RocketMq 消费位点上报

系列

开篇

这篇文章主要解析下RocketMq的Consumer侧的位移上报，每个consumer会周期性上报该consumer负责的topic的MessageQueue的消费位移。
consumer负责在消费位移的时候会保存消费位移在consumer侧。
consumer周期性的上报消费位移到broker当中。

consumer持久化消费进度

public class ConsumeMessageConcurrentlyService implements ConsumeMessageService {

    public void processConsumeResult(
        final ConsumeConcurrentlyStatus status,
        final ConsumeConcurrentlyContext context,
        final ConsumeRequest consumeRequest
    ) {
        int ackIndex = context.getAckIndex();

        // 省略消费消息的逻辑

        // 持久化当前消费进度
        long offset = consumeRequest.getProcessQueue().removeMessage(consumeRequest.getMsgs());
        if (offset >= 0 && !consumeRequest.getProcessQueue().isDropped()) {
            this.defaultMQPushConsumerImpl.getOffsetStore().updateOffset(consumeRequest.getMessageQueue(), offset, true);
        }
    }
}

consumer在处理消费逻辑后持久化当前消费进度，持久化的维度为MessageQueue。
持久化指定MessageQueue的消费位移。

public class RemoteBrokerOffsetStore implements OffsetStore {

    private final static InternalLogger log = ClientLogger.getLog();
    private final MQClientInstance mQClientFactory;
    private final String groupName;
    private ConcurrentMap<MessageQueue, AtomicLong> offsetTable =
        new ConcurrentHashMap<MessageQueue, AtomicLong>();

    @Override
    public void updateOffset(MessageQueue mq, long offset, boolean increaseOnly) {
        if (mq != null) {
            AtomicLong offsetOld = this.offsetTable.get(mq);
            if (null == offsetOld) {
                offsetOld = this.offsetTable.putIfAbsent(mq, new AtomicLong(offset));
            }

            if (null != offsetOld) {
                if (increaseOnly) {
                    MixAll.compareAndIncreaseOnly(offsetOld, offset);
                } else {
                    offsetOld.set(offset);
                }
            }
        }
    }
}

通过AtomicLong保存消费位移，通过cms保证原子性。

定时持久化任务

public class MQClientInstance {

    private void startScheduledTask() {

        this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {

            @Override
            public void run() {
                try {
                    MQClientInstance.this.persistAllConsumerOffset();
                } catch (Exception e) {
                    log.error("ScheduledTask persistAllConsumerOffset exception", e);
                }
            }
        }, 1000 * 10, this.clientConfig.getPersistConsumerOffsetInterval(), TimeUnit.MILLISECONDS);
    }

    private void persistAllConsumerOffset() {
        Iterator<Entry<String, MQConsumerInner>> it = this.consumerTable.entrySet().iterator();
        while (it.hasNext()) {
            Entry<String, MQConsumerInner> entry = it.next();
            MQConsumerInner impl = entry.getValue();
            impl.persistConsumerOffset();
        }
    }
}

startScheduledTask每隔10s持久化，通过persistAllConsumerOffset实现。

public class DefaultMQPullConsumerImpl implements MQConsumerInner {

    //ConcurrentMap<MessageQueue, ProcessQueue> processQueueTable = new ConcurrentHashMap<MessageQueue, ProcessQueue>(64);

    @Override
    public void persistConsumerOffset() {
        try {
            this.isRunning();
            Set<MessageQueue> mqs = new HashSet<MessageQueue>();
            Set<MessageQueue> allocateMq = this.rebalanceImpl.getProcessQueueTable().keySet();
            mqs.addAll(allocateMq);
            this.offsetStore.persistAll(mqs);
        } catch (Exception e) {
            log.error("group: " + this.defaultMQPullConsumer.getConsumerGroup() + " persistConsumerOffset exception", e);
        }
    }
}

DefaultMQPullConsumerImpl持久化该client负责的MessageQueue。

public class RemoteBrokerOffsetStore implements OffsetStore {

    @Override
    public void persistAll(Set<MessageQueue> mqs) {
        if (null == mqs || mqs.isEmpty())
            return;

        final HashSet<MessageQueue> unusedMQ = new HashSet<MessageQueue>();

        for (Map.Entry<MessageQueue, AtomicLong> entry : this.offsetTable.entrySet()) {
            MessageQueue mq = entry.getKey();
            AtomicLong offset = entry.getValue();
            if (offset != null) {
                if (mqs.contains(mq)) {
                    try {
                        this.updateConsumeOffsetToBroker(mq, offset.get());
                    } catch (Exception e) {
                        log.error("updateConsumeOffsetToBroker exception, " + mq.toString(), e);
                    }
                } else {
                    unusedMQ.add(mq);
                }
            }
        }

        if (!unusedMQ.isEmpty()) {
            for (MessageQueue mq : unusedMQ) {
                this.offsetTable.remove(mq);
                log.info("remove unused mq, {}, {}", mq, this.groupName);
            }
        }
    }


    private void updateConsumeOffsetToBroker(MessageQueue mq, long offset) throws RemotingException,
        MQBrokerException, InterruptedException, MQClientException {
        updateConsumeOffsetToBroker(mq, offset, true);
    }


    public void updateConsumeOffsetToBroker(MessageQueue mq, long offset, boolean isOneway) throws RemotingException,
        MQBrokerException, InterruptedException, MQClientException {
        FindBrokerResult findBrokerResult = this.mQClientFactory.findBrokerAddressInAdmin(mq.getBrokerName());
        if (null == findBrokerResult) {
            this.mQClientFactory.updateTopicRouteInfoFromNameServer(mq.getTopic());
            findBrokerResult = this.mQClientFactory.findBrokerAddressInAdmin(mq.getBrokerName());
        }

        if (findBrokerResult != null) {
            // UpdateConsumerOffsetRequestHeader设置Topic+groupName+queueId+offset
            UpdateConsumerOffsetRequestHeader requestHeader = new UpdateConsumerOffsetRequestHeader();
            requestHeader.setTopic(mq.getTopic());
            requestHeader.setConsumerGroup(this.groupName);
            requestHeader.setQueueId(mq.getQueueId());
            requestHeader.setCommitOffset(offset);

            if (isOneway) {
                this.mQClientFactory.getMQClientAPIImpl().updateConsumerOffsetOneway(
                    findBrokerResult.getBrokerAddr(), requestHeader, 1000 * 5);
            } else {
                this.mQClientFactory.getMQClientAPIImpl().updateConsumerOffset(
                    findBrokerResult.getBrokerAddr(), requestHeader, 1000 * 5);
            }
        } else {
            throw new MQClientException("The broker[" + mq.getBrokerName() + "] not exist", null);
        }
    }
}

persistAll执行核心的消费位移的持久化。
updateConsumeOffsetToBroker负责把MessageQueue的位移上报broker。