Merge pull request #384 from mnzt/master

Renaming upper-case 'Sirupsen' to 'sirupsen'
diff --git a/.travis.yml b/.travis.yml
index dee4eb2..804c569 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,9 +1,7 @@
 language: go
 go:
-  - 1.3
-  - 1.4
-  - 1.5
   - 1.6
+  - 1.7
   - tip
 install:
   - go get -t ./...
diff --git a/README.md b/README.md
index 8ce5db9..429725a 100644
--- a/README.md
+++ b/README.md
@@ -228,7 +228,13 @@
 | [Typetalk](https://github.com/dragon3/logrus-typetalk-hook) | Hook for logging to [Typetalk](https://www.typetalk.in/) |
 | [ElasticSearch](https://github.com/sohlich/elogrus) | Hook for logging to ElasticSearch|
 | [Sumorus](https://github.com/doublefree/sumorus) | Hook for logging to [SumoLogic](https://www.sumologic.com/)|
+| [Scribe](https://github.com/sagar8192/logrus-scribe-hook) | Hook for logging to [Scribe](https://github.com/facebookarchive/scribe)|
 | [Logstash](https://github.com/bshuster-repo/logrus-logstash-hook) | Hook for logging to [Logstash](https://www.elastic.co/products/logstash) |
+| [logz.io](https://github.com/ripcurld00d/logrus-logzio-hook) | Hook for logging to [logz.io](https://logz.io), a Log as a Service using Logstash |
+| [Logmatic.io](https://github.com/logmatic/logmatic-go) | Hook for logging to [Logmatic.io](http://logmatic.io/) |
+| [Pushover](https://github.com/toorop/logrus_pushover) | Send error via [Pushover](https://pushover.net) |
+| [PostgreSQL](https://github.com/gemnasium/logrus-postgresql-hook) | Send logs to [PostgreSQL](http://postgresql.org) |
+
 
 #### Level logging
 
@@ -365,6 +371,7 @@
 | Tool | Description |
 | ---- | ----------- |
 |[Logrus Mate](https://github.com/gogap/logrus_mate)|Logrus mate is a tool for Logrus to manage loggers, you can initial logger's level, hook and formatter by config file, the logger will generated with different config at different environment.|
+|[Logrus Viper Helper](https://github.com/heirko/go-contrib/tree/master/logrusHelper)|An Helper arround Logrus to wrap with spf13/Viper to load configuration with fangs! And to simplify Logrus configuration use some behavior of [Logrus Mate](https://github.com/gogap/logrus_mate). [sample](https://github.com/heirko/iris-contrib/blob/master/middleware/logrus-logger/example) |
 
 #### Testing
 
@@ -400,3 +407,20 @@
 logrus.RegisterExitHandler(handler)
 ...
 ```
+
+#### Thread safety
+
+By default Logger is protected by mutex for concurrent writes, this mutex is invoked when calling hooks and writing logs.
+If you are sure such locking is not needed, you can call logger.SetNoLock() to disable the locking.
+
+Situation when locking is not needed includes:
+
+* You have no hooks registered, or hooks calling is already thread-safe.
+
+* Writing to logger.Out is already thread-safe, for example:
+
+  1) logger.Out is protected by locks.
+
+  2) logger.Out is a os.File handler opened with `O_APPEND` flag, and every write is smaller than 4k. (This allow multi-thread/multi-process writing)
+
+     (Refer to http://www.notthewizard.com/2014/06/17/are-files-appends-really-atomic/)
diff --git a/entry.go b/entry.go
index 54bfc57..4edbe7a 100644
--- a/entry.go
+++ b/entry.go
@@ -3,11 +3,21 @@
 import (
 	"bytes"
 	"fmt"
-	"io"
 	"os"
+	"sync"
 	"time"
 )
 
+var bufferPool *sync.Pool
+
+func init() {
+	bufferPool = &sync.Pool{
+		New: func() interface{} {
+			return new(bytes.Buffer)
+		},
+	}
+}
+
 // Defines the key when adding errors using WithError.
 var ErrorKey = "error"
 
@@ -29,6 +39,9 @@
 
 	// Message passed to Debug, Info, Warn, Error, Fatal or Panic
 	Message string
+
+	// When formatter is called in entry.log(), an Buffer may be set to entry
+	Buffer *bytes.Buffer
 }
 
 func NewEntry(logger *Logger) *Entry {
@@ -39,21 +52,15 @@
 	}
 }
 
-// Returns a reader for the entry, which is a proxy to the formatter.
