RocketMQ流程
大黄 Lv4
  2023-04-06 11:14:15 2023-04-06 11:14    12.7k Words  70 Mins  

Nameserver 启动流程

流程图

NameServer启动流程.png
此处不做过多赘述，NameServer主要是维护了消息服务端和客户端的信息
但是这边提一个RocketMQ中比较优雅的写法（利用JVM的钩子函数）

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public static NamesrvController start(final NamesrvController controller) throws Exception {
    // 利用JVM的钩子函数，在停机时进行一下流的关闭，线程池的停机
	Runtime.getRuntime().addShutdownHook(new ShutdownHookThread(log, new Callable<Void>() {
        @Override
        public Void call() throws Exception {
            controller.shutdown();
            return null;
        }
    }));
    controller.start();
}

public void start() throws Exception {
    this.remotingServer.start();

    if (this.fileWatchService != null) {
        this.fileWatchService.start();
    }
}

public void shutdown() {
    this.remotingServer.shutdown();
    this.remotingExecutor.shutdown();
    this.scheduledExecutorService.shutdown();

    if (this.fileWatchService != null) {
        this.fileWatchService.shutdown();
    }
}

Broker 启动

主要内容

Broker启动流程.png
这边我们主要知道Broker启动流程都做了哪些事情，具体这些事情是怎么做的，将在后续的模块中进行介绍

客户端启动 Producer/Consumer

流程图

ClientInstance启动流程.png

关键代码

Producer

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public void start(final boolean startFactory) throws MQClientException {
    switch (this.serviceState) {
        case CREATE_JUST:
            this.serviceState = ServiceState.START_FAILED;

            // 校验producerGroup是否符合要求
            this.checkConfig();

            if (!this.defaultMQProducer.getProducerGroup().equals(MixAll.CLIENT_INNER_PRODUCER_GROUP)) {
                // 更改生产者id为进程id
                this.defaultMQProducer.changeInstanceNameToPID();
            }

            // 创建实例
            this.mQClientFactory = MQClientManager.getInstance().getOrCreateMQClientInstance(this.defaultMQProducer, rpcHook);

            // 向MQClientInstance注册实例（将当前实体加入MQClientInstance管理）方便后续调用网络请求、心跳检测等
            boolean registerOK = mQClientFactory.registerProducer(this.defaultMQProducer.getProducerGroup(), this);
            if (!registerOK) {
                this.serviceState = ServiceState.CREATE_JUST;
                throw new MQClientException("The producer group[" + this.defaultMQProducer.getProducerGroup()
                    + "] has been created before, specify another name please." + FAQUrl.suggestTodo(FAQUrl.GROUP_NAME_DUPLICATE_URL),
                    null);
            }

            this.topicPublishInfoTable.put(this.defaultMQProducer.getCreateTopicKey(), new TopicPublishInfo());

            // 如果MQClientInstance已经启动，本次启动不会真正执行
            if (startFactory) {
                // 没有启动，启动MQClientInstance
                mQClientFactory.start();
            }

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

    this.mQClientFactory.sendHeartbeatToAllBrokerWithLock();

    this.timer.scheduleAtFixedRate(new TimerTask() {
        @Override
        public void run() {
            try {
                RequestFutureTable.scanExpiredRequest();
            } catch (Throwable e) {
                log.error("scan RequestFutureTable exception", e);
            }
        }
    }, 1000 * 3, 1000);
}

Consumer

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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();

            // 构建订阅信息并加入到RebalanceImpl的订阅消息中
            this.copySubscription();

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

            // 初始化MQClientInstance
            this.mQClientFactory = MQClientManager.getInstance().getOrCreateMQClientInstance(this.defaultMQPushConsumer, this.rpcHook);

            // 初始化RebalanceImpl
            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);

            // 初始化消息进度
            if (this.defaultMQPushConsumer.getOffsetStore() != null) {
                this.offsetStore = this.defaultMQPushConsumer.getOffsetStore();
            } else {
                switch (this.defaultMQPushConsumer.getMessageModel()) {
                    case BROADCASTING:
                        // 广播模式，进度存在消费端
                        this.offsetStore = new LocalFileOffsetStore(this.mQClientFactory, this.defaultMQPushConsumer.getConsumerGroup());
                        break;
                    case CLUSTERING:
                        // 集群模式，进度存在Broker
                        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) {
                // 顺序消费
                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();

            // 向MQClientInstance注册消费者
            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);
            }

            // 启动MQClientInstance（统一JVM中的所有的消费者生产者共用同一个MQClientInstance，且MQClientInstance只会启动一次）
            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();
}

公共部分

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// 获取实例
public MQClientInstance getOrCreateMQClientInstance(final ClientConfig clientConfig, RPCHook rpcHook) {
    // ip + instance + unitname (关于同一个机器的问题，instance是上一步修改的进程id，但是同一个jvm的消费者和生产者，client是同一个)
    String clientId = clientConfig.buildMQClientId();
    MQClientInstance instance = this.factoryTable.get(clientId);
    // 同一个clientId只会有一个实例
    if (null == instance) {
        instance =
            // 封装了RocketMQ网络处理的API =》 客户端与NameServer，Broker交互的网络通道
            new MQClientInstance(clientConfig.cloneClientConfig(),
                this.factoryIndexGenerator.getAndIncrement(), clientId, rpcHook);
        MQClientInstance prev = this.factoryTable.putIfAbsent(clientId, instance);
        if (prev != null) {
            instance = prev;
            log.warn("Returned Previous MQClientInstance for clientId:[{}]", clientId);
        } else {
            log.info("Created new MQClientInstance for clientId:[{}]", clientId);
        }
    }

    return instance;
}
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public void start() throws MQClientException {
    synchronized (this) {
        switch (this.serviceState) {
            case CREATE_JUST:
                this.serviceState = ServiceState.START_FAILED;
                // If not specified,looking address from name server
                if (null == this.clientConfig.getNamesrvAddr()) {
                    this.mQClientAPIImpl.fetchNameServerAddr();
                }
                // Start request-response channel
                this.mQClientAPIImpl.start();
                // Start various schedule tasks
                this.startScheduledTask();
                // Start pull service
                // 拉取消息
                this.pullMessageService.start();
                // Start rebalance service
                this.rebalanceService.start();
                // Start push service
                this.defaultMQProducer.getDefaultMQProducerImpl().start(false);
                log.info("the client factory [{}] start OK", this.clientId);
                this.serviceState = ServiceState.RUNNING;
                break;
            case START_FAILED:
                throw new MQClientException("The Factory object[" + this.getClientId() + "] has been created before, and failed.", null);
            default:
                break;
        }
    }
}

备注

其中，关于消费者的ReblanceImpl流程，加载消费进度之类的，在后续消费者模块会详细介绍。此处就不做过多的介绍

消息发送流程

Produer 发送消息

流程图

Producer消息发送流程.png

关键代码

发送消息主干流程

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private SendResult sendDefaultImpl(
    Message msg,
    final CommunicationMode communicationMode,
    final SendCallback sendCallback,
    final long timeout
) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
    this.makeSureStateOK();
    // 校验消息topic，内容，长度等
    Validators.checkMessage(msg, this.defaultMQProducer);
    final long invokeID = random.nextLong();
    long beginTimestampFirst = System.currentTimeMillis();
    long beginTimestampPrev = beginTimestampFirst;
    long endTimestamp = beginTimestampFirst;
    // 获取主题路由信息
    TopicPublishInfo topicPublishInfo = this.tryToFindTopicPublishInfo(msg.getTopic());
    if (topicPublishInfo != null && topicPublishInfo.ok()) {
        boolean callTimeout = false;
        MessageQueue mq = null;
        Exception exception = null;
        SendResult sendResult = null;
        // 重试次数（异步才重试）
        int timesTotal = communicationMode == CommunicationMode.SYNC ? 1 + this.defaultMQProducer.getRetryTimesWhenSendFailed() : 1;
        int times = 0;
        String[] brokersSent = new String[timesTotal];
        for (; times < timesTotal; times++) {
            String lastBrokerName = null == mq ? null : mq.getBrokerName();
            // 获取的队列
            MessageQueue mqSelected = this.selectOneMessageQueue(topicPublishInfo, lastBrokerName);
            if (mqSelected != null) {
                mq = mqSelected;
                brokersSent[times] = mq.getBrokerName();
                try {
                    beginTimestampPrev = System.currentTimeMillis();
                    if (times > 0) {
                        //Reset topic with namespace during resend.
                        msg.setTopic(this.defaultMQProducer.withNamespace(msg.getTopic()));
                    }
                    long costTime = beginTimestampPrev - beginTimestampFirst;
                    if (timeout < costTime) {
                        callTimeout = true;
                        break;
                    }

