Fix Context.Stack() (#303)

Co-authored-by: Emre Arslan <emre.arslan@trendyol.com>

.travis.yml

@@ -1,9 +1,13 @@
 language: go
 go:
-- "1.7"
-- "1.8"
 - "1.9"
 - "1.10"
+- "1.11"
+- "1.12"
+- "1.13"
+- "1.14"
+- "1.15"
+- "1.16"
 - "master"
 matrix:
   allow_failures:

README.md

@@ -18,20 +18,21 @@ Find out [who uses zerolog](https://github.com/rs/zerolog/wiki/Who-uses-zerolog)
 
 ## Features
 
-* Blazing fast
-* Low to zero allocation
-* Level logging
-* Sampling
-* Hooks
-* Contextual fields
+* [Blazing fast](#benchmarks)
+* [Low to zero allocation](#benchmarks)
+* [Leveled logging](#leveled-logging)
+* [Sampling](#log-sampling)
+* [Hooks](#hooks)
+* [Contextual fields](#contextual-logging)
 * `context.Context` integration
-* `net/http` helpers
-* JSON and CBOR encoding formats
-* Pretty logging for development
+* [Integration with `net/http`](#integration-with-nethttp)
+* [JSON and CBOR encoding formats](#binary-encoding)
+* [Pretty logging for development](#pretty-logging)
+* [Error Logging (with optional Stacktrace)](#error-logging)
 
 ## Installation
 
-```go
+```bash
 go get -u github.com/rs/zerolog/log
 ```
 
@@ -51,9 +52,7 @@ import (
 
 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 = ""
+    zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
 
     log.Print("hello world")
 }
@@ -76,15 +75,20 @@ import (
 )
 
 func main() {
-    zerolog.TimeFieldFormat = ""
+    zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
 
     log.Debug().
         Str("Scale", "833 cents").
         Float64("Interval", 833.09).
         Msg("Fibonacci is everywhere")
+    
+    log.Debug().
+        Str("Name", "Tom").
+        Send()
 }
 
-// Output: {"time":1524104936,"level":"debug","Scale":"833 cents","Interval":833.09,"message":"Fibonacci is everywhere"}
+// Output: {"level":"debug","Scale":"833 cents","Interval":833.09,"time":1562212768,"message":"Fibonacci is everywhere"}
+// Output: {"level":"debug","Name":"Tom","time":1562212768}
 ```
 
 > 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)
@@ -102,7 +106,7 @@ import (
 )
 
 func main() {
-    zerolog.TimeFieldFormat = ""
+    zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
 
     log.Info().Msg("hello world")
 }
@@ -120,6 +124,7 @@ func main() {
 * warn (`zerolog.WarnLevel`, 2)
 * info (`zerolog.InfoLevel`, 1)
 * debug (`zerolog.DebugLevel`, 0)
+* trace (`zerolog.TraceLevel`, -1)
 
 You can set the Global logging level to any of these options using the `SetGlobalLevel` function in the zerolog package, passing in one of the given constants above, e.g. `zerolog.InfoLevel` would be the "info" level.  Whichever level is chosen, all logs with a level greater than or equal to that level will be written. To turn off logging entirely, pass the `zerolog.Disabled` constant.
 
@@ -138,7 +143,7 @@ import (
 )
 
 func main() {
-    zerolog.TimeFieldFormat = ""
+    zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
     debug := flag.Bool("debug", false, "sets log level to debug")
 
     flag.Parse()
@@ -189,7 +194,7 @@ import (
 )
 
 func main() {
-    zerolog.TimeFieldFormat = ""
+    zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
 
     log.Log().
         Str("foo", "bar").
@@ -199,6 +204,80 @@ func main() {
 // Output: {"time":1494567715,"foo":"bar"}
 ```
 
+### Error Logging
+
+You can log errors using the `Err` method
+
+```go
+package main
+
+import (
+	"errors"
+
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/log"
+)
+
+func main() {
+	zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
+
+	err := errors.New("seems we have an error here")
+	log.Error().Err(err).Msg("")
+}
+
+// Output: {"level":"error","error":"seems we have an error here","time":1609085256}
+```
+
+> The default field name for errors is `error`, you can change this by setting `zerolog.ErrorFieldName` to meet your needs.
+
+#### Error Logging with Stacktrace
+
+Using `github.com/pkg/errors`, you can add a formatted stacktrace to your errors. 
+
+```go
+package main
+
+import (
+	"github.com/pkg/errors"
+	"github.com/rs/zerolog/pkgerrors"
+
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/log"
+)
+
+func main() {
+	zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
+	zerolog.ErrorStackMarshaler = pkgerrors.MarshalStack
+
+	err := outer()
+	log.Error().Stack().Err(err).Msg("")
+}
+
+func inner() error {
+	return errors.New("seems we have an error here")
+}
+
+func middle() error {
+	err := inner()
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func outer() error {
+	err := middle()
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+// Output: {"level":"error","stack":[{"func":"inner","line":"20","source":"errors.go"},{"func":"middle","line":"24","source":"errors.go"},{"func":"outer","line":"32","source":"errors.go"},{"func":"main","line":"15","source":"errors.go"},{"func":"main","line":"204","source":"proc.go"},{"func":"goexit","line":"1374","source":"asm_amd64.s"}],"error":"seems we have an error here","time":1609086683}
+```
+
+> zerolog.ErrorStackMarshaler must be set in order for the stack to output anything.
+
 #### Logging Fatal Messages
 
 ```go
@@ -215,7 +294,7 @@ func main() {
     err := errors.New("A repo man spends his life getting into tense situations")
     service := "myservice"
 
-    zerolog.TimeFieldFormat = ""
+    zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
 
     log.Fatal().
         Err(err).
@@ -229,6 +308,7 @@ func main() {
 
 > NOTE: Using `Msgf` generates one allocation even when the logger is disabled.
 
+
 ### Create logger instance to manage different outputs
 
 ```go
@@ -335,7 +415,7 @@ If your writer might be slow or not thread-safe and you need your log producers
 wr := diode.NewWriter(os.Stdout, 1000, 10*time.Millisecond, func(missed int) {
 		fmt.Printf("Logger Dropped %d messages", missed)
 	})
-log := zerolog.New(w)
+log := zerolog.New(wr)
 log.Print("test")
 ```
 
@@ -429,11 +509,11 @@ c := alice.New()
 c = c.Append(hlog.NewHandler(log))
 
 // Install some provided extra handler to set some request's context fields.
-// Thanks to those handler, all our logs will come with some pre-populated fields.
+// Thanks to that handler, all our logs will come with some prepopulated fields.
 c = c.Append(hlog.AccessHandler(func(r *http.Request, status, size int, duration time.Duration) {
     hlog.FromRequest(r).Info().
         Str("method", r.Method).
-        Str("url", r.URL.String()).
+        Stringer("url", r.URL).
         Int("status", status).
         Int("size", size).
         Dur("duration", duration).
@@ -463,23 +543,40 @@ if err := http.ListenAndServe(":8080", nil); err != nil {
 }
 ```
 
+## Multiple Log Output
+`zerolog.MultiLevelWriter` may be used to send the log message to multiple outputs. 
+In this example, we send the log message to both `os.Stdout` and the in-built ConsoleWriter.
+```go
+func main() {
+	consoleWriter := zerolog.ConsoleWriter{Out: os.Stdout}
+
+	multi := zerolog.MultiLevelWriter(consoleWriter, os.Stdout)
+
+	logger := zerolog.New(multi).With().Timestamp().Logger()
+
+	logger.Info().Msg("Hello World!")
+}
+
+// Output (Line 1: Console; Line 2: Stdout)
+// 12:36PM INF Hello World!
+// {"level":"info","time":"2019-11-07T12:36:38+03:00","message":"Hello World!"}
+``` 
+
 ## Global Settings
 
 Some settings can be changed and will by applied to all loggers:
 
 * `log.Logger`: You can set this value to customize the global logger (the one used by package level methods).
-* `zerolog.SetGlobalLevel`: Can raise the minimum level of all loggers. Set this to `zerolog.Disabled` to disable logging altogether (quiet mode).
+* `zerolog.SetGlobalLevel`: Can raise the minimum level of all loggers. Call this with `zerolog.Disabled` to disable logging altogether (quiet mode).
 * `zerolog.DisableSampling`: If argument is `true`, all sampled loggers will stop sampling and issue 100% of their log events.
 * `zerolog.TimestampFieldName`: Can be set to customize `Timestamp` field name.
 * `zerolog.LevelFieldName`: Can be set to customize level field name.
 * `zerolog.MessageFieldName`: Can be set to customize message field name.
 * `zerolog.ErrorFieldName`: Can be set to customize `Err` field name.
-* `zerolog.TimeFieldFormat`: Can be set to customize `Time` field value formatting. If set with an empty string, times are formated as UNIX timestamp.
-    // DurationFieldUnit defines the unit for time.Duration type fields added
-    // using the Dur method.
-* `DurationFieldUnit`: Sets the unit of the fields added by `Dur` (default: `time.Millisecond`).
-* `DurationFieldInteger`: If set to true, `Dur` fields are formatted as integers instead of floats.
-* `ErrorHandler`: Called whenever zerolog fails to write an event on its output. If not set, an error is printed on the stderr. This handler must be thread safe and non-blocking.
+* `zerolog.TimeFieldFormat`: Can be set to customize `Time` field value formatting. If set with `zerolog.TimeFormatUnix`, `zerolog.TimeFormatUnixMs` or `zerolog.TimeFormatUnixMicro`, times are formated as UNIX timestamp.
+* `zerolog.DurationFieldUnit`: Can be set to customize the unit for time.Duration type fields added by `Dur` (default: `time.Millisecond`).
+* `zerolog.DurationFieldInteger`: If set to `true`, `Dur` fields are formatted as integers instead of floats (default: `false`). 
+* `zerolog.ErrorHandler`: Called whenever zerolog fails to write an event on its output. If not set, an error is printed on the stderr. This handler must be thread safe and non-blocking.
 
 ## Field Types
 
@@ -493,13 +590,17 @@ Some settings can be changed and will by applied to all loggers:
 
 ### Advanced Fields
 
-* `Err`: Takes an `error` and render it as a string using the `zerolog.ErrorFieldName` field name.
-* `Timestamp`: Insert a timestamp field with `zerolog.TimestampFieldName` field name and formatted using `zerolog.TimeFieldFormat`.
-* `Time`: Adds a field with the time formated with the `zerolog.TimeFieldFormat`.
-* `Dur`: Adds a field with a `time.Duration`.
+* `Err`: Takes an `error` and renders it as a string using the `zerolog.ErrorFieldName` field name.
+* `Timestamp`: Inserts a timestamp field with `zerolog.TimestampFieldName` field name, formatted using `zerolog.TimeFieldFormat`.
+* `Time`: Adds a field with time formatted with `zerolog.TimeFieldFormat`.
+* `Dur`: Adds a field with `time.Duration`.
 * `Dict`: Adds a sub-key/value as a field of the event.
+* `RawJSON`: Adds a field with an already encoded JSON (`[]byte`)
+* `Hex`: Adds a field with value formatted as a hexadecimal string (`[]byte`)
 * `Interface`: Uses reflection to marshal the type.
 
+Most fields are also available in the slice format (`Strs` for `[]string`, `Errs` for `[]error` etc.)
+
 ## Binary Encoding
 
 In addition to the default JSON encoding, `zerolog` can produce binary logs using [CBOR](http://cbor.io) encoding. The choice of encoding can be decided at compile time using the build tag `binary_log` as follows:
@@ -514,6 +615,7 @@ with zerolog library is [CSD](https://github.com/toravir/csd/).
 ## Related Projects
 
 * [grpc-zerolog](https://github.com/cheapRoc/grpc-zerolog): Implementation of `grpclog.LoggerV2` interface using `zerolog`
+* [overlog](https://github.com/Trendyol/overlog): Implementation of `Mapped Diagnostic Context` interface using `zerolog`
 
 ## Benchmarks
 
@@ -578,7 +680,7 @@ Log a static string, without any context or `printf`-style templating:
 
 ## Caveats
 
-Note that zerolog does de-duplication fields. Using the same key multiple times creates multiple keys in final JSON:
+Note that zerolog does no de-duplication of fields. Using the same key multiple times creates multiple keys in final JSON:
 
