mirror of
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353 lines
10 KiB
Go
353 lines
10 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package log implements a simple logging package. It defines a type, Logger,
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// with methods for formatting output. It also has a predefined 'standard'
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// Logger accessible through helper functions Print[f|ln], Fatal[f|ln], and
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// Panic[f|ln], which are easier to use than creating a Logger manually.
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// That logger writes to standard error and prints the date and time
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// of each logged message.
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// Every log message is output on a separate line: if the message being
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// printed does not end in a newline, the logger will add one.
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// The Fatal functions call os.Exit(1) after writing the log message.
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// The Panic functions call panic after writing the log message.
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package log
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import (
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"fmt"
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"io"
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"os"
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"runtime"
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"sync"
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"time"
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)
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// These flags define which text to prefix to each log entry generated by the Logger.
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// Bits are or'ed together to control what's printed.
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// There is no control over the order they appear (the order listed
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// here) or the format they present (as described in the comments).
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// The prefix is followed by a colon only when Llongfile or Lshortfile
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// is specified.
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// For example, flags Ldate | Ltime (or LstdFlags) produce,
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// 2009/01/23 01:23:23 message
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// while flags Ldate | Ltime | Lmicroseconds | Llongfile produce,
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// 2009/01/23 01:23:23.123123 /a/b/c/d.go:23: message
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const (
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Ldate = 1 << iota // the date in the local time zone: 2009/01/23
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Ltime // the time in the local time zone: 01:23:23
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Lmicroseconds // microsecond resolution: 01:23:23.123123. assumes Ltime.
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Llongfile // full file name and line number: /a/b/c/d.go:23
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Lshortfile // final file name element and line number: d.go:23. overrides Llongfile
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LUTC // if Ldate or Ltime is set, use UTC rather than the local time zone
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LstdFlags = Ldate | Ltime // initial values for the standard logger
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)
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// A Logger represents an active logging object that generates lines of
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// output to an io.Writer. Each logging operation makes a single call to
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// the Writer's Write method. A Logger can be used simultaneously from
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// multiple goroutines; it guarantees to serialize access to the Writer.
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type Logger struct {
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mu sync.Mutex // ensures atomic writes; protects the following fields
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prefix string // prefix to write at beginning of each line
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flag int // properties
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out io.Writer // destination for output
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buf []byte // for accumulating text to write
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}
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// New creates a new Logger. The out variable sets the
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// destination to which log data will be written.
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// The prefix appears at the beginning of each generated log line.
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// The flag argument defines the logging properties.
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func New(out io.Writer, prefix string, flag int) *Logger {
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return &Logger{out: out, prefix: prefix, flag: flag}
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}
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// SetOutput sets the output destination for the logger.
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func (l *Logger) SetOutput(w io.Writer) {
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l.mu.Lock()
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defer l.mu.Unlock()
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l.out = w
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}
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var std = New(os.Stderr, "", LstdFlags)
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// Cheap integer to fixed-width decimal ASCII. Give a negative width to avoid zero-padding.
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func itoa(buf *[]byte, i int, wid int) {
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// Assemble decimal in reverse order.
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var b [20]byte
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bp := len(b) - 1
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for i >= 10 || wid > 1 {
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wid--
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q := i / 10
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b[bp] = byte('0' + i - q*10)
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bp--
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i = q
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}
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// i < 10
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b[bp] = byte('0' + i)
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*buf = append(*buf, b[bp:]...)
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}
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// formatHeader writes log header to buf in following order:
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// * l.prefix (if it's not blank),
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// * date and/or time (if corresponding flags are provided),
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// * file and line number (if corresponding flags are provided).
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func (l *Logger) formatHeader(buf *[]byte, t time.Time, file string, line int) {
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*buf = append(*buf, l.prefix...)
