1 files changed, 322 insertions, 0 deletions
diff --git a/src/log/log.go b/src/log/log.go
new file mode 100644
index 000000000..d37e4375e
--- /dev/null
+++ b/src/log/log.go
@@ -0,0 +1,322 @@
+// 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.
+// 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"
+	"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).  A colon appears after these items:
+	//	2009/01/23 01:23:23.123123 /a/b/c/d.go:23: message
+	Ldate         = 1 << iota     // the date: 2009/01/23
+	Ltime                         // the time: 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
+	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}
+}
+
+var std = New(os.Stderr, "", LstdFlags)
+
+// Cheap integer to fixed-width decimal ASCII.  Give a negative width to avoid zero-padding.
+// Knows the buffer has capacity.
+func itoa(buf *[]byte, i int, wid int) {
+	var u uint = uint(i)
+	if u == 0 && wid <= 1 {
+		*buf = append(*buf, '0')
+		return
+	}
+
+	// Assemble decimal in reverse order.
+	var b [32]byte
+	bp := len(b)
+	for ; u > 0 || wid > 0; u /= 10 {
+		bp--
+		wid--
+		b[bp] = byte(u%10) + '0'
+	}
+	*buf = append(*buf, b[bp:]...)
+}
+
+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&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 {
+	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 ...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)
+}