@ func ExampleContext_Dur() {
 
 	// Output: {"foo":"bar","dur":10000,"message":"hello world"}
 }
+
+func ExampleContext_Durs() {
+	d := []time.Duration{
+		time.Duration(10 * time.Second),
+		time.Duration(20 * time.Second),
+	}
+
+	log := zerolog.New(os.Stdout).With().
+		Str("foo", "bar").
+		Durs("durs", d).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	// Output: {"foo":"bar","durs":[10000,20000],"message":"hello world"}
+}

log_test.go

@@ -14,7 +14,7 @@ func TestLog(t *testing.T) {
 		log := New(out)
 		log.Log().Msg("")
 		if got, want := out.String(), "{}\n"; got != want {
-			t.Errorf("invalid log output: got %q, want %q", got, want)
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
 
@@ -23,7 +23,7 @@ func TestLog(t *testing.T) {
 		log := New(out)
 		log.Log().Str("foo", "bar").Msg("")
 		if got, want := out.String(), `{"foo":"bar"}`+"\n"; got != want {
-			t.Errorf("invalid log output: got %q, want %q", got, want)
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
 
@@ -35,7 +35,7 @@ func TestLog(t *testing.T) {
 			Int("n", 123).
 			Msg("")
 		if got, want := out.String(), `{"foo":"bar","n":123}`+"\n"; got != want {
-			t.Errorf("invalid log output: got %q, want %q", got, want)
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
 }
@@ -46,7 +46,7 @@ func TestInfo(t *testing.T) {
 		log := New(out)
 		log.Info().Msg("")
 		if got, want := out.String(), `{"level":"info"}`+"\n"; got != want {
-			t.Errorf("invalid log output: got %q, want %q", got, want)
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
 
@@ -55,7 +55,7 @@ func TestInfo(t *testing.T) {
 		log := New(out)
 		log.Info().Str("foo", "bar").Msg("")
 		if got, want := out.String(), `{"level":"info","foo":"bar"}`+"\n"; got != want {
-			t.Errorf("invalid log output: got %q, want %q", got, want)
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
 
@@ -67,7 +67,7 @@ func TestInfo(t *testing.T) {
 			Int("n", 123).
 			Msg("")
 		if got, want := out.String(), `{"level":"info","foo":"bar","n":123}`+"\n"; got != want {
-			t.Errorf("invalid log output: got %q, want %q", got, want)
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
 }
@@ -95,15 +95,46 @@ func TestWith(t *testing.T) {
 		Logger()
 	log.Log().Msg("")
 	if got, want := out.String(), `{"foo":"bar","error":"some error","bool":true,"int":1,"int8":2,"int16":3,"int32":4,"int64":5,"uint":6,"uint8":7,"uint16":8,"uint32":9,"uint64":10,"float32":11,"float64":12,"time":"0001-01-01T00:00:00Z"}`+"\n"; got != want {
-		t.Errorf("invalid log output: got %q, want %q", got, want)
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestFieldsMap(t *testing.T) {
+	out := &bytes.Buffer{}
+	log := New(out)
+	log.Log().Fields(map[string]interface{}{
+		"nil":     nil,
+		"string":  "foo",
+		"bytes":   []byte("bar"),
+		"error":   errors.New("some error"),
+		"bool":    true,
+		"int":     int(1),
+		"int8":    int8(2),
+		"int16":   int16(3),
+		"int32":   int32(4),
+		"int64":   int64(5),
+		"uint":    uint(6),
+		"uint8":   uint8(7),
+		"uint16":  uint16(8),
+		"uint32":  uint32(9),
+		"uint64":  uint64(10),
+		"float32": float32(11),
+		"float64": float64(12),
+		"dur":     1 * time.Second,
+		"time":    time.Time{},
+	}).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 {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
 