                    // 发送消息
                    sendResult = this.sendKernelImpl(msg, mq, communicationMode, sendCallback, topicPublishInfo, timeout - costTime);
                    endTimestamp = System.currentTimeMillis();
                    // 假如要规避的话，根据具体的消息发送耗时来决定规避
                    this.updateFaultItem(mq.getBrokerName(), endTimestamp - beginTimestampPrev, false);
                    switch (communicationMode) {
                        case ASYNC:
                            return null;
                        case ONEWAY:
                            return null;
                        case SYNC:
                            if (sendResult.getSendStatus() != SendStatus.SEND_OK) {
                                if (this.defaultMQProducer.isRetryAnotherBrokerWhenNotStoreOK()) {
                                    continue;
                                }
                            }

                            return sendResult;
                        default:
                            break;
                    }
                } catch (RemotingException e) {
                    endTimestamp = System.currentTimeMillis();
                    // 假如要规避的话，isolation = true，直接30s失败规避
                    this.updateFaultItem(mq.getBrokerName(), endTimestamp - beginTimestampPrev, true);
                    log.warn(String.format("sendKernelImpl exception, resend at once, InvokeID: %s, RT: %sms, Broker: %s", invokeID, endTimestamp - beginTimestampPrev, mq), e);
                    log.warn(msg.toString());
                    exception = e;
                    continue;
                } catch (MQClientException e) {
                    endTimestamp = System.currentTimeMillis();
                    this.updateFaultItem(mq.getBrokerName(), endTimestamp - beginTimestampPrev, true);
                    log.warn(String.format("sendKernelImpl exception, resend at once, InvokeID: %s, RT: %sms, Broker: %s", invokeID, endTimestamp - beginTimestampPrev, mq), e);
                    log.warn(msg.toString());
                    exception = e;
                    continue;
                } catch (MQBrokerException e) {
                    endTimestamp = System.currentTimeMillis();
                    this.updateFaultItem(mq.getBrokerName(), endTimestamp - beginTimestampPrev, true);
                    log.warn(String.format("sendKernelImpl exception, resend at once, InvokeID: %s, RT: %sms, Broker: %s", invokeID, endTimestamp - beginTimestampPrev, mq), e);
                    log.warn(msg.toString());
                    exception = e;
                    switch (e.getResponseCode()) {
                        case ResponseCode.TOPIC_NOT_EXIST:
                        case ResponseCode.SERVICE_NOT_AVAILABLE:
                        case ResponseCode.SYSTEM_ERROR:
                        case ResponseCode.NO_PERMISSION:
                        case ResponseCode.NO_BUYER_ID:
                        case ResponseCode.NOT_IN_CURRENT_UNIT:
                            continue;
                        default:
                            if (sendResult != null) {
                                return sendResult;
                            }

                            throw e;
                    }
                } catch (InterruptedException e) {
                    endTimestamp = System.currentTimeMillis();
                    this.updateFaultItem(mq.getBrokerName(), endTimestamp - beginTimestampPrev, false);
                    log.warn(String.format("sendKernelImpl exception, throw exception, InvokeID: %s, RT: %sms, Broker: %s", invokeID, endTimestamp - beginTimestampPrev, mq), e);
                    log.warn(msg.toString());

                    log.warn("sendKernelImpl exception", e);
                    log.warn(msg.toString());
                    throw e;
                }
            } else {
                break;
            }
        }

        if (sendResult != null) {
            return sendResult;
        }

        String info = String.format("Send [%d] times, still failed, cost [%d]ms, Topic: %s, BrokersSent: %s",
            times,
            System.currentTimeMillis() - beginTimestampFirst,
            msg.getTopic(),
            Arrays.toString(brokersSent));

        info += FAQUrl.suggestTodo(FAQUrl.SEND_MSG_FAILED);

        MQClientException mqClientException = new MQClientException(info, exception);
        if (callTimeout) {
            throw new RemotingTooMuchRequestException("sendDefaultImpl call timeout");
        }

        if (exception instanceof MQBrokerException) {
            mqClientException.setResponseCode(((MQBrokerException) exception).getResponseCode());
        } else if (exception instanceof RemotingConnectException) {
            mqClientException.setResponseCode(ClientErrorCode.CONNECT_BROKER_EXCEPTION);
        } else if (exception instanceof RemotingTimeoutException) {
            mqClientException.setResponseCode(ClientErrorCode.ACCESS_BROKER_TIMEOUT);
        } else if (exception instanceof MQClientException) {
            mqClientException.setResponseCode(ClientErrorCode.BROKER_NOT_EXIST_EXCEPTION);
        }

        throw mqClientException;
    }

    validateNameServerSetting();

    throw new MQClientException("No route info of this topic: " + msg.getTopic() + FAQUrl.suggestTodo(FAQUrl.NO_TOPIC_ROUTE_INFO),
        null).setResponseCode(ClientErrorCode.NOT_FOUND_TOPIC_EXCEPTION);
}

失败规避

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 // 开不开启失败规避的区别：
// 开启的话：只要失败一次，就悲观的认为失败的Broker不可用，在接下来一段时间内就不会再发送消息
// 不开启的话：只是在本次消息发送过程中规避该Broker，下次消息发送还是会继续尝试
// 之所以需要失败规避，是因为Broker变动NameServer不会主动推送，而是客户端每隔30s定时去拉取
public MessageQueue selectOneMessageQueue(final TopicPublishInfo tpInfo, final String lastBrokerName) {
    // 为true代表开启故障延迟机制
    if (this.sendLatencyFaultEnable) {
        try {
            int index = tpInfo.getSendWhichQueue().getAndIncrement();
            for (int i = 0; i < tpInfo.getMessageQueueList().size(); i++) {
                int pos = Math.abs(index++) % tpInfo.getMessageQueueList().size();
                if (pos < 0)
                    pos = 0;
                MessageQueue mq = tpInfo.getMessageQueueList().get(pos);
                // 当前broker是否可用
                if (latencyFaultTolerance.isAvailable(mq.getBrokerName())) {
                    if (null == lastBrokerName || mq.getBrokerName().equals(lastBrokerName))
                        return mq;
                }
            }

            // 没有可用的broker, 从之前的失败规避列表中选出一个broker
            final String notBestBroker = latencyFaultTolerance.pickOneAtLeast();
            int writeQueueNums = tpInfo.getQueueIdByBroker(notBestBroker);
            if (writeQueueNums > 0) {
                final MessageQueue mq = tpInfo.selectOneMessageQueue();
                if (notBestBroker != null) {
                    mq.setBrokerName(notBestBroker);
                    mq.setQueueId(tpInfo.getSendWhichQueue().getAndIncrement() % writeQueueNums);
                }
                return mq;
            } else {
                latencyFaultTolerance.remove(notBestBroker);
            }
        } catch (Exception e) {
            log.error("Error occurred when selecting message queue", e);
        }

        return tpInfo.selectOneMessageQueue();
    }

    return tpInfo.selectOneMessageQueue(lastBrokerName);
}

public void updateFaultItem(final String brokerName, final long currentLatency, boolean isolation) {
    // currentLatency 发送消息消耗时间
    if (this.sendLatencyFaultEnable) {
        long duration = computeNotAvailableDuration(isolation ? 30000 : currentLatency);
        this.latencyFaultTolerance.updateFaultItem(brokerName, currentLatency, duration);
    }
}
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private final ConcurrentHashMap<String, FaultItem> faultItemTable = new ConcurrentHashMap<String, FaultItem>(16);

@Override
public boolean isAvailable(final String name) {
    final FaultItem faultItem = this.faultItemTable.get(name);
    if (faultItem != null) {
        return faultItem.isAvailable();
    }
    return true;
}

消息发送具体逻辑

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private SendResult sendKernelImpl(final Message msg,
    final MessageQueue mq,
    final CommunicationMode communicationMode,
    final SendCallback sendCallback,
    final TopicPublishInfo topicPublishInfo,
    final long timeout) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
    long beginStartTime = System.currentTimeMillis();
    // 获取broker地址
    String brokerAddr = this.mQClientFactory.findBrokerAddressInPublish(mq.getBrokerName());
    if (null == brokerAddr) {
        // 从NameServer主动更新topic路由信息
        tryToFindTopicPublishInfo(mq.getTopic());
        brokerAddr = this.mQClientFactory.findBrokerAddressInPublish(mq.getBrokerName());
    }

