Golang message.Message类代码示例

// peekMessage() reads a message from the buffer, but the bytes are NOT committed.
// This means the buffer still thinks the bytes are not read yet.
func (this *service) peekMessage(mtype message.MessageType, total int) (message.Message, int, error) {
	var (
		b    []byte
		err  error
		i, n int
		msg  message.Message
	)

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

	// Peek until we get total bytes
	for i = 0; ; i++ {
		// Peek remlen bytes from the input buffer.
		b, err = this.in.ReadWait(total)
		if err != nil && err != ErrBufferInsufficientData {
			return nil, 0, err
		}

		// If not enough bytes are returned, then continue until there's enough.
		if len(b) >= total {
			break
		}
	}

	msg, err = mtype.New()
	if err != nil {
		return nil, 0, err
	}

	n, err = msg.Decode(b)
	return msg, n, err
}

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)
}

// Wait() copies the message into a waiting queue, and waits for the corresponding
// ack message to be received.
func (this *Ackqueue) Wait(msg message.Message, onComplete interface{}) error {
	this.mu.Lock()
	defer this.mu.Unlock()

	switch msg := msg.(type) {
	case *message.PublishMessage:
		if msg.QoS() == message.QosAtMostOnce {
			//return fmt.Errorf("QoS 0 messages don't require ack")
			return errWaitMessage
		}

		this.insert(msg.PacketId(), msg, onComplete)

	case *message.SubscribeMessage:
		this.insert(msg.PacketId(), msg, onComplete)

	case *message.UnsubscribeMessage:
		this.insert(msg.PacketId(), msg, onComplete)

	case *message.PingreqMessage:
		this.ping = ackmsg{
			Mtype:      message.PINGREQ,
			State:      message.RESERVED,
			OnComplete: onComplete,
		}

	default:
		return errWaitMessage
	}

	return nil
}

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
}

// readMessage() reads and copies a message from the buffer. The buffer bytes are
// committed as a result of the read.
func (this *service) readMessage(mtype message.MessageType, total int) (message.Message, int, error) {
	var (
		b   []byte
		err error
		n   int
		msg message.Message
	)

	if this.in == nil {
		err = ErrBufferNotReady
		return nil, 0, err
	}

	if len(this.intmp) < total {
		this.intmp = make([]byte, total)
	}

	// Read until we get total bytes
	l := 0
	for l < total {
		n, err = this.in.Read(this.intmp[l:])
		l += n
		glog.Debugf("read %d bytes, total %d", n, l)
		if err != nil {
			return nil, 0, err
		}
	}

	b = this.intmp[:total]

	msg, err = mtype.New()
	if err != nil {
		return msg, 0, err
	}

	n, err = msg.Decode(b)
	return msg, n, err
}

// 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
			}
			//glog.Debugf("Acked: %v", msg)
			//} else {
			//glog.Debugf("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
}

func (this *service) processIncoming(msg message.Message) error {
	var err error = nil

	switch msg := msg.(type) {
	case *message.PublishMessage:
		// For PUBLISH message, we should figure out what QoS it is and process accordingly
		// If QoS == 0, we should just take the next step, no ack required
		// If QoS == 1, we should send back PUBACK, then take the next step
		// If QoS == 2, we need to put it in the ack queue, send back PUBREC
		err = this.processPublish(msg)

	case *message.PubackMessage:
		// For PUBACK message, it means QoS 1, we should send to ack queue
		this.sess.Pub1ack.Ack(msg)
		this.processAcked(this.sess.Pub1ack)

	case *message.PubrecMessage:
		// For PUBREC message, it means QoS 2, we should send to ack queue, and send back PUBREL
		if err = this.sess.Pub2out.Ack(msg); err != nil {
			break
		}

		resp := message.NewPubrelMessage()
		resp.SetPacketId(msg.PacketId())
		_, err = this.writeMessage(resp)

	case *message.PubrelMessage:
		// For PUBREL message, it means QoS 2, we should send to ack queue, and send back PUBCOMP
		if err = this.sess.Pub2in.Ack(msg); err != nil {
			break
		}

		this.processAcked(this.sess.Pub2in)

		resp := message.NewPubcompMessage()
		resp.SetPacketId(msg.PacketId())
		_, err = this.writeMessage(resp)

	case *message.PubcompMessage:
		// For PUBCOMP message, it means QoS 2, we should send to ack queue
		if err = this.sess.Pub2out.Ack(msg); err != nil {
			break
		}

		this.processAcked(this.sess.Pub2out)

	case *message.SubscribeMessage:
		// For SUBSCRIBE message, we should add subscriber, then send back SUBACK
		return this.processSubscribe(msg)

	case *message.SubackMessage:
		// For SUBACK message, we should send to ack queue
		this.sess.Suback.Ack(msg)
		this.processAcked(this.sess.Suback)

	case *message.UnsubscribeMessage:
		// For UNSUBSCRIBE message, we should remove subscriber, then send back UNSUBACK
		return this.processUnsubscribe(msg)

	case *message.UnsubackMessage:
		// For UNSUBACK message, we should send to ack queue
		this.sess.Unsuback.Ack(msg)
		this.processAcked(this.sess.Unsuback)

	case *message.PingreqMessage:
		// For PINGREQ message, we should send back PINGRESP
		resp := message.NewPingrespMessage()
		_, err = this.writeMessage(resp)

	case *message.PingrespMessage:
		this.sess.Pingack.Ack(msg)
		this.processAcked(this.sess.Pingack)

	case *message.DisconnectMessage:
		// For DISCONNECT message, we should quit
		this.sess.Cmsg.SetWillFlag(false)
		return errDisconnect

	default:
		return fmt.Errorf("(%s) invalid message type %s.", this.cid(), msg.Name())
	}

	if err != nil {
		glog.Debugf("(%s) Error processing acked message: %v", this.cid(), err)
	}

	return err
}

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

	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, wrap, err = this.out.WriteWait(l)
	if err != nil {
		return 0, err
	}

	if wrap {
		if len(this.outtmp) < l {
			this.outtmp = make([]byte, l)
		}

		n, err = msg.Encode(this.outtmp[0:])
		if err != nil {
			return 0, err
		}

		m, err = this.out.Write(this.outtmp[0:n])
		if err != nil {
			return m, err
		}
	} else {
		n, err = msg.Encode(buf[0:])
		if err != nil {
			return 0, err
		}

		m, err = this.out.WriteCommit(n)
		if err != nil {
			return 0, err
		}
	}

	this.outStat.increment(int64(m))

	return m, nil
}