activeMq发送消息流程

1,发送消息入口

  Message message = messageBean.getMessageCreator().createMessage(session);  producer.send(message);

2,调用ActiveMQMessageProducerSupport的send方法。该类实现了MessageProducer接口

 public void send(Message message) throws JMSException {        this.send(this.getDestination(),                  message,                  this.defaultDeliveryMode,                  this.defaultPriority,                  this.defaultTimeToLive);    }        public void send(Destination destination, Message message, int deliveryMode, int priority, long timeToLive, AsyncCallback onComplete) throws JMSException {        checkClosed();        if (destination == null) {            if (info.getDestination() == null) {                throw new UnsupportedOperationException("A destination must be specified.");            }            throw new InvalidDestinationException("Don't understand null destinations");        }        ActiveMQDestination dest;        if (destination.equals(info.getDestination())) {            dest = (ActiveMQDestination)destination;        } else if (info.getDestination() == null) {            dest = ActiveMQDestination.transform(destination);        } else {            throw new UnsupportedOperationException("This producer can only send messages to: " + this.info.getDestination().getPhysicalName());        }        if (dest == null) {            throw new JMSException("No destination specified");        }        if (transformer != null) {            Message transformedMessage = transformer.producerTransform(session, this, message);            if (transformedMessage != null) {                message = transformedMessage;            }        }        if (producerWindow != null) {            try {                producerWindow.waitForSpace();            } catch (InterruptedException e) {                throw new JMSException("Send aborted due to thread interrupt.");            }        }        this.session.send(this, dest, message, deliveryMode, priority, timeToLive, producerWindow, sendTimeout, onComplete);        stats.onMessage();    }

3调用ActiveMQSession的send接口进行消息发送

protected void send(ActiveMQMessageProducer producer, ActiveMQDestination destination, Message message, int deliveryMode, int priority, long timeToLive,                        MemoryUsage producerWindow, int sendTimeout, AsyncCallback onComplete) throws JMSException {        checkClosed();        if (destination.isTemporary() && connection.isDeleted(destination)) {            throw new InvalidDestinationException("Cannot publish to a deleted Destination: " + destination);        }        synchronized (sendMutex) {            // tell the Broker we are about to start a new transaction            doStartTransaction();            TransactionId txid = transactionContext.getTransactionId();            long sequenceNumber = producer.getMessageSequence();            //Set the "JMS" header fields on the original message, see 1.1 spec section 3.4.11            message.setJMSDeliveryMode(deliveryMode);            long expiration = 0L;            if (!producer.getDisableMessageTimestamp()) {                long timeStamp = System.currentTimeMillis();                message.setJMSTimestamp(timeStamp);                if (timeToLive > 0) {                    expiration = timeToLive + timeStamp;                }            }            message.setJMSExpiration(expiration);            message.setJMSPriority(priority);            message.setJMSRedelivered(false);            // transform to our own message format here            ActiveMQMessage msg = ActiveMQMessageTransformation.transformMessage(message, connection);            // Set the message id.            if (msg == message) {                msg.setMessageId(new MessageId(producer.getProducerInfo().getProducerId(), sequenceNumber));            } else {                msg.setMessageId(new MessageId(producer.getProducerInfo().getProducerId(), sequenceNumber));                message.setJMSMessageID(msg.getMessageId().toString());            }            //clear the brokerPath in case we are re-sending this message            msg.setBrokerPath(null);            // destination format is provider specific so only set on transformed message            msg.setJMSDestination(destination);            msg.setTransactionId(txid);            if (connection.isCopyMessageOnSend()) {                msg = (ActiveMQMessage)msg.copy();            }            msg.setConnection(connection);            msg.onSend();            msg.setProducerId(msg.getMessageId().getProducerId());            if (LOG.isTraceEnabled()) {                LOG.trace(getSessionId() + " sending message: " + msg);            }            if (onComplete==null && sendTimeout <= 0 && !msg.isResponseRequired() && !connection.isAlwaysSyncSend() && (!msg.isPersistent() || connection.isUseAsyncSend() || txid != null)) {                this.connection.asyncSendPacket(msg);                if (producerWindow != null) {                    // Since we defer lots of the marshaling till we hit the                    // wire, this might not                    // provide and accurate size. We may change over to doing                    // more aggressive marshaling,                    // to get more accurate sizes.. this is more important once                    // users start using producer window                    // flow control.                    int size = msg.getSize();                    producerWindow.increaseUsage(size);                }            } else {                if (sendTimeout > 0 && onComplete==null) {                    this.connection.syncSendPacket(msg,sendTimeout);                }else {                    this.connection.syncSendPacket(msg, onComplete);                }            }        }    }