 ```go
 logger := zerolog.New(os.Stderr).With().Timestamp().Logger()
@@ -588,4 +690,4 @@ logger.Info().
 // 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.
+In this case, many consumers will take the last value, but this is not guaranteed; check yours if in doubt.

array.go

@@ -85,10 +85,15 @@ func (a *Array) Hex(val []byte) *Array {
 	return a
 }
 
+// RawJSON adds already encoded JSON to the array.
+func (a *Array) RawJSON(val []byte) *Array {
+	a.buf = appendJSON(enc.AppendArrayDelim(a.buf), val)
+	return a
+}
+
 // Err serializes and appends the err to the array.
 func (a *Array) Err(err error) *Array {
-	marshaled := ErrorMarshalFunc(err)
-	switch m := marshaled.(type) {
+	switch m := ErrorMarshalFunc(err).(type) {
 	case LogObjectMarshaler:
 		e := newEvent(nil, 0)
 		e.buf = e.buf[:0]
@@ -96,7 +101,11 @@ func (a *Array) Err(err error) *Array {
 		a.buf = append(enc.AppendArrayDelim(a.buf), e.buf...)
 		putEvent(e)
 	case error:
-		a.buf = enc.AppendString(enc.AppendArrayDelim(a.buf), m.Error())
+		if m == nil || isNilValue(m) {
+			a.buf = enc.AppendNil(enc.AppendArrayDelim(a.buf))
+		} else {
+			a.buf = enc.AppendString(enc.AppendArrayDelim(a.buf), m.Error())
+		}
 	case string:
 		a.buf = enc.AppendString(enc.AppendArrayDelim(a.buf), m)
 	default:

array_test.go

@@ -24,10 +24,11 @@ func TestArray(t *testing.T) {
 		Str("a").
 		Bytes([]byte("b")).
 		Hex([]byte{0x1f}).
+		RawJSON([]byte(`{"some":"json"}`)).
 		Time(time.Time{}).
 		IPAddr(net.IP{192, 168, 0, 10}).
 		Dur(0)
-	want := `[true,1,2,3,4,5,6,7,8,9,10,11.98122,12.987654321,"a","b","1f","0001-01-01T00:00:00Z","192.168.0.10",0]`
+	want := `[true,1,2,3,4,5,6,7,8,9,10,11.98122,12.987654321,"a","b","1f",{"some":"json"},"0001-01-01T00:00:00Z","192.168.0.10",0]`
 	if got := decodeObjectToStr(a.write([]byte{})); got != want {
 		t.Errorf("Array.write()\ngot:  %s\nwant: %s", got, want)
 	}

benchmark_test.go

@@ -3,6 +3,7 @@ package zerolog
 import (
 	"errors"
 	"io/ioutil"
+	"net"
 	"testing"
 	"time"
 )
@@ -234,12 +235,13 @@ func BenchmarkLogFieldType(b *testing.B) {
 
 func BenchmarkContextFieldType(b *testing.B) {
 	oldFormat := TimeFieldFormat
-	TimeFieldFormat = ""
+	TimeFieldFormat = TimeFormatUnix
 	defer func() { TimeFieldFormat = oldFormat }()
 	bools := []bool{true, false, true, false, true, false, true, false, true, false}
 	ints := []int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
 	floats := []float64{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
 	strings := []string{"a", "b", "c", "d", "e", "f", "g", "h", "i", "j"}
+	stringer := net.IP{127, 0, 0, 1}
 	durations := []time.Duration{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
 	times := []time.Time{
 		time.Unix(0, 0),
@@ -307,6 +309,9 @@ func BenchmarkContextFieldType(b *testing.B) {
 		"Strs": func(c Context) Context {
 			return c.Strs("k", strings)
 		},
+		"Stringer": func(c Context) Context {
+			return c.Stringer("k", stringer)
+		},
 		"Err": func(c Context) Context {
 			return c.Err(errs[0])
 		},

binary_test.go

@@ -108,6 +108,19 @@ func ExampleLogger_Printf() {
 	// Output: {"level":"debug","message":"hello world"}
 }
 
+func ExampleLogger_Trace() {
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	log.Trace().
+		Str("foo", "bar").
+		Int("n", 123).
+		Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"level":"trace","foo":"bar","n":123,"message":"hello world"}
+}
+
 func ExampleLogger_Debug() {
 	dst := bytes.Buffer{}
 	log := New(&dst)

console.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"path/filepath"
 	"sort"
 	"strconv"
 	"strings"
@@ -13,11 +14,6 @@ import (
 	"time"
 )
 
-const (
-	colorBold = iota + 1
-	colorFaint
-)
-
 const (
 	colorBlack = iota + 30
 	colorRed
@@ -27,6 +23,9 @@ const (
 	colorMagenta
 	colorCyan
 	colorWhite
+
+	colorBold     = 1
+	colorDarkGray = 90
 )
 
 var (
@@ -59,6 +58,9 @@ type ConsoleWriter struct {
 	// PartsOrder defines the order of parts in output.
 	PartsOrder []string
 
+	// PartsExclude defines parts to not display in output.
+	PartsExclude []string
+
 	FormatTimestamp     Formatter
 	FormatLevel         Formatter
 	FormatCaller        Formatter
@@ -210,6 +212,14 @@ func (w ConsoleWriter) writeFields(evt map[string]interface{}, buf *bytes.Buffer
 func (w ConsoleWriter) writePart(buf *bytes.Buffer, evt map[string]interface{}, p string) {
 	var f Formatter
 
+	if w.PartsExclude != nil && len(w.PartsExclude) > 0 {
+		for _, exclude := range w.PartsExclude {
+			if exclude == p {
+				return
+			}
+		}
+	}
+
 	switch p {
 	case LevelFieldName:
 		if w.FormatLevel == nil {
@@ -297,9 +307,24 @@ func consoleDefaultFormatTimestamp(timeFormat string, noColor bool) Formatter {
 				t = ts.Format(timeFormat)
 			}
 		case json.Number:
-			t = tt.String()
+			i, err := tt.Int64()
+			if err != nil {
+				t = tt.String()
+			} else {
+				var sec, nsec int64 = i, 0
+				switch TimeFieldFormat {
+				case TimeFormatUnixMs:
+					nsec = int64(time.Duration(i) * time.Millisecond)
+					sec = 0
+				case TimeFormatUnixMicro:
+					nsec = int64(time.Duration(i) * time.Microsecond)
+					sec = 0
+				}
+				ts := time.Unix(sec, nsec).UTC()
+				t = ts.Format(timeFormat)
+			}
 		}
-		return colorize(t, colorFaint, noColor)
+		return colorize(t, colorDarkGray, noColor)
 	}
 }
 
@@ -308,6 +333,8 @@ func consoleDefaultFormatLevel(noColor bool) Formatter {
 		var l string
 		if ll, ok := i.(string); ok {
 			switch ll {
+			case "trace":
+				l = colorize("TRC", colorMagenta, noColor)
 			case "debug":
 				l = colorize("DBG", colorYellow, noColor)
 			case "info":
@@ -324,7 +351,11 @@ func consoleDefaultFormatLevel(noColor bool) Formatter {
 				l = colorize("???", colorBold, noColor)
 			}
 		} else {
-			l = strings.ToUpper(fmt.Sprintf("%s", i))[0:3]
+			if i == nil {
+				l = colorize("???", colorBold, noColor)
+			} else {
+				l = strings.ToUpper(fmt.Sprintf("%s", i))[0:3]
+			}
 		}
 		return l
 	}
@@ -337,24 +368,27 @@ func consoleDefaultFormatCaller(noColor bool) Formatter {
 			c = cc
 		}
 		if len(c) > 0 {
-			cwd, err := os.Getwd()
-			if err == nil {
-				c = strings.TrimPrefix(c, cwd)
-				c = strings.TrimPrefix(c, "/")
+			if cwd, err := os.Getwd(); err == nil {
+				if rel, err := filepath.Rel(cwd, c); err == nil {
+					c = rel
+				}
 			}
-			c = colorize(c, colorBold, noColor) + colorize(" >", colorFaint, noColor)
+			c = colorize(c, colorBold, noColor) + colorize(" >", colorCyan, noColor)
 		}
 		return c
 	}
 }
 
 func consoleDefaultFormatMessage(i interface{}) string {
+	if i == nil {
+		return ""
+	}
 	return fmt.Sprintf("%s", i)
 }
 
 func consoleDefaultFormatFieldName(noColor bool) Formatter {
 	return func(i interface{}) string {
-		return colorize(fmt.Sprintf("%s=", i), colorFaint, noColor)
+		return colorize(fmt.Sprintf("%s=", i), colorCyan, noColor)
 	}
 }
 

console_test.go

@@ -76,7 +76,7 @@ func TestConsoleWriter(t *testing.T) {
 		buf := &bytes.Buffer{}
 		w := zerolog.ConsoleWriter{Out: buf, NoColor: true, PartsOrder: []string{"foo"}}
 
-		_, err := w.Write([]byte(`{"foo" : "DEFAULT"}`))
+		_, err := w.Write([]byte(`{"foo": "DEFAULT"}`))
 		if err != nil {
 			t.Errorf("Unexpected error when writing output: %s", err)
 		}
@@ -92,12 +92,12 @@ func TestConsoleWriter(t *testing.T) {
 		buf := &bytes.Buffer{}
 		w := zerolog.ConsoleWriter{Out: buf, NoColor: false}
 
-		_, err := w.Write([]byte(`{"level" : "warn", "message" : "Foobar"}`))
+		_, err := w.Write([]byte(`{"level": "warn", "message": "Foobar"}`))
 		if err != nil {
 			t.Errorf("Unexpected error when writing output: %s", err)
 		}
 
-		expectedOutput := "\x1b[2m<nil>\x1b[0m \x1b[31mWRN\x1b[0m Foobar\n"
+		expectedOutput := "\x1b[90m<nil>\x1b[0m \x1b[31mWRN\x1b[0m Foobar\n"
 		actualOutput := buf.String()
 		if actualOutput != expectedOutput {
 			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
@@ -109,7 +109,7 @@ func TestConsoleWriter(t *testing.T) {
 		w := zerolog.ConsoleWriter{Out: buf, NoColor: true}
 
 		d := time.Unix(0, 0).UTC().Format(time.RFC3339)
-		_, err := w.Write([]byte(`{"time" : "` + d + `", "level" : "debug", "message" : "Foobar", "foo" : "bar"}`))
+		_, err := w.Write([]byte(`{"time": "` + d + `", "level": "debug", "message": "Foobar", "foo": "bar"}`))
 		if err != nil {
 			t.Errorf("Unexpected error when writing output: %s", err)
 		}
@@ -121,12 +121,126 @@ func TestConsoleWriter(t *testing.T) {
 		}
 	})
 
