add synchronization for calls to the buffer used for logging

integrationtests/tools/testlog/testlog.go

@@ -15,10 +15,36 @@ import (
 
 const logBufSize = 100 * 1 << 20 // initial size of the log buffer: 100 MB
 
+type syncedBuffer struct {
+	mutex sync.Mutex
+
+	*bytes.Buffer
+}
+
+func (b *syncedBuffer) Write(p []byte) (int, error) {
+	b.mutex.Lock()
+	n, err := b.Buffer.Write(p)
+	b.mutex.Unlock()
+	return n, err
+}
+
+func (b *syncedBuffer) Bytes() []byte {
+	b.mutex.Lock()
+	p := b.Buffer.Bytes()
+	b.mutex.Unlock()
+	return p
+}
+
+func (b *syncedBuffer) Reset() {
+	b.mutex.Lock()
+	b.Buffer.Reset()
+	b.mutex.Unlock()
+}
+
 var (
 	logFileName string // the log file set in the ginkgo flags
 	logBufOnce  sync.Once
-	logBuf      *bytes.Buffer
+	logBuf      *syncedBuffer
 )
 
 // read the logfile command line flag
@@ -32,7 +58,7 @@ var _ = BeforeEach(func() {
 
 	if Debug() {
 		logBufOnce.Do(func() {
-			logBuf = bytes.NewBuffer(make([]byte, 0, logBufSize))
+			logBuf = &syncedBuffer{Buffer: bytes.NewBuffer(make([]byte, 0, logBufSize))}
 		})
 		utils.DefaultLogger.SetLogLevel(utils.LogLevelDebug)
 		log.SetOutput(logBuf)