    SendMessageContext context = null;
    if (brokerAddr != null) {
        brokerAddr = MixAll.brokerVIPChannel(this.defaultMQProducer.isSendMessageWithVIPChannel(), brokerAddr);

        byte[] prevBody = msg.getBody();
        try {
            //for MessageBatch,ID has been set in the generating process
            if (!(msg instanceof MessageBatch)) {
                // 批量发送消息，在生成过程中已设置id
                // 此处针对单挑发送消息的情况，分配全局唯一id
                MessageClientIDSetter.setUniqID(msg);
            }

            boolean topicWithNamespace = false;
            if (null != this.mQClientFactory.getClientConfig().getNamespace()) {
                msg.setInstanceId(this.mQClientFactory.getClientConfig().getNamespace());
                topicWithNamespace = true;
            }

            int sysFlag = 0;
            boolean msgBodyCompressed = false;
            // 消息大小默认超过4kb，zip压缩消息
            if (this.tryToCompressMessage(msg)) {
                sysFlag |= MessageSysFlag.COMPRESSED_FLAG;
                msgBodyCompressed = true;
            }

            // 如果是事务消息，对sysFlag打上事务消息的标记
            final String tranMsg = msg.getProperty(MessageConst.PROPERTY_TRANSACTION_PREPARED);
            if (tranMsg != null && Boolean.parseBoolean(tranMsg)) {
                sysFlag |= MessageSysFlag.TRANSACTION_PREPARED_TYPE;
            }

            if (hasCheckForbiddenHook()) {
                CheckForbiddenContext checkForbiddenContext = new CheckForbiddenContext();
                checkForbiddenContext.setNameSrvAddr(this.defaultMQProducer.getNamesrvAddr());
                checkForbiddenContext.setGroup(this.defaultMQProducer.getProducerGroup());
                checkForbiddenContext.setCommunicationMode(communicationMode);
                checkForbiddenContext.setBrokerAddr(brokerAddr);
                checkForbiddenContext.setMessage(msg);
                checkForbiddenContext.setMq(mq);
                checkForbiddenContext.setUnitMode(this.isUnitMode());
                this.executeCheckForbiddenHook(checkForbiddenContext);
            }

            // 如果注册了消息钩子函数
            if (this.hasSendMessageHook()) {
                // 对消息进行增强（发送前后）
                context = new SendMessageContext();
                context.setProducer(this);
                context.setProducerGroup(this.defaultMQProducer.getProducerGroup());
                context.setCommunicationMode(communicationMode);
                context.setBornHost(this.defaultMQProducer.getClientIP());
                context.setBrokerAddr(brokerAddr);
                context.setMessage(msg);
                context.setMq(mq);
                context.setNamespace(this.defaultMQProducer.getNamespace());
                String isTrans = msg.getProperty(MessageConst.PROPERTY_TRANSACTION_PREPARED);
                if (isTrans != null && isTrans.equals("true")) {
                    context.setMsgType(MessageType.Trans_Msg_Half);
                }

                if (msg.getProperty("__STARTDELIVERTIME") != null || msg.getProperty(MessageConst.PROPERTY_DELAY_TIME_LEVEL) != null) {
                    context.setMsgType(MessageType.Delay_Msg);
                }
                this.executeSendMessageHookBefore(context);
            }

            // 构建消息发送请求包
            SendMessageRequestHeader requestHeader = new SendMessageRequestHeader();
            requestHeader.setProducerGroup(this.defaultMQProducer.getProducerGroup());
            requestHeader.setTopic(msg.getTopic());
            requestHeader.setDefaultTopic(this.defaultMQProducer.getCreateTopicKey());
            requestHeader.setDefaultTopicQueueNums(this.defaultMQProducer.getDefaultTopicQueueNums());
            requestHeader.setQueueId(mq.getQueueId());
            requestHeader.setSysFlag(sysFlag);
            requestHeader.setBornTimestamp(System.currentTimeMillis());
            requestHeader.setFlag(msg.getFlag());
            requestHeader.setProperties(MessageDecoder.messageProperties2String(msg.getProperties()));
            requestHeader.setReconsumeTimes(0);
            requestHeader.setUnitMode(this.isUnitMode());
            requestHeader.setBatch(msg instanceof MessageBatch);
            if (requestHeader.getTopic().startsWith(MixAll.RETRY_GROUP_TOPIC_PREFIX)) {
                String reconsumeTimes = MessageAccessor.getReconsumeTime(msg);
                if (reconsumeTimes != null) {
                    requestHeader.setReconsumeTimes(Integer.valueOf(reconsumeTimes));
                    MessageAccessor.clearProperty(msg, MessageConst.PROPERTY_RECONSUME_TIME);
                }

                String maxReconsumeTimes = MessageAccessor.getMaxReconsumeTimes(msg);
                if (maxReconsumeTimes != null) {
                    requestHeader.setMaxReconsumeTimes(Integer.valueOf(maxReconsumeTimes));
                    MessageAccessor.clearProperty(msg, MessageConst.PROPERTY_MAX_RECONSUME_TIMES);
                }
            }

            SendResult sendResult = null;
            switch (communicationMode) {
                case ASYNC:
                    Message tmpMessage = msg;
                    boolean messageCloned = false;
                    if (msgBodyCompressed) {
                        //If msg body was compressed, msgbody should be reset using prevBody.
                        //Clone new message using commpressed message body and recover origin massage.
                        //Fix bug:https://github.com/apache/rocketmq-externals/issues/66
                        tmpMessage = MessageAccessor.cloneMessage(msg);
                        messageCloned = true;
                        msg.setBody(prevBody);
                    }

                    if (topicWithNamespace) {
                        if (!messageCloned) {
                            tmpMessage = MessageAccessor.cloneMessage(msg);
                            messageCloned = true;
                        }
                        msg.setTopic(NamespaceUtil.withoutNamespace(msg.getTopic(), this.defaultMQProducer.getNamespace()));
                    }

                    long costTimeAsync = System.currentTimeMillis() - beginStartTime;
                    if (timeout < costTimeAsync) {
                        throw new RemotingTooMuchRequestException("sendKernelImpl call timeout");
                    }
                    sendResult = this.mQClientFactory.getMQClientAPIImpl().sendMessage(
                        brokerAddr,
                        mq.getBrokerName(),
                        tmpMessage,
                        requestHeader,
                        timeout - costTimeAsync,
                        communicationMode,
                        sendCallback,
                        topicPublishInfo,
                        this.mQClientFactory,
                        this.defaultMQProducer.getRetryTimesWhenSendAsyncFailed(),
                        context,
                        this);
                    break;
                case ONEWAY:
                case SYNC:
                    long costTimeSync = System.currentTimeMillis() - beginStartTime;
                    if (timeout < costTimeSync) {
                        throw new RemotingTooMuchRequestException("sendKernelImpl call timeout");
                    }
                    sendResult = this.mQClientFactory.getMQClientAPIImpl().sendMessage(
                        brokerAddr,
                        mq.getBrokerName(),
                        msg,
                        requestHeader,
                        timeout - costTimeSync,
                        communicationMode,
                        context,
                        this);
                    break;
                default:
                    assert false;
                    break;
            }

            if (this.hasSendMessageHook()) {
                context.setSendResult(sendResult);
                this.executeSendMessageHookAfter(context);
            }

            return sendResult;
        } catch (RemotingException e) {
            if (this.hasSendMessageHook()) {
                context.setException(e);
                this.executeSendMessageHookAfter(context);
            }
            throw e;
        } catch (MQBrokerException e) {
            if (this.hasSendMessageHook()) {
                context.setException(e);
                this.executeSendMessageHookAfter(context);
            }
            throw e;
        } catch (InterruptedException e) {
            if (this.hasSendMessageHook()) {
                context.setException(e);
                this.executeSendMessageHookAfter(context);
            }
            throw e;
        } finally {
            msg.setBody(prevBody);
            msg.setTopic(NamespaceUtil.withoutNamespace(msg.getTopic(), this.defaultMQProducer.getNamespace()));
        }
    }

    throw new MQClientException("The broker[" + mq.getBrokerName() + "] not exist", null);
}