+	t.Run("Unix timestamp input format", func(t *testing.T) {
+		of := zerolog.TimeFieldFormat
+		defer func() {
+			zerolog.TimeFieldFormat = of
+		}()
+		zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
+
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, TimeFormat: time.StampMilli, NoColor: true}
+
+		_, err := w.Write([]byte(`{"time": 1234, "level": "debug", "message": "Foobar", "foo": "bar"}`))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := "Jan  1 00:20:34.000 DBG Foobar foo=bar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("Unix timestamp ms input format", func(t *testing.T) {
+		of := zerolog.TimeFieldFormat
+		defer func() {
+			zerolog.TimeFieldFormat = of
+		}()
+		zerolog.TimeFieldFormat = zerolog.TimeFormatUnixMs
+
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, TimeFormat: time.StampMilli, NoColor: true}
+
+		_, err := w.Write([]byte(`{"time": 1234567, "level": "debug", "message": "Foobar", "foo": "bar"}`))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := "Jan  1 00:20:34.567 DBG Foobar foo=bar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("Unix timestamp us input format", func(t *testing.T) {
+		of := zerolog.TimeFieldFormat
+		defer func() {
+			zerolog.TimeFieldFormat = of
+		}()
+		zerolog.TimeFieldFormat = zerolog.TimeFormatUnixMicro
+
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, TimeFormat: time.StampMicro, NoColor: true}
+
+		_, err := w.Write([]byte(`{"time": 1234567891, "level": "debug", "message": "Foobar", "foo": "bar"}`))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := "Jan  1 00:20:34.567891 DBG Foobar foo=bar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("No message field", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, NoColor: true}
+
+		_, err := w.Write([]byte(`{"level": "debug", "foo": "bar"}`))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := "<nil> DBG  foo=bar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("No level field", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, NoColor: true}
+
+		_, err := w.Write([]byte(`{"message": "Foobar", "foo": "bar"}`))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := "<nil> ??? Foobar foo=bar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
+	t.Run("Write colorized fields", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, NoColor: false}
+
+		_, err := w.Write([]byte(`{"level": "warn", "message": "Foobar", "foo": "bar"}`))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := "\x1b[90m<nil>\x1b[0m \x1b[31mWRN\x1b[0m Foobar \x1b[36mfoo=\x1b[0mbar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
+
 	t.Run("Write error field", func(t *testing.T) {
 		buf := &bytes.Buffer{}
 		w := zerolog.ConsoleWriter{Out: buf, NoColor: true}
 
 		d := time.Unix(0, 0).UTC().Format(time.RFC3339)
-		evt := `{"time" : "` + d + `", "level" : "error", "message" : "Foobar", "aaa" : "bbb", "error" : "Error"}`
+		evt := `{"time": "` + d + `", "level": "error", "message": "Foobar", "aaa": "bbb", "error": "Error"}`
 		// t.Log(evt)
 
 		_, err := w.Write([]byte(evt))
@@ -151,7 +265,7 @@ func TestConsoleWriter(t *testing.T) {
 		}
 
 		d := time.Unix(0, 0).UTC().Format(time.RFC3339)
-		evt := `{"time" : "` + d + `", "level" : "debug", "message" : "Foobar", "foo" : "bar", "caller" : "` + cwd + `/foo/bar.go"}`
+		evt := `{"time": "` + d + `", "level": "debug", "message": "Foobar", "foo": "bar", "caller": "` + cwd + `/foo/bar.go"}`
 		// t.Log(evt)
 
 		_, err = w.Write([]byte(evt))
@@ -170,7 +284,7 @@ func TestConsoleWriter(t *testing.T) {
 		buf := &bytes.Buffer{}
 		w := zerolog.ConsoleWriter{Out: buf, NoColor: true}
 
-		evt := `{"level" : "debug", "message" : "Foobar", "foo" : [1, 2, 3], "bar" : true}`
+		evt := `{"level": "debug", "message": "Foobar", "foo": [1, 2, 3], "bar": true}`
 		// t.Log(evt)
 
 		_, err := w.Write([]byte(evt))
@@ -192,7 +306,7 @@ func TestConsoleWriterConfiguration(t *testing.T) {
 		w := zerolog.ConsoleWriter{Out: buf, NoColor: true, TimeFormat: time.RFC3339}
 
 		d := time.Unix(0, 0).UTC().Format(time.RFC3339)
-		evt := `{"time" : "` + d + `", "level" : "info", "message" : "Foobar"}`
+		evt := `{"time": "` + d + `", "level": "info", "message": "Foobar"}`
 
 		_, err := w.Write([]byte(evt))
 		if err != nil {
@@ -210,7 +324,7 @@ func TestConsoleWriterConfiguration(t *testing.T) {
 		buf := &bytes.Buffer{}
 		w := zerolog.ConsoleWriter{Out: buf, NoColor: true, PartsOrder: []string{"message", "level"}}
 
-		evt := `{"level" : "info", "message" : "Foobar"}`
+		evt := `{"level": "info", "message": "Foobar"}`
 		_, err := w.Write([]byte(evt))
 		if err != nil {
 			t.Errorf("Unexpected error when writing output: %s", err)
@@ -222,13 +336,31 @@ func TestConsoleWriterConfiguration(t *testing.T) {
 			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
 		}
 	})
+
+	t.Run("Sets PartsExclude", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		w := zerolog.ConsoleWriter{Out: buf, NoColor: true, PartsExclude: []string{"time"}}
+
+		d := time.Unix(0, 0).UTC().Format(time.RFC3339)
+		evt := `{"time": "` + d + `", "level": "info", "message": "Foobar"}`
+		_, err := w.Write([]byte(evt))
+		if err != nil {
+			t.Errorf("Unexpected error when writing output: %s", err)
+		}
+
+		expectedOutput := "INF Foobar\n"
+		actualOutput := buf.String()
+		if actualOutput != expectedOutput {
+			t.Errorf("Unexpected output %q, want: %q", actualOutput, expectedOutput)
+		}
+	})
 }
 
 func BenchmarkConsoleWriter(b *testing.B) {
 	b.ResetTimer()
 	b.ReportAllocs()
 
-	var msg = []byte(`{"level" : "info", "foo" : "bar", "message" : "HELLO", "time" : "1990-01-01"}`)
+	var msg = []byte(`{"level": "info", "foo": "bar", "message": "HELLO", "time": "1990-01-01"}`)
 
 	w := zerolog.ConsoleWriter{Out: ioutil.Discard, NoColor: false}
 

context.go

@@ -1,7 +1,9 @@
 package zerolog
 
 import (
+	"fmt"
 	"io/ioutil"
+	"math"
 	"net"
 	"time"
 )
@@ -80,6 +82,17 @@ func (c Context) Strs(key string, vals []string) Context {
 	return c
 }
 
+// Stringer adds the field key with val.String() (or null if val is nil) to the logger context.
+func (c Context) Stringer(key string, val fmt.Stringer) Context {
+	if val != nil {
+		c.l.context = enc.AppendString(enc.AppendKey(c.l.context, key), val.String())
+		return c
+	}
+
+	c.l.context = enc.AppendInterface(enc.AppendKey(c.l.context, key), nil)
+	return c
+}
+
 // Bytes adds the field key with val as a []byte to the logger context.
 func (c Context) Bytes(key string, val []byte) Context {
 	c.l.context = enc.AppendBytes(enc.AppendKey(c.l.context, key), val)
@@ -103,14 +116,17 @@ func (c Context) RawJSON(key string, b []byte) Context {
 
 // AnErr adds the field key with serialized err to the logger context.
 func (c Context) AnErr(key string, err error) Context {
-	marshaled := ErrorMarshalFunc(err)
-	switch m := marshaled.(type) {
+	switch m := ErrorMarshalFunc(err).(type) {
 	case nil:
 		return c
 	case LogObjectMarshaler:
 		return c.Object(key, m)
 	case error:
-		return c.Str(key, m.Error())
+		if m == nil || isNilValue(m) {
+			return c
+		} else {
+			return c.Str(key, m.Error())
+		}
 	case string:
 		return c.Str(key, m)
 	default:
@@ -123,12 +139,15 @@ func (c Context) AnErr(key string, err error) Context {
 func (c Context) Errs(key string, errs []error) Context {
 	arr := Arr()
 	for _, err := range errs {
-		marshaled := ErrorMarshalFunc(err)
-		switch m := marshaled.(type) {
+		switch m := ErrorMarshalFunc(err).(type) {
 		case LogObjectMarshaler:
 			arr = arr.Object(m)
 		case error:
-			arr = arr.Str(m.Error())
+			if m == nil || isNilValue(m) {
+				arr = arr.Interface(nil)
+			} else {
+				arr = arr.Str(m.Error())
+			}
 		case string:
 			arr = arr.Str(m)
 		default:
@@ -347,14 +366,31 @@ func (c Context) Interface(key string, i interface{}) Context {
 	return c
 }
 
-type callerHook struct{}
-
-func (ch callerHook) Run(e *Event, level Level, msg string) {
-	// Three extra frames to skip (added by hook infra).
-	e.caller(CallerSkipFrameCount + 3)
+type callerHook struct {
+	callerSkipFrameCount int
 }
 
-var ch = callerHook{}
+func newCallerHook(skipFrameCount int) callerHook {
+	return callerHook{callerSkipFrameCount: skipFrameCount}
+}
+
+func (ch callerHook) Run(e *Event, level Level, msg string) {
+	switch ch.callerSkipFrameCount {
+	case useGlobalSkipFrameCount:
+		// Extra frames to skip (added by hook infra).
+		e.caller(CallerSkipFrameCount + contextCallerSkipFrameCount)
+	default:
+		// Extra frames to skip (added by hook infra).
+		e.caller(ch.callerSkipFrameCount + contextCallerSkipFrameCount)
+	}
+}
+
+// useGlobalSkipFrameCount acts as a flag to informat callerHook.Run
+// to use the global CallerSkipFrameCount.
+const useGlobalSkipFrameCount = math.MinInt32
+
+// ch is the default caller hook using the global CallerSkipFrameCount.
+var ch = newCallerHook(useGlobalSkipFrameCount)
 
 // Caller adds the file:line of the caller with the zerolog.CallerFieldName key.
 func (c Context) Caller() Context {
@@ -362,17 +398,17 @@ func (c Context) Caller() Context {
 	return c
 }
 
-type stackTraceHook struct{}
-
-func (sh stackTraceHook) Run(e *Event, level Level, msg string) {
-	e.Stack()
+// CallerWithSkipFrameCount adds the file:line of the caller with the zerolog.CallerFieldName key.
+// The specified skipFrameCount int will override the global CallerSkipFrameCount for this context's respective logger.
+// If set to -1 the global CallerSkipFrameCount will be used.
+func (c Context) CallerWithSkipFrameCount(skipFrameCount int) Context {
+	c.l = c.l.Hook(newCallerHook(skipFrameCount))
+	return c
 }
 
-var sh = stackTraceHook{}
-
 // Stack enables stack trace printing for the error passed to Err().
 func (c Context) Stack() Context {
-	c.l = c.l.Hook(sh)
+	c.l.stack = true
 	return c
 }
 

ctx.go

@@ -7,6 +7,7 @@ import (
 var disabledLogger *Logger
 
 func init() {
+	SetGlobalLevel(TraceLevel)
 	l := Nop()
 	disabledLogger = &l
 }

diode/diode.go

@@ -48,7 +48,7 @@ type Writer struct {
 // used.
 //
 // See code.cloudfoundry.org/go-diodes for more info on diode.
-func NewWriter(w io.Writer, size int, poolInterval time.Duration, f Alerter) Writer {
+func NewWriter(w io.Writer, size int, pollInterval time.Duration, f Alerter) Writer {
 	ctx, cancel := context.WithCancel(context.Background())
 	dw := Writer{
 		w:    w,
@@ -59,9 +59,9 @@ func NewWriter(w io.Writer, size int, poolInterval time.Duration, f Alerter) Wri
 		f = func(int) {}
 	}
 	d := diodes.NewManyToOne(size, diodes.AlertFunc(f))
-	if poolInterval > 0 {
+	if pollInterval > 0 {
 		dw.d = diodes.NewPoller(d,
-			diodes.WithPollingInterval(poolInterval),
+			diodes.WithPollingInterval(pollInterval),
 			diodes.WithPollingContext(ctx))
 	} else {
 		dw.d = diodes.NewWaiter(d,

diode/internal/diodes/many_to_one.go

@@ -9,9 +9,9 @@ import (
 // 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
+	buffer     []unsafe.Pointer
 	alerter    Alerter
 }
 

diode/internal/diodes/one_to_one.go

@@ -31,9 +31,9 @@ type bucket struct {
 // 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
+	buffer     []unsafe.Pointer
 	alerter    Alerter
 }
 

event.go

@@ -5,7 +5,6 @@ import (
 	"net"
 	"os"
 	"runtime"
-	"strconv"
 	"sync"
 	"time"
 )
@@ -62,6 +61,7 @@ func newEvent(w LevelWriter, level Level) *Event {
 	e.buf = enc.AppendBeginMarker(e.buf)
 	e.w = w
 	e.level = level
+	e.stack = false
 	return e
 }
 
