From c412566267ae05305c21226d35d05216b1da05bd Mon Sep 17 00:00:00 2001
From: mstmdev <mstmdev@gmail.com>
Date: Fri, 7 Jan 2022 00:42:39 +0800
Subject: [PATCH] Fix the problem of data race for fileLogger

---
 VERSION        |  2 +-
 file_logger.go | 24 ++++++++++++++++++++----
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/VERSION b/VERSION
index 04eddb2..e1d848b 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-v0.0.7
\ No newline at end of file
+v0.0.8
\ No newline at end of file
diff --git a/file_logger.go b/file_logger.go
index 88065d3..823a7fd 100644
--- a/file_logger.go
+++ b/file_logger.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"sync"
 	"time"
 )
 
@@ -20,6 +21,7 @@ type fileLogger struct {
 	close         chan bool // the log is closed, and wait to write all the logs
 	autoFlush     bool
 	flushInterval time.Duration
+	mu            sync.Mutex // avoid data race for writer
 }
 
 type logMsg struct {
@@ -47,6 +49,7 @@ func NewFileLoggerWithAutoFlush(level Level, logDir string, filePrefix string, a
 		filePrefix:    filePrefix,
 		autoFlush:     autoFlush,
 		flushInterval: flushInterval,
+		mu:            sync.Mutex{},
 	}
 	// init baseLogger
 	logger.baseLogger.init(logger, level)
@@ -116,6 +119,8 @@ func (l *fileLogger) start() {
 
 func (l *fileLogger) write() {
 	msg := <-l.in
+	l.mu.Lock()
+	defer l.mu.Unlock()
 	// if received a closed message, flush logs to file, and notify close finished.
 	if msg.closed {
 		if l.initialized && l.writer != nil {
@@ -151,10 +156,13 @@ func (l *fileLogger) startAutoFlush() {
 		for {
 			<-time.After(wait)
 			if l.closed || l.writer == nil {
-				l.innerLog("autoFlush stopped")
+				l.innerLog("auto flush stopped")
 				return
 			}
-			if l.writer.Buffered() > 0 {
+			l.mu.Lock()
+			buffered := l.writer.Buffered()
+			l.mu.Unlock()
+			if buffered > 0 {
 				l.in <- flushLogMsg
 				wait = l.flushInterval
 				nop = 0
@@ -169,13 +177,21 @@ func (l *fileLogger) startAutoFlush() {
 	}()
 }
 
+// Write see io.Writer
 func (l *fileLogger) Write(p []byte) (n int, err error) {
+	// copy data to avoid data race from caller
+	pLen := len(p)
+	if pLen == 0 {
+		return 0, nil
+	}
+	cp := make([]byte, pLen)
+	copy(cp, p)
 	if l.initialized && !l.closed {
 		l.in <- logMsg{
-			log:    p,
+			log:    cp,
 			closed: false,
 		}
-		return len(p), nil
+		return pLen, nil
 	} else {
 		return 0, errors.New("file logger is uninitialized or closed")
 	}