4,ActiveMQConnection发送消息

    public Response syncSendPacket(Command command) throws JMSException {        if (isClosed()) {            throw new ConnectionClosedException();        } else {            try {                Response response = (Response)this.transport.request(command);                if (response.isException()) {                    ExceptionResponse er = (ExceptionResponse)response;                    if (er.getException() instanceof JMSException) {                        throw (JMSException)er.getException();                    } else {                        if (isClosed()||closing.get()) {                            LOG.debug("Received an exception but connection is closing");                        }                        JMSException jmsEx = null;                        try {                            jmsEx = JMSExceptionSupport.create(er.getException());                        } catch(Throwable e) {                            LOG.error("Caught an exception trying to create a JMSException for " +er.getException(),e);                        }                        //dispose of transport for security exceptions                        if (er.getException() instanceof SecurityException && command instanceof ConnectionInfo){                            Transport t = this.transport;                            if (null != t){                                ServiceSupport.dispose(t);                            }                        }                        if (jmsEx !=null) {                            throw jmsEx;                        }                    }                }                return response;            } catch (IOException e) {                throw JMSExceptionSupport.create(e);            }        }    }        public Response syncSendPacket(Command command) throws JMSException {        if (isClosed()) {            throw new ConnectionClosedException();        } else {            try {                Response response = (Response)this.transport.request(command);                if (response.isException()) {                    ExceptionResponse er = (ExceptionResponse)response;                    if (er.getException() instanceof JMSException) {                        throw (JMSException)er.getException();                    } else {                        if (isClosed()||closing.get()) {                            LOG.debug("Received an exception but connection is closing");                        }                        JMSException jmsEx = null;                        try {                            jmsEx = JMSExceptionSupport.create(er.getException());                        } catch(Throwable e) {                            LOG.error("Caught an exception trying to create a JMSException for " +er.getException(),e);                        }                        //dispose of transport for security exceptions                        if (er.getException() instanceof SecurityException && command instanceof ConnectionInfo){                            Transport t = this.transport;                            if (null != t){                                ServiceSupport.dispose(t);                            }                        }                        if (jmsEx !=null) {                            throw jmsEx;                        }                    }                }                return response;            } catch (IOException e) {                throw JMSExceptionSupport.create(e);            }        }    }

5,ResponseCorrelator发送request

    public Object request(Object command) throws IOException {        FutureResponse response = asyncRequest(command, null);        return response.getResult();    }        public FutureResponse asyncRequest(Object o, ResponseCallback responseCallback) throws IOException {        Command command = (Command) o;        command.setCommandId(sequenceGenerator.getNextSequenceId());        command.setResponseRequired(true);        FutureResponse future = new FutureResponse(responseCallback);        IOException priorError = null;        synchronized (requestMap) {            priorError = this.error;            if (priorError == null) {                requestMap.put(new Integer(command.getCommandId()), future);            }        }        if (priorError != null) {            future.set(new ExceptionResponse(priorError));            throw priorError;        }        next.oneway(command);        return future;    }

6,调用MutexTransport来发送消息

    @Override    public void oneway(Object command) throws IOException {        writeLock.lock();        try {            next.oneway(command);        } finally {            writeLock.unlock();        }    }    

7,调用AbstractInactivityMonitor完成消息发送准备

    public void oneway(Object o) throws IOException {        // To prevent the inactivity monitor from sending a message while we        // are performing a send we take a read lock.  The inactivity monitor        // sends its Heart-beat commands under a write lock.  This means that        // the MutexTransport is still responsible for synchronizing sends        this.sendLock.readLock().lock();        inSend.set(true);        try {            doOnewaySend(o);        } finally {            commandSent.set(true);            inSend.set(false);            this.sendLock.readLock().unlock();        }    }            private void doOnewaySend(Object command) throws IOException {        if( failed.get() ) {            throw new InactivityIOException("Cannot send, channel has already failed: "+next.getRemoteAddress());        }        if (command.getClass() == WireFormatInfo.class) {            synchronized (this) {                processOutboundWireFormatInfo((WireFormatInfo) command);            }        }        next.oneway(command);    }

8，调用TcpTransport，OpenWireFormat，DataOutputStream最终完成通过tcp发送消息

   public void oneway(Object command) throws IOException {        checkStarted();        wireFormat.marshal(command, dataOut);        dataOut.flush();    }     public synchronized void marshal(Object o, DataOutput dataOut) throws IOException {        if (cacheEnabled) {            runMarshallCacheEvictionSweep();        }        int size = 1;        if (o != null) {            DataStructure c = (DataStructure)o;            byte type = c.getDataStructureType();            DataStreamMarshaller dsm = (DataStreamMarshaller)dataMarshallers[type & 0xFF];            if (dsm == null) {                throw new IOException("Unknown data type: " + type);            }            if (tightEncodingEnabled) {                BooleanStream bs = new BooleanStream();                size += dsm.tightMarshal1(this, c, bs);                size += bs.marshalledSize();                if (!sizePrefixDisabled) {                    dataOut.writeInt(size);                }                dataOut.writeByte(type);                bs.marshal(dataOut);                dsm.tightMarshal2(this, c, dataOut, bs);            } else {                DataOutput looseOut = dataOut;                if (!sizePrefixDisabled) {                    bytesOut.restart();                    looseOut = bytesOut;                }                looseOut.writeByte(type);                dsm.looseMarshal(this, c, looseOut);                if (!sizePrefixDisabled) {                    ByteSequence sequence = bytesOut.toByteSequence();                    dataOut.writeInt(sequence.getLength());                    dataOut.write(sequence.getData(), sequence.getOffset(), sequence.getLength());                }            }        } else {            if (!sizePrefixDisabled) {            dataOut.writeInt(size);            }            dataOut.writeByte(NULL_TYPE);        }    }        public final void writeInt(int v) throws IOException {        out.write((v >>> 24) & 0xFF);        out.write((v >>> 16) & 0xFF);        out.write((v >>>  8) & 0xFF);        out.write((v >>>  0) & 0xFF);        incCount(4);    }

附图

备注:MessageId是通过ProducerId+sequenceNumber来生成的，sequenceNumber通过原子变量的加1完成