Broker 接收消息

流程图

Broker消息发送流程.png

关键代码

主干流程

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private RemotingCommand sendMessage(final ChannelHandlerContext ctx,
                                    final RemotingCommand request,
                                    final SendMessageContext sendMessageContext,
                                    final SendMessageRequestHeader requestHeader) throws RemotingCommandException {

    final RemotingCommand response = RemotingCommand.createResponseCommand(SendMessageResponseHeader.class);
    final SendMessageResponseHeader responseHeader = (SendMessageResponseHeader)response.readCustomHeader();

    response.setOpaque(request.getOpaque());

    response.addExtField(MessageConst.PROPERTY_MSG_REGION, this.brokerController.getBrokerConfig().getRegionId());
    response.addExtField(MessageConst.PROPERTY_TRACE_SWITCH, String.valueOf(this.brokerController.getBrokerConfig().isTraceOn()));

    log.debug("receive SendMessage request command, {}", request);

    final long startTimstamp = this.brokerController.getBrokerConfig().getStartAcceptSendRequestTimeStamp();
    if (this.brokerController.getMessageStore().now() < startTimstamp) {
        response.setCode(ResponseCode.SYSTEM_ERROR);
        response.setRemark(String.format("broker unable to service, until %s", UtilAll.timeMillisToHumanString2(startTimstamp)));
        return response;
    }

    response.setCode(-1);
    // 消息校验
    super.msgCheck(ctx, requestHeader, response);
    if (response.getCode() != -1) {
        return response;
    }

    final byte[] body = request.getBody();

    int queueIdInt = requestHeader.getQueueId();
    TopicConfig topicConfig = this.brokerController.getTopicConfigManager().selectTopicConfig(requestHeader.getTopic());

    if (queueIdInt < 0) {
        queueIdInt = Math.abs(this.random.nextInt() % 99999999) % topicConfig.getWriteQueueNums();
    }

    MessageExtBrokerInner msgInner = new MessageExtBrokerInner();
    msgInner.setTopic(requestHeader.getTopic());
    msgInner.setQueueId(queueIdInt);

    // 校验重试次数是否超过最大次数，超过则丢入死信队列
    // %DLQ%+消费组名
    if (!handleRetryAndDLQ(requestHeader, response, request, msgInner, topicConfig)) {
        return response;
    }

    msgInner.setBody(body);
    msgInner.setFlag(requestHeader.getFlag());
    MessageAccessor.setProperties(msgInner, MessageDecoder.string2messageProperties(requestHeader.getProperties()));
    msgInner.setBornTimestamp(requestHeader.getBornTimestamp());
    msgInner.setBornHost(ctx.channel().remoteAddress());
    msgInner.setStoreHost(this.getStoreHost());
    msgInner.setReconsumeTimes(requestHeader.getReconsumeTimes() == null ? 0 : requestHeader.getReconsumeTimes());
    String clusterName = this.brokerController.getBrokerConfig().getBrokerClusterName();
    MessageAccessor.putProperty(msgInner, MessageConst.PROPERTY_CLUSTER, clusterName);
    msgInner.setPropertiesString(MessageDecoder.messageProperties2String(msgInner.getProperties()));
    PutMessageResult putMessageResult = null;
    Map<String, String> oriProps = MessageDecoder.string2messageProperties(requestHeader.getProperties());
    String traFlag = oriProps.get(MessageConst.PROPERTY_TRANSACTION_PREPARED);
    if (traFlag != null && Boolean.parseBoolean(traFlag)) {
        if (this.brokerController.getBrokerConfig().isRejectTransactionMessage()) {
            response.setCode(ResponseCode.NO_PERMISSION);
            response.setRemark(
                "the broker[" + this.brokerController.getBrokerConfig().getBrokerIP1()
                    + "] sending transaction message is forbidden");
            return response;
        }
        putMessageResult = this.brokerController.getTransactionalMessageService().prepareMessage(msgInner);
    } else {
        // 存储消息
        putMessageResult = this.brokerController.getMessageStore().putMessage(msgInner);
    }

    return handlePutMessageResult(putMessageResult, response, request, msgInner, responseHeader, sendMessageContext, ctx, queueIdInt);

}

校验消息

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 protected RemotingCommand msgCheck(final ChannelHandlerContext ctx,
    final SendMessageRequestHeader requestHeader, final RemotingCommand response) {
    // 校验broker是否有写的权限
    if (!PermName.isWriteable(this.brokerController.getBrokerConfig().getBrokerPermission())
        && this.brokerController.getTopicConfigManager().isOrderTopic(requestHeader.getTopic())) {
        response.setCode(ResponseCode.NO_PERMISSION);
        response.setRemark("the broker[" + this.brokerController.getBrokerConfig().getBrokerIP1()
            + "] sending message is forbidden");
        return response;
    }
    // 检查topic是否可以进行消息发送，主要针对默认主题，默认主题不能发送消息，仅供路由查找
    if (!this.brokerController.getTopicConfigManager().isTopicCanSendMessage(requestHeader.getTopic())) {
        String errorMsg = "the topic[" + requestHeader.getTopic() + "] is conflict with system reserved words.";
        log.warn(errorMsg);
        response.setCode(ResponseCode.SYSTEM_ERROR);
        response.setRemark(errorMsg);
        return response;
    }

    // 获取topic信息
    TopicConfig topicConfig =
        this.brokerController.getTopicConfigManager().selectTopicConfig(requestHeader.getTopic());
    if (null == topicConfig) {
        int topicSysFlag = 0;
        if (requestHeader.isUnitMode()) {
            if (requestHeader.getTopic().startsWith(MixAll.RETRY_GROUP_TOPIC_PREFIX)) {
                topicSysFlag = TopicSysFlag.buildSysFlag(false, true);
            } else {
                topicSysFlag = TopicSysFlag.buildSysFlag(true, false);
            }
        }

        log.warn("the topic {} not exist, producer: {}", requestHeader.getTopic(), ctx.channel().remoteAddress());
        topicConfig = this.brokerController.getTopicConfigManager().createTopicInSendMessageMethod(
            requestHeader.getTopic(),
            requestHeader.getDefaultTopic(),
            RemotingHelper.parseChannelRemoteAddr(ctx.channel()),
            requestHeader.getDefaultTopicQueueNums(), topicSysFlag);

        if (null == topicConfig) {
            if (requestHeader.getTopic().startsWith(MixAll.RETRY_GROUP_TOPIC_PREFIX)) {
                topicConfig =
                    this.brokerController.getTopicConfigManager().createTopicInSendMessageBackMethod(
                        requestHeader.getTopic(), 1, PermName.PERM_WRITE | PermName.PERM_READ,
                        topicSysFlag);
            }
        }

        if (null == topicConfig) {
            response.setCode(ResponseCode.TOPIC_NOT_EXIST);
            response.setRemark("topic[" + requestHeader.getTopic() + "] not exist, apply first please!"
                + FAQUrl.suggestTodo(FAQUrl.APPLY_TOPIC_URL));
            return response;
        }
    }

    // 检查队列id是否有效
    int queueIdInt = requestHeader.getQueueId();
    int idValid = Math.max(topicConfig.getWriteQueueNums(), topicConfig.getReadQueueNums());
    if (queueIdInt >= idValid) {
        String errorInfo = String.format("request queueId[%d] is illegal, %s Producer: %s",
            queueIdInt,
            topicConfig.toString(),
            RemotingHelper.parseChannelRemoteAddr(ctx.channel()));

        log.warn(errorInfo);
        response.setCode(ResponseCode.SYSTEM_ERROR);
        response.setRemark(errorInfo);

        return response;
    }
    return response;
}

Broker接收到消息之后，就涉及到了消息的存储与刷盘

消息存储流程

消息存储

流程图

Broker存储消息流程.png

关键代码

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public PutMessageResult putMessage(MessageExtBrokerInner msg) {
    if (this.shutdown) {
        log.warn("message store has shutdown, so putMessage is forbidden");
        return new PutMessageResult(PutMessageStatus.SERVICE_NOT_AVAILABLE, null);
    }

    if (BrokerRole.SLAVE == this.messageStoreConfig.getBrokerRole()) {
        long value = this.printTimes.getAndIncrement();
        if ((value % 50000) == 0) {
            log.warn("message store is slave mode, so putMessage is forbidden ");
        }

        return new PutMessageResult(PutMessageStatus.SERVICE_NOT_AVAILABLE, null);
    }

    // 磁盘空间不足
    if (!this.runningFlags.isWriteable()) {
        long value = this.printTimes.getAndIncrement();
        if ((value % 50000) == 0) {
            log.warn("message store is not writeable, so putMessage is forbidden " + this.runningFlags.getFlagBits());
        }

        return new PutMessageResult(PutMessageStatus.SERVICE_NOT_AVAILABLE, null);
    } else {
        this.printTimes.set(0);
    }

