use and swap two buffer (#8)

* log new buffer

* use rotate buffers

lib/agent/logholder.go

@@ -7,35 +7,39 @@ import (
 
 var (
 	BufferSize = 1024 * 1024
-	BufferPool = sync.Pool{New: func() interface{} {
-		return bytes.NewBuffer(make([]byte, 0, BufferSize))
-	}}
 )
 
+const bufferCount = 2
+
 type LogHolder struct {
-	buffer *bytes.Buffer
-	lock   sync.Mutex
+	useIdx  int
+	buffers [bufferCount]*bytes.Buffer
+	lock    sync.RWMutex
 }
 
 func NewLogHolder() *LogHolder {
 	return &LogHolder{
-		buffer: BufferPool.Get().(*bytes.Buffer),
+		buffers: [bufferCount]*bytes.Buffer{
+			bytes.NewBuffer(make([]byte, 0, BufferSize)),
+			bytes.NewBuffer(make([]byte, 0, BufferSize)),
+		},
 	}
 }
 
 func (b *LogHolder) Write(d []byte) {
-	b.lock.Lock()
-	defer b.lock.Unlock()
-	b.buffer.Write(d)
+	b.lock.RLock()
+	defer b.lock.RUnlock()
+	b.buffers[b.useIdx].Write(d)
 }
 
-func (b *LogHolder) GetAndClear() (*bytes.Buffer, bool) {
+func (b *LogHolder) GetAndSwapBuffer() (*bytes.Buffer, bool) {
 	b.lock.Lock()
 	defer b.lock.Unlock()
-	if b.buffer.Len() == 0 {
+	current := b.buffers[b.useIdx]
+	if current.Len() == 0 {
 		return nil, false
 	}
-	resp := b.buffer
-	b.buffer = BufferPool.Get().(*bytes.Buffer)
-	return resp, true
+	b.useIdx = (b.useIdx + 1) % bufferCount
+	b.buffers[b.useIdx].Reset()
+	return current, true
 }

lib/client/async_client.go

@@ -8,9 +8,8 @@ import (
 	"time"
 
 	"github.com/KyberNetwork/cclog/lib/agent"
-	"github.com/pierrec/lz4/v3"
-
 	"github.com/KyberNetwork/cclog/lib/common"
+	"github.com/pierrec/lz4/v3"
 )
 
 type SendFailedFn = func(error)
@@ -122,10 +121,8 @@ func (l *AsyncLogClient) loop() {
 	for {
 		select {
 		case <-tick.C:
-			if buffer, ok := l.logHolder.GetAndClear(); ok {
+			if buffer, ok := l.logHolder.GetAndSwapBuffer(); ok {
 				write(buffer.Bytes())
-				buffer.Reset()
-				agent.BufferPool.Put(buffer)
 			}
 		case <-l.closeChan:
 			break