1。MessageDispatch消息分发信息
public static final byte DATA_STRUCTURE_TYPE = CommandTypes.MESSAGE_DISPATCH; protected ConsumerId consumerId; protected ActiveMQDestination destination; protected Message message; protected int redeliveryCounter; protected transient long deliverySequenceId; protected transient Object consumer; protected transient Runnable transmitCallback; protected transient Throwable rollbackCause;
2,自己主动确认。是再接受到消息,反馈给上层应用之前就给确认
在afterMessageIsConsumed方法中 先deliveredMessages.clear();接着 session.sendAck(ack);
3,在从tcp取到消息后放到unconsumedMessages等待消费
4,在从unconsumedMessages取出消息预处理后。在beforeMessageIsConsumed方法加消息加到deliveredMessages 里面。
unconsumedMessages; 消费者从mq接受到消息存储的位置,还没有消费
5,receive内部消费之前
private void beforeMessageIsConsumed(MessageDispatch md) throws JMSException { md.setDeliverySequenceId(session.getNextDeliveryId()); lastDeliveredSequenceId = md.getMessage().getMessageId().getBrokerSequenceId(); if (!isAutoAcknowledgeBatch()) { synchronized(deliveredMessages) { deliveredMessages.addFirst(md); } if (session.getTransacted()) { if (transactedIndividualAck) { immediateIndividualTransactedAck(md); } else { ackLater(md, MessageAck.DELIVERED_ACK_TYPE); } } } }
6,receive内部消费之后
private void afterMessageIsConsumed(MessageDispatch md, boolean messageExpired) throws JMSException { if (unconsumedMessages.isClosed()) { return; } if (messageExpired) { acknowledge(md, MessageAck.DELIVERED_ACK_TYPE); stats.getExpiredMessageCount().increment(); } else { stats.onMessage(); if (session.getTransacted()) { // Do nothing. } else if (isAutoAcknowledgeEach()) { if (deliveryingAcknowledgements.compareAndSet(false, true)) { synchronized (deliveredMessages) { if (!deliveredMessages.isEmpty()) { if (optimizeAcknowledge) { ackCounter++; // AMQ-3956 evaluate both expired and normal msgs as // otherwise consumer may get stalled if (ackCounter + deliveredCounter >= (info.getPrefetchSize() * .65) || (optimizeAcknowledgeTimeOut > 0 && System.currentTimeMillis() >= (optimizeAckTimestamp + optimizeAcknowledgeTimeOut))) { MessageAck ack = makeAckForAllDeliveredMessages(MessageAck.STANDARD_ACK_TYPE); if (ack != null) { deliveredMessages.clear(); ackCounter = 0; session.sendAck(ack); optimizeAckTimestamp = System.currentTimeMillis(); } // AMQ-3956 - as further optimization send // ack for expired msgs when there are any. // This resets the deliveredCounter to 0 so that // we won't sent standard acks with every msg just // because the deliveredCounter just below // 0.5 * prefetch as used in ackLater() if (pendingAck != null && deliveredCounter > 0) { session.sendAck(pendingAck); pendingAck = null; deliveredCounter = 0; } } } else { MessageAck ack = makeAckForAllDeliveredMessages(MessageAck.STANDARD_ACK_TYPE); if (ack!=null) { deliveredMessages.clear(); session.sendAck(ack); } } } } deliveryingAcknowledgements.set(false); } } else if (isAutoAcknowledgeBatch()) { ackLater(md, MessageAck.STANDARD_ACK_TYPE); } else if (session.isClientAcknowledge()||session.isIndividualAcknowledge()) { boolean messageUnackedByConsumer = false; synchronized (deliveredMessages) { messageUnackedByConsumer = deliveredMessages.contains(md); } if (messageUnackedByConsumer) { ackLater(md, MessageAck.DELIVERED_ACK_TYPE); } } else { throw new IllegalStateException("Invalid session state."); } } }