    // 消息topic长度不能超过127个字符
    if (msg.getTopic().length() > Byte.MAX_VALUE) {
        log.warn("putMessage message topic length too long " + msg.getTopic().length());
        return new PutMessageResult(PutMessageStatus.MESSAGE_ILLEGAL, null);
    }

    // 消息属性长度不能超过32767
    if (msg.getPropertiesString() != null && msg.getPropertiesString().length() > Short.MAX_VALUE) {
        log.warn("putMessage message properties length too long " + msg.getPropertiesString().length());
        return new PutMessageResult(PutMessageStatus.PROPERTIES_SIZE_EXCEEDED, null);
    }

    if (this.isOSPageCacheBusy()) {
        return new PutMessageResult(PutMessageStatus.OS_PAGECACHE_BUSY, null);
    }

    long beginTime = this.getSystemClock().now();
    PutMessageResult result = this.commitLog.putMessage(msg);

    long elapsedTime = this.getSystemClock().now() - beginTime;
    if (elapsedTime > 500) {
        log.warn("putMessage not in lock elapsed time(ms)={}, bodyLength={}", elapsedTime, msg.getBody().length);
    }
    this.storeStatsService.setPutMessageEntireTimeMax(elapsedTime);

    if (null == result || !result.isOk()) {
        this.storeStatsService.getPutMessageFailedTimes().incrementAndGet();
    }

    return result;
}
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public PutMessageResult putMessage(final MessageExtBrokerInner msg) {
    // Set the storage time
    msg.setStoreTimestamp(System.currentTimeMillis());
    // Set the message body BODY CRC (consider the most appropriate setting
    // on the client)
    msg.setBodyCRC(UtilAll.crc32(msg.getBody()));
    // Back to Results
    AppendMessageResult result = null;

    StoreStatsService storeStatsService = this.defaultMessageStore.getStoreStatsService();

    String topic = msg.getTopic();
    int queueId = msg.getQueueId();

    // 事务消息逻辑
    final int tranType = MessageSysFlag.getTransactionValue(msg.getSysFlag());
    // 非事务消息 或 事务已经提交
    if (tranType == MessageSysFlag.TRANSACTION_NOT_TYPE
        || tranType == MessageSysFlag.TRANSACTION_COMMIT_TYPE) {
        // Delay Delivery
        if (msg.getDelayTimeLevel() > 0) {
            // 设置延时等级
            if (msg.getDelayTimeLevel() > this.defaultMessageStore.getScheduleMessageService().getMaxDelayLevel()) {
                msg.setDelayTimeLevel(this.defaultMessageStore.getScheduleMessageService().getMaxDelayLevel());
            }

            // 替换topic为 SCHEDULE_TOPIC_XXXX , 延时消息的topic
            topic = ScheduleMessageService.SCHEDULE_TOPIC;
            // 计算要丢到哪个队列中 根据延时等级计算队列id
            queueId = ScheduleMessageService.delayLevel2QueueId(msg.getDelayTimeLevel());

            // Backup real topic, queueId
            MessageAccessor.putProperty(msg, MessageConst.PROPERTY_REAL_TOPIC, msg.getTopic());
            MessageAccessor.putProperty(msg, MessageConst.PROPERTY_REAL_QUEUE_ID, String.valueOf(msg.getQueueId()));
            msg.setPropertiesString(MessageDecoder.messageProperties2String(msg.getProperties()));

            msg.setTopic(topic);
            msg.setQueueId(queueId);
        }
    }

    InetSocketAddress bornSocketAddress = (InetSocketAddress) msg.getBornHost();
    if (bornSocketAddress.getAddress() instanceof Inet6Address) {
        msg.setBornHostV6Flag();
    }

    InetSocketAddress storeSocketAddress = (InetSocketAddress) msg.getStoreHost();
    if (storeSocketAddress.getAddress() instanceof Inet6Address) {
        msg.setStoreHostAddressV6Flag();
    }

    long eclipsedTimeInLock = 0;

    // 获取mappedFile
    MappedFile unlockMappedFile = null;
    MappedFile mappedFile = this.mappedFileQueue.getLastMappedFile();

    // 申请锁
    putMessageLock.lock(); //spin or ReentrantLock ,depending on store config
    try {
        long beginLockTimestamp = this.defaultMessageStore.getSystemClock().now();
        this.beginTimeInLock = beginLockTimestamp;

        // Here settings are stored timestamp, in order to ensure an orderly
        // global
        msg.setStoreTimestamp(beginLockTimestamp);

        // 代表第一次写入，以偏移量0创建CommitLog文件
        if (null == mappedFile || mappedFile.isFull()) {
            mappedFile = this.mappedFileQueue.getLastMappedFile(0); // Mark: NewFile may be cause noise
        }
        if (null == mappedFile) {
            log.error("create mapped file1 error, topic: " + msg.getTopic() + " clientAddr: " + msg.getBornHostString());
            beginTimeInLock = 0;
            return new PutMessageResult(PutMessageStatus.CREATE_MAPEDFILE_FAILED, null);
        }

        // 写入消息
        result = mappedFile.appendMessage(msg, this.appendMessageCallback);
        switch (result.getStatus()) {
            case PUT_OK:
                break;
            case END_OF_FILE:
                unlockMappedFile = mappedFile;
                // Create a new file, re-write the message
                mappedFile = this.mappedFileQueue.getLastMappedFile(0);
                if (null == mappedFile) {
                    // XXX: warn and notify me
                    log.error("create mapped file2 error, topic: " + msg.getTopic() + " clientAddr: " + msg.getBornHostString());
                    beginTimeInLock = 0;
                    return new PutMessageResult(PutMessageStatus.CREATE_MAPEDFILE_FAILED, result);
                }
                result = mappedFile.appendMessage(msg, this.appendMessageCallback);
                break;
            case MESSAGE_SIZE_EXCEEDED:
            case PROPERTIES_SIZE_EXCEEDED:
                beginTimeInLock = 0;
                return new PutMessageResult(PutMessageStatus.MESSAGE_ILLEGAL, result);
            case UNKNOWN_ERROR:
                beginTimeInLock = 0;
                return new PutMessageResult(PutMessageStatus.UNKNOWN_ERROR, result);
            default:
                beginTimeInLock = 0;
                return new PutMessageResult(PutMessageStatus.UNKNOWN_ERROR, result);
        }

        eclipsedTimeInLock = this.defaultMessageStore.getSystemClock().now() - beginLockTimestamp;
        beginTimeInLock = 0;
    } finally {
        // 释放锁
        putMessageLock.unlock();
    }

    if (eclipsedTimeInLock > 500) {
        log.warn("[NOTIFYME]putMessage in lock cost time(ms)={}, bodyLength={} AppendMessageResult={}", eclipsedTimeInLock, msg.getBody().length, result);
    }

    if (null != unlockMappedFile && this.defaultMessageStore.getMessageStoreConfig().isWarmMapedFileEnable()) {
        this.defaultMessageStore.unlockMappedFile(unlockMappedFile);
    }

    PutMessageResult putMessageResult = new PutMessageResult(PutMessageStatus.PUT_OK, result);

    // Statistics
    storeStatsService.getSinglePutMessageTopicTimesTotal(msg.getTopic()).incrementAndGet();
    storeStatsService.getSinglePutMessageTopicSizeTotal(topic).addAndGet(result.getWroteBytes());

    // 刷盘
    handleDiskFlush(result, putMessageResult, msg);
    // HA主从同步复制
    handleHA(result, putMessageResult, msg);

    return putMessageResult;
}
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public AppendMessageResult appendMessagesInner(final MessageExt messageExt, final AppendMessageCallback cb) {
    assert messageExt != null;
    assert cb != null;

    int currentPos = this.wrotePosition.get();

    if (currentPos < this.fileSize) {
        // 创建一个与原ByteBuffer共享的内存区(根据是否开启堆外内存来决定使用 writeBuffer 还是 mappedByteBuffer)
        ByteBuffer byteBuffer = writeBuffer != null ? writeBuffer.slice() : this.mappedByteBuffer.slice();
        byteBuffer.position(currentPos);
        AppendMessageResult result;
        if (messageExt instanceof MessageExtBrokerInner) {
            result = cb.doAppend(this.getFileFromOffset(), byteBuffer, this.fileSize - currentPos, (MessageExtBrokerInner) messageExt);
        } else if (messageExt instanceof MessageExtBatch) {
            result = cb.doAppend(this.getFileFromOffset(), byteBuffer, this.fileSize - currentPos, (MessageExtBatch) messageExt);
        } else {
            return new AppendMessageResult(AppendMessageStatus.UNKNOWN_ERROR);
        }
        this.wrotePosition.addAndGet(result.getWroteBytes());
        this.storeTimestamp = result.getStoreTimestamp();
        return result;
    }
    // 代表文件写满
    log.error("MappedFile.appendMessage return null, wrotePosition: {} fileSize: {}", currentPos, this.fileSize);
    return new AppendMessageResult(AppendMessageStatus.UNKNOWN_ERROR);
}