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if l.flag&(Ldate|Ltime|Lmicroseconds) != 0 {
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if l.flag&LUTC != 0 {
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t = t.UTC()
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}
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if l.flag&Ldate != 0 {
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year, month, day := t.Date()
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itoa(buf, year, 4)
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*buf = append(*buf, '/')
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itoa(buf, int(month), 2)
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*buf = append(*buf, '/')
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itoa(buf, day, 2)
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*buf = append(*buf, ' ')
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}
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if l.flag&(Ltime|Lmicroseconds) != 0 {
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hour, min, sec := t.Clock()
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itoa(buf, hour, 2)
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*buf = append(*buf, ':')
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itoa(buf, min, 2)
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*buf = append(*buf, ':')
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itoa(buf, sec, 2)
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if l.flag&Lmicroseconds != 0 {
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*buf = append(*buf, '.')
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itoa(buf, t.Nanosecond()/1e3, 6)
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}
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*buf = append(*buf, ' ')
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}
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}
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if l.flag&(Lshortfile|Llongfile) != 0 {
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if l.flag&Lshortfile != 0 {
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short := file
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for i := len(file) - 1; i > 0; i-- {
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if file[i] == '/' {
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short = file[i+1:]
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break
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}
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}
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file = short
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}
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*buf = append(*buf, file...)
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*buf = append(*buf, ':')
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itoa(buf, line, -1)
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*buf = append(*buf, ": "...)
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}
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}
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// Output writes the output for a logging event. The string s contains
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// the text to print after the prefix specified by the flags of the
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// Logger. A newline is appended if the last character of s is not
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// already a newline. Calldepth is used to recover the PC and is
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// provided for generality, although at the moment on all pre-defined
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// paths it will be 2.
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func (l *Logger) Output(calldepth int, s string) error {
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now := time.Now() // get this early.
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var file string
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var line int
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l.mu.Lock()
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defer l.mu.Unlock()
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if l.flag&(Lshortfile|Llongfile) != 0 {
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// Release lock while getting caller info - it's expensive.
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l.mu.Unlock()
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var ok bool
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_, file, line, ok = runtime.Caller(calldepth)
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if !ok {
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file = "???"
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line = 0
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}
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l.mu.Lock()
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}
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l.buf = l.buf[:0]
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l.formatHeader(&l.buf, now, file, line)
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l.buf = append(l.buf, s...)
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if len(s) == 0 || s[len(s)-1] != '\n' {
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l.buf = append(l.buf, '\n')
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}
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_, err := l.out.Write(l.buf)
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return err
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}
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// Printf calls l.Output to print to the logger.
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// Arguments are handled in the manner of fmt.Printf.
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func (l *Logger) Printf(format string, v ...interface{}) {
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l.Output(2, fmt.Sprintf(format, v...))
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}
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// Print calls l.Output to print to the logger.
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// Arguments are handled in the manner of fmt.Print.
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func (l *Logger) Print(v ...interface{}) { l.Output(2, fmt.Sprint(v...)) }
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// Println calls l.Output to print to the logger.
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// Arguments are handled in the manner of fmt.Println.
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func (l *Logger) Println(v ...interface{}) { l.Output(2, fmt.Sprintln(v...)) }
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// Fatal is equivalent to l.Print() followed by a call to os.Exit(1).
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func (l *Logger) Fatal(v ...interface{}) {
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l.Output(2, fmt.Sprint(v...))
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os.Exit(1)
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}
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// Fatalf is equivalent to l.Printf() followed by a call to os.Exit(1).
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func (l *Logger) Fatalf(format string, v ...interface{}) {
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l.Output(2, fmt.Sprintf(format, v...))
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os.Exit(1)
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}
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// Fatalln is equivalent to l.Println() followed by a call to os.Exit(1).
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func (l *Logger) Fatalln(v ...interface{}) {
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l.Output(2, fmt.Sprintln(v...))
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os.Exit(1)
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}
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// Panic is equivalent to l.Print() followed by a call to panic().
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func (l *Logger) Panic(v ...interface{}) {
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s := fmt.Sprint(v...)
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l.Output(2, s)
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panic(s)
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}
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// Panicf is equivalent to l.Printf() followed by a call to panic().
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func (l *Logger) Panicf(format string, v ...interface{}) {
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s := fmt.Sprintf(format, v...)
