fix logrotate close fd before rename file, add a MuxWriter for Logger

log.go

@@ -14,6 +14,7 @@ import (
 
 type FileLogWriter struct {
 	*log.Logger
+	mw *MuxWriter
 	// The opened file
 	filename string
 
@@ -34,6 +35,24 @@ type FileLogWriter struct {
 	startLock sync.Mutex //only one log can writer to the file
 }
 
+type MuxWriter struct {
+	sync.Mutex
+	fd *os.File
+}
+
+func (l *MuxWriter) Write(b []byte) (int, error) {
+	l.Lock()
+	defer l.Unlock()
+	return l.fd.Write(b)
+}
+
+func (l *MuxWriter) SetFd(fd *os.File) {
+	if l.fd != nil {
+		l.fd.Close()
+	}
+	l.fd = fd
+}
+
 func NewFileWriter(fname string, rotate bool) *FileLogWriter {
 	w := &FileLogWriter{
 		filename: fname,
@@ -43,6 +62,10 @@ func NewFileWriter(fname string, rotate bool) *FileLogWriter {
 		maxdays:  7,
 		rotate:   rotate,
 	}
+	// use MuxWriter instead direct use os.File for lock write when rotate
+	w.mw = new(MuxWriter)
+	// set MuxWriter as Logger's io.Writer
+	w.Logger = log.New(w.mw, "", log.Ldate|log.Ltime)
 	return w
 }
 
@@ -71,9 +94,16 @@ func (w *FileLogWriter) SetRotateMaxDays(maxdays int64) *FileLogWriter {
 }
 
 func (w *FileLogWriter) StartLogger() error {
-	if err := w.DoRotate(false); err != nil {
+	fd, err := w.createLogFile()
+	if err != nil {
 		return err
 	}
+	w.mw.SetFd(fd)
+	err = w.initFd()
+	if err != nil {
+		return err
+	}
+	BeeLogger = w
 	return nil
 }
 
@@ -83,7 +113,7 @@ func (w *FileLogWriter) docheck(size int) {
 	if (w.maxlines > 0 && w.maxlines_curlines >= w.maxlines) ||
 		(w.maxsize > 0 && w.maxsize_cursize >= w.maxsize) ||
 		(w.daily && time.Now().Day() != w.daily_opendate) {
-		if err := w.DoRotate(true); err != nil {
+		if err := w.DoRotate(); err != nil {
 			fmt.Fprintf(os.Stderr, "FileLogWriter(%q): %s\n", w.filename, err)
 			return
 		}
@@ -101,8 +131,33 @@ func (w *FileLogWriter) Printf(format string, v ...interface{}) {
 	w.Logger.Printf(format, v...)
 }
 
-func (w *FileLogWriter) DoRotate(rotate bool) error {
-	if rotate {
+func (w *FileLogWriter) createLogFile() (*os.File, error) {
+	// Open the log file
+	fd, err := os.OpenFile(w.filename, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0660)
+	return fd, err
+}
+
+func (w *FileLogWriter) initFd() error {
+	fd := w.mw.fd
+	finfo, err := fd.Stat()
+	if err != nil {
+		return fmt.Errorf("get stat err: %s\n", err)
+	}
+	w.maxsize_cursize = int(finfo.Size())
+	w.daily_opendate = time.Now().Day()
+	if finfo.Size() > 0 {
+		content, err := ioutil.ReadFile(w.filename)
+		if err != nil {
+			fmt.Println(err)
+		}
+		w.maxlines_curlines = len(strings.Split(string(content), "\n"))
+	} else {
+		w.maxlines_curlines = 0
+	}
+	return nil
+}
+
+func (w *FileLogWriter) DoRotate() error {
 	_, err := os.Lstat(w.filename)
 	if err == nil { // file exists
 		// Find the next available number
@@ -117,38 +172,29 @@ func (w *FileLogWriter) DoRotate(rotate bool) error {
 			return fmt.Errorf("Rotate: Cannot find free log number to rename %s\n", w.filename)
 		}
 
+		// block Logger's io.Writer
+		w.mw.Lock()
+		defer w.mw.Unlock()
+
+		fd := w.mw.fd
+		fd.Close()
+
+		// close fd before rename
 		// Rename the file to its newfound home
 		err = os.Rename(w.filename, fname)
 		if err != nil {
 			return fmt.Errorf("Rotate: %s\n", err)
 		}
+
+		// re-start logger
+		err = w.StartLogger()
+		if err != nil {
+			return fmt.Errorf("Rotate StartLogger: %s\n", err)
+		}
+
 		go w.deleteOldLog()
 	}
-	}
 
-	// Open the log file
-	fd, err := os.OpenFile(w.filename, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0660)
-	if err != nil {
-		return err
-	}
-	w.Logger = log.New(fd, "", log.Ldate|log.Ltime)
-	finfo, err := fd.Stat()
-	if err != nil {
-		return fmt.Errorf("get stat err: %s\n", err)
-	}
-	w.maxsize_cursize = int(finfo.Size())
-	w.daily_opendate = time.Now().Day()
-	if finfo.Size() > 0 {
-		content, err := ioutil.ReadFile(w.filename)
-		if err != nil {
-			fmt.Println(err)
-		}
-		w.maxlines_curlines = len(strings.Split(string(content), "\n"))
-
-	} else {
-		w.maxlines_curlines = 0
-	}
-	BeeLogger = w
 	return nil
 }