消息刷盘

流程图

RocketMQ CommitLog 刷盘.png

关键代码

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public void handleDiskFlush(AppendMessageResult result, PutMessageResult putMessageResult, MessageExt messageExt) {
    // Synchronization flush
    if (FlushDiskType.SYNC_FLUSH == this.defaultMessageStore.getMessageStoreConfig().getFlushDiskType()) {
        final GroupCommitService service = (GroupCommitService) this.flushCommitLogService;
        if (messageExt.isWaitStoreMsgOK()) {
            // 构建 GroupCommitRequest 同步任务并提交到 GroupCommitService
            GroupCommitRequest request = new GroupCommitRequest(result.getWroteOffset() + result.getWroteBytes());
            service.putRequest(request);
            boolean flushOK = request.waitForFlush(this.defaultMessageStore.getMessageStoreConfig().getSyncFlushTimeout());
            if (!flushOK) {
                log.error("do groupcommit, wait for flush failed, topic: " + messageExt.getTopic() + " tags: " + messageExt.getTags()
                    + " client address: " + messageExt.getBornHostString());
                putMessageResult.setPutMessageStatus(PutMessageStatus.FLUSH_DISK_TIMEOUT);
            }
        } else {
            service.wakeup();
        }
    }
    // Asynchronous flush
    else {
        if (!this.defaultMessageStore.getMessageStoreConfig().isTransientStorePoolEnable()) {
            flushCommitLogService.wakeup();
        } else {
            commitLogService.wakeup();
        }
    }
}
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public void run() {
    CommitLog.log.info(this.getServiceName() + " service started");

    while (!this.isStopped()) {
        try {
            this.waitForRunning(10);
            this.doCommit();
        } catch (Exception e) {
            CommitLog.log.warn(this.getServiceName() + " service has exception. ", e);
        }
    }

    // Under normal circumstances shutdown, wait for the arrival of the
    // request, and then flush
    try {
        Thread.sleep(10);
    } catch (InterruptedException e) {
        CommitLog.log.warn("GroupCommitService Exception, ", e);
    }

    synchronized (this) {
        // 交换请求
        this.swapRequests();
    }

    this.doCommit();

    CommitLog.log.info(this.getServiceName() + " service end");
}

private void doCommit() {
    synchronized (this.requestsRead) {
        if (!this.requestsRead.isEmpty()) {
            for (GroupCommitRequest req : this.requestsRead) {
                // There may be a message in the next file, so a maximum of
                // two times the flush
                boolean flushOK = false;
                for (int i = 0; i < 2 && !flushOK; i++) {
                    flushOK = CommitLog.this.mappedFileQueue.getFlushedWhere() >= req.getNextOffset();

                    if (!flushOK) {
                        // 文件刷盘
                        CommitLog.this.mappedFileQueue.flush(0);
                    }
                }

                req.wakeupCustomer(flushOK);
            }

            long storeTimestamp = CommitLog.this.mappedFileQueue.getStoreTimestamp();
            if (storeTimestamp > 0) {
                CommitLog.this.defaultMessageStore.getStoreCheckpoint().setPhysicMsgTimestamp(storeTimestamp);
            }

            this.requestsRead.clear();
        } else {
            // Because of individual messages is set to not sync flush, it
            // will come to this process
            CommitLog.this.mappedFileQueue.flush(0);
        }
    }
}

// 为了避免同步刷盘消费任务与其他消息生产者提交任务产生锁竞争，
// GroupCommitService提供读容器与写容器，
// 这两个容器每执行完一次任务后交互，继续消费任务
private void swapRequests() {
    List<GroupCommitRequest> tmp = this.requestsWrite;
    this.requestsWrite = this.requestsRead;
    this.requestsRead = tmp;
}

消息存储堆外内存相关

RocketMQ使用堆外内存（Direct Memory）可以提高消息传输的效率和性能，主要表现在以下几个方面：
减少了GC的开销：在使用堆内存时，生产者和消费者将消息转换成字节数组并存储在堆中，这些数据最终会被JVM垃圾回收器清理掉。如果消息量很大，就会产生大量的垃圾回收，导致系统效率下降。而使用堆外内存可以避免这个问题，因为这些内存不受JVM垃圾回收的管理，因此可以减少GC的开销。
提高了消息传输的效率：在使用堆外内存时，生产者和消费者可以直接将消息写入到内存中，而不需要将数据从堆中拷贝到直接内存中，这样可以减少内存拷贝的次数和数据在内存中的复制次数，从而提高了消息传输的效率。
提高了内存使用效率：由于JVM会为堆内存预留一定的内存空间，因此在堆内存使用时，很难将整个JVM进程的内存使用控制在合理的范围内。而使用堆外内存可以将内存管理的责任交给操作系统，避免了JVM管理内存带来的一些问题。需要注意的是，使用堆外内存也会带来一些额外的内存管理和维护的负担，例如需要管理内存映射和释放等问题。此外，在某些情况下，如果使用不当，可能会导致内存泄漏等问题，因此需要谨慎使用。

消息消费流程

Consumer

流程图

Consumer消息消费流程.png
整体的流程：
Rebalance对消息队列进行负载均衡，然后创建PullRequest => PullRequest拉取消息，拉取成功后创建ConsumeRequest => ConsumeRequest消息消息

关键代码

负载均衡

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private boolean updateProcessQueueTableInRebalance(final String topic, final Set<MessageQueue> mqSet,
    final boolean isOrder) {
    boolean changed = false;

    Iterator<Entry<MessageQueue, ProcessQueue>> it = this.processQueueTable.entrySet().iterator();
    while (it.hasNext()) {
        Entry<MessageQueue, ProcessQueue> next = it.next();
        MessageQueue mq = next.getKey();
        ProcessQueue pq = next.getValue();

        if (mq.getTopic().equals(topic)) {
            if (!mqSet.contains(mq)) {
                // 经过本次负载均衡，该mq被分配给其他消费者，需要暂停该消息队列消息的消费
                pq.setDropped(true);
                // ProcessQueue中的消息将不会再被消费
                // 将MessageQueue，ProcessQueue从缓存列表中移除，且持久化要移除的MessageQueue的消费进度
                if (this.removeUnnecessaryMessageQueue(mq, pq)) {
                    it.remove();
                    changed = true;
                    log.info("doRebalance, {}, remove unnecessary mq, {}", consumerGroup, mq);
                }
            } else if (pq.isPullExpired()) {
                switch (this.consumeType()) {
                    case CONSUME_ACTIVELY:
                        break;
                    case CONSUME_PASSIVELY:
                        pq.setDropped(true);
                        if (this.removeUnnecessaryMessageQueue(mq, pq)) {
                            it.remove();
                            changed = true;
                            log.error("[BUG]doRebalance, {}, remove unnecessary mq, {}, because pull is pause, so try to fixed it",
                                consumerGroup, mq);
                        }
                        break;
                    default:
                        break;
                }
            }
        }
    }

    List<PullRequest> pullRequestList = new ArrayList<PullRequest>();
    for (MessageQueue mq : mqSet) {
        if (!this.processQueueTable.containsKey(mq)) {
            // 顺序消息，上锁(向Broker发起锁定请求)
            if (isOrder && !this.lock(mq)) {
                // => 等待其他消费者释放锁，一直到下一次Rebalance时再尝试加锁
                log.warn("doRebalance, {}, add a new mq failed, {}, because lock failed", consumerGroup, mq);
                continue;
            }