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l.Output(2, s)
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panic(s)
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}
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// Panicln is equivalent to l.Println() followed by a call to panic().
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func (l *Logger) Panicln(v ...interface{}) {
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s := fmt.Sprintln(v...)
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l.Output(2, s)
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panic(s)
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}
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// Flags returns the output flags for the logger.
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func (l *Logger) Flags() int {
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l.mu.Lock()
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defer l.mu.Unlock()
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return l.flag
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}
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// SetFlags sets the output flags for the logger.
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func (l *Logger) SetFlags(flag int) {
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l.mu.Lock()
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defer l.mu.Unlock()
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l.flag = flag
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}
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// Prefix returns the output prefix for the logger.
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func (l *Logger) Prefix() string {
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l.mu.Lock()
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defer l.mu.Unlock()
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return l.prefix
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}
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// SetPrefix sets the output prefix for the logger.
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func (l *Logger) SetPrefix(prefix string) {
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l.mu.Lock()
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defer l.mu.Unlock()
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l.prefix = prefix
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}
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// SetOutput sets the output destination for the standard logger.
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func SetOutput(w io.Writer) {
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std.mu.Lock()
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defer std.mu.Unlock()
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std.out = w
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}
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// Flags returns the output flags for the standard logger.
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func Flags() int {
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return std.Flags()
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}
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// SetFlags sets the output flags for the standard logger.
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func SetFlags(flag int) {
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std.SetFlags(flag)
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}
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// Prefix returns the output prefix for the standard logger.
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func Prefix() string {
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return std.Prefix()
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}
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// SetPrefix sets the output prefix for the standard logger.
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func SetPrefix(prefix string) {
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std.SetPrefix(prefix)
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}
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// These functions write to the standard logger.
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// Print calls Output to print to the standard logger.
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// Arguments are handled in the manner of fmt.Print.
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func Print(v ...interface{}) {
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std.Output(2, fmt.Sprint(v...))
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}
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// Printf calls Output to print to the standard logger.
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// Arguments are handled in the manner of fmt.Printf.
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func Printf(format string, v ...interface{}) {
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std.Output(2, fmt.Sprintf(format, v...))
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}
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// Println calls Output to print to the standard logger.
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// Arguments are handled in the manner of fmt.Println.
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func Println(v ...interface{}) {
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std.Output(2, fmt.Sprintln(v...))
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}
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// Fatal is equivalent to Print() followed by a call to os.Exit(1).
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func Fatal(v ...interface{}) {
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std.Output(2, fmt.Sprint(v...))
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os.Exit(1)
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}
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// Fatalf is equivalent to Printf() followed by a call to os.Exit(1).
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func Fatalf(format string, v ...interface{}) {
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std.Output(2, fmt.Sprintf(format, v...))
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os.Exit(1)
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}
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// Fatalln is equivalent to Println() followed by a call to os.Exit(1).
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func Fatalln(v ...interface{}) {
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std.Output(2, fmt.Sprintln(v...))
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os.Exit(1)
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}
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// Panic is equivalent to Print() followed by a call to panic().
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func Panic(v ...interface{}) {
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s := fmt.Sprint(v...)
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std.Output(2, s)
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panic(s)
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}
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// Panicf is equivalent to Printf() followed by a call to panic().
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func Panicf(format string, v ...interface{}) {
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s := fmt.Sprintf(format, v...)
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std.Output(2, s)
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panic(s)
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}
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// Panicln is equivalent to Println() followed by a call to panic().
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func Panicln(v ...interface{}) {
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s := fmt.Sprintln(v...)
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std.Output(2, s)
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panic(s)
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}
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// Output writes the output for a logging event. The string s contains
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// the text to print after the prefix specified by the flags of the
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// Logger. A newline is appended if the last character of s is not
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// already a newline. Calldepth is the count of the number of
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// frames to skip when computing the file name and line number
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// if Llongfile or Lshortfile is set; a value of 1 will print the details
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// for the caller of Output.
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func Output(calldepth int, s string) error {
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return std.Output(calldepth+1, s) // +1 for this frame.
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}
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