@@ -106,10 +106,20 @@ func (e *Event) Msg(msg string) {
 	e.msg(msg)
 }
 
-// Msgf sends the event with formated msg added as the message field if not empty.
+// Send is equivalent to calling Msg("").
 //
-// NOTICE: once this methid is called, the *Event should be disposed.
-// Calling Msg twice can have unexpected result.
+// NOTICE: once this method is called, the *Event should be disposed.
+func (e *Event) Send() {
+	if e == nil {
+		return
+	}
+	e.msg("")
+}
+
+// Msgf sends the event with formatted msg added as the message field if not empty.
+//
+// NOTICE: once this method is called, the *Event should be disposed.
+// Calling Msgf twice can have unexpected result.
 func (e *Event) Msgf(format string, v ...interface{}) {
 	if e == nil {
 		return
@@ -118,13 +128,8 @@ func (e *Event) Msgf(format string, v ...interface{}) {
 }
 
 func (e *Event) msg(msg string) {
-	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)
-			}
-		}
+	for _, hook := range e.ch {
+		hook.Run(e, e.level, msg)
 	}
 	if msg != "" {
 		e.buf = enc.AppendString(enc.AppendKey(e.buf, MessageFieldName), msg)
@@ -204,7 +209,7 @@ func (e *Event) Object(key string, obj LogObjectMarshaler) *Event {
 	return e
 }
 
-// Object marshals an object that implement the LogObjectMarshaler interface.
+// EmbedObject marshals an object that implement the LogObjectMarshaler interface.
 func (e *Event) EmbedObject(obj LogObjectMarshaler) *Event {
 	if e == nil {
 		return e
@@ -231,6 +236,21 @@ func (e *Event) Strs(key string, vals []string) *Event {
 	return e
 }
 
+// Stringer adds the field key with val.String() (or null if val is nil) to the *Event context.
+func (e *Event) Stringer(key string, val fmt.Stringer) *Event {
+	if e == nil {
+		return e
+	}
+
+	if val != nil {
+		e.buf = enc.AppendString(enc.AppendKey(e.buf, key), val.String())
+		return e
+	}
+
+	e.buf = enc.AppendInterface(enc.AppendKey(e.buf, key), nil)
+	return e
+}
+
 // Bytes adds the field key with val as a string to the *Event context.
 //
 // Runes outside of normal ASCII ranges will be hex-encoded in the resulting
@@ -276,7 +296,11 @@ func (e *Event) AnErr(key string, err error) *Event {
 	case LogObjectMarshaler:
 		return e.Object(key, m)
 	case error:
-		return e.Str(key, m.Error())
+		if m == nil || isNilValue(m) {
+			return e
+		} else {
+			return e.Str(key, m.Error())
+		}
 	case string:
 		return e.Str(key, m)
 	default:
@@ -309,7 +333,6 @@ func (e *Event) Errs(key string, errs []error) *Event {
 
 // Err adds the field "error" with serialized err to the *Event context.
 // If err is nil, no field is added.
-// To customize the key name, change zerolog.ErrorFieldName.
 //
 // To customize the key name, change zerolog.ErrorFieldName.
 //
@@ -326,7 +349,9 @@ func (e *Event) Err(err error) *Event {
 		case LogObjectMarshaler:
 			e.Object(ErrorStackFieldName, m)
 		case error:
-			e.Str(ErrorStackFieldName, m.Error())
+			if m != nil && !isNilValue(m) {
+				e.Str(ErrorStackFieldName, m.Error())
+			}
 		case string:
 			e.Str(ErrorStackFieldName, m)
 		default:
@@ -661,8 +686,14 @@ func (e *Event) Interface(key string, i interface{}) *Event {
 }
 
 // Caller adds the file:line of the caller with the zerolog.CallerFieldName key.
-func (e *Event) Caller() *Event {
-	return e.caller(CallerSkipFrameCount)
+// The argument skip is the number of stack frames to ascend
+// Skip If not passed, use the global variable CallerSkipFrameCount
+func (e *Event) Caller(skip ...int) *Event {
+	sk := CallerSkipFrameCount
+	if len(skip) > 0 {
+		sk = skip[0] + CallerSkipFrameCount
+	}
+	return e.caller(sk)
 }
 
 func (e *Event) caller(skip int) *Event {
@@ -673,7 +704,7 @@ func (e *Event) caller(skip int) *Event {
 	if !ok {
 		return e
 	}
-	e.buf = enc.AppendString(enc.AppendKey(e.buf, CallerFieldName), file+":"+strconv.Itoa(line))
+	e.buf = enc.AppendString(enc.AppendKey(e.buf, CallerFieldName), CallerMarshalFunc(file, line))
 	return e
 }
 

event_test.go

@@ -0,0 +1,39 @@
+// +build !binary_log
+
+package zerolog
+
+import (
+	"bytes"
+	"errors"
+	"strings"
+	"testing"
+)
+
+type nilError struct{}
+
+func (nilError) Error() string {
+	return ""
+}
+
+func TestEvent_AnErr(t *testing.T) {
+	tests := []struct {
+		name string
+		err  error
+		want string
+	}{
+		{"nil", nil, `{}`},
+		{"error", errors.New("test"), `{"err":"test"}`},
+		{"nil interface", func() *nilError { return nil }(), `{}`},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var buf bytes.Buffer
+			e := newEvent(levelWriterAdapter{&buf}, DebugLevel)
+			e.AnErr("err", tt.err)
+			_ = e.write()
+			if got, want := strings.TrimSpace(buf.String()), tt.want; got != want {
+				t.Errorf("Event.AnErr() = %v, want %v", got, want)
+			}
+		})
+	}
+}

fields.go

@@ -4,8 +4,13 @@ import (
 	"net"
 	"sort"
 	"time"
+	"unsafe"
 )
 
+func isNilValue(i interface{}) bool {
+	return (*[2]uintptr)(unsafe.Pointer(&i))[1] == 0
+}
+
 func appendFields(dst []byte, fields map[string]interface{}) []byte {
 	keys := make([]string, 0, len(fields))
 	for key := range fields {
@@ -29,8 +34,7 @@ func appendFields(dst []byte, fields map[string]interface{}) []byte {
 		case []byte:
 			dst = enc.AppendBytes(dst, val)
 		case error:
-			marshaled := ErrorMarshalFunc(val)
-			switch m := marshaled.(type) {
+			switch m := ErrorMarshalFunc(val).(type) {
 			case LogObjectMarshaler:
 				e := newEvent(nil, 0)
 				e.buf = e.buf[:0]
@@ -38,7 +42,11 @@ func appendFields(dst []byte, fields map[string]interface{}) []byte {
 				dst = append(dst, e.buf...)
 				putEvent(e)
 			case error:
-				dst = enc.AppendString(dst, m.Error())
+				if m == nil || isNilValue(m) {
+					dst = enc.AppendNil(dst)
+				} else {
+					dst = enc.AppendString(dst, m.Error())
+				}
 			case string:
 				dst = enc.AppendString(dst, m)
 			default:
@@ -47,8 +55,7 @@ func appendFields(dst []byte, fields map[string]interface{}) []byte {
 		case []error:
 			dst = enc.AppendArrayStart(dst)
 			for i, err := range val {
-				marshaled := ErrorMarshalFunc(err)
-				switch m := marshaled.(type) {
+				switch m := ErrorMarshalFunc(err).(type) {
 				case LogObjectMarshaler:
 					e := newEvent(nil, 0)
 					e.buf = e.buf[:0]
@@ -56,7 +63,11 @@ func appendFields(dst []byte, fields map[string]interface{}) []byte {
 					dst = append(dst, e.buf...)
 					putEvent(e)
 				case error:
-					dst = enc.AppendString(dst, m.Error())
+					if m == nil || isNilValue(m) {
+						dst = enc.AppendNil(dst)
+					} else {
+						dst = enc.AppendString(dst, m.Error())
+					}
 				case string:
 					dst = enc.AppendString(dst, m)
 				default:

globals.go

@@ -1,7 +1,24 @@
 package zerolog
 
-import "time"
-import "sync/atomic"
+import (
+	"strconv"
+	"sync/atomic"
+	"time"
+)
+
+const (
+	// TimeFormatUnix defines a time format that makes time fields to be
+	// serialized as Unix timestamp integers.
+	TimeFormatUnix = ""
+
+	// TimeFormatUnixMs defines a time format that makes time fields to be
+	// serialized as Unix timestamp integers in milliseconds.
+	TimeFormatUnixMs = "UNIXMS"
+
+	// TimeFormatUnixMicro defines a time format that makes time fields to be
+	// serialized as Unix timestamp integers in microseconds.
+	TimeFormatUnixMicro = "UNIXMICRO"
+)
 
 var (
 	// TimestampFieldName is the field name used for the timestamp field.
@@ -10,6 +27,11 @@ var (
 	// LevelFieldName is the field name used for the level field.
 	LevelFieldName = "level"
 
+	// LevelFieldMarshalFunc allows customization of global level field marshaling
+	LevelFieldMarshalFunc = func(l Level) string {
+		return l.String()
+	}
+
 	// MessageFieldName is the field name used for the message field.
 	MessageFieldName = "message"
 
@@ -22,6 +44,11 @@ var (
 	// CallerSkipFrameCount is the number of stack frames to skip to find the caller.
 	CallerSkipFrameCount = 2
 
+	// CallerMarshalFunc allows customization of global caller marshaling
+	CallerMarshalFunc = func(file string, line int) string {
+		return file + ":" + strconv.Itoa(line)
+	}
+
 	// ErrorStackFieldName is the field name used for error stacks.
 	ErrorStackFieldName = "stack"
 
@@ -33,9 +60,9 @@ var (
 		return err
 	}
 
-	// TimeFieldFormat defines the time format of the Time field type.
-	// If set to an empty string, the time is formatted as an UNIX timestamp
-	// as integer.
+	// TimeFieldFormat defines the time format of the Time field type. If set to
+	// TimeFormatUnix, TimeFormatUnixMs or TimeFormatUnixMicro, the time is formatted as an UNIX
+	// timestamp as integer.
 	TimeFieldFormat = time.RFC3339
 
 	// TimestampFunc defines the function called to generate a timestamp.
@@ -56,8 +83,8 @@ var (
 )
 
 var (
-	gLevel          = new(uint32)
-	disableSampling = new(uint32)
+	gLevel          = new(int32)
+	disableSampling = new(int32)
 )
 
 // SetGlobalLevel sets the global override for log level. If this
@@ -65,23 +92,23 @@ var (
 //
 // To globally disable logs, set GlobalLevel to Disabled.
 func SetGlobalLevel(l Level) {
-	atomic.StoreUint32(gLevel, uint32(l))
+	atomic.StoreInt32(gLevel, int32(l))
 }
 
 // GlobalLevel returns the current global log level
 func GlobalLevel() Level {
-	return Level(atomic.LoadUint32(gLevel))
+	return Level(atomic.LoadInt32(gLevel))
 }
 
 // DisableSampling will disable sampling in all Loggers if true.
 func DisableSampling(v bool) {
-	var i uint32
+	var i int32
 	if v {
 		i = 1
 	}
-	atomic.StoreUint32(disableSampling, i)
+	atomic.StoreInt32(disableSampling, i)
 }
 
 func samplingDisabled() bool {
-	return atomic.LoadUint32(disableSampling) == 1
+	return atomic.LoadInt32(disableSampling) == 1
 }

go.mod

@@ -1 +1,8 @@
 module github.com/rs/zerolog
+
+require (
+	github.com/coreos/go-systemd v0.0.0-20190321100706-95778dfbb74e
+	github.com/pkg/errors v0.9.1
+	github.com/rs/xid v1.2.1
+	golang.org/x/tools v0.1.0
+)

go.sum

@@ -0,0 +1,32 @@
+github.com/coreos/go-systemd v0.0.0-20190321100706-95778dfbb74e h1:Wf6HqHfScWJN9/ZjdUKyjop4mf3Qdd+1TvvltAvM3m8=
+github.com/coreos/go-systemd v0.0.0-20190321100706-95778dfbb74e/go.mod h1:F5haX7vjVVG0kc13fIWeqUViNPyEJxv/OmvnBo0Yme4=
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/rs/xid v1.2.1 h1:mhH9Nq+C1fY2l1XIpgxIiUOfNpRBYH1kKcr+qfKgjRc=
+github.com/rs/xid v1.2.1/go.mod h1:+uKXf+4Djp6Md1KODXJxgGQPKngRmWyn10oCKFzNHOQ=
+github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/mod v0.3.0 h1:RM4zey1++hCTbCVQfnWeKs9/IEsaBLA8vTkd0WVtmH4=
+golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20201021035429-f5854403a974/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210119212857-b64e53b001e4 h1:myAQVi0cGEoqQVR5POX+8RR2mrocKqNN1hmeMqhX27k=
+golang.org/x/sys v0.0.0-20210119212857-b64e53b001e4/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.1.0 h1:po9/4sTYwZU9lPhi1tOrb4hCv3qrhiQ77LZfGa2OjwY=
+golang.org/x/tools v0.1.0/go.mod h1:xkSsbof2nBLbhDlRMhhhyNLN/zl3eTqcnHD5viDpcZ0=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
+golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

go112.go

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

hlog/hlog.go

@@ -9,8 +9,8 @@ import (
 
 	"github.com/rs/xid"
 	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/hlog/internal/mutil"
 	"github.com/rs/zerolog/log"
-	"github.com/zenazn/goji/web/mutil"
 )
 