            // 删除内存中过期的消费进度
            this.removeDirtyOffset(mq);
            ProcessQueue pq = new ProcessQueue();
            // 获取最新的消费进度
            long nextOffset = this.computePullFromWhere(mq);
            if (nextOffset >= 0) {
                ProcessQueue pre = this.processQueueTable.putIfAbsent(mq, pq);
                if (pre != null) {
                    log.info("doRebalance, {}, mq already exists, {}", consumerGroup, mq);
                } else {
                    // 首次消费该队列，创建PullRequest请求
                    log.info("doRebalance, {}, add a new mq, {}", consumerGroup, mq);
                    PullRequest pullRequest = new PullRequest();
                    pullRequest.setConsumerGroup(consumerGroup);
                    pullRequest.setNextOffset(nextOffset);
                    pullRequest.setMessageQueue(mq);
                    pullRequest.setProcessQueue(pq);
                    pullRequestList.add(pullRequest);
                    changed = true;
                }
            } else {
                log.warn("doRebalance, {}, add new mq failed, {}", consumerGroup, mq);
            }
        }
    }

    this.dispatchPullRequest(pullRequestList);

    return changed;
}

拉取消息

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public void pullMessage(final PullRequest pullRequest) {
    // 从PullRequest中获取ProcessQueue
    final ProcessQueue processQueue = pullRequest.getProcessQueue();
    if (processQueue.isDropped()) {
        // ProcessQueue丢弃
        log.info("the pull request[{}] is dropped.", pullRequest.toString());
        return;
    }

    // 更新最后一次拉取时间为当前时间
    pullRequest.getProcessQueue().setLastPullTimestamp(System.currentTimeMillis());

    try {
        // 消费者状态不对，延迟3s后拉取
        this.makeSureStateOK();
    } catch (MQClientException e) {
        log.warn("pullMessage exception, consumer state not ok", e);
        this.executePullRequestLater(pullRequest, pullTimeDelayMillsWhenException);
        return;
    }

    if (this.isPause()) {
        // 消费者被挂起，延迟1s后再拉取
        log.warn("consumer was paused, execute pull request later. instanceName={}, group={}", this.defaultMQPushConsumer.getInstanceName(), this.defaultMQPushConsumer.getConsumerGroup());
        this.executePullRequestLater(pullRequest, PULL_TIME_DELAY_MILLS_WHEN_SUSPEND);
        return;
    }

    long cachedMessageCount = processQueue.getMsgCount().get();
    long cachedMessageSizeInMiB = processQueue.getMsgSize().get() / (1024 * 1024);

    // 流控 消息数量/消息占用内存
    if (cachedMessageCount > this.defaultMQPushConsumer.getPullThresholdForQueue()) {
        this.executePullRequestLater(pullRequest, PULL_TIME_DELAY_MILLS_WHEN_FLOW_CONTROL);
        if ((queueFlowControlTimes++ % 1000) == 0) {
            log.warn(
                "the cached message count exceeds the threshold {}, so do flow control, minOffset={}, maxOffset={}, count={}, size={} MiB, pullRequest={}, flowControlTimes={}",
                this.defaultMQPushConsumer.getPullThresholdForQueue(), processQueue.getMsgTreeMap().firstKey(), processQueue.getMsgTreeMap().lastKey(), cachedMessageCount, cachedMessageSizeInMiB, pullRequest, queueFlowControlTimes);
        }
        return;
    }

    if (cachedMessageSizeInMiB > this.defaultMQPushConsumer.getPullThresholdSizeForQueue()) {
        this.executePullRequestLater(pullRequest, PULL_TIME_DELAY_MILLS_WHEN_FLOW_CONTROL);
        if ((queueFlowControlTimes++ % 1000) == 0) {
            log.warn(
                "the cached message size exceeds the threshold {} MiB, so do flow control, minOffset={}, maxOffset={}, count={}, size={} MiB, pullRequest={}, flowControlTimes={}",
                this.defaultMQPushConsumer.getPullThresholdSizeForQueue(), processQueue.getMsgTreeMap().firstKey(), processQueue.getMsgTreeMap().lastKey(), cachedMessageCount, cachedMessageSizeInMiB, pullRequest, queueFlowControlTimes);
        }
        return;
    }

    if (!this.consumeOrderly) {
        // 非顺序消费
        if (processQueue.getMaxSpan() > this.defaultMQPushConsumer.getConsumeConcurrentlyMaxSpan()) {
            // 消息跨度（队列中最大偏移量-最小偏移量的间距） => 流控
            this.executePullRequestLater(pullRequest, PULL_TIME_DELAY_MILLS_WHEN_FLOW_CONTROL);
            if ((queueMaxSpanFlowControlTimes++ % 1000) == 0) {
                log.warn(
                    "the queue's messages, span too long, so do flow control, minOffset={}, maxOffset={}, maxSpan={}, pullRequest={}, flowControlTimes={}",
                    processQueue.getMsgTreeMap().firstKey(), processQueue.getMsgTreeMap().lastKey(), processQueue.getMaxSpan(),
                    pullRequest, queueMaxSpanFlowControlTimes);
            }
            return;
        }
    } else {
        // 顺序消费
        if (processQueue.isLocked()) {
            if (!pullRequest.isLockedFirst()) {
                // 如果该处理队列是第一次拉取任务，则首先计算拉取偏移量，然后向消息服务端拉取消息
                final long offset = this.rebalanceImpl.computePullFromWhere(pullRequest.getMessageQueue());
                boolean brokerBusy = offset < pullRequest.getNextOffset();
                log.info("the first time to pull message, so fix offset from broker. pullRequest: {} NewOffset: {} brokerBusy: {}",
                    pullRequest, offset, brokerBusy);
                if (brokerBusy) {
                    log.info("[NOTIFYME]the first time to pull message, but pull request offset larger than broker consume offset. pullRequest: {} NewOffset: {}",
                        pullRequest, offset);
                }

                pullRequest.setLockedFirst(true);
                pullRequest.setNextOffset(offset);
            }
        } else {
            // 如果消息处理队列未被锁定，则延迟3s后再将PullRequest对象放入拉取任务中
            this.executePullRequestLater(pullRequest, pullTimeDelayMillsWhenException);
            log.info("pull message later because not locked in broker, {}", pullRequest);
            return;
        }
    }

    // 获取该主题的订阅信息
    final SubscriptionData subscriptionData = this.rebalanceImpl.getSubscriptionInner().get(pullRequest.getMessageQueue().getTopic());
    if (null == subscriptionData) {
        this.executePullRequestLater(pullRequest, pullTimeDelayMillsWhenException);
        log.warn("find the consumer's subscription failed, {}", pullRequest);
        return;
    }

    final long beginTimestamp = System.currentTimeMillis();

    // 拉取的回调方法
    PullCallback pullCallback = new PullCallback() {
        @Override
        public void onSuccess(PullResult pullResult) {
            if (pullResult != null) {
                // 对象转换，消息过滤
                pullResult = DefaultMQPushConsumerImpl.this.pullAPIWrapper.processPullResult(pullRequest.getMessageQueue(), pullResult,
                    subscriptionData);

                switch (pullResult.getPullStatus()) {
                    case FOUND:
                        long prevRequestOffset = pullRequest.getNextOffset();
                        // 更新下次拉取的偏移量
                        pullRequest.setNextOffset(pullResult.getNextBeginOffset());
                        long pullRT = System.currentTimeMillis() - beginTimestamp;
                        DefaultMQPushConsumerImpl.this.getConsumerStatsManager().incPullRT(pullRequest.getConsumerGroup(),
                            pullRequest.getMessageQueue().getTopic(), pullRT);

                        long firstMsgOffset = Long.MAX_VALUE;
                        if (pullResult.getMsgFoundList() == null || pullResult.getMsgFoundList().isEmpty()) {
                            // 无消息，立即再次拉取（broker端有符合的消息，但是经过客户端过滤后，没有消息）
                            DefaultMQPushConsumerImpl.this.executePullRequestImmediately(pullRequest);
                        } else {
                            // 第一条消息的偏移量
                            firstMsgOffset = pullResult.getMsgFoundList().get(0).getQueueOffset();

                            DefaultMQPushConsumerImpl.this.getConsumerStatsManager().incPullTPS(pullRequest.getConsumerGroup(),
                                pullRequest.getMessageQueue().getTopic(), pullResult.getMsgFoundList().size());

                            // 将拉取到的消息存入ProcessQueue中
                            boolean dispatchToConsume = processQueue.putMessage(pullResult.getMsgFoundList());
                            // 提交到ConsumeMessageService中供消费者消费 => 拉取线程不关心消息消费结果
                            DefaultMQPushConsumerImpl.this.consumeMessageService.submitConsumeRequest(
                                pullResult.getMsgFoundList(),
                                processQueue,
                                pullRequest.getMessageQueue(),
                                dispatchToConsume);

                            if (DefaultMQPushConsumerImpl.this.defaultMQPushConsumer.getPullInterval() > 0) {
                                DefaultMQPushConsumerImpl.this.executePullRequestLater(pullRequest,
                                    DefaultMQPushConsumerImpl.this.defaultMQPushConsumer.getPullInterval());
                            } else {
                                DefaultMQPushConsumerImpl.this.executePullRequestImmediately(pullRequest);
                            }
                        }