-func (entry *Entry) Reader() (*bytes.Buffer, error) {
-	serialized, err := entry.Logger.Formatter.Format(entry)
-	return bytes.NewBuffer(serialized), err
-}
-
 // Returns the string representation from the reader and ultimately the
 // formatter.
 func (entry *Entry) String() (string, error) {
-	reader, err := entry.Reader()
+	serialized, err := entry.Logger.Formatter.Format(entry)
 	if err != nil {
 		return "", err
 	}
-
-	return reader.String(), err
+	str := string(serialized)
+	return str, nil
 }
 
 // Add an error as single field (using the key defined in ErrorKey) to the Entry.
@@ -81,6 +88,7 @@
 // This function is not declared with a pointer value because otherwise
 // race conditions will occur when using multiple goroutines
 func (entry Entry) log(level Level, msg string) {
+	var buffer *bytes.Buffer
 	entry.Time = time.Now()
 	entry.Level = level
 	entry.Message = msg
@@ -90,20 +98,23 @@
 		fmt.Fprintf(os.Stderr, "Failed to fire hook: %v\n", err)
 		entry.Logger.mu.Unlock()
 	}
-
-	reader, err := entry.Reader()
+	buffer = bufferPool.Get().(*bytes.Buffer)
+	buffer.Reset()
+	defer bufferPool.Put(buffer)
+	entry.Buffer = buffer
+	serialized, err := entry.Logger.Formatter.Format(&entry)
+	entry.Buffer = nil
 	if err != nil {
 		entry.Logger.mu.Lock()
 		fmt.Fprintf(os.Stderr, "Failed to obtain reader, %v\n", err)
 		entry.Logger.mu.Unlock()
-	}
-
-	entry.Logger.mu.Lock()
-	defer entry.Logger.mu.Unlock()
-
-	_, err = io.Copy(entry.Logger.Out, reader)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "Failed to write to log, %v\n", err)
+	} else {
+		entry.Logger.mu.Lock()
+		_, err = entry.Logger.Out.Write(serialized)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "Failed to write to log, %v\n", err)
+		}
+		entry.Logger.mu.Unlock()
 	}
 
 	// To avoid Entry#log() returning a value that only would make sense for
diff --git a/json_formatter.go b/json_formatter.go
index 47da504..47325a7 100644
--- a/json_formatter.go
+++ b/json_formatter.go
@@ -5,9 +5,37 @@
 	"fmt"
 )
 
+type fieldKey string
+type FieldMap map[fieldKey]string
+
+const (
+	FieldKeyMsg   = "msg"
+	FieldKeyLevel = "level"
+	FieldKeyTime  = "time"
+)
+
+func (f FieldMap) resolve(key fieldKey) string {
+	if k, ok := f[key]; ok {
+		return k
+	}
+
+	return string(key)
+}
+
 type JSONFormatter struct {
 	// TimestampFormat sets the format used for marshaling timestamps.
 	TimestampFormat string
+
+	// FieldMap allows users to customize the names of keys for various fields.