 // FromRequest gets the logger in the request's context.
@@ -138,6 +138,11 @@ func IDFromCtx(ctx context.Context) (id xid.ID, ok bool) {
 	return
 }
 
+// CtxWithID adds the given xid.ID to the context
+func CtxWithID(ctx context.Context, id xid.ID) context.Context {
+	return context.WithValue(ctx, idKey{}, id)
+}
+
 // RequestIDHandler returns a handler setting a unique id to the request which can
 // be gathered using IDFromRequest(req). This generated id is added as a field to the
 // logger using the passed fieldKey as field name. The id is also added as a response
@@ -154,7 +159,7 @@ func RequestIDHandler(fieldKey, headerName string) func(next http.Handler) http.
 			id, ok := IDFromRequest(r)
 			if !ok {
 				id = xid.New()
-				ctx = context.WithValue(ctx, idKey{}, id)
+				ctx = CtxWithID(ctx, id)
 				r = r.WithContext(ctx)
 			}
 			if fieldKey != "" {
@@ -171,6 +176,22 @@ func RequestIDHandler(fieldKey, headerName string) func(next http.Handler) http.
 	}
 }
 
+// CustomHeaderHandler adds given header from request's header as a field to
+// the context's logger using fieldKey as field key.
+func CustomHeaderHandler(fieldKey, header string) func(next http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			if val := r.Header.Get(header); val != "" {
+				log := zerolog.Ctx(r.Context())
+				log.UpdateContext(func(c zerolog.Context) zerolog.Context {
+					return c.Str(fieldKey, val)
+				})
+			}
+			next.ServeHTTP(w, r)
+		})
+	}
+}
+
 // AccessHandler returns a handler that call f after each request.
 func AccessHandler(f func(r *http.Request, status, size int, duration time.Duration)) func(next http.Handler) http.Handler {
 	return func(next http.Handler) http.Handler {

hlog/hlog_test.go

@@ -4,16 +4,16 @@ package hlog
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"io/ioutil"
 	"net/http"
+	"net/http/httptest"
 	"net/url"
+	"reflect"
 	"testing"
 
-	"reflect"
-
-	"net/http/httptest"
-
+	"github.com/rs/xid"
 	"github.com/rs/zerolog"
 	"github.com/rs/zerolog/internal/cbor"
 )
@@ -182,6 +182,24 @@ func TestRequestIDHandler(t *testing.T) {
 	h.ServeHTTP(httptest.NewRecorder(), r)
 }
 
+func TestCustomHeaderHandler(t *testing.T) {
+	out := &bytes.Buffer{}
+	r := &http.Request{
+		Header: http.Header{
+			"X-Request-Id": []string{"514bbe5bb5251c92bd07a9846f4a1ab6"},
+		},
+	}
+	h := CustomHeaderHandler("reqID", "X-Request-Id")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		l := FromRequest(r)
+		l.Log().Msg("")
+	}))
+	h = NewHandler(zerolog.New(out))(h)
+	h.ServeHTTP(nil, r)
+	if want, got := `{"reqID":"514bbe5bb5251c92bd07a9846f4a1ab6"}`+"\n", decodeIfBinary(out); want != got {
+		t.Errorf("Invalid log output, got: %s, want: %s", got, want)
+	}
+}
+
 func TestCombinedHandlers(t *testing.T) {
 	out := &bytes.Buffer{}
 	r := &http.Request{
@@ -244,3 +262,16 @@ func BenchmarkDataRace(b *testing.B) {
 		}
 	})
 }
+
+func TestCtxWithID(t *testing.T) {
+	ctx := context.Background()
+
+	id, _ := xid.FromString(`c0umremcie6smuu506pg`)
+
+	want := context.Background()
+	want = context.WithValue(want, idKey{}, id)
+
+	if got := CtxWithID(ctx, id); !reflect.DeepEqual(got, want) {
+		t.Errorf("CtxWithID() = %v, want %v", got, want)
+	}
+}

hlog/internal/mutil/LICENSE

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

hlog/internal/mutil/mutil.go

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

hlog/internal/mutil/writer_proxy.go

@@ -0,0 +1,149 @@
+package mutil
+
+import (
+	"bufio"
+	"io"
+	"net"
+	"net/http"
+)
+
+// WriterProxy is a proxy around an http.ResponseWriter that allows you to hook
+// into various parts of the response process.
+type WriterProxy interface {
+	http.ResponseWriter
+	// Status returns the HTTP status of the request, or 0 if one has not
+	// yet been sent.
+	Status() int
+	// BytesWritten returns the total number of bytes sent to the client.
+	BytesWritten() int
+	// Tee causes the response body to be written to the given io.Writer in
+	// addition to proxying the writes through. Only one io.Writer can be
+	// tee'd to at once: setting a second one will overwrite the first.
+	// Writes will be sent to the proxy before being written to this
+	// io.Writer. It is illegal for the tee'd writer to be modified
+	// concurrently with writes.
+	Tee(io.Writer)
+	// Unwrap returns the original proxied target.
+	Unwrap() http.ResponseWriter
+}
+
+// WrapWriter wraps an http.ResponseWriter, returning a proxy that allows you to
+// hook into various parts of the response process.
+func WrapWriter(w http.ResponseWriter) WriterProxy {
+	_, cn := w.(http.CloseNotifier)
+	_, fl := w.(http.Flusher)
+	_, hj := w.(http.Hijacker)
+	_, rf := w.(io.ReaderFrom)
+
+	bw := basicWriter{ResponseWriter: w}
+	if cn && fl && hj && rf {
+		return &fancyWriter{bw}
+	}
+	if fl {
+		return &flushWriter{bw}
+	}
+	return &bw
+}
+
+// basicWriter wraps a http.ResponseWriter that implements the minimal
+// http.ResponseWriter interface.
+type basicWriter struct {
+	http.ResponseWriter
+	wroteHeader bool
+	code        int
+	bytes       int
+	tee         io.Writer
+}
+
+func (b *basicWriter) WriteHeader(code int) {
+	if !b.wroteHeader {
+		b.code = code
+		b.wroteHeader = true
+		b.ResponseWriter.WriteHeader(code)
+	}
+}
+
+func (b *basicWriter) Write(buf []byte) (int, error) {
+	b.WriteHeader(http.StatusOK)
+	n, err := b.ResponseWriter.Write(buf)
+	if b.tee != nil {
+		_, err2 := b.tee.Write(buf[:n])
+		// Prefer errors generated by the proxied writer.
+		if err == nil {
+			err = err2
+		}
+	}
+	b.bytes += n
+	return n, err
+}
+
+func (b *basicWriter) maybeWriteHeader() {
+	if !b.wroteHeader {
+		b.WriteHeader(http.StatusOK)
+	}
+}
+
+func (b *basicWriter) Status() int {
+	return b.code
+}
+
+func (b *basicWriter) BytesWritten() int {
+	return b.bytes
+}
+
+func (b *basicWriter) Tee(w io.Writer) {
+	b.tee = w
+}
+
+func (b *basicWriter) Unwrap() http.ResponseWriter {
+	return b.ResponseWriter
+}
+
+// fancyWriter is a writer that additionally satisfies http.CloseNotifier,
+// http.Flusher, http.Hijacker, and io.ReaderFrom. It exists for the common case
+// of wrapping the http.ResponseWriter that package http gives you, in order to
+// make the proxied object support the full method set of the proxied object.
+type fancyWriter struct {
+	basicWriter
+}
+
+func (f *fancyWriter) CloseNotify() <-chan bool {
+	cn := f.basicWriter.ResponseWriter.(http.CloseNotifier)
+	return cn.CloseNotify()
+}
+
+func (f *fancyWriter) Flush() {
+	fl := f.basicWriter.ResponseWriter.(http.Flusher)
+	fl.Flush()
+}
+
+func (f *fancyWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	hj := f.basicWriter.ResponseWriter.(http.Hijacker)
+	return hj.Hijack()
+}
+
+func (f *fancyWriter) ReadFrom(r io.Reader) (int64, error) {
+	if f.basicWriter.tee != nil {
+		return io.Copy(&f.basicWriter, r)
+	}
+	rf := f.basicWriter.ResponseWriter.(io.ReaderFrom)
+	f.basicWriter.maybeWriteHeader()
+	return rf.ReadFrom(r)
+}
+
+type flushWriter struct {
+	basicWriter
+}
+
+func (f *flushWriter) Flush() {
+	fl := f.basicWriter.ResponseWriter.(http.Flusher)
+	fl.Flush()
+}
+
+var (
+	_ http.CloseNotifier = &fancyWriter{}
+	_ http.Flusher       = &fancyWriter{}
+	_ http.Hijacker      = &fancyWriter{}
+	_ io.ReaderFrom      = &fancyWriter{}
+	_ http.Flusher       = &flushWriter{}
+)

hook.go

@@ -17,12 +17,16 @@ func (h HookFunc) 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
+	NoLevelHook, TraceHook, DebugHook, InfoHook, WarnHook, ErrorHook, FatalHook, PanicHook Hook
 }
 
 // Run implements the Hook interface.
 func (h LevelHook) Run(e *Event, level Level, message string) {
 	switch level {
+	case TraceLevel:
+		if h.TraceHook != nil {
+			h.TraceHook.Run(e, level, message)
+		}
 	case DebugLevel:
 		if h.DebugHook != nil {
 			h.DebugHook.Run(e, level, message)

internal/cbor/types.go

@@ -24,9 +24,9 @@ func (Encoder) AppendEndMarker(dst []byte) []byte {
 
 // 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:]...)
+	// 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.

internal/cbor/types_64_test.go

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

internal/cbor/types_test.go

@@ -88,11 +88,8 @@ var integerTestCases = []struct {
 	{0xFFFF, "\x19\xff\xff"},
 	// Value in 4 bytes.
 	{0x10000, "\x1a\x00\x01\x00\x00"},
-	{0xFFFFFFFE, "\x1a\xff\xff\xff\xfe"},
+	{0x7FFFFFFE, "\x1a\x7f\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"},
@@ -116,11 +113,9 @@ var integerTestCases = []struct {
 	{-1000, "\x39\x03\xe7"},
 	// Value in 4 bytes.
 	{-0x10001, "\x3a\x00\x01\x00\x00"},
-	{-0xFFFFFFFE, "\x3a\xff\xff\xff\xfd"},
+	{-0x7FFFFFFE, "\x3a\x7f\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) {

internal/json/base.go

@@ -4,9 +4,8 @@ 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] != '{' {
+	if dst[len(dst)-1] != '{' {
 		dst = append(dst, ',')
 	}
-	dst = e.AppendString(dst, key)
-	return append(dst, ':')
-}
+	return append(e.AppendString(dst, key), ':')
+}

internal/json/time.go

@@ -5,11 +5,23 @@ import (
 	"time"
 )
 