 func TestFields(t *testing.T) {
 	out := &bytes.Buffer{}
 	log := New(out)
+	now := time.Now()
 	log.Log().
-		Str("foo", "bar").
+		Str("string", "foo").
+		Bytes("bytes", []byte("bar")).
 		AnErr("some_err", nil).
 		Err(errors.New("some error")).
 		Bool("bool", true).
@@ -121,18 +152,101 @@ func TestFields(t *testing.T) {
 		Float64("float64", 12).
 		Dur("dur", 1*time.Second).
 		Time("time", time.Time{}).
-		TimeDiff("diff", time.Now(), time.Now().Add(-10*time.Second)).
+		TimeDiff("diff", now, now.Add(-10*time.Second)).
 		Msg("")
-	if got, want := out.String(), `{"foo":"bar","error":"some error","bool":true,"int":1,"int8":2,"int16":3,"int32":4,"int64":5,"uint":6,"uint8":7,"uint16":8,"uint32":9,"uint64":10,"float32":11,"float64":12,"dur":1000,"time":"0001-01-01T00:00:00Z","diff":10000}`+"\n"; got != want {
-		t.Errorf("invalid log output: got %q, want %q", got, want)
+	if got, want := 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 {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestFieldsArrayEmpty(t *testing.T) {
+	out := &bytes.Buffer{}
+	log := New(out)
+	log.Log().
+		Strs("string", []string{}).
+		Errs("err", []error{}).
+		Bools("bool", []bool{}).
+		Ints("int", []int{}).
+		Ints8("int8", []int8{}).
+		Ints16("int16", []int16{}).
+		Ints32("int32", []int32{}).
+		Ints64("int64", []int64{}).
+		Uints("uint", []uint{}).
+		Uints8("uint8", []uint8{}).
+		Uints16("uint16", []uint16{}).
+		Uints32("uint32", []uint32{}).
+		Uints64("uint64", []uint64{}).
+		Floats32("float32", []float32{}).
+		Floats64("float64", []float64{}).
+		Durs("dur", []time.Duration{}).
+		Times("time", []time.Time{}).
+		Msg("")
+	if got, want := out.String(), `{"string":[],"err":[],"bool":[],"int":[],"int8":[],"int16":[],"int32":[],"int64":[],"uint":[],"uint8":[],"uint16":[],"uint32":[],"uint64":[],"float32":[],"float64":[],"dur":[],"time":[]}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestFieldsArraySingleElement(t *testing.T) {
+	out := &bytes.Buffer{}
+	log := New(out)
+	log.Log().
+		Strs("string", []string{"foo"}).
+		Errs("err", []error{errors.New("some error")}).
+		Bools("bool", []bool{true}).
+		Ints("int", []int{1}).
+		Ints8("int8", []int8{2}).
+		Ints16("int16", []int16{3}).
+		Ints32("int32", []int32{4}).
+		Ints64("int64", []int64{5}).
+		Uints("uint", []uint{6}).
+		Uints8("uint8", []uint8{7}).
+		Uints16("uint16", []uint16{8}).
+		Uints32("uint32", []uint32{9}).
+		Uints64("uint64", []uint64{10}).
+		Floats32("float32", []float32{11}).
+		Floats64("float64", []float64{12}).
+		Durs("dur", []time.Duration{1 * time.Second}).
+		Times("time", []time.Time{time.Time{}}).
+		Msg("")
+	if got, want := 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 {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestFieldsArrayMultipleElement(t *testing.T) {
+	out := &bytes.Buffer{}
+	log := New(out)
+	log.Log().
+		Strs("string", []string{"foo", "bar"}).
+		Errs("err", []error{errors.New("some error"), nil}).
+		Bools("bool", []bool{true, false}).
+		Ints("int", []int{1, 0}).
+		Ints8("int8", []int8{2, 0}).
+		Ints16("int16", []int16{3, 0}).
+		Ints32("int32", []int32{4, 0}).
+		Ints64("int64", []int64{5, 0}).
+		Uints("uint", []uint{6, 0}).
+		Uints8("uint8", []uint8{7, 0}).
+		Uints16("uint16", []uint16{8, 0}).
+		Uints32("uint32", []uint32{9, 0}).
+		Uints64("uint64", []uint64{10, 0}).
+		Floats32("float32", []float32{11, 0}).
+		Floats64("float64", []float64{12, 0}).
+		Durs("dur", []time.Duration{1 * time.Second, 0}).
+		Times("time", []time.Time{time.Time{}, time.Time{}}).
+		Msg("")
+	if got, want := 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 {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
 
 func TestFieldsDisabled(t *testing.T) {
 	out := &bytes.Buffer{}
 	log := New(out).Level(InfoLevel)
+	now := time.Now()
 	log.Debug().
-		Str("foo", "bar").
+		Str("string", "foo").
+		Bytes("bytes", []byte("bar")).
 		AnErr("some_err", nil).
 		Err(errors.New("some error")).
 		Bool("bool", true).
@@ -150,10 +264,10 @@ func TestFieldsDisabled(t *testing.T) {
 		Float64("float64", 12).
 		Dur("dur", 1*time.Second).
 		Time("time", time.Time{}).
-		TimeDiff("diff", time.Now(), time.Now().Add(-10*time.Second)).
+		TimeDiff("diff", now, now.Add(-10*time.Second)).
 		Msg("")
 	if got, want := out.String(), ""; got != want {
-		t.Errorf("invalid log output: got %q, want %q", got, want)
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
 
