decrease the memory footprint of request/reply procedure

core/channel.go

@@ -171,11 +171,11 @@ func (ch *Channel) nextSeqNum() uint16 {
 }
 
 func (ch *Channel) newRequest(msg api.Message, multi bool) *vppRequest {
-	return &vppRequest{
-		msg:    msg,
-		seqNum: ch.nextSeqNum(),
-		multi:  multi,
-	}
+	request := ch.conn.requestPool.Get().(*vppRequest)
+	request.msg = msg
+	request.seqNum = ch.nextSeqNum()
+	request.multi = multi
+	return request
 }
 
 func (ch *Channel) CheckCompatiblity(msgs ...api.Message) error {

core/connection.go

@@ -135,6 +135,9 @@ type Connection struct {
 	msgControlPing      api.Message
 	msgControlPingReply api.Message
 
+	requestPool sync.Pool
+	replyPool   sync.Pool
+
 	traceLock sync.Mutex
 	trace     *Trace // API tracer (disabled by default)
 }
@@ -170,6 +173,8 @@ func newConnection(binapi adapter.VppAPI, attempts int, interval time.Duration,
 		msgControlPing:      msgControlPing,
 		msgControlPingReply: msgControlPingReply,
 		channelIdPool:       newIDPool(0x7fff),
+		requestPool:         sync.Pool{New: func() interface{} { return &vppRequest{} }},
+		replyPool:           sync.Pool{New: func() interface{} { return &vppReply{} }},
 	}
 	c.channelPool = genericpool.New[*Channel](func() *Channel {
 		if isDebugOn(debugOptChannels) {

core/request_handler.go

@@ -266,14 +266,15 @@ func (c *Connection) msgCallback(msgID uint16, data []byte) {
 	// treat this as a last part of the reply
 	lastReplyReceived := isMulti && msgID == c.pingReplyID
 
+	reply := c.replyPool.Get().(*vppReply)
+	reply.msgID = msgID
+	reply.seqNum = seqNum
+	reply.data = append([]byte(nil), data...)
+	reply.lastReceived = lastReplyReceived
+
 	// send the data to the channel, it needs to be copied,
 	// because it will be freed after this function returns
-	sendReply(ch, &vppReply{
-		msgID:        msgID,
-		seqNum:       seqNum,
-		data:         append([]byte(nil), data...),
-		lastReceived: lastReplyReceived,
-	})
+	sendReply(ch, reply)
 
 	// store actual time of this reply
 	c.lastReplyLock.Lock()

core/stream.go

@@ -194,6 +194,7 @@ func (s *Stream) SendMsg(msg api.Message) error {
 	if err := s.conn.processRequest(s.channel, req); err != nil {
 		return err
 	}
+	s.conn.requestPool.Put(req)
 	s.Lock()
 	s.pkgPath = s.conn.GetMessagePath(msg)
 	s.Unlock()
@@ -216,9 +217,12 @@ func (s *Stream) RecvMsg() (api.Message, error) {
 	// allocate message instance
 	msg = reflect.New(reflect.TypeOf(msg).Elem()).Interface().(api.Message)
 	// decode message data
-	if err := s.channel.msgCodec.DecodeMsg(reply.data, msg); err != nil {
+	if err = s.channel.msgCodec.DecodeMsg(reply.data, msg); err != nil {
 		return nil, err
 	}
+	reply.err = nil
+	s.conn.replyPool.Put(reply)
+
 	return msg, nil
 }