golang log 代码
文件路径：/src/log/log.go
/ 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 log implements a simple logging package. It defines a type, Logger,
/ with methods for formatting output. It also has a predefined 'standard'
/ Logger accessible through helper functions Print[f|ln], Fatal[f|ln], and
/ Panic[f|ln], which are easier to use than creating a Logger manually.
/ That logger writes to standard error and prints the date and time
/ of each logged message.
/ Every log message is output on a separate line: if the message being
/ printed does not end in a newline, the logger will add one.
/ The Fatal functions call os.Exit(1) after writing the log message.
/ The Panic functions call panic after writing the log message.
package log
import (
"fmt"
"io"
"os"
"runtime"
"sync"
"sync/atomic"
"time"
)
/ These flags define which text to prefix to each log entry generated by the Logger.
/ Bits are or'ed together to control what's printed.
/ With the exception of the Lmsgprefix flag, 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 (or LstdFlags) produce,
/
/ 2009/01/23 01:23:23 message
/
/ while flags Ldate | Ltime | Lmicroseconds | Llongfile produce,
/
/ 2009/01/23 01:23:23.123123 /a/b/c/d.go:23: message
const (
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
Lmsgprefix / move the "prefix" from the beginning of the line to before the message
LstdFlags = Ldate | Ltime / initial values for the standard logger
)
/ 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 {
mu sync.Mutex / ensures atomic writes; protects the following fields
prefix string / prefix on each line to identify the logger (but see Lmsgprefix)
flag int / properties
out io.Writer / destination for output
buf []byte / for accumulating text to write
isDiscard int32 / atomic boolean: whether out == io.Discard
}
/ 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, or
/ after the log header if the Lmsgprefix flag is provided.
/ The flag argument defines the logging properties.
func New(out io.Writer, prefix string, flag int) *Logger {
l := &Logger{out: out, prefix: prefix, flag: flag}
if out == io.Discard {
l.isDiscard = 1
}
return l
}
/ SetOutput sets the output destination for the logger.
func (l *Logger) SetOutput(w io.Writer) {
l.mu.Lock()
defer l.mu.Unlock()
l.out = w
isDiscard := int32(0)
if w == io.Discard {
isDiscard = 1
}
atomic.StoreInt32(&l.isDiscard, isDiscard)
}
var std = New(os.Stderr, "", LstdFlags)
/ Default returns the standard logger used by the package-level output functions.
func Default() *Logger { return std }
/ 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:]...)
}
/ formatHeader writes log header to buf in following order:
/ - l.prefix (if it's not blank and Lmsgprefix is unset),
/ - date and/or time (if corresponding flags are provided),
/ - file and line number (if corresponding flags are provided),
/ - l.prefix (if it's not blank and Lmsgprefix is set).
func (l *Logger) formatHeader(buf *[]byte, t time.Time, file string, line int) {
if l.flag&Lmsgprefix == 0 {
*buf = append(*buf, l.prefix...)
}
if l.flag&(Ldate|Ltime|Lmicroseconds) != 0 {
if l.flag&LUTC != 0 {
t = t.UTC()
}
if l.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 l.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 l.flag&Lmicroseconds != 0 {
*buf = append(*buf, '.')
itoa(buf, t.Nanosecond()/1e3, 6)
}
*buf = append(*buf, ' ')
}
}
if l.flag&(Lshortfile|Llongfile) != 0 {
if l.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 l.flag&Lmsgprefix != 0 {
*buf = append(*buf, l.prefix...)
}
}
/ 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(calldepth int, s string) error {
now := time.Now() / get this early.
var file string
var line int
l.mu.Lock()
defer l.mu.Unlock()
if l.flag&(Lshortfile|Llongfile) != 0 {
/ Release lock while getting caller info - it's expensive.
l.mu.Unlock()
var ok bool
_, file, line, ok = runtime.Caller(calldepth)
if !ok {
file = "???"
line = 0
}
l.mu.Lock()
}
l.buf = l.buf[:0]
l.formatHeader(&l.buf, now, file, line)
l.buf = append(l.buf, s...)
if len(s) == 0 || s[len(s)-1] != '\n' {
l.buf = append(l.buf, '\n')
}
_, err := l.out.Write(l.buf)
return err
}
/ Printf calls l.Output to print to the logger.
/ Arguments are handled in the manner of fmt.Printf.
func (l *Logger) Printf(format string, v ...any) {
if atomic.LoadInt32(&l.isDiscard) != 0 {
return
}
l.Output(2, fmt.Sprintf(format, v...))
}
/ Print calls l.Output to print to the logger.
/ Arguments are handled in the manner of fmt.Print.
func (l *Logger) Print(v ...any) {
if atomic.LoadInt32(&l.isDiscard) != 0 {
return
}
l.Output(2, fmt.Sprint(v...))
}
/ Println calls l.Output to print to the logger.
/ Arguments are handled in the manner of fmt.Println.
func (l *Logger) Println(v ...any) {
if atomic.LoadInt32(&l.isDiscard) != 0 {
return
}
l.Output(2, fmt.Sprintln(v...))