+	// As an example:
+	// formatter := &JSONFormatter{
+	//   	FieldMap: FieldMap{
+	// 		 FieldKeyTime: "@timestamp",
+	// 		 FieldKeyLevel: "@level",
+	// 		 FieldKeyLevel: "@message",
+	//    },
+	// }
+	FieldMap FieldMap
 }
 
 func (f *JSONFormatter) Format(entry *Entry) ([]byte, error) {
@@ -29,9 +57,9 @@
 		timestampFormat = DefaultTimestampFormat
 	}
 
-	data["time"] = entry.Time.Format(timestampFormat)
-	data["msg"] = entry.Message
-	data["level"] = entry.Level.String()
+	data[f.FieldMap.resolve(FieldKeyTime)] = entry.Time.Format(timestampFormat)
+	data[f.FieldMap.resolve(FieldKeyMsg)] = entry.Message
+	data[f.FieldMap.resolve(FieldKeyLevel)] = entry.Level.String()
 
 	serialized, err := json.Marshal(data)
 	if err != nil {
diff --git a/json_formatter_test.go b/json_formatter_test.go
index 1d70873..5baa93e 100644
--- a/json_formatter_test.go
+++ b/json_formatter_test.go
@@ -3,7 +3,7 @@
 import (
 	"encoding/json"
 	"errors"
-
+	"strings"
 	"testing"
 )
 
@@ -118,3 +118,54 @@
 		t.Fatal("Expected JSON log entry to end with a newline")
 	}
 }
+
+func TestJSONMessageKey(t *testing.T) {
+	formatter := &JSONFormatter{
+		FieldMap: FieldMap{
+			FieldKeyMsg: "message",
+		},
+	}
+
+	b, err := formatter.Format(&Entry{Message: "oh hai"})
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+	s := string(b)
+	if !(strings.Contains(s, "message") && strings.Contains(s, "oh hai")) {
+		t.Fatal("Expected JSON to format message key")
+	}
+}
+
+func TestJSONLevelKey(t *testing.T) {
+	formatter := &JSONFormatter{
+		FieldMap: FieldMap{
+			FieldKeyLevel: "somelevel",
+		},
+	}
+
+	b, err := formatter.Format(WithField("level", "something"))
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+	s := string(b)
+	if !strings.Contains(s, "somelevel") {
+		t.Fatal("Expected JSON to format level key")
+	}
+}
+
+func TestJSONTimeKey(t *testing.T) {
+	formatter := &JSONFormatter{
+		FieldMap: FieldMap{
+			FieldKeyTime: "timeywimey",
+		},
+	}
+
+	b, err := formatter.Format(WithField("level", "something"))
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+	s := string(b)
+	if !strings.Contains(s, "timeywimey") {
+		t.Fatal("Expected JSON to format time key")
+	}
+}
diff --git a/logger.go b/logger.go
index 9052a80..b769f3d 100644
--- a/logger.go
+++ b/logger.go
@@ -26,8 +26,31 @@
 	// to) `logrus.Info`, which allows Info(), Warn(), Error() and Fatal() to be
 	// logged. `logrus.Debug` is useful in
 	Level Level
-	// Used to sync writing to the log.
-	mu sync.Mutex
+	// Used to sync writing to the log. Locking is enabled by Default
+	mu MutexWrap
+	// Reusable empty entry
+	entryPool sync.Pool
+}
+
+type MutexWrap struct {
+	lock     sync.Mutex
+	disabled bool
+}
+
+func (mw *MutexWrap) Lock() {
+	if !mw.disabled {
+		mw.lock.Lock()
+	}
+}
+
+func (mw *MutexWrap) Unlock() {
+	if !mw.disabled {
+		mw.lock.Unlock()
+	}
+}
+
+func (mw *MutexWrap) Disable() {
+	mw.disabled = true
 }
 
 // Creates a new logger. Configuration should be set by changing `Formatter`,
@@ -51,162 +74,235 @@
 	}
 }
 
+func (logger *Logger) newEntry() *Entry {
+	entry, ok := logger.entryPool.Get().(*Entry)
+	if ok {
+		return entry
+	}
+	return NewEntry(logger)
+}
+
+func (logger *Logger) releaseEntry(entry *Entry) {
+	logger.entryPool.Put(entry)
+}
+
 // Adds a field to the log entry, note that it doesn't log until you call
 // Debug, Print, Info, Warn, Fatal or Panic. It only creates a log entry.
 // If you want multiple fields, use `WithFields`.
 func (logger *Logger) WithField(key string, value interface{}) *Entry {
-	return NewEntry(logger).WithField(key, value)
+	entry := logger.newEntry()
+	defer logger.releaseEntry(entry)
+	return entry.WithField(key, value)
 }
 
 // Adds a struct of fields to the log entry. All it does is call `WithField` for
 // each `Field`.
 func (logger *Logger) WithFields(fields Fields) *Entry {
-	return NewEntry(logger).WithFields(fields)
+	entry := logger.newEntry()
+	defer logger.releaseEntry(entry)
+	return entry.WithFields(fields)
 }
 
 // Add an error as single field to the log entry.  All it does is call
 // `WithError` for the given `error`.
 func (logger *Logger) WithError(err error) *Entry {
-	return NewEntry(logger).WithError(err)
+	entry := logger.newEntry()
+	defer logger.releaseEntry(entry)
+	return entry.WithError(err)
 }
 
 func (logger *Logger) Debugf(format string, args ...interface{}) {
 	if logger.Level >= DebugLevel {
-		NewEntry(logger).Debugf(format, args...)