+const (
+	// Import from zerolog/global.go
+	timeFormatUnix   = ""
+	timeFormatUnixMs = "UNIXMS"
+	timeFormatUnixMicro = "UNIXMICRO"
+)
+
 // AppendTime formats the input time with the given format
 // and appends the encoded string to the input byte slice.
 func (e Encoder) AppendTime(dst []byte, t time.Time, format string) []byte {
-	if format == "" {
+	switch format {
+	case timeFormatUnix:
 		return e.AppendInt64(dst, t.Unix())
+	case timeFormatUnixMs:
+		return e.AppendInt64(dst, t.UnixNano()/1000000)
+	case timeFormatUnixMicro:
+		return e.AppendInt64(dst, t.UnixNano()/1000)
 	}
 	return append(t.AppendFormat(append(dst, '"'), format), '"')
 }
@@ -17,8 +29,11 @@ func (e Encoder) AppendTime(dst []byte, t 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 == "" {
+	switch format {
+	case timeFormatUnix:
 		return appendUnixTimes(dst, vals)
+	case timeFormatUnixMs:
+		return appendUnixMsTimes(dst, vals)
 	}
 	if len(vals) == 0 {
 		return append(dst, '[', ']')
@@ -49,6 +64,21 @@ func appendUnixTimes(dst []byte, vals []time.Time) []byte {
 	return dst
 }
 
+func appendUnixMsTimes(dst []byte, vals []time.Time) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = strconv.AppendInt(dst, vals[0].UnixNano()/1000000, 10)
+	if len(vals) > 1 {
+		for _, t := range vals[1:] {
+			dst = strconv.AppendInt(append(dst, ','), t.UnixNano()/1000000, 10)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
 // AppendDuration formats the input duration with the given unit & format
 // and appends the encoded string to the input byte slice.
 func (e Encoder) AppendDuration(dst []byte, d time.Duration, unit time.Duration, useInt bool) []byte {

internal/json/types.go

@@ -350,7 +350,7 @@ func (Encoder) AppendFloats64(dst []byte, vals []float64) []byte {
 		return append(dst, '[', ']')
 	}
 	dst = append(dst, '[')
-	dst = appendFloat(dst, vals[0], 32)
+	dst = appendFloat(dst, vals[0], 64)
 	if len(vals) > 1 {
 		for _, val := range vals[1:] {
 			dst = appendFloat(append(dst, ','), val, 64)
@@ -373,12 +373,16 @@ func (e Encoder) AppendInterface(dst []byte, i interface{}) []byte {
 // 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
+	// Three conditions apply here:
+	// 1. new content starts with '{' - which should be dropped   OR
+	// 2. new content starts with '{' - which should be replaced with ','
+	//    to separate with existing content OR
+	// 3. existing content has already other fields
 	if o[0] == '{' {
-		o[0] = ','
+		if len(dst) > 1 {
+			dst = append(dst, ',')
+		}
+		o = o[1:]
 	} else if len(dst) > 1 {
 		dst = append(dst, ',')
 	}

internal/json/types_test.go

@@ -165,3 +165,23 @@ func Test_appendMac(t *testing.T) {
 		})
 	}
 }
+
+func Test_appendObjectData(t *testing.T) {
+	tests := []struct {
+		dst  []byte
+		obj  []byte
+		want []byte
+	}{
+		{[]byte{}, []byte(`{"foo":"bar"}`), []byte(`"foo":"bar"}`)},
+		{[]byte(`{"qux":"quz"`), []byte(`{"foo":"bar"}`), []byte(`{"qux":"quz","foo":"bar"}`)},
+		{[]byte{}, []byte(`"foo":"bar"`), []byte(`"foo":"bar"`)},
+		{[]byte(`{"qux":"quz"`), []byte(`"foo":"bar"`), []byte(`{"qux":"quz","foo":"bar"`)},
+	}
+	for _, tt := range tests {
+		t.Run("ObjectData", func(t *testing.T) {
+			if got := enc.AppendObjectData(tt.dst, tt.obj); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("appendObjectData() = %s, want %s", got, tt.want)
+			}
+		})
+	}
+}

journald/journald.go

@@ -20,11 +20,12 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
+	"io"
+	"strings"
+
 	"github.com/coreos/go-systemd/journal"
 	"github.com/rs/zerolog"
 	"github.com/rs/zerolog/internal/cbor"
-	"io"
-	"strings"
 )
 
 const defaultJournalDPrio = journal.PriNotice
@@ -47,6 +48,8 @@ func levelToJPrio(zLevel string) journal.Priority {
 	lvl, _ := zerolog.ParseLevel(zLevel)
 
 	switch lvl {
+	case zerolog.TraceLevel:
+		return journal.PriDebug
 	case zerolog.DebugLevel:
 		return journal.PriDebug
 	case zerolog.InfoLevel:
@@ -67,10 +70,12 @@ func levelToJPrio(zLevel string) journal.Priority {
 
 func (w journalWriter) Write(p []byte) (n int, err error) {
 	if !journal.Enabled() {
-		err = fmt.Errorf("Cannot connect to journalD!!")
+		err = fmt.Errorf("cannot connect to journalD")
 		return
 	}
+
 	var event map[string]interface{}
+	origPLen := len(p)
 	p = cbor.DecodeIfBinaryToBytes(p)
 	d := json.NewDecoder(bytes.NewReader(p))
 	d.UseNumber()
@@ -111,5 +116,10 @@ func (w journalWriter) Write(p []byte) (n int, err error) {
 	}
 	args["JSON"] = string(p)
 	err = journal.Send(msg, jPrio, args)
+
+	if err == nil {
+		n = origPLen
+	}
+
 	return
 }

journald/journald_test.go

@@ -1,9 +1,15 @@
-// +build !windows
+// +build linux
 
 package journald_test
 
-import "github.com/rs/zerolog"
-import "github.com/rs/zerolog/journald"
+import (
+	"bytes"
+	"io"
+	"testing"
+
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/journald"
+)
 
 func ExampleNewJournalDWriter() {
 	log := zerolog.New(journald.NewJournalDWriter())
@@ -42,3 +48,39 @@ Thu 2018-04-26 22:30:20.768136 PDT [s=3284d695bde946e4b5017c77a399237f;i=329f0;b
     _PID=27103
     _SOURCE_REALTIME_TIMESTAMP=1524807020768136
 */
+
+func TestWriteReturnsNoOfWrittenBytes(t *testing.T) {
+	input := []byte(`{"level":"info","time":1570912626,"message":"Starting..."}`)
+	wr := journald.NewJournalDWriter()
+	want := len(input)
+	got, err := wr.Write(input)
+
+	if err != nil {
+		t.Errorf("Unexpected error %v", err)
+	}
+
+	if want != got {
+		t.Errorf("Expected %d bytes to be written got %d", want, got)
+	}
+}
+
+func TestMultiWrite(t *testing.T) {
+	var (
+		w1 = new(bytes.Buffer)
+		w2 = new(bytes.Buffer)
+		w3 = journald.NewJournalDWriter()
+	)
+
+	zerolog.ErrorHandler = func(err error) {
+		if err == io.ErrShortWrite {
+			t.Errorf("Unexpected ShortWriteError")
+			t.FailNow()
+		}
+	}
+
+	log := zerolog.New(io.MultiWriter(w1, w2, w3)).With().Logger()
+
+	for i := 0; i < 10; i++ {
+		log.Info().Msg("Tick!")
+	}
+}

log.go

@@ -94,8 +94,8 @@
 //            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.
+// In this case, many consumers will take the last value,
+// but this is not guaranteed; check yours if in doubt.
 package zerolog
 
 import (
@@ -107,7 +107,7 @@ import (
 )
 
 // Level defines log levels.
-type Level uint8
+type Level int8
 
 const (
 	// DebugLevel defines debug log level.
@@ -126,10 +126,15 @@ const (
 	NoLevel
 	// Disabled disables the logger.
 	Disabled
+
+	// TraceLevel defines trace log level.
+	TraceLevel Level = -1
 )
 
 func (l Level) String() string {
 	switch l {
+	case TraceLevel:
+		return "trace"
 	case DebugLevel:
 		return "debug"
 	case InfoLevel:
@@ -152,19 +157,21 @@ func (l Level) String() string {
 // returns an error if the input string does not match known values.
 func ParseLevel(levelStr string) (Level, error) {
 	switch levelStr {
-	case DebugLevel.String():
+	case LevelFieldMarshalFunc(TraceLevel):
+		return TraceLevel, nil
+	case LevelFieldMarshalFunc(DebugLevel):
 		return DebugLevel, nil
-	case InfoLevel.String():
+	case LevelFieldMarshalFunc(InfoLevel):
 		return InfoLevel, nil
-	case WarnLevel.String():
+	case LevelFieldMarshalFunc(WarnLevel):
 		return WarnLevel, nil
-	case ErrorLevel.String():
+	case LevelFieldMarshalFunc(ErrorLevel):
 		return ErrorLevel, nil
-	case FatalLevel.String():
+	case LevelFieldMarshalFunc(FatalLevel):
 		return FatalLevel, nil
-	case PanicLevel.String():
+	case LevelFieldMarshalFunc(PanicLevel):
 		return PanicLevel, nil
-	case NoLevel.String():
+	case LevelFieldMarshalFunc(NoLevel):
 		return NoLevel, nil
 	}
 	return NoLevel, fmt.Errorf("Unknown Level String: '%s', defaulting to NoLevel", levelStr)
@@ -172,7 +179,7 @@ func ParseLevel(levelStr string) (Level, error) {
 
 // A Logger represents an active logging object that generates lines
 // of JSON output to an io.Writer. Each logging operation makes a single
-// call to the Writer's Write method. There is no guaranty on access
+// call to the Writer's Write method. There is no guarantee on access
 // serialization to the Writer. If your Writer is not thread safe,
 // you may consider a sync wrapper.
 type Logger struct {
@@ -181,6 +188,7 @@ type Logger struct {
 	sampler Sampler
 	context []byte
 	hooks   []Hook
+	stack   bool
 }
 
 // New creates a root logger with given output writer. If the output writer implements
@@ -188,7 +196,7 @@ type Logger struct {
 // one.
 //
 // Each logging operation makes a single call to the Writer's Write method. There is no
-// guaranty on access serialization to the Writer. If your Writer is not thread safe,
+// guarantee on access serialization to the Writer. If your Writer is not thread safe,
 // you may consider using sync wrapper.
 func New(w io.Writer) Logger {
 	if w == nil {
@@ -198,7 +206,7 @@ func New(w io.Writer) Logger {
 	if !ok {
 		lw = levelWriterAdapter{w}
 	}
-	return Logger{w: lw}
+	return Logger{w: lw, level: TraceLevel}
 }
 
 // Nop returns a disabled logger for which all operation are no-op.
@@ -227,6 +235,10 @@ func (l Logger) With() Context {
 	l.context = make([]byte, 0, 500)
 	if context != nil {
 		l.context = append(l.context, context...)
+	} else {
+		// This is needed for AppendKey to not check len of input
+		// thus making it inlinable
+		l.context = enc.AppendBeginMarker(l.context)
 	}
 	return Context{l}
 }
@@ -241,6 +253,9 @@ func (l *Logger) UpdateContext(update func(c Context) Context) {
 	if cap(l.context) == 0 {
 		l.context = make([]byte, 0, 500)
 	}
+	if len(l.context) == 0 {
+		l.context = enc.AppendBeginMarker(l.context)
+	}
 	c := update(Context{*l})
 	l.context = c.l.context
 }
@@ -251,6 +266,11 @@ func (l Logger) Level(lvl Level) Logger {
 	return l
 }
 
+// GetLevel returns the current Level of l.
+func (l Logger) GetLevel() Level {
+	return l.level
+}
+
 // Sample returns a logger with the s sampler.
 func (l Logger) Sample(s Sampler) Logger {
 	l.sampler = s
@@ -263,6 +283,13 @@ func (l Logger) Hook(h Hook) Logger {
 	return l
 }
 
+// Trace starts a new message with trace level.
+//
+// You must call Msg on the returned event in order to send the event.
+func (l *Logger) Trace() *Event {
+	return l.newEvent(TraceLevel, nil)
+}
+
 // Debug starts a new message with debug level.
 //
 // You must call Msg on the returned event in order to send the event.
@@ -291,6 +318,18 @@ func (l *Logger) Error() *Event {
 	return l.newEvent(ErrorLevel, nil)
 }
 