}
/ Fatal is equivalent to l.Print() followed by a call to os.Exit(1).
func (l *Logger) Fatal(v ...any) {
l.Output(2, fmt.Sprint(v...))
os.Exit(1)
}
/ Fatalf is equivalent to l.Printf() followed by a call to os.Exit(1).
func (l *Logger) Fatalf(format string, v ...any) {
l.Output(2, fmt.Sprintf(format, v...))
os.Exit(1)
}
/ Fatalln is equivalent to l.Println() followed by a call to os.Exit(1).
func (l *Logger) Fatalln(v ...any) {
l.Output(2, fmt.Sprintln(v...))
os.Exit(1)
}
/ Panic is equivalent to l.Print() followed by a call to panic().
func (l *Logger) Panic(v ...any) {
s := fmt.Sprint(v...)
l.Output(2, s)
panic(s)
}
/ Panicf is equivalent to l.Printf() followed by a call to panic().
func (l *Logger) Panicf(format string, v ...any) {
s := fmt.Sprintf(format, v...)
l.Output(2, s)
panic(s)
}
/ Panicln is equivalent to l.Println() followed by a call to panic().
func (l *Logger) Panicln(v ...any) {
s := fmt.Sprintln(v...)
l.Output(2, s)
panic(s)
}
/ Flags returns the output flags for the logger.
/ The flag bits are Ldate, Ltime, and so on.
func (l *Logger) Flags() int {
l.mu.Lock()
defer l.mu.Unlock()
return l.flag
}
/ SetFlags sets the output flags for the logger.
/ The flag bits are Ldate, Ltime, and so on.
func (l *Logger) SetFlags(flag int) {
l.mu.Lock()
defer l.mu.Unlock()
l.flag = flag
}
/ Prefix returns the output prefix for the logger.
func (l *Logger) Prefix() string {
l.mu.Lock()
defer l.mu.Unlock()
return l.prefix
}
/ SetPrefix sets the output prefix for the logger.
func (l *Logger) SetPrefix(prefix string) {
l.mu.Lock()
defer l.mu.Unlock()
l.prefix = prefix
}
/ Writer returns the output destination for the logger.
func (l *Logger) Writer() io.Writer {
l.mu.Lock()
defer l.mu.Unlock()
return l.out
}
/ SetOutput sets the output destination for the standard logger.
func SetOutput(w io.Writer) {
std.SetOutput(w)
}
/ Flags returns the output flags for the standard logger.
/ The flag bits are Ldate, Ltime, and so on.
func Flags() int {
return std.Flags()
}
/ SetFlags sets the output flags for the standard logger.
/ The flag bits are Ldate, Ltime, and so on.
func SetFlags(flag int) {
std.SetFlags(flag)
}
/ Prefix returns the output prefix for the standard logger.
func Prefix() string {
return std.Prefix()
}
/ SetPrefix sets the output prefix for the standard logger.
func SetPrefix(prefix string) {
std.SetPrefix(prefix)
}
/ Writer returns the output destination for the standard logger.
func Writer() io.Writer {
return std.Writer()
}
/ These functions write to the standard logger.
/ Print calls Output to print to the standard logger.
/ Arguments are handled in the manner of fmt.Print.
func Print(v ...any) {
if atomic.LoadInt32(&std.isDiscard) != 0 {
return
}
std.Output(2, fmt.Sprint(v...))
}
/ Printf calls Output to print to the standard logger.
/ Arguments are handled in the manner of fmt.Printf.
func Printf(format string, v ...any) {
if atomic.LoadInt32(&std.isDiscard) != 0 {
return
}
std.Output(2, fmt.Sprintf(format, v...))
}
/ Println calls Output to print to the standard logger.
/ Arguments are handled in the manner of fmt.Println.
func Println(v ...any) {
if atomic.LoadInt32(&std.isDiscard) != 0 {
return
}
std.Output(2, fmt.Sprintln(v...))
}
/ Fatal is equivalent to Print() followed by a call to os.Exit(1).
func Fatal(v ...any) {
std.Output(2, fmt.Sprint(v...))
os.Exit(1)
}
/ Fatalf is equivalent to Printf() followed by a call to os.Exit(1).
func Fatalf(format string, v ...any) {
std.Output(2, fmt.Sprintf(format, v...))
os.Exit(1)
}
/ Fatalln is equivalent to Println() followed by a call to os.Exit(1).
func Fatalln(v ...any) {
std.Output(2, fmt.Sprintln(v...))
os.Exit(1)
}
/ Panic is equivalent to Print() followed by a call to panic().
func Panic(v ...any) {
s := fmt.Sprint(v...)
std.Output(2, s)
panic(s)
}
/ Panicf is equivalent to Printf() followed by a call to panic().
func Panicf(format string, v ...any) {
s := fmt.Sprintf(format, v...)
std.Output(2, s)
panic(s)
}
/ Panicln is equivalent to Println() followed by a call to panic().
func Panicln(v ...any) {
s := fmt.Sprintln(v...)
std.Output(2, s)
panic(s)
}
/ 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 the count of the number of
/ frames to skip when computing the file name and line number
/ if Llongfile or Lshortfile is set; a value of 1 will print the details
/ for the caller of Output.
func Output(calldepth int, s string) error {
return std.Output(calldepth+1, s) / +1 for this frame.
}