+		entry := logger.newEntry()
+		entry.Debugf(format, args...)
+		logger.releaseEntry(entry)
 	}
 }
 
 func (logger *Logger) Infof(format string, args ...interface{}) {
 	if logger.Level >= InfoLevel {
-		NewEntry(logger).Infof(format, args...)
+		entry := logger.newEntry()
+		entry.Infof(format, args...)
+		logger.releaseEntry(entry)
 	}
 }
 
 func (logger *Logger) Printf(format string, args ...interface{}) {
-	NewEntry(logger).Printf(format, args...)
+	entry := logger.newEntry()
+	entry.Printf(format, args...)
+	logger.releaseEntry(entry)
 }
 
 func (logger *Logger) Warnf(format string, args ...interface{}) {
 	if logger.Level >= WarnLevel {
-		NewEntry(logger).Warnf(format, args...)
+		entry := logger.newEntry()
+		entry.Warnf(format, args...)
+		logger.releaseEntry(entry)
 	}
 }
 
 func (logger *Logger) Warningf(format string, args ...interface{}) {
 	if logger.Level >= WarnLevel {
-		NewEntry(logger).Warnf(format, args...)
+		entry := logger.newEntry()
+		entry.Warnf(format, args...)
+		logger.releaseEntry(entry)
 	}
 }
 
 func (logger *Logger) Errorf(format string, args ...interface{}) {
 	if logger.Level >= ErrorLevel {
-		NewEntry(logger).Errorf(format, args...)
+		entry := logger.newEntry()
+		entry.Errorf(format, args...)
+		logger.releaseEntry(entry)
 	}
 }
 
 func (logger *Logger) Fatalf(format string, args ...interface{}) {
 	if logger.Level >= FatalLevel {
-		NewEntry(logger).Fatalf(format, args...)
+		entry := logger.newEntry()
+		entry.Fatalf(format, args...)
+		logger.releaseEntry(entry)
 	}
 	Exit(1)
 }
 
 func (logger *Logger) Panicf(format string, args ...interface{}) {
 	if logger.Level >= PanicLevel {
-		NewEntry(logger).Panicf(format, args...)
+		entry := logger.newEntry()
+		entry.Panicf(format, args...)
+		logger.releaseEntry(entry)
 	}
 }
 
 func (logger *Logger) Debug(args ...interface{}) {
 	if logger.Level >= DebugLevel {
-		NewEntry(logger).Debug(args...)
+		entry := logger.newEntry()
+		entry.Debug(args...)
+		logger.releaseEntry(entry)
 	}
 }
 
 func (logger *Logger) Info(args ...interface{}) {
 	if logger.Level >= InfoLevel {
-		NewEntry(logger).Info(args...)
+		entry := logger.newEntry()
+		entry.Info(args...)
+		logger.releaseEntry(entry)
 	}
 }
 
 func (logger *Logger) Print(args ...interface{}) {
-	NewEntry(logger).Info(args...)
+	entry := logger.newEntry()
+	entry.Info(args...)
+	logger.releaseEntry(entry)
 }
 
 func (logger *Logger) Warn(args ...interface{}) {
 	if logger.Level >= WarnLevel {
-		NewEntry(logger).Warn(args...)
+		entry := logger.newEntry()
+		entry.Warn(args...)
+		logger.releaseEntry(entry)
 	}
 }
 
 func (logger *Logger) Warning(args ...interface{}) {
 	if logger.Level >= WarnLevel {
-		NewEntry(logger).Warn(args...)
+		entry := logger.newEntry()
+		entry.Warn(args...)
+		logger.releaseEntry(entry)
 	}
 }
 
 func (logger *Logger) Error(args ...interface{}) {
 	if logger.Level >= ErrorLevel {
-		NewEntry(logger).Error(args...)
+		entry := logger.newEntry()
+		entry.Error(args...)
+		logger.releaseEntry(entry)
 	}
 }
 
 func (logger *Logger) Fatal(args ...interface{}) {
 	if logger.Level >= FatalLevel {
-		NewEntry(logger).Fatal(args...)
+		entry := logger.newEntry()
+		entry.Fatal(args...)
+		logger.releaseEntry(entry)
 	}
 	Exit(1)
 }
 
 func (logger *Logger) Panic(args ...interface{}) {
 	if logger.Level >= PanicLevel {
-		NewEntry(logger).Panic(args...)
