fix application bug

vendor/github.com/lucas-clemente/quic-go/buffer_pool.go

@@ -6,22 +6,70 @@ import (
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 )
 
-var bufferPool sync.Pool
+type packetBuffer struct {
+	Slice []byte
 
-func getPacketBuffer() *[]byte {
-	return bufferPool.Get().(*[]byte)
+	// refCount counts how many packets the Slice is used in.
+	// It doesn't support concurrent use.
+	// It is > 1 when used for coalesced packet.
+	refCount int
 }
 
-func putPacketBuffer(buf *[]byte) {
-	if cap(*buf) != int(protocol.MaxReceivePacketSize) {
+// Split increases the refCount.
+// It must be called when a packet buffer is used for more than one packet,
+// e.g. when splitting coalesced packets.
+func (b *packetBuffer) Split() {
+	b.refCount++
+}
+
+// Decrement decrements the reference counter.
+// It doesn't put the buffer back into the pool.
+func (b *packetBuffer) Decrement() {
+	b.refCount--
+	if b.refCount < 0 {
+		panic("negative packetBuffer refCount")
+	}
+}
+
+// MaybeRelease puts the packet buffer back into the pool,
+// if the reference counter already reached 0.
+func (b *packetBuffer) MaybeRelease() {
+	// only put the packetBuffer back if it's not used any more
+	if b.refCount == 0 {
+		b.putBack()
+	}
+}
+
+// Release puts back the packet buffer into the pool.
+// It should be called when processing is definitely finished.
+func (b *packetBuffer) Release() {
+	b.Decrement()
+	if b.refCount != 0 {
+		panic("packetBuffer refCount not zero")
+	}
+	b.putBack()
+}
+
+func (b *packetBuffer) putBack() {
+	if cap(b.Slice) != int(protocol.MaxReceivePacketSize) {
 		panic("putPacketBuffer called with packet of wrong size!")
 	}
-	bufferPool.Put(buf)
+	bufferPool.Put(b)
+}
+
+var bufferPool sync.Pool
+
+func getPacketBuffer() *packetBuffer {
+	buf := bufferPool.Get().(*packetBuffer)
+	buf.refCount = 1
+	buf.Slice = buf.Slice[:protocol.MaxReceivePacketSize]
+	return buf
 }
 
 func init() {
 	bufferPool.New = func() interface{} {
-		b := make([]byte, 0, protocol.MaxReceivePacketSize)
-		return &b
+		return &packetBuffer{
+			Slice: make([]byte, 0, protocol.MaxReceivePacketSize),
+		}
 	}
 }