@@ -161,7 +275,7 @@ func TestMsgf(t *testing.T) {
 	out := &bytes.Buffer{}
 	New(out).Log().Msgf("one %s %.1f %d %v", "two", 3.4, 5, errors.New("six"))
 	if got, want := out.String(), `{"message":"one two 3.4 5 six"}`+"\n"; got != want {
-		t.Errorf("invalid log output: got %q, want %q", got, want)
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
 
@@ -170,7 +284,7 @@ func TestWithAndFieldsCombined(t *testing.T) {
 	log := New(out).With().Str("f1", "val").Str("f2", "val").Logger()
 	log.Log().Str("f3", "val").Msg("")
 	if got, want := out.String(), `{"f1":"val","f2":"val","f3":"val"}`+"\n"; got != want {
-		t.Errorf("invalid log output: got %q, want %q", got, want)
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
 
@@ -180,7 +294,7 @@ func TestLevel(t *testing.T) {
 		log := New(out).Level(Disabled)
 		log.Info().Msg("test")
 		if got, want := out.String(), ""; got != want {
-			t.Errorf("invalid log output: got %q, want %q", got, want)
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
 
@@ -189,7 +303,7 @@ func TestLevel(t *testing.T) {
 		log := New(out).Level(InfoLevel)
 		log.Info().Msg("test")
 		if got, want := out.String(), `{"level":"info","message":"test"}`+"\n"; got != want {
-			t.Errorf("invalid log output: got %q, want %q", got, want)
+			t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 		}
 	})
 }
@@ -202,7 +316,7 @@ func TestSampling(t *testing.T) {
 	log.Log().Int("i", 3).Msg("")
 	log.Log().Int("i", 4).Msg("")
 	if got, want := out.String(), "{\"sample\":2,\"i\":2}\n{\"sample\":2,\"i\":4}\n"; got != want {
-		t.Errorf("invalid log output: got %q, want %q", got, want)
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
 
@@ -237,6 +351,11 @@ func TestLevelWriter(t *testing.T) {
 	log.Info().Msg("2")
 	log.Warn().Msg("3")
 	log.Error().Msg("4")
+	log.WithLevel(DebugLevel).Msg("5")
+	log.WithLevel(InfoLevel).Msg("6")
+	log.WithLevel(WarnLevel).Msg("7")
+	log.WithLevel(ErrorLevel).Msg("8")
+
 	want := []struct {
 		l Level
 		p string
@@ -245,6 +364,10 @@ func TestLevelWriter(t *testing.T) {
 		{InfoLevel, `{"level":"info","message":"2"}` + "\n"},
 		{WarnLevel, `{"level":"warn","message":"3"}` + "\n"},
 		{ErrorLevel, `{"level":"error","message":"4"}` + "\n"},
+		{DebugLevel, `{"level":"debug","message":"5"}` + "\n"},
+		{InfoLevel, `{"level":"info","message":"6"}` + "\n"},
+		{WarnLevel, `{"level":"warn","message":"7"}` + "\n"},
+		{ErrorLevel, `{"level":"error","message":"8"}` + "\n"},
 	}
 	if got := lw.ops; !reflect.DeepEqual(got, want) {
 		t.Errorf("invalid ops:\ngot:\n%v\nwant:\n%v", got, want)
@@ -263,7 +386,7 @@ func TestContextTimestamp(t *testing.T) {
 	log.Log().Msg("hello world")
 
 	if got, want := out.String(), `{"time":"2001-02-03T04:05:06Z","foo":"bar","message":"hello world"}`+"\n"; got != want {
-		t.Errorf("invalid log output: got %q, want %q", got, want)
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
 
@@ -279,6 +402,6 @@ func TestEventTimestamp(t *testing.T) {
 	log.Log().Timestamp().Msg("hello world")
 
 	if got, want := out.String(), `{"foo":"bar","time":"2001-02-03T04:05:06Z","message":"hello world"}`+"\n"; got != want {
-		t.Errorf("invalid log output: got %q, want %q", got, want)
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }