/
glog.go
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/
glog.go
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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package glog implements a simple level logging package based on golang's
// standard log and glog package. It has fully compatible interface to standard
// log package. It defines a type, Logger, with methods for formatting output.
// Basic examples:
//
// options := glog.LogOptions{
// File: "./abc.log",
// Flag: glog.LstdFlags,
// Level: glog.Ldebug,
// Mode: glog.R_None,
// }
// logger, err := glog.New(options)
// if err != nil {
// panic(err)
// }
// logger.Debug("hello world")
// logger.Infof("hello, %s", "chasex")
// logger.Warn("testing message")
// logger.Flush()
//
// The output contents in abc.log will be:
//
// 2016/02/16 17:50:07 DEBUG hello world
// 2016/02/16 17:50:07 INFO hello, chasex
// 2016/02/16 17:50:07 WARN testing message
//
// It also support rotating log file by size, hour or day.
// According to rotate mode, log file name has distinct suffix:
//
// R_None: no suffix, abc.log.
// R_Size: suffix with date and clock, abc.log-YYYYMMDD-HHMMSS.
// R_Hour: suffix with date and hour, abc.log-YYYYMMDD-HH.
// R_Day: suffix with date, abc.log-YYYYMMDD.
//
// Note that it has a daemon routine flushing buffered data to underlying file
// periodically (default every 30s). When exit, remember calling Flush() manually,
// otherwise it may cause some date loss.
package glog
import (
"bufio"
"fmt"
"os"
"runtime"
"sync"
"time"
)
// These flags define which text to prefix to each log entry generated by the Logger.
const (
// Bits or'ed together to control what's printed.
// There is no control over the order they appear (the order listed
// here) or the format they present (as described in the comments).
// The prefix is followed by a colon only when Llongfile or Lshortfile
// is specified.
// For example, flags Ldate | Ltime | Llevel (or LstdFlags) produce,
// 2009/01/23 01:23:23 DEBUG message
// while flags Ldate | Ltime | Lmicroseconds | Llongfile produce,
// 2009/01/23 01:23:23.123123 /a/b/c/d.go:23: message
Ldate = 1 << iota // the date in the local time zone: 2009/01/23
Ltime // the time in the local time zone: 01:23:23
Lmicroseconds // microsecond resolution: 01:23:23.123123. assumes Ltime.
Llongfile // full file name and line number: /a/b/c/d.go:23
Lshortfile // final file name element and line number: d.go:23. overrides Llongfile
LUTC // if Ldate or Ltime is set, use UTC rather than the local time zone
Llevel // log entry level: DEBUG, INFO, ...
LstdFlags = Ldate | Ltime | Llevel // standard prefix
LstdNull = 0 // no prefix
)
// Level defines each log entry's level of verbosity.
type Level int
const (
Ldebug Level = iota
Linfo
Lwarn
Lerror
Lfatal
Lpanic
)
var levelName = []string{
Ldebug: "DEBUG",
Linfo: "INFO",
Lwarn: "WARN",
Lerror: "ERROR",
Lfatal: "FATAL",
Lpanic: "PANIC",
}
// RotateMode defines log file's rotating mode.
type RotateMode int
const (
R_None RotateMode = iota // Never rotate
R_Size // Rotate file by size
R_Hour // Rotate file by hour
R_Day // Rotate file by day
)
// LogOptions control logger's behaviour.
type LogOptions struct {
File string // base name for log file
Flag int // log entry prefix flag
Level Level // threshold level for logging
Mode RotateMode // file rotating mode
Maxsize uint64 // maximum size for R_Size mode
}
// A Logger represents an active logging object that generates lines of
// output to an io.Writer. Each logging operation makes a single call to
// the Writer's Write method. A Logger can be used simultaneously from
// multiple goroutines; it guarantees to serialize access to the Writer.
type Logger struct {
options LogOptions
freeList *buffer
freeListMu sync.Mutex
mu sync.Mutex // ensures atomic writes; protects the following fields
out *bufio.Writer // destination for output
file *os.File
nbytes uint64
hour int
day int
}
type buffer struct {
buf []byte
next *buffer
}
// getBuffer returns a new, ready-to-use buffer.
func (l *Logger) getBuffer() *buffer {
l.freeListMu.Lock()
b := l.freeList
if b != nil {
l.freeList = b.next
}
l.freeListMu.Unlock()
if b == nil {
b = &buffer{buf: make([]byte, 64)}
} else {
b.next = nil
}
return b
}
// putBuffer returns a buffer to the free list.
func (l *Logger) putBuffer(b *buffer) {
if len(b.buf) >= 256 {
// Let big buffers die a natural death.
return
}
l.freeListMu.Lock()
b.next = l.freeList
l.freeList = b
l.freeListMu.Unlock()
}
// New creates a new Logger. The out variable sets the
// destination to which log data will be written.
// The prefix appears at the beginning of each generated log line.
// The flag argument defines the logging properties.
func New(options LogOptions) (*Logger, error) {
logger := &Logger{options: options}
err := logger.createFile(time.Now())
if err != nil {
return logger, err
}
go logger.flushDaemon()
return logger, nil
}
// bufferSize sizes the buffer associated with each log file. It's large
// so that log records can accumulate without the logging thread blocking
// on disk I/O. The flushDaemon will block instead.
const bufferSize = 256 * 1024
// createFile creates log file with specified timestamp.
// l.mu held
func (l *Logger) createFile(t time.Time) error {
year, month, day := t.Date()
hour, min, sec := t.Clock()
var file string
switch l.options.Mode {
case R_Size:
file = fmt.Sprintf("%s-%04d%02d%02d-%02d%02d%02d", l.options.File, year, month, day, hour, min, sec)
case R_Hour:
file = fmt.Sprintf("%s-%04d%02d%02d-%02d", l.options.File, year, month, day, hour)
case R_Day:
file = fmt.Sprintf("%s-%04d%02d%02d", l.options.File, year, month, day)
default: // R_None
file = l.options.File
}
if l.file != nil {
l.out.Flush()
l.file.Close()
}
f, err := os.OpenFile(file, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0664)
if err != nil {
return err
}
l.file = f
l.out = bufio.NewWriterSize(f, bufferSize)
l.nbytes = 0
l.hour = hour
l.day = day
return nil
}
// Cheap integer to fixed-width decimal ASCII. Give a negative width to avoid zero-padding.
func itoa(buf *[]byte, i int, wid int) {
// Assemble decimal in reverse order.
var b [20]byte
bp := len(b) - 1
for i >= 10 || wid > 1 {
wid--
q := i / 10
b[bp] = byte('0' + i - q*10)
bp--
i = q
}
// i < 10
b[bp] = byte('0' + i)
*buf = append(*buf, b[bp:]...)
}
func (l *Logger) formatHeader(buf *[]byte, s Level, calldepth int, t time.Time) {
flag := l.options.Flag
if flag&LUTC != 0 {
t = t.UTC()
}
if flag&(Ldate|Ltime|Lmicroseconds) != 0 {
if flag&Ldate != 0 {
year, month, day := t.Date()
itoa(buf, year, 4)
*buf = append(*buf, '/')
itoa(buf, int(month), 2)
*buf = append(*buf, '/')
itoa(buf, day, 2)
*buf = append(*buf, ' ')
}
if flag&(Ltime|Lmicroseconds) != 0 {
hour, min, sec := t.Clock()
itoa(buf, hour, 2)
*buf = append(*buf, ':')
itoa(buf, min, 2)
*buf = append(*buf, ':')
itoa(buf, sec, 2)
if flag&Lmicroseconds != 0 {
*buf = append(*buf, '.')
itoa(buf, t.Nanosecond()/1e3, 6)
}
*buf = append(*buf, ' ')
}
}
if flag&(Lshortfile|Llongfile) != 0 {
_, file, line, ok := runtime.Caller(calldepth)
if !ok {
file = "???"
line = 0
}
if flag&Lshortfile != 0 {
short := file
for i := len(file) - 1; i > 0; i-- {
if file[i] == '/' {
short = file[i+1:]
break
}
}
file = short
}
*buf = append(*buf, file...)
*buf = append(*buf, ':')
itoa(buf, line, -1)
*buf = append(*buf, ' ')
}
if flag&Llevel != 0 {
*buf = append(*buf, levelName[s]...)
*buf = append(*buf, ' ')
}
}
// Output writes the output for a logging event. The string s contains
// the text to print after the prefix specified by the flags of the
// Logger. A newline is appended if the last character of s is not
// already a newline. Calldepth is used to recover the PC and is
// provided for generality, although at the moment on all pre-defined
// paths it will be 2.
func (l *Logger) Output(level Level, calldepth int, s string) error {
b := l.getBuffer()
defer l.putBuffer(b)
now := time.Now() // get this early.
b.buf = b.buf[:0]
l.formatHeader(&b.buf, level, calldepth, now)
b.buf = append(b.buf, s...)
if len(s) == 0 || s[len(s)-1] != '\n' {
b.buf = append(b.buf, '\n')
}
l.mu.Lock()
rotate := false
switch l.options.Mode {
case R_Size:
if l.nbytes+uint64(len(b.buf)) > l.options.Maxsize {
rotate = true
}
case R_Hour:
if l.hour != now.Hour() || l.day != now.Day() {
rotate = true
}
case R_Day:
if l.day != now.Day() {
rotate = true
}
}
if rotate {
if err := l.createFile(now); err != nil {
fmt.Fprintf(os.Stderr, "log: exiting because of error: %s\n", err)
os.Exit(2)
}
}
_, err := l.out.Write(b.buf)
l.nbytes += uint64(len(b.buf))
if level == Lfatal || level == Lpanic {
l.out.Flush()
l.file.Close()
l.mu.Unlock()
if level == Lpanic {
panic(s)
}
os.Exit(1)
}
l.mu.Unlock()
return err
}
// stacks is a wrapper for runtime.Stack that attempts to recover the data for all goroutines.
func stacks(all bool) []byte {
// We don't know how big the traces are, so grow a few times if they don't fit. Start large, though.
n := 10000
if all {
n = 100000
}
var trace []byte
for i := 0; i < 5; i++ {
trace = make([]byte, n)
nbytes := runtime.Stack(trace, all)
if nbytes < len(trace) {
return trace[:nbytes]
}
n *= 2
}
return trace
}
// Flush flush buffered data to underlying file and sync contents to stable storage.
func (l *Logger) Flush() {
l.mu.Lock()
l.out.Flush()
l.file.Sync()
l.mu.Unlock()
}
const flushInterval = 30 * time.Second
// flushDaemon periodically flushes the log file buffers.
func (l *Logger) flushDaemon() {
for _ = range time.NewTicker(flushInterval).C {
l.Flush()
}
}
// Debugf calls l.Output to print to the logger.
// Arguments are handled in the manner of fmt.Printf.
func (l *Logger) Debugf(format string, v ...interface{}) {
if l.options.Level <= Ldebug {
l.Output(Ldebug, 3, fmt.Sprintf(format, v...))
}
}
// Debug calls l.Output to print to the logger.
// Arguments are handled in the manner of fmt.Print.
func (l *Logger) Debug(v ...interface{}) {
if l.options.Level <= Ldebug {
l.Output(Ldebug, 3, fmt.Sprint(v...))
}
}
// Debugln calls l.Output to print to the logger.
// Arguments are handled in the manner of fmt.Println.
func (l *Logger) Debugln(v ...interface{}) {
if l.options.Level <= Ldebug {
l.Output(Ldebug, 3, fmt.Sprintln(v...))
}
}
// Infof calls l.Output to print to the logger.
// Arguments are handled in the manner of fmt.Printf.
func (l *Logger) Infof(format string, v ...interface{}) {
if l.options.Level <= Linfo {
l.Output(Linfo, 3, fmt.Sprintf(format, v...))
}
}
// Info calls l.Output to print to the logger.
// Arguments are handled in the manner of fmt.Print.
func (l *Logger) Info(v ...interface{}) {
if l.options.Level <= Linfo {
l.Output(Linfo, 3, fmt.Sprint(v...))
}
}
// Infoln calls l.Output to print to the logger.
// Arguments are handled in the manner of fmt.Println.
func (l *Logger) Infoln(v ...interface{}) {
if l.options.Level <= Linfo {
l.Output(Linfo, 3, fmt.Sprintln(v...))
}
}
// Warnf calls l.Output to print to the logger.
// Arguments are handled in the manner of fmt.Printf.
func (l *Logger) Warnf(format string, v ...interface{}) {
if l.options.Level <= Lwarn {
l.Output(Lwarn, 3, fmt.Sprintf(format, v...))
}
}
// Warn calls l.Output to print to the logger.
// Arguments are handled in the manner of fmt.Print.
func (l *Logger) Warn(v ...interface{}) {
if l.options.Level <= Lwarn {
l.Output(Lwarn, 3, fmt.Sprint(v...))
}
}
// Warnln calls l.Output to print to the logger.
// Arguments are handled in the manner of fmt.Println.
func (l *Logger) Warnln(v ...interface{}) {
if l.options.Level <= Lwarn {
l.Output(Lwarn, 3, fmt.Sprintln(v...))
}
}
// Errorf calls l.Output to print to the logger.
// Arguments are handled in the manner of fmt.Printf.
func (l *Logger) Errorf(format string, v ...interface{}) {
if l.options.Level <= Lerror {
l.Output(Lerror, 3, fmt.Sprintf(format, v...))
}
}
// Error calls l.Output to print to the logger.
// Arguments are handled in the manner of fmt.Print.
func (l *Logger) Error(v ...interface{}) {
if l.options.Level <= Lerror {
l.Output(Lerror, 3, fmt.Sprint(v...))
}
}
// Errorln calls l.Output to print to the logger.
// Arguments are handled in the manner of fmt.Println.
func (l *Logger) Errorln(v ...interface{}) {
if l.options.Level <= Lerror {
l.Output(Lerror, 3, fmt.Sprintln(v...))
}
}
// Fatal is equivalent to l.Print() followed by a call to os.Exit(1).
func (l *Logger) Fatal(v ...interface{}) {
l.Output(Lfatal, 2, fmt.Sprint(v...))
}
// Fatalf is equivalent to l.Printf() followed by a call to os.Exit(1).
func (l *Logger) Fatalf(format string, v ...interface{}) {
l.Output(Lfatal, 2, fmt.Sprintf(format, v...))
}
// Fatalln is equivalent to l.Println() followed by a call to os.Exit(1).
func (l *Logger) Fatalln(v ...interface{}) {
l.Output(Lfatal, 2, fmt.Sprintln(v...))
}
// Panic is equivalent to l.Print() followed by a call to panic().
func (l *Logger) Panic(v ...interface{}) {
l.Output(Lpanic, 2, fmt.Sprint(v...))
}
// Panicf is equivalent to l.Printf() followed by a call to panic().
func (l *Logger) Panicf(format string, v ...interface{}) {
l.Output(Lpanic, 2, fmt.Sprintf(format, v...))
}
// Panicln is equivalent to l.Println() followed by a call to panic().
func (l *Logger) Panicln(v ...interface{}) {
l.Output(Lpanic, 2, fmt.Sprintln(v...))
}