+// Err starts a new message with error level with err as a field if not nil or
+// with info level if err is nil.
+//
+// You must call Msg on the returned event in order to send the event.
+func (l *Logger) Err(err error) *Event {
+	if err != nil {
+		return l.Error().Err(err)
+	}
+
+	return l.Info()
+}
+
 // Fatal starts a new message with fatal level. The os.Exit(1) function
 // is called by the Msg method, which terminates the program immediately.
 //
@@ -314,6 +353,8 @@ func (l *Logger) Panic() *Event {
 // You must call Msg on the returned event in order to send the event.
 func (l *Logger) WithLevel(level Level) *Event {
 	switch level {
+	case TraceLevel:
+		return l.Trace()
 	case DebugLevel:
 		return l.Debug()
 	case InfoLevel:
@@ -380,11 +421,14 @@ func (l *Logger) newEvent(level Level, done func(string)) *Event {
 	e.done = done
 	e.ch = l.hooks
 	if level != NoLevel {
-		e.Str(LevelFieldName, level.String())
+		e.Str(LevelFieldName, LevelFieldMarshalFunc(level))
 	}
-	if l.context != nil && len(l.context) > 0 {
+	if l.context != nil && len(l.context) > 1 {
 		e.buf = enc.AppendObjectData(e.buf, l.context)
 	}
+	if l.stack {
+		e.Stack()
+	}
 	return e
 }
 

log/log.go

@@ -37,6 +37,21 @@ func Hook(h zerolog.Hook) zerolog.Logger {
 	return Logger.Hook(h)
 }
 
+// Err starts a new message with error level with err as a field if not nil or
+// with info level if err is nil.
+//
+// You must call Msg on the returned event in order to send the event.
+func Err(err error) *zerolog.Event {
+	return Logger.Err(err)
+}
+
+// Trace starts a new message with trace level.
+//
+// You must call Msg on the returned event in order to send the event.
+func Trace() *zerolog.Event {
+	return Logger.Trace()
+}
+
 // Debug starts a new message with debug level.
 //
 // You must call Msg on the returned event in order to send the event.

log/log_example_test.go

@@ -54,6 +54,25 @@ func ExampleLog() {
 	// Output: {"time":1199811905,"message":"hello world"}
 }
 
+// Example of a conditional level based on the presence of an error.
+func ExampleErr() {
+	setup()
+	err := errors.New("some error")
+	log.Err(err).Msg("hello world")
+	log.Err(nil).Msg("hello world")
+
+	// Output: {"level":"error","error":"some error","time":1199811905,"message":"hello world"}
+	// {"level":"info","time":1199811905,"message":"hello world"}
+}
+
+// Example of a log at a particular "level" (in this case, "trace")
+func ExampleTrace() {
+	setup()
+	log.Trace().Msg("hello world")
+
+	// Output: {"level":"trace","time":1199811905,"message":"hello world"}
+}
+
 // Example of a log at a particular "level" (in this case, "debug")
 func ExampleDebug() {
 	setup()

log_example_test.go

@@ -95,6 +95,17 @@ func ExampleLogger_Printf() {
 	// Output: {"level":"debug","message":"hello world"}
 }
 
+func ExampleLogger_Trace() {
+	log := zerolog.New(os.Stdout)
+
+	log.Trace().
+		Str("foo", "bar").
+		Int("n", 123).
+		Msg("hello world")
+
+	// Output: {"level":"trace","foo":"bar","n":123,"message":"hello world"}
+}
+
 func ExampleLogger_Debug() {
 	log := zerolog.New(os.Stdout)
 

log_test.go

@@ -7,6 +7,8 @@ import (
 	"net"
 	"reflect"
 	"runtime"
+	"strconv"
+	"strings"
 	"testing"
 	"time"
 )
@@ -79,6 +81,8 @@ func TestWith(t *testing.T) {
 	out := &bytes.Buffer{}
 	ctx := New(out).With().
 		Str("string", "foo").
+		Stringer("stringer", net.IP{127, 0, 0, 1}).
+		Stringer("stringer_nil", nil).
 		Bytes("bytes", []byte("bar")).
 		Hex("hex", []byte{0x12, 0xef}).
 		RawJSON("json", []byte(`{"some":"json"}`)).
@@ -102,7 +106,21 @@ func TestWith(t *testing.T) {
 	caller := fmt.Sprintf("%s:%d", file, line+3)
 	log := ctx.Caller().Logger()
 	log.Log().Msg("")
-	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 {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"string":"foo","stringer":"127.0.0.1","stringer_nil":null,"bytes":"bar","hex":"12ef","json":{"some":"json"},"error":"some error","bool":true,"int":1,"int8":2,"int16":3,"int32":4,"int64":5,"uint":6,"uint8":7,"uint16":8,"uint32":9,"uint64":10,"float32":11.101,"float64":12.30303,"time":"0001-01-01T00:00:00Z","caller":"`+caller+`"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+
+	// Validate CallerWithSkipFrameCount.
+	out.Reset()
+	_, file, line, _ = runtime.Caller(0)
+	caller = fmt.Sprintf("%s:%d", file, line+5)
+	log = ctx.CallerWithSkipFrameCount(3).Logger()
+	func() {
+		log.Log().Msg("")
+	}()
+	// The above line is a little contrived, but the line above should be the line due
+	// to the extra frame skip.
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"string":"foo","stringer":"127.0.0.1","stringer_nil":null,"bytes":"bar","hex":"12ef","json":{"some":"json"},"error":"some error","bool":true,"int":1,"int8":2,"int16":3,"int32":4,"int64":5,"uint":6,"uint8":7,"uint16":8,"uint32":9,"uint64":10,"float32":11.101,"float64":12.30303,"time":"0001-01-01T00:00:00Z","caller":"`+caller+`"}`+"\n"; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
@@ -219,6 +237,8 @@ func TestFields(t *testing.T) {
 	log.Log().
 		Caller().
 		Str("string", "foo").
+		Stringer("stringer", net.IP{127, 0, 0, 1}).
+		Stringer("stringer_nil", nil).
 		Bytes("bytes", []byte("bar")).
 		Hex("hex", []byte{0x12, 0xef}).
 		RawJSON("json", []byte(`{"some":"json"}`)).
@@ -245,7 +265,7 @@ func TestFields(t *testing.T) {
 		Time("time", time.Time{}).
 		TimeDiff("diff", now, now.Add(-10*time.Second)).
 		Msg("")
-	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 {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"caller":"`+caller+`","string":"foo","stringer":"127.0.0.1","stringer_nil":null,"bytes":"bar","hex":"12ef","json":{"some":"json"},"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)
 	}
 }
@@ -437,6 +457,24 @@ func TestLevel(t *testing.T) {
 	})
 }
 
+func TestGetLevel(t *testing.T) {
+	levels := []Level{
+		DebugLevel,
+		InfoLevel,
+		WarnLevel,
+		ErrorLevel,
+		FatalLevel,
+		PanicLevel,
+		NoLevel,
+		Disabled,
+	}
+	for _, level := range levels {
+		if got, want := New(nil).Level(level).GetLevel(), level; got != want {
+			t.Errorf("GetLevel() = %v, want: %v", got, want)
+		}
+	}
+}
+
 func TestSampling(t *testing.T) {
 	out := &bytes.Buffer{}
 	log := New(out).Sample(&BasicSampler{N: 2})
@@ -492,30 +530,34 @@ func TestLevelWriter(t *testing.T) {
 		}{},
 	}
 	log := New(lw)
+	log.Trace().Msg("0")
 	log.Debug().Msg("1")
 	log.Info().Msg("2")
 	log.Warn().Msg("3")
 	log.Error().Msg("4")
 	log.Log().Msg("nolevel-1")
-	log.WithLevel(DebugLevel).Msg("5")
-	log.WithLevel(InfoLevel).Msg("6")
-	log.WithLevel(WarnLevel).Msg("7")
-	log.WithLevel(ErrorLevel).Msg("8")
+	log.WithLevel(TraceLevel).Msg("5")
+	log.WithLevel(DebugLevel).Msg("6")
+	log.WithLevel(InfoLevel).Msg("7")
+	log.WithLevel(WarnLevel).Msg("8")
+	log.WithLevel(ErrorLevel).Msg("9")
 	log.WithLevel(NoLevel).Msg("nolevel-2")
 
 	want := []struct {
 		l Level
 		p string
 	}{
+		{TraceLevel, `{"level":"trace","message":"0"}` + "\n"},
 		{DebugLevel, `{"level":"debug","message":"1"}` + "\n"},
 		{InfoLevel, `{"level":"info","message":"2"}` + "\n"},
 		{WarnLevel, `{"level":"warn","message":"3"}` + "\n"},
 		{ErrorLevel, `{"level":"error","message":"4"}` + "\n"},
 		{NoLevel, `{"message":"nolevel-1"}` + "\n"},
-		{DebugLevel, `{"level":"debug","message":"5"}` + "\n"},
-		{InfoLevel, `{"level":"info","message":"6"}` + "\n"},
-		{WarnLevel, `{"level":"warn","message":"7"}` + "\n"},
-		{ErrorLevel, `{"level":"error","message":"8"}` + "\n"},
+		{TraceLevel, `{"level":"trace","message":"5"}` + "\n"},
+		{DebugLevel, `{"level":"debug","message":"6"}` + "\n"},
+		{InfoLevel, `{"level":"info","message":"7"}` + "\n"},
+		{WarnLevel, `{"level":"warn","message":"8"}` + "\n"},
+		{ErrorLevel, `{"level":"error","message":"9"}` + "\n"},
 		{NoLevel, `{"message":"nolevel-2"}` + "\n"},
 	}
 	if got := lw.ops; !reflect.DeepEqual(got, want) {
@@ -641,6 +683,75 @@ func TestErrorMarshalFunc(t *testing.T) {
 	}
 }
 
+func TestCallerMarshalFunc(t *testing.T) {
+	out := &bytes.Buffer{}
+	log := New(out)
+
+	// test default behaviour this is really brittle due to the line numbers
+	// actually mattering for validation
+	_, file, line, _ := runtime.Caller(0)
+	caller := fmt.Sprintf("%s:%d", file, line+2)
+	log.Log().Caller().Msg("msg")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"caller":"`+caller+`","message":"msg"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+	out.Reset()
+
+	// test custom behavior. In this case we'll take just the last directory
+	origCallerMarshalFunc := CallerMarshalFunc
+	defer func() { CallerMarshalFunc = origCallerMarshalFunc }()
+	CallerMarshalFunc = func(file string, line int) string {
+		parts := strings.Split(file, "/")
+		if len(parts) > 1 {
+			return strings.Join(parts[len(parts)-2:], "/") + ":" + strconv.Itoa(line)
+		}
+
+		return file + ":" + strconv.Itoa(line)
+	}
+	_, file, line, _ = runtime.Caller(0)
+	caller = CallerMarshalFunc(file, line+2)
+	log.Log().Caller().Msg("msg")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"caller":"`+caller+`","message":"msg"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
+func TestLevelFieldMarshalFunc(t *testing.T) {
+	origLevelFieldMarshalFunc := LevelFieldMarshalFunc
+	LevelFieldMarshalFunc = func(l Level) string {
+		return strings.ToUpper(l.String())
+	}
+	defer func() {
+		LevelFieldMarshalFunc = origLevelFieldMarshalFunc
+	}()
+	out := &bytes.Buffer{}
+	log := New(out)
+
+	log.Debug().Msg("test")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"DEBUG","message":"test"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+	out.Reset()
+
+	log.Info().Msg("test")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"INFO","message":"test"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+	out.Reset()
+
+	log.Warn().Msg("test")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"WARN","message":"test"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+	out.Reset()
+
+	log.Error().Msg("test")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"level":"ERROR","message":"test"}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+	out.Reset()
+}
+
 type errWriter struct {
 	error
 }
@@ -661,3 +772,19 @@ func TestErrorHandler(t *testing.T) {
 		t.Errorf("ErrorHandler err = %#v, want %#v", got, want)
 	}
 }
+
+func TestUpdateEmptyContext(t *testing.T) {
+	var buf bytes.Buffer
+	log := New(&buf)
+
+	log.UpdateContext(func(c Context) Context {
+		return c.Str("foo", "bar")
+	})
+	log.Info().Msg("no panic")
+
+	want := `{"level":"info","foo":"bar","message":"no panic"}` + "\n"
+
+	if got := decodeIfBinaryToString(buf.Bytes()); got != want {
+		t.Errorf("invalid log output:\ngot:  %q\nwant: %q", got, want)
+	}
+}