                        if (pullResult.getNextBeginOffset() < prevRequestOffset
                            || firstMsgOffset < prevRequestOffset) {
                            log.warn(
                                "[BUG] pull message result maybe data wrong, nextBeginOffset: {} firstMsgOffset: {} prevRequestOffset: {}",
                                pullResult.getNextBeginOffset(),
                                firstMsgOffset,
                                prevRequestOffset);
                        }

                        break;
                    case NO_NEW_MSG:
                        pullRequest.setNextOffset(pullResult.getNextBeginOffset());

                        DefaultMQPushConsumerImpl.this.correctTagsOffset(pullRequest);

                        DefaultMQPushConsumerImpl.this.executePullRequestImmediately(pullRequest);
                        break;
                    case NO_MATCHED_MSG:
                        pullRequest.setNextOffset(pullResult.getNextBeginOffset());

                        DefaultMQPushConsumerImpl.this.correctTagsOffset(pullRequest);

                        DefaultMQPushConsumerImpl.this.executePullRequestImmediately(pullRequest);
                        break;
                    case OFFSET_ILLEGAL:
                        log.warn("the pull request offset illegal, {} {}",
                            pullRequest.toString(), pullResult.toString());
                        pullRequest.setNextOffset(pullResult.getNextBeginOffset());

                        // 首先将ProcessQueue的dropped设置为true => 丢弃该消费队列，拉取到的消息停止消费
                        pullRequest.getProcessQueue().setDropped(true);
                        DefaultMQPushConsumerImpl.this.executeTaskLater(new Runnable() {

                            @Override
                            public void run() {
                                try {
                                    // 根据服务端下一次校对的偏移量尝试更新消息消费进度（内存中）
                                    DefaultMQPushConsumerImpl.this.offsetStore.updateOffset(pullRequest.getMessageQueue(),
                                        pullRequest.getNextOffset(), false);

                                    // 持久化消息消费进度
                                    DefaultMQPushConsumerImpl.this.offsetStore.persist(pullRequest.getMessageQueue());

                                    // 将该消息队列从RebalanceImpl中移除, 等待消息队列的下一次重负载
                                    DefaultMQPushConsumerImpl.this.rebalanceImpl.removeProcessQueue(pullRequest.getMessageQueue());

                                    log.warn("fix the pull request offset, {}", pullRequest);
                                } catch (Throwable e) {
                                    log.error("executeTaskLater Exception", e);
                                }
                            }
                        }, 10000);
                        break;
                    default:
                        break;
                }
        }

        @Override
        public void onException(Throwable e) {
            if (!pullRequest.getMessageQueue().getTopic().startsWith(MixAll.RETRY_GROUP_TOPIC_PREFIX)) {
                log.warn("execute the pull request exception", e);
            }

            DefaultMQPushConsumerImpl.this.executePullRequestLater(pullRequest, pullTimeDelayMillsWhenException);
        }
    };

    boolean commitOffsetEnable = false;
    long commitOffsetValue = 0L;
    if (MessageModel.CLUSTERING == this.defaultMQPushConsumer.getMessageModel()) {
        commitOffsetValue = this.offsetStore.readOffset(pullRequest.getMessageQueue(), ReadOffsetType.READ_FROM_MEMORY);
        if (commitOffsetValue > 0) {
            commitOffsetEnable = true;
        }
    }

    String subExpression = null;
    boolean classFilter = false;
    SubscriptionData sd = this.rebalanceImpl.getSubscriptionInner().get(pullRequest.getMessageQueue().getTopic());
    if (sd != null) {
        if (this.defaultMQPushConsumer.isPostSubscriptionWhenPull() && !sd.isClassFilterMode()) {
            subExpression = sd.getSubString();
        }

        classFilter = sd.isClassFilterMode();
    }

    // 消息拉取系统编辑
    int sysFlag = PullSysFlag.buildSysFlag(
        commitOffsetEnable, // commitOffset
        true, // suspend
        subExpression != null, // subscription
        classFilter // class filter
    );
    try {
        // 拉取消息
        this.pullAPIWrapper.pullKernelImpl(
            pullRequest.getMessageQueue(),
            subExpression,
            subscriptionData.getExpressionType(),
            subscriptionData.getSubVersion(),
            pullRequest.getNextOffset(),
            this.defaultMQPushConsumer.getPullBatchSize(),
            sysFlag,
            commitOffsetValue,
            BROKER_SUSPEND_MAX_TIME_MILLIS,
            CONSUMER_TIMEOUT_MILLIS_WHEN_SUSPEND,
            CommunicationMode.ASYNC,
            pullCallback
        );
    } catch (Exception e) {
        log.error("pullKernelImpl exception", e);
        this.executePullRequestLater(pullRequest, pullTimeDelayMillsWhenException);
    }
}

消费消息

顺序消费
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@Override
public void run() {
    if (this.processQueue.isDropped()) {
        log.warn("run, the message queue not be able to consume, because it's dropped. {}", this.messageQueue);
        return;
    }

    // 对当前的消息队列申请独占锁 => 锁粒度：MessageQueue
    final Object objLock = messageQueueLock.fetchLockObject(this.messageQueue);
    synchronized (objLock) {
        if (MessageModel.BROADCASTING.equals(ConsumeMessageOrderlyService.this.defaultMQPushConsumerImpl.messageModel())
            || (this.processQueue.isLocked() && !this.processQueue.isLockExpired())) {
            final long beginTime = System.currentTimeMillis();
            for (boolean continueConsume = true; continueConsume; ) {
                if (this.processQueue.isDropped()) {
                    log.warn("the message queue not be able to consume, because it's dropped. {}", this.messageQueue);
                    break;
                }

                if (MessageModel.CLUSTERING.equals(ConsumeMessageOrderlyService.this.defaultMQPushConsumerImpl.messageModel())
                    && !this.processQueue.isLocked()) {
                    log.warn("the message queue not locked, so consume later, {}", this.messageQueue);
                    ConsumeMessageOrderlyService.this.tryLockLaterAndReconsume(this.messageQueue, this.processQueue, 10);
                    break;
                }

                if (MessageModel.CLUSTERING.equals(ConsumeMessageOrderlyService.this.defaultMQPushConsumerImpl.messageModel())
                    && this.processQueue.isLockExpired()) {
                    log.warn("the message queue lock expired, so consume later, {}", this.messageQueue);
                    ConsumeMessageOrderlyService.this.tryLockLaterAndReconsume(this.messageQueue, this.processQueue, 10);
                    break;
                }

                long interval = System.currentTimeMillis() - beginTime;
                if (interval > MAX_TIME_CONSUME_CONTINUOUSLY) {
                    // 消息消费时间大于 MAX_TIME_CONSUME_CONTINUOUSLY，放弃本次消息消费，交由消费组其他线程继续消费
                    ConsumeMessageOrderlyService.this.submitConsumeRequestLater(processQueue, messageQueue, 10);
                    break;
                }

                final int consumeBatchSize =
                    ConsumeMessageOrderlyService.this.defaultMQPushConsumer.getConsumeMessageBatchMaxSize();

                // 获取消息
                // 从 msgTreeMap 取出，放到 consumingMsgOrderlyTreeMap 中
                List<MessageExt> msgs = this.processQueue.takeMessags(consumeBatchSize);
                defaultMQPushConsumerImpl.resetRetryAndNamespace(msgs, defaultMQPushConsumer.getConsumerGroup());
                if (!msgs.isEmpty()) {
                    final ConsumeOrderlyContext context = new ConsumeOrderlyContext(this.messageQueue);

                    ConsumeOrderlyStatus status = null;

                    ConsumeMessageContext consumeMessageContext = null;
                    // 钩子函数
                    if (ConsumeMessageOrderlyService.this.defaultMQPushConsumerImpl.hasHook()) {
                        consumeMessageContext = new ConsumeMessageContext();
                        consumeMessageContext
                            .setConsumerGroup(ConsumeMessageOrderlyService.this.defaultMQPushConsumer.getConsumerGroup());
                        consumeMessageContext.setNamespace(defaultMQPushConsumer.getNamespace());
                        consumeMessageContext.setMq(messageQueue);
                        consumeMessageContext.setMsgList(msgs);
                        consumeMessageContext.setSuccess(false);
                        // init the consume context type
                        consumeMessageContext.setProps(new HashMap<String, String>());
                        ConsumeMessageOrderlyService.this.defaultMQPushConsumerImpl.executeHookBefore(consumeMessageContext);
                    }

                    long beginTimestamp = System.currentTimeMillis();
                    ConