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本文主要研究一下rocketmq的PushConsumerImpl

PushConsumerImpl

io/openmessaging/rocketmq/consumer/PushConsumerImpl.java

public class PushConsumerImpl implements PushConsumer {
    private final DefaultMQPushConsumer rocketmqPushConsumer;
    private final KeyValue properties;
    private boolean started = false;
    private final Map<String, MessageListener> subscribeTable = new ConcurrentHashMap<>();
    private final ClientConfig clientConfig;

    public PushConsumerImpl(final KeyValue properties) {
        this.rocketmqPushConsumer = new DefaultMQPushConsumer();
        this.properties = properties;
        this.clientConfig = BeanUtils.populate(properties, ClientConfig.class);

        String accessPoints = clientConfig.getOmsAccessPoints();
        if (accessPoints == null || accessPoints.isEmpty()) {
            throw new OMSRuntimeException("-1", "OMS AccessPoints is null or empty.");
        }
        this.rocketmqPushConsumer.setNamesrvAddr(accessPoints.replace(',', ';'));

        String consumerGroup = clientConfig.getRmqConsumerGroup();
        if (null == consumerGroup || consumerGroup.isEmpty()) {
            throw new OMSRuntimeException("-1", "Consumer Group is necessary for RocketMQ, please set it.");
        }
        this.rocketmqPushConsumer.setConsumerGroup(consumerGroup);
        this.rocketmqPushConsumer.setMaxReconsumeTimes(clientConfig.getRmqMaxRedeliveryTimes());
        this.rocketmqPushConsumer.setConsumeTimeout(clientConfig.getRmqMessageConsumeTimeout());
        this.rocketmqPushConsumer.setConsumeThreadMax(clientConfig.getRmqMaxConsumeThreadNums());
        this.rocketmqPushConsumer.setConsumeThreadMin(clientConfig.getRmqMinConsumeThreadNums());

        String consumerId = OMSUtil.buildInstanceName();
        this.rocketmqPushConsumer.setInstanceName(consumerId);
        properties.put(PropertyKeys.CONSUMER_ID, consumerId);

        this.rocketmqPushConsumer.registerMessageListener(new MessageListenerImpl());
    }

    @Override
    public KeyValue properties() {
        return properties;
    }

    @Override
    public void resume() {
        this.rocketmqPushConsumer.resume();
    }

    @Override
    public void suspend() {
        this.rocketmqPushConsumer.suspend();
    }

    @Override
    public boolean isSuspended() {
        return this.rocketmqPushConsumer.getDefaultMQPushConsumerImpl().isPause();
    }

    @Override
    public PushConsumer attachQueue(final String queueName, final MessageListener listener) {
        this.subscribeTable.put(queueName, listener);
        try {
            this.rocketmqPushConsumer.subscribe(queueName, "*");
        } catch (MQClientException e) {
            throw new OMSRuntimeException("-1", String.format("RocketMQ push consumer can't attach to %s.", queueName));
        }
        return this;
    }

    @Override
    public synchronized void startup() {
        if (!started) {
            try {
                this.rocketmqPushConsumer.start();
            } catch (MQClientException e) {
                throw new OMSRuntimeException("-1", e);
            }
        }
        this.started = true;
    }

    @Override
    public synchronized void shutdown() {
        if (this.started) {
            this.rocketmqPushConsumer.shutdown();
        }
        this.started = false;
    }
    //......
}

• 这里创建的是DefaultMQPushConsumer，同时设置的messageListener为MessageListenerImpl
• attachQueue的时候，使用的是rocketmqPushConsumer.subscribe
• 启动时调用rocketmqPushConsumer.start()，关闭时调用rocketmqPushConsumer.shutdown()

MessageListenerImpl

io/openmessaging/rocketmq/consumer/PushConsumerImpl.java

    class MessageListenerImpl implements MessageListenerConcurrently {

        @Override
        public ConsumeConcurrentlyStatus consumeMessage(List<MessageExt> rmqMsgList,
            ConsumeConcurrentlyContext contextRMQ) {
            MessageExt rmqMsg = rmqMsgList.get(0);
            BytesMessage omsMsg = OMSUtil.msgConvert(rmqMsg);

            MessageListener listener = PushConsumerImpl.this.subscribeTable.get(rmqMsg.getTopic());

            if (listener == null) {
                throw new OMSRuntimeException("-1",
                    String.format("The topic/queue %s isn't attached to this consumer", rmqMsg.getTopic()));
            }

            final KeyValue contextProperties = OMS.newKeyValue();
            final CountDownLatch sync = new CountDownLatch(1);

            contextProperties.put(NonStandardKeys.MESSAGE_CONSUME_STATUS, ConsumeConcurrentlyStatus.RECONSUME_LATER.name());

            ReceivedMessageContext context = new ReceivedMessageContext() {
                @Override
                public KeyValue properties() {
                    return contextProperties;
                }

                @Override
                public void ack() {
                    sync.countDown();
                    contextProperties.put(NonStandardKeys.MESSAGE_CONSUME_STATUS,
                        ConsumeConcurrentlyStatus.CONSUME_SUCCESS.name());
                }

                @Override
                public void ack(final KeyValue properties) {
                    sync.countDown();
                    contextProperties.put(NonStandardKeys.MESSAGE_CONSUME_STATUS,
                        properties.getString(NonStandardKeys.MESSAGE_CONSUME_STATUS));
                }
            };
            long begin = System.currentTimeMillis();
            listener.onMessage(omsMsg, context);
            long costs = System.currentTimeMillis() - begin;
            long timeoutMills = clientConfig.getRmqMessageConsumeTimeout() * 60 * 1000;
            try {
                sync.await(Math.max(0, timeoutMills - costs), TimeUnit.MILLISECONDS);
            } catch (InterruptedException ignore) {
            }

            return ConsumeConcurrentlyStatus.valueOf(contextProperties.getString(NonStandardKeys.MESSAGE_CONSUME_STATUS));
        }
    }

• 实现了MessageListenerConcurrently接口的consumeMessage方法
• 这个方法接收到omsMsg的时候，调用了该topic对应的listener的onMessage方法，然后同步阻塞等待指定时间再返回

DefaultMQPushConsumerImpl.start

org/apache/rocketmq/client/impl/consumer/DefaultMQPushConsumerImpl.java

    public synchronized void start() throws MQClientException {
        switch (this.serviceState) {
            case CREATE_JUST:
                log.info("the consumer [{}] start beginning. messageModel={}, isUnitMode={}", this.defaultMQPushConsumer.getConsumerGroup(),
                    this.defaultMQPushConsumer.getMessageModel(), this.defaultMQPushConsumer.isUnitMode());
                this.serviceState = ServiceState.START_FAILED;

                this.checkConfig();

                this.copySubscription();

                if (this.defaultMQPushConsumer.getMessageModel() == MessageModel.CLUSTERING) {
                    this.defaultMQPushConsumer.changeInstanceNameToPID();
                }

                this.mQClientFactory = MQClientManager.getInstance().getAndCreateMQClientInstance(this.defaultMQPushConsumer, this.rpcHook);

                this.rebalanceImpl.setConsumerGroup(this.defaultMQPushConsumer.getConsumerGroup());
                this.rebalanceImpl.setMessageModel(this.defaultMQPushConsumer.getMessageModel());
                this.rebalanceImpl.setAllocateMessageQueueStrategy(this.defaultMQPushConsumer.getAllocateMessageQueueStrategy());
                this.rebalanceImpl.setmQClientFactory(this.mQClientFactory);

                this.pullAPIWrapper = new PullAPIWrapper(
                    mQClientFactory,
                    this.defaultMQPushConsumer.getConsumerGroup(), isUnitMode());
                this.pullAPIWrapper.registerFilterMessageHook(filterMessageHookList);

                if (this.defaultMQPushConsumer.getOffsetStore() != null) {
                    this.offsetStore = this.defaultMQPushConsumer.getOffsetStore();
                } else {
                    switch (this.defaultMQPushConsumer.getMessageModel()) {
                        case BROADCASTING:
                            this.offsetStore = new LocalFileOffsetStore(this.mQClientFactory, this.defaultMQPushConsumer.getConsumerGroup());
                            break;
                        case CLUSTERING:
                            this.offsetStore = new RemoteBrokerOffsetStore(this.mQClientFactory, this.defaultMQPushConsumer.getConsumerGroup());
                            break;
                        default:
                            break;
                    }
                    this.defaultMQPushConsumer.setOffsetStore(this.offsetStore);
                }
                this.offsetStore.load();

                if (this.getMessageListenerInner() instanceof MessageListenerOrderly) {
                    this.consumeOrderly = true;
                    this.consumeMessageService =
                        new ConsumeMessageOrderlyService(this, (MessageListenerOrderly) this.getMessageListenerInner());
                } else if (this.getMessageListenerInner() instanceof MessageListenerConcurrently) {
                    this.consumeOrderly = false;
                    this.consumeMessageService =
                        new ConsumeMessageConcurrentlyService(this, (MessageListenerConcurrently) this.getMessageListenerInner());
                }

                this.consumeMessageService.start();

                boolean registerOK = mQClientFactory.registerConsumer(this.defaultMQPushConsumer.getConsumerGroup(), this);
                if (!registerOK) {
                    this.serviceState = ServiceState.CREATE_JUST;
                    this.consumeMessageService.shutdown();
                    throw new MQClientException("The consumer group[" + this.defaultMQPushConsumer.getConsumerGroup()
                        + "] has been created before, specify another name please." + FAQUrl.suggestTodo(FAQUrl.GROUP_NAME_DUPLICATE_URL),
                        null);
                }

                mQClientFactory.start();
                log.info("the consumer [{}] start OK.", this.defaultMQPushConsumer.getConsumerGroup());
                this.serviceState = ServiceState.RUNNING;
                break;
            case RUNNING:
            case START_FAILED:
            case SHUTDOWN_ALREADY:
                throw new MQClientException("The PushConsumer service state not OK, maybe started once, "
                    + this.serviceState
                    + FAQUrl.suggestTodo(FAQUrl.CLIENT_SERVICE_NOT_OK),
                    null);
            default:
                break;
        }

        this.updateTopicSubscribeInfoWhenSubscriptionChanged();
        this.mQClientFactory.checkClientInBroker();
        this.mQClientFactory.sendHeartbeatToAllBrokerWithLock();
        this.mQClientFactory.rebalanceImmediately();
    }

• start方法根据serviceState的状态值来执行不同的逻辑
• CREATE_JUST的时候，如果messageListener是MessageListenerOrderly，则创建ConsumeMessageOrderlyService，否则创建ConsumeMessageConcurrentlyService
• 之后调用consumeMessageService.start()

ConsumeMessageConcurrentlyService.consumeMessageDirectly

org/apache/rocketmq/client/impl/consumer/ConsumeMessageConcurrentlyService.java

    @Override
    public ConsumeMessageDirectlyResult consumeMessageDirectly(MessageExt msg, String brokerName) {
        ConsumeMessageDirectlyResult result = new ConsumeMessageDirectlyResult();
        result.setOrder(false);
        result.setAutoCommit(true);

        List<MessageExt> msgs = new ArrayList<MessageExt>();
        msgs.add(msg);
        MessageQueue mq = new MessageQueue();
        mq.setBrokerName(brokerName);
        mq.setTopic(msg.getTopic());
        mq.setQueueId(msg.getQueueId());

        ConsumeConcurrentlyContext context = new ConsumeConcurrentlyContext(mq);

        this.resetRetryTopic(msgs);

        final long beginTime = System.currentTimeMillis();

        log.info("consumeMessageDirectly receive new message: {}", msg);

        try {
            ConsumeConcurrentlyStatus status = this.messageListener.consumeMessage(msgs, context);
            if (status != null) {
                switch (status) {
                    case CONSUME_SUCCESS:
                        result.setConsumeResult(CMResult.CR_SUCCESS);
                        break;
                    case RECONSUME_LATER:
                        result.setConsumeResult(CMResult.CR_LATER);
                        break;
                    default:
                        break;
                }
            } else {
                result.setConsumeResult(CMResult.CR_RETURN_NULL);
            }
        } catch (Throwable e) {
            result.setConsumeResult(CMResult.CR_THROW_EXCEPTION);
            result.setRemark(RemotingHelper.exceptionSimpleDesc(e));

            log.warn(String.format("consumeMessageDirectly exception: %s Group: %s Msgs: %s MQ: %s",
                RemotingHelper.exceptionSimpleDesc(e),
                ConsumeMessageConcurrentlyService.this.consumerGroup,
                msgs,
                mq), e);
        }

        result.setSpentTimeMills(System.currentTimeMillis() - beginTime);

        log.info("consumeMessageDirectly Result: {}", result);

        return result;
    }

• 这里调用messageListener.consumeMessage方法
• ConsumeMessageOrderlyService的consumeMessageDirectly方法也是调用messageListener.consumeMessage方法

ClientRemotingProcessor

org/apache/rocketmq/client/impl/ClientRemotingProcessor.java

public class ClientRemotingProcessor implements NettyRequestProcessor {
    private final Logger log = ClientLogger.getLog();
    private final MQClientInstance mqClientFactory;

    public ClientRemotingProcessor(final MQClientInstance mqClientFactory) {
        this.mqClientFactory = mqClientFactory;
    }

    @Override
    public RemotingCommand processRequest(ChannelHandlerContext ctx,
        RemotingCommand request) throws RemotingCommandException {
        switch (request.getCode()) {
            case RequestCode.CHECK_TRANSACTION_STATE:
                return this.checkTransactionState(ctx, request);
            case RequestCode.NOTIFY_CONSUMER_IDS_CHANGED:
                return this.notifyConsumerIdsChanged(ctx, request);
            case RequestCode.RESET_CONSUMER_CLIENT_OFFSET:
                return this.resetOffset(ctx, request);
            case RequestCode.GET_CONSUMER_STATUS_FROM_CLIENT:
                return this.getConsumeStatus(ctx, request);

            case RequestCode.GET_CONSUMER_RUNNING_INFO:
                return this.getConsumerRunningInfo(ctx, request);

            case RequestCode.CONSUME_MESSAGE_DIRECTLY:
                return this.consumeMessageDirectly(ctx, request);
            default:
                break;
        }
        return null;
    }

    private RemotingCommand consumeMessageDirectly(ChannelHandlerContext ctx,
        RemotingCommand request) throws RemotingCommandException {
        final RemotingCommand response = RemotingCommand.createResponseCommand(null);
        final ConsumeMessageDirectlyResultRequestHeader requestHeader =
            (ConsumeMessageDirectlyResultRequestHeader) request
                .decodeCommandCustomHeader(ConsumeMessageDirectlyResultRequestHeader.class);

        final MessageExt msg = MessageDecoder.decode(ByteBuffer.wrap(request.getBody()));

        ConsumeMessageDirectlyResult result =
            this.mqClientFactory.consumeMessageDirectly(msg, requestHeader.getConsumerGroup(), requestHeader.getBrokerName());

        if (null != result) {
            response.setCode(ResponseCode.SUCCESS);
            response.setBody(result.encode());
        } else {
            response.setCode(ResponseCode.SYSTEM_ERROR);
            response.setRemark(String.format("The Consumer Group <%s> not exist in this consumer", requestHeader.getConsumerGroup()));
        }

        return response;
    }

    //......
}

• client在接收到server的消息的时候，会解析消息的类型，如果是RequestCode.CONSUME_MESSAGE_DIRECTLY，则会调用consumeMessageDirectly
• consumeMessageDirectly则调用this.mqClientFactory.consumeMessageDirectly

MQClientInstance.consumeMessageDirectly

org/apache/rocketmq/client/impl/factory/MQClientInstance.java

    public ConsumeMessageDirectlyResult consumeMessageDirectly(final MessageExt msg,
        final String consumerGroup,
        final String brokerName) {
        MQConsumerInner mqConsumerInner = this.consumerTable.get(consumerGroup);
        if (null != mqConsumerInner) {
            DefaultMQPushConsumerImpl consumer = (DefaultMQPushConsumerImpl) mqConsumerInner;

            ConsumeMessageDirectlyResult result = consumer.getConsumeMessageService().consumeMessageDirectly(msg, brokerName);
            return result;
        }

        return null;
    }

• 这里是直接调用DefaultMQPushConsumerImpl的getConsumeMessageService()的consumeMessageDirectly方法
• 这个方法则触发messageListener.consumeMessage，进行消息推动

小结

• rocketmq的PushConsumerImpl主要是注册MessageListenerImpl，实现consumeMessage方法
• consumeMessage方法又会触发topic的MessageListener的onMessage方法实现推送
• 而mq的client端在接收到RequestCode.CONSUME_MESSAGE_DIRECTLY请求的时候，则会触发consumeMessageDirectly方法
• consumeMessageDirectly方法最后是调用了ConsumeMessageService的consumeMessageDirectly方法
• 而ConsumeMessageConcurrentlyService则会回调到MessageListenerImpl(实现MessageListenerConcurrently接口)的consumeMessage方法
• ConsumeMessageOrderlyService的consumeMessageDirectly，则回调用户自定义的实现MessageListener(实现MessageListenerOrderly接口)的consumeMessage方法

doc

• PushConsumerImpl