not_go112.go

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

pkgerrors/stacktrace_test.go

@@ -27,6 +27,22 @@ func TestLogStack(t *testing.T) {
 	}
 }
 
+func TestLogStackFromContext(t *testing.T) {
+	zerolog.ErrorStackMarshaler = MarshalStack
+
+	out := &bytes.Buffer{}
+	log := zerolog.New(out).With().Stack().Logger() // calling Stack() on log context instead of event
+
+	err := errors.Wrap(errors.New("error message"), "from error")
+	log.Log().Err(err).Msg("") // not explicitly calling Stack()
+
+	got := out.String()
+	want := `\{"stack":\[\{"func":"TestLogStackFromContext","line":"36","source":"stacktrace_test.go"\},.*\],"error":"from error: error message"\}\n`
+	if ok, _ := regexp.MatchString(want, got); !ok {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+
 func BenchmarkLogStack(b *testing.B) {
 	zerolog.ErrorStackMarshaler = MarshalStack
 	out := &bytes.Buffer{}

sampler.go

@@ -46,8 +46,12 @@ type BasicSampler struct {
 
 // Sample implements the Sampler interface.
 func (s *BasicSampler) Sample(lvl Level) bool {
+	n := s.N
+	if n == 1 {
+		return true
+	}
 	c := atomic.AddUint32(&s.counter, 1)
-	return c%s.N == s.N-1
+	return c%n == 1
 }
 
 // BurstSampler lets Burst events pass per Period then pass the decision to
@@ -100,11 +104,15 @@ func (s *BurstSampler) inc() uint32 {
 
 // LevelSampler applies a different sampler for each level.
 type LevelSampler struct {
-	DebugSampler, InfoSampler, WarnSampler, ErrorSampler Sampler
+	TraceSampler, DebugSampler, InfoSampler, WarnSampler, ErrorSampler Sampler
 }
 
 func (s LevelSampler) Sample(lvl Level) bool {
 	switch lvl {
+	case TraceLevel:
+		if s.TraceSampler != nil {
+			return s.TraceSampler.Sample(lvl)
+		}
 	case DebugLevel:
 		if s.DebugSampler != nil {
 			return s.DebugSampler.Sample(lvl)

syslog.go

@@ -7,6 +7,10 @@ import (
 	"io"
 )
 
+// See http://cee.mitre.org/language/1.0-beta1/clt.html#syslog
+// or https://www.rsyslog.com/json-elasticsearch/
+const ceePrefix = "@cee:"
+
 // SyslogWriter is an interface matching a syslog.Writer struct.
 type SyslogWriter interface {
 	io.Writer
@@ -19,39 +23,58 @@ type SyslogWriter interface {
 }
 
 type syslogWriter struct {
-	w SyslogWriter
+	w      SyslogWriter
+	prefix string
 }
 
 // SyslogLevelWriter wraps a SyslogWriter and call the right syslog level
 // method matching the zerolog level.
 func SyslogLevelWriter(w SyslogWriter) LevelWriter {
-	return syslogWriter{w}
+	return syslogWriter{w, ""}
+}
+
+// SyslogCEEWriter wraps a SyslogWriter with a SyslogLevelWriter that adds a
+// MITRE CEE prefix for JSON syslog entries, compatible with rsyslog 
+// and syslog-ng JSON logging support. 
+// See https://www.rsyslog.com/json-elasticsearch/
+func SyslogCEEWriter(w SyslogWriter) LevelWriter {
+	return syslogWriter{w, ceePrefix}
 }
 
 func (sw syslogWriter) Write(p []byte) (n int, err error) {
-	return sw.w.Write(p)
+	var pn int
+	if sw.prefix != "" {
+		pn, err = sw.w.Write([]byte(sw.prefix))
+		if err != nil {
+			return pn, err
+		}
+	}
+	n, err = sw.w.Write(p)
+	return pn + n, err
 }
 
 // WriteLevel implements LevelWriter interface.
 func (sw syslogWriter) WriteLevel(level Level, p []byte) (n int, err error) {
 	switch level {
+	case TraceLevel:
 	case DebugLevel:
-		err = sw.w.Debug(string(p))
+		err = sw.w.Debug(sw.prefix + string(p))
 	case InfoLevel:
-		err = sw.w.Info(string(p))
+		err = sw.w.Info(sw.prefix + string(p))
 	case WarnLevel:
-		err = sw.w.Warning(string(p))
+		err = sw.w.Warning(sw.prefix + string(p))
 	case ErrorLevel:
-		err = sw.w.Err(string(p))
+		err = sw.w.Err(sw.prefix + string(p))
 	case FatalLevel:
-		err = sw.w.Emerg(string(p))
+		err = sw.w.Emerg(sw.prefix + string(p))
 	case PanicLevel:
-		err = sw.w.Crit(string(p))
+		err = sw.w.Crit(sw.prefix + string(p))
 	case NoLevel:
-		err = sw.w.Info(string(p))
+		err = sw.w.Info(sw.prefix + string(p))
 	default:
 		panic("invalid level")
 	}
+	// Any CEE prefix is not part of the message, so we don't include its length
 	n = len(p)
 	return
 }

syslog_test.go

@@ -3,8 +3,12 @@
 
 package zerolog
 
-import "testing"
-import "reflect"
+import (
+	"bytes"
+	"reflect"
+	"strings"
+	"testing"
+)
 
 type syslogEvent struct {
 	level string
@@ -17,6 +21,10 @@ type syslogTestWriter struct {
 func (w *syslogTestWriter) Write(p []byte) (int, error) {
 	return 0, nil
 }
+func (w *syslogTestWriter) Trace(m string) error {
+	w.events = append(w.events, syslogEvent{"Trace", m})
+	return nil
+}
 func (w *syslogTestWriter) Debug(m string) error {
 	w.events = append(w.events, syslogEvent{"Debug", m})
 	return nil
@@ -45,6 +53,7 @@ func (w *syslogTestWriter) Crit(m string) error {
 func TestSyslogWriter(t *testing.T) {
 	sw := &syslogTestWriter{}
 	log := New(SyslogLevelWriter(sw))
+	log.Trace().Msg("trace")
 	log.Debug().Msg("debug")
 	log.Info().Msg("info")
 	log.Warn().Msg("warn")
@@ -61,3 +70,39 @@ func TestSyslogWriter(t *testing.T) {
 		t.Errorf("Invalid syslog message routing: want %v, got %v", want, got)
 	}
 }
+
+type testCEEwriter struct {
+	buf *bytes.Buffer
+}
+
+// Only implement one method as we're just testing the prefixing
+func (c testCEEwriter) Debug(m string) error { return nil }
+
+func (c testCEEwriter) Info(m string) error {
+	_, err := c.buf.Write([]byte(m))
+	return err
+}
+
+func (c testCEEwriter) Warning(m string) error { return nil }
+
+func (c testCEEwriter) Err(m string) error { return nil }
+
+func (c testCEEwriter) Emerg(m string) error { return nil }
+
+func (c testCEEwriter) Crit(m string) error { return nil }
+
+func (c testCEEwriter) Write(b []byte) (int, error) {
+	return c.buf.Write(b)
+}
+
+func TestSyslogWriter_WithCEE(t *testing.T) {
+	var buf bytes.Buffer
+	sw := testCEEwriter{&buf}
+	log := New(SyslogCEEWriter(sw))
+	log.Info().Str("key", "value").Msg("message string")
+	got := string(buf.Bytes())
+	want := "@cee:{"
+	if !strings.HasPrefix(got, want) {
+		t.Errorf("Bad CEE message start: want %v, got %v", want, got)
+	}
+}

writer.go

@@ -26,11 +26,9 @@ type syncWriter struct {
 }
 
 // SyncWriter wraps w so that each call to Write is synchronized with a mutex.
-// This syncer can be the call to writer's Write method is not thread safe.
-// Note that os.File Write operation is using write() syscall which is supposed
-// to be thread-safe on POSIX systems. So there is no need to use this with
-// os.File on such systems as zerolog guaranties to issue a single Write call
-// per log event.
+// This syncer can be used to wrap the call to writer's Write method if it is
+// not thread safe. Note that you do not need this wrapper for os.File Write
+// operations on POSIX and Windows systems as they are already thread-safe.
 func SyncWriter(w io.Writer) io.Writer {
 	if lw, ok := w.(LevelWriter); ok {
 		return &syncWriter{lw: lw}
@@ -58,30 +56,30 @@ type multiLevelWriter struct {
 
 func (t multiLevelWriter) Write(p []byte) (n int, err error) {
 	for _, w := range t.writers {
-		n, err = w.Write(p)
-		if err != nil {
-			return
-		}
-		if n != len(p) {
-			err = io.ErrShortWrite
-			return
+		if _n, _err := w.Write(p); err == nil {
+			n = _n
+			if _err != nil {
+				err = _err
+			} else if _n != len(p) {
+				err = io.ErrShortWrite
+			}
 		}
 	}
-	return len(p), nil
+	return n, err
 }
 
 func (t multiLevelWriter) WriteLevel(l Level, p []byte) (n int, err error) {
 	for _, w := range t.writers {
-		n, err = w.WriteLevel(l, p)
-		if err != nil {
-			return
-		}
-		if n != len(p) {
-			err = io.ErrShortWrite
-			return
+		if _n, _err := w.WriteLevel(l, p); err == nil {
+			n = _n
+			if _err != nil {
+				err = _err
+			} else if _n != len(p) {
+				err = io.ErrShortWrite
+			}
 		}
 	}
-	return len(p), nil
+	return n, err
 }
 
 // MultiLevelWriter creates a writer that duplicates its writes to all the

writer_test.go

@@ -4,6 +4,8 @@
 package zerolog
 
 import (
+	"errors"
+	"io"
 	"reflect"
 	"testing"
 )
@@ -27,3 +29,85 @@ func TestMultiSyslogWriter(t *testing.T) {
 		t.Errorf("Invalid syslog message routing: want %v, got %v", want, got)
 	}
 }
+
+var writeCalls int
+
+type mockedWriter struct {
+	wantErr bool
+}
+
+func (c mockedWriter) Write(p []byte) (int, error) {
+	writeCalls++
+
+	if c.wantErr {
+		return -1, errors.New("Expected error")
+	}
+
+	return len(p), nil
+}
+
+// Tests that a new writer is only used if it actually works.
+func TestResilientMultiWriter(t *testing.T) {
+	tests := []struct {
+		name    string
+		writers []io.Writer
+	}{
+		{
+			name:    "All valid writers",
+			writers: []io.Writer{
+				mockedWriter {
+					wantErr: false,
+				},
+				mockedWriter {
+					wantErr: false,
+				},
+			},
+		},
+		{
+			name:    "All invalid writers",
+			writers: []io.Writer{
+				mockedWriter {
+					wantErr: true,
+				},
+				mockedWriter {
+					wantErr: true,
+				},
+			},
+		},
+		{
+			name:    "First invalid writer",
+			writers: []io.Writer{
+				mockedWriter {
+					wantErr: true,
+				},
+				mockedWriter {
+					wantErr: false,
+				},
+			},
+		},
+		{
+			name:    "First valid writer",
+			writers: []io.Writer{
+				mockedWriter {
+					wantErr: false,
+				},
+				mockedWriter {
+					wantErr: true,
+				},
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		writers := tt.writers
+		multiWriter := MultiLevelWriter(writers...)
+
+		logger := New(multiWriter).With().Timestamp().Logger().Level(InfoLevel)
+		logger.Info().Msg("Test msg")
+
+		if len(writers) != writeCalls {
+			t.Errorf("Expected %d writers to have been called but only %d were.", len(writers), writeCalls)
+		}
+		writeCalls = 0
+	}
+}