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log_file.go
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/
log_file.go
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package main
import (
"os"
"sync"
"time"
)
type LogFile struct {
mu sync.Mutex
name string
file *os.File
}
// NewLogFile creates a new LogFile. The file is optional - it will be created if needed.
func NewLogFile(name string, file *os.File) (*LogFile, error) {
rw := &LogFile{
file: file,
name: name,
}
if file == nil {
if err := rw.Rotate(); err != nil {
return nil, err
}
}
return rw, nil
}
func (l *LogFile) Write(b []byte) (n int, err error) {
l.mu.Lock()
n, err = l.file.Write(b)
l.mu.Unlock()
return
}
// Rotate renames old log file, creates new one, switches log and closes the old file.
func (l *LogFile) Rotate() error {
// rename dest file if it already exists.
if _, err := os.Stat(l.name); err == nil {
name := l.name + "." + time.Now().Format(time.RFC3339)
if err = os.Rename(l.name, name); err != nil {
return err
}
}
// create new file.
file, err := os.Create(l.name)
if err != nil {
return err
}
// switch dest file safely.
l.mu.Lock()
file, l.file = l.file, file
l.mu.Unlock()
// close old file if open.
if file != nil {
if err := file.Close(); err != nil {
return err
}
}
return nil
}