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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 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 golog
import (
"fmt"
"io"
"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 (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
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
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 to write at beginning of each line
// flag int // properties
// out io.Writer // destination for output
// buf []byte // for accumulating text to write
//}
//// 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(out io.Writer, prefix string, flag int) *Logger {
// return &Logger{out: out, prefix: prefix, flag: flag}
//}
//// 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
//}
var std = New(os.Stderr, "", LstdFlags)
// 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),
// * date and/or time (if corresponding flags are provided),
// * file and line number (if corresponding flags are provided).
func (l *Logger) formatHeader(buf *[]byte, t time.Time, file string, line int) {
*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, ": "...)
}
}
//// 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 {
// // Get time early if we need it.
// var now time.Time
// if l.flag&(Ldate|Ltime|Lmicroseconds) != 0 {
// now = time.Now()
// }
// 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 ...interface{}) {
// 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 ...interface{}) { 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 ...interface{}) { 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 ...interface{}) {
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 ...interface{}) {
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 ...interface{}) {
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 ...interface{}) {
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 ...interface{}) {
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 ...interface{}) {
s := fmt.Sprintln(v...)
l.Output(2, s)
panic(s)
}
// Flags returns the output flags for the logger.
func (l *Logger) Flags() int {
l.mu.Lock()
defer l.mu.Unlock()
return l.flag
}
// SetFlags sets the output flags for the logger.
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
}
// SetOutput sets the output destination for the standard logger.
func SetOutput(w io.Writer) {
std.mu.Lock()
defer std.mu.Unlock()
std.out = w
}
// Flags returns the output flags for the standard logger.
func Flags() int {
return std.Flags()
}
// SetFlags sets the output flags for the standard logger.
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)
}
// 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 ...interface{}) {
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 ...interface{}) {
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 ...interface{}) {
std.Output(2, fmt.Sprintln(v...))
}
// Fatal is equivalent to Print() followed by a call to os.Exit(1).
func Fatal(v ...interface{}) {
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 ...interface{}) {
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 ...interface{}) {
std.Output(2, fmt.Sprintln(v...))
os.Exit(1)
}
// Panic is equivalent to Print() followed by a call to panic().
func Panic(v ...interface{}) {
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 ...interface{}) {
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 ...interface{}) {
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.
}