Golang Message.Len方法代码示例

func writeMessage(conn io.Closer, msg message.Message) error {
	buf := make([]byte, msg.Len())
	_, err := msg.Encode(buf)
	if err != nil {
		//glog.Debugf("Write error: %v", err)
		return err
	}
	//glog.Debugf("Writing: %s", msg)

	return writeMessageBuffer(conn, buf)
}

func (this *Ackqueue) insert(pktid uint16, msg message.Message, onComplete interface{}) error {
	if this.full() {
		this.grow()
	}

	if _, ok := this.emap[pktid]; !ok {
		// message length
		ml := msg.Len()

		// ackmsg
		am := ackmsg{
			Mtype:      msg.Type(),
			State:      message.RESERVED,
			Pktid:      msg.PacketId(),
			Msgbuf:     make([]byte, ml),
			OnComplete: onComplete,
		}

		if _, err := msg.Encode(am.Msgbuf); err != nil {
			return err
		}

		this.ring[this.tail] = am
		this.emap[pktid] = this.tail
		this.tail = this.increment(this.tail)
		this.count++
	} else {
		// If packet w/ pktid already exist, then this must be a PUBLISH message
		// Other message types should never send with the same packet ID
		pm, ok := msg.(*message.PublishMessage)
		if !ok {
			return fmt.Errorf("ack/insert: duplicate packet ID for %s message", msg.Name())
		}

		// If this is a publish message, then the DUP flag must be set. This is the
		// only scenario in which we will receive duplicate messages.
		if pm.Dup() {
			return fmt.Errorf("ack/insert: duplicate packet ID for PUBLISH message, but DUP flag is not set")
		}

		// Since it's a dup, there's really nothing we need to do. Moving on...
	}

	return nil
}

// writeMessage() writes a message to the outgoing buffer
func (this *service) writeMessage(msg message.Message) (int, error) {
	var (
		l   int = msg.Len()
		n   int
		err error
		buf []byte
	)

	if this.out == nil {
		return 0, ErrBufferNotReady
	}

	// This is to serialize writes to the underlying buffer. Multiple goroutines could
	// potentially get here because of calling Publish() or Subscribe() or other
	// functions that will send messages. For example, if a message is received in
	// another connetion, and the message needs to be published to this client, then
	// the Publish() function is called, and at the same time, another client could
	// do exactly the same thing.
	//
	// Not an ideal fix though. If possible we should remove mutex and be lockfree.
	// Mainly because when there's a large number of goroutines that want to publish
	// to this client, then they will all block. However, this will do for now.
	//
	// FIXME: Try to find a better way than a mutex...if possible.
	this.wmu.Lock()
	defer this.wmu.Unlock()
	//buf = make([]byte, l)
	buf = this.server.CreateAndGetBytes(int64(l))
	n, err = msg.Encode(buf[0:l])
	if err != nil {
		return 0, err
	}

	//m, err = this.out.WriteCommit(n)
	ok := this.out.WriteBuffer(&buf)
	if !ok {
		return 0, err
	}
	//}

	this.outStat.increment(int64(n))

	return n, nil
}

// Ack() takes the ack message supplied and updates the status of messages waiting.
func (this *Ackqueue) Ack(msg message.Message) error {
	this.mu.Lock()
	defer this.mu.Unlock()

	switch msg.Type() {
	case message.PUBACK, message.PUBREC, message.PUBREL, message.PUBCOMP, message.SUBACK, message.UNSUBACK:
		// Check to see if the message w/ the same packet ID is in the queue
		i, ok := this.emap[msg.PacketId()]
		if ok {
			// If message w/ the packet ID exists, update the message state and copy
			// the ack message
			this.ring[i].State = msg.Type()

			ml := msg.Len()
			this.ring[i].Ackbuf = make([]byte, ml)

			_, err := msg.Encode(this.ring[i].Ackbuf)
			if err != nil {
				return err
			}
			//Log.Debugc(func() string{ return fmt.Sprintf("Acked: %v", msg)})
			//} else {
			//Log.Debugc(func() string{ return fmt.Sprintf("Cannot ack %s message with packet ID %d", msg.Type(), msg.PacketId())})
		}

	case message.PINGRESP:
		if this.ping.Mtype == message.PINGREQ {
			this.ping.State = message.PINGRESP
		}

	default:
		return errAckMessage
	}

	return nil
}