+		entry := logger.newEntry()
+		entry.Panic(args...)
+		logger.releaseEntry(entry)
 	}
 }
 
 func (logger *Logger) Debugln(args ...interface{}) {
 	if logger.Level >= DebugLevel {
-		NewEntry(logger).Debugln(args...)
+		entry := logger.newEntry()
+		entry.Debugln(args...)
+		logger.releaseEntry(entry)
 	}
 }
 
 func (logger *Logger) Infoln(args ...interface{}) {
 	if logger.Level >= InfoLevel {
-		NewEntry(logger).Infoln(args...)
+		entry := logger.newEntry()
+		entry.Infoln(args...)
+		logger.releaseEntry(entry)
 	}
 }
 
 func (logger *Logger) Println(args ...interface{}) {
-	NewEntry(logger).Println(args...)
+	entry := logger.newEntry()
+	entry.Println(args...)
+	logger.releaseEntry(entry)
 }
 
 func (logger *Logger) Warnln(args ...interface{}) {
 	if logger.Level >= WarnLevel {
-		NewEntry(logger).Warnln(args...)
+		entry := logger.newEntry()
+		entry.Warnln(args...)
+		logger.releaseEntry(entry)
 	}
 }
 
 func (logger *Logger) Warningln(args ...interface{}) {
 	if logger.Level >= WarnLevel {
-		NewEntry(logger).Warnln(args...)
+		entry := logger.newEntry()
+		entry.Warnln(args...)
+		logger.releaseEntry(entry)
 	}
 }
 
 func (logger *Logger) Errorln(args ...interface{}) {
 	if logger.Level >= ErrorLevel {
-		NewEntry(logger).Errorln(args...)
+		entry := logger.newEntry()
+		entry.Errorln(args...)
+		logger.releaseEntry(entry)
 	}
 }
 
 func (logger *Logger) Fatalln(args ...interface{}) {
 	if logger.Level >= FatalLevel {
-		NewEntry(logger).Fatalln(args...)
+		entry := logger.newEntry()
+		entry.Fatalln(args...)
+		logger.releaseEntry(entry)
 	}
 	Exit(1)
 }
 
 func (logger *Logger) Panicln(args ...interface{}) {
 	if logger.Level >= PanicLevel {
-		NewEntry(logger).Panicln(args...)
+		entry := logger.newEntry()
+		entry.Panicln(args...)
+		logger.releaseEntry(entry)
 	}
 }
+
+//When file is opened with appending mode, it's safe to
+//write concurrently to a file (within 4k message on Linux).
+//In these cases user can choose to disable the lock.
+func (logger *Logger) SetNoLock() {
+	logger.mu.Disable()
+}
diff --git a/logger_bench_test.go b/logger_bench_test.go
new file mode 100644
index 0000000..dd23a35
--- /dev/null
+++ b/logger_bench_test.go
@@ -0,0 +1,61 @@
+package logrus
+
+import (
+	"os"
+	"testing"
+)
+
+// smallFields is a small size data set for benchmarking
+var loggerFields = Fields{
+	"foo":   "bar",
+	"baz":   "qux",
+	"one":   "two",
+	"three": "four",
+}
+
+func BenchmarkDummyLogger(b *testing.B) {
+	nullf, err := os.OpenFile("/dev/null", os.O_WRONLY, 0666)
+	if err != nil {
+		b.Fatalf("%v", err)
+	}
+	defer nullf.Close()
+	doLoggerBenchmark(b, nullf, &TextFormatter{DisableColors: true}, smallFields)
+}
+
+func BenchmarkDummyLoggerNoLock(b *testing.B) {
+	nullf, err := os.OpenFile("/dev/null", os.O_WRONLY|os.O_APPEND, 0666)
+	if err != nil {
+		b.Fatalf("%v", err)
+	}
+	defer nullf.Close()
+	doLoggerBenchmarkNoLock(b, nullf, &TextFormatter{DisableColors: true}, smallFields)
+}
+
+func doLoggerBenchmark(b *testing.B, out *os.File, formatter Formatter, fields Fields) {
+	logger := Logger{
+		Out:       out,
+		Level:     InfoLevel,
+		Formatter: formatter,
+	}
+	entry := logger.WithFields(fields)
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			entry.Info("aaa")
+		}
+	})
+}
+
+func doLoggerBenchmarkNoLock(b *testing.B, out *os.File, formatter Formatter, fields Fields) {
+	logger := Logger{
+		Out:       out,
+		Level:     InfoLevel,
+		Formatter: formatter,
+	}
+	logger.SetNoLock()
+	entry := logger.WithFields(fields)
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			entry.Info("aaa")
+		}
+	})
+}
diff --git a/terminal_appengine.go b/terminal_appengine.go
new file mode 100644
index 0000000..1960169
--- /dev/null
+++ b/terminal_appengine.go
@@ -0,0 +1,8 @@
+// +build appengine
+
+package logrus
+
+// IsTerminal returns true if stderr's file descriptor is a terminal.
