commit 00fcb4936669a40036c4d2d3985c6d45e1a926ea
Author: Guoqiang Chen <subchen@gmail.com>
Date:   Tue Aug 23 08:31:40 2016 +0000

    Default Log implementions

diff --git a/log.go b/log.go
new file mode 100644
index 0000000..8219fb1
--- /dev/null
+++ b/log.go
@@ -0,0 +1,94 @@
+package log
+
+import (
+	"io"
+	"os"
+)
+
+// std is a default logger for console
+var std = New(os.Stdout).EnableColorizedLevel(true).SkipCaller(3)
+
+// Get log level
+func GetLevel() int {
+	return std.GetLevel()
+}
+
+// Set log level
+func SetLevel(level int) {
+	std.SetLevel(level)
+}
+
+// Set a name to indicate a process
+func SetName(name string) {
+	std.SetName(name)
+}
+
+// Set time layout for log line
+func SetTimeLayout(layout string) {
+	std.SetTimeLayout(layout)
+}
+
+// EnableGoroutineId output goroutinue id
+func EnableGoroutineId(enable bool) {
+	std.EnableGoroutineId(enable)
+}
+
+// EnableLongFileFormat output long file name
+func EnableLongFileFormat(enable bool) {
+	std.EnableLongFileFormat(enable)
+}
+
+// EnableColorizedLevel output colorized level
+func EnableColorizedLevel(enable bool) {
+	std.EnableColorizedLevel(enable)
+}
+
+// Set a writer
+func SetWriter(w io.Writer) {
+	std.SetWriter(w)
+}
+
+// Indicate whether output debug message
+func IsDebugEnabled() bool {
+	return std.IsDebugEnabled()
+}
+
+// Indicate whether output info message
+func IsInfoEnabled() bool {
+	return std.IsInfoEnabled()
+}
+
+// Indicate whether output warning message
+func IsWarnEnabled() bool {
+	return std.IsWarnEnabled()
+}
+
+// Indicate whether output error message
+func IsErrorEnabled() bool {
+	return std.IsErrorEnabled()
+}
+
+// Output an debug message
+func Debug(msg string, args ...interface{}) {
+	std.Debug(msg, args...)
+}
+
+// Output an info message
+func Info(msg string, args ...interface{}) {
+	std.Info(msg, args...)
+}
+
+// Output a warning message
+func Warn(msg string, args ...interface{}) {
+	std.Warn(msg, args...)
+}
+
+// Output an error message
+func Error(msg string, args ...interface{}) {
+	std.Error(msg, args)
+}
+
+// Output a fatal message with full stack
+func Fatal(msg string, args ...interface{}) {
+	std.Fatal(msg, args)
+}
diff --git a/logger.go b/logger.go
new file mode 100644
index 0000000..7749541
--- /dev/null
+++ b/logger.go
@@ -0,0 +1,215 @@
+package log
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+	"runtime"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/subchen/gstack/gls"
+)
+
+// Log Level
+const (
+	DEBUG = iota
+	INFO
+	WARN
+	ERROR
+	FATAL
+)
+
+var (
+	levelStr = []string{
+		"DEBUG",
+		"INFO",
+		"WARN",
+		"ERROR",
+		"FATAL",
+	}
+	levelStrWithColor = []string{
+		"\033[34mDEBUG\033[0m",
+		"\033[32mINFO\033[0m",
+		"\033[33mWARN\033[0m",
+		"\033[31mERROR\033[0m",
+		"\033[35mFATAL\033[0m",
+	}
+)
+
+func New(out io.Writer) *Logger {
+	return &Logger{
+		out:            out,
+		level:          INFO,
+		pid:            os.Getpid(),
+		name:           "",
+		timeLayout:     "2006-01-02 15:04:05.000",
+		goroutineId:    false,
+		longFileFormat: false,
+		colorizedLevel: false,
+		callerSkip:     2,
+	}
+}
+
+type Logger struct {
+	mu             sync.Mutex
+	out            io.Writer
+	level          int
+	pid            int
+	name           string
+	timeLayout     string
+	goroutineId    bool
+	longFileFormat bool
+	colorizedLevel bool
+	callerSkip     int
+}
+
+func (l *Logger) GetLevel() int {
+	return l.level
+}
+
+func (l *Logger) SetLevel(level int) *Logger {
+	l.level = level
+	return l
+}
+
+func (l *Logger) SetName(name string) *Logger {
+	l.name = name
+	return l
+}
+
+func (l *Logger) SetTimeLayout(layout string) *Logger {
+	l.timeLayout = layout
+	return l
+}
+
+func (l *Logger) EnableGoroutineId(enable bool) *Logger {
+	l.goroutineId = enable
+	return l
+}
+
+func (l *Logger) EnableLongFileFormat(enable bool) *Logger {
+	l.longFileFormat = enable
+	return l
+}
+
+func (l *Logger) EnableColorizedLevel(enable bool) *Logger {
+	l.colorizedLevel = enable
+	return l
+}
+
+func (l *Logger) SkipCaller(skip int) *Logger {
+	l.callerSkip = skip
+	return l
+}
+
+func (l *Logger) SetWriter(w io.Writer) *Logger {
+	l.out = w
+	return l
+}
+
+func (l *Logger) IsDebugEnabled() bool {
+	return l.level <= DEBUG
+}
+
+func (l *Logger) IsInfoEnabled() bool {
+	return l.level <= INFO
+}
+
+func (l *Logger) IsWarnEnabled() bool {
+	return l.level <= WARN
+}
+
+func (l *Logger) IsErrorEnabled() bool {
+	return l.level <= ERROR
+}
+
+func (l *Logger) Debug(msg string, args ...interface{}) {
+	if l.level <= DEBUG {
+		l.log(DEBUG, msg, args...)
+	}
+}
+
+func (l *Logger) Info(msg string, args ...interface{}) {
+	if l.level <= INFO {
+		l.log(INFO, msg, args...)
+	}
+}
+
+func (l *Logger) Warn(msg string, args ...interface{}) {
+	if l.level <= WARN {
+		l.log(WARN, msg, args...)
+	}
+}
+
+func (l *Logger) Error(msg string, args ...interface{}) {
+	if l.level <= ERROR {
+		l.log(ERROR, msg, args...)
+	}
+}
+
+func (l *Logger) Fatal(msg string, args ...interface{}) {
+	l.log(FATAL, msg, args...)
+}
+
+func (l *Logger) log(level int, msg string, args ...interface{}) {
+	_, file, line, ok := runtime.Caller(l.callerSkip)
+	if !ok {
+		file = "???"
+		line = 0
+	} else if !l.longFileFormat {
+		if index := strings.LastIndex(file, "/"); index >= 0 {
+			file = file[index+1:]
+		} else if index = strings.LastIndex(file, "\\"); index >= 0 {
+			file = file[index+1:]
+		}
+	}
+
+	// output format: DATE PID [NAME] [GID] LEVEL file:line message
+	// 2001-10-10 12:00:00,000+0800 1234 app 987 INFO main.go:1234 log message ...
+	buf := new(bytes.Buffer)
+	buf.WriteByte(' ')
+	buf.WriteString(strconv.Itoa(l.pid))
+	buf.WriteByte(' ')
+	if l.name != "" {
+		buf.WriteString(l.name)
+		buf.WriteByte(' ')
+	}
+	if l.goroutineId || l.level == DEBUG {
+		buf.WriteString(strconv.FormatUint(gls.GoroutineID(), 10))
+		buf.WriteByte(' ')
+	}
+	if l.colorizedLevel {
+		buf.WriteString(levelStrWithColor[level])
+	} else {
+		buf.WriteString(levelStr[level])
+	}
+	buf.WriteByte(' ')
+	buf.WriteString(file)
+	buf.WriteByte(':')
+	buf.WriteString(strconv.Itoa(line))
+	buf.WriteByte(' ')
+	fmt.Fprintf(buf, msg, args...)
+	buf.WriteByte('\n')
+
+	if level == FATAL {
+		for i := l.callerSkip; ; i++ {
+			pc, file, line, ok := runtime.Caller(i)
+			if !ok {
+				break
+			}
+			fmt.Fprintf(buf, "\tat %s:%d (0x%x)\n", file, line, pc)
+		}
+	}
+
+	l.mu.Lock()
+	defer l.mu.Unlock()
+
+	timeStr := time.Now().Format(l.timeLayout)
+
+	l.out.Write([]byte(timeStr))
+	l.out.Write(buf.Bytes())
+}
diff --git a/logger_test.go b/logger_test.go
new file mode 100644
index 0000000..c12f455
--- /dev/null
+++ b/logger_test.go
@@ -0,0 +1,34 @@
+package log
+
+import (
+	"os"
+	"testing"
+	"time"
+)
+
+func TestLogger(t *testing.T) {
+	stdout := New(os.Stdout)
+	stdout.SetTimeLayout("15:04:05.999")
+	stdout.SetName("main")
+	stdout.SetLevel(DEBUG)
+	stdout.EnableColorizedLevel(true)
+	stdout.EnableGoroutineId(true)
+	for i := 0; i < 3; i++ {
+		go func(i int) {
+			stdout.Debug("i = %d", i)
+			stdout.Info("i = %d", i)
+		}(i)
+	}
+	for i := 0; i < 3; i++ {
+		go func(i int) {
+			stdout.Debug("i = %d", i)
+			stdout.Info("i = %d", i)
+		}(i)
+	}
+
+	stdout.Warn("warning")
+	stdout.Error("error")
+	stdout.Fatal("fatal")
+
+	time.Sleep(1 * time.Second)
+}