+func IsTerminal() bool {
+	return true
+}
diff --git a/terminal_bsd.go b/terminal_bsd.go
index 71f8d67..5f6be4d 100644
--- a/terminal_bsd.go
+++ b/terminal_bsd.go
@@ -1,4 +1,5 @@
 // +build darwin freebsd openbsd netbsd dragonfly
+// +build !appengine
 
 package logrus
 
diff --git a/terminal_linux.go b/terminal_linux.go
index a2c0b40..308160c 100644
--- a/terminal_linux.go
+++ b/terminal_linux.go
@@ -3,6 +3,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !appengine
+
 package logrus
 
 import "syscall"
diff --git a/terminal_notwindows.go b/terminal_notwindows.go
index b343b3a..329038f 100644
--- a/terminal_notwindows.go
+++ b/terminal_notwindows.go
@@ -4,6 +4,7 @@
 // license that can be found in the LICENSE file.
 
 // +build linux darwin freebsd openbsd netbsd dragonfly
+// +build !appengine
 
 package logrus
 
diff --git a/terminal_solaris.go b/terminal_solaris.go
index 3e70bf7..a3c6f6e 100644
--- a/terminal_solaris.go
+++ b/terminal_solaris.go
@@ -1,4 +1,4 @@
-// +build solaris
+// +build solaris,!appengine
 
 package logrus
 
diff --git a/terminal_windows.go b/terminal_windows.go
index 0146845..3727e8a 100644
--- a/terminal_windows.go
+++ b/terminal_windows.go
@@ -3,7 +3,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build windows
+// +build windows,!appengine
 
 package logrus
 
diff --git a/text_formatter.go b/text_formatter.go
index 6afd0e0..9114b3c 100644
--- a/text_formatter.go
+++ b/text_formatter.go
@@ -57,6 +57,7 @@
 }
 
 func (f *TextFormatter) Format(entry *Entry) ([]byte, error) {
+	var b *bytes.Buffer
 	var keys []string = make([]string, 0, len(entry.Data))
 	for k := range entry.Data {
 		keys = append(keys, k)
@@ -65,8 +66,11 @@
 	if !f.DisableSorting {
 		sort.Strings(keys)
 	}
-
-	b := &bytes.Buffer{}
+	if entry.Buffer != nil {
+		b = entry.Buffer
+	} else {
+		b = &bytes.Buffer{}
+	}
 
 	prefixFieldClashes(entry.Data)
 
@@ -118,7 +122,8 @@
 	}
 	for _, k := range keys {
 		v := entry.Data[k]
-		fmt.Fprintf(b, " \x1b[%dm%s\x1b[0m=%+v", levelColor, k, v)
+		fmt.Fprintf(b, " \x1b[%dm%s\x1b[0m=", levelColor, k)
+		f.appendValue(b, v)
 	}
 }
 
@@ -138,7 +143,11 @@
 
 	b.WriteString(key)
 	b.WriteByte('=')
+	f.appendValue(b, value)
+	b.WriteByte(' ')
+}
 
+func (f *TextFormatter) appendValue(b *bytes.Buffer, value interface{}) {
 	switch value := value.(type) {
 	case string:
 		if !needsQuoting(value) {
@@ -151,11 +160,9 @@
 		if !needsQuoting(errmsg) {
 			b.WriteString(errmsg)
 		} else {
-			fmt.Fprintf(b, "%q", value)
+			fmt.Fprintf(b, "%q", errmsg)
 		}
 	default:
 		fmt.Fprint(b, value)
 	}
-
-	b.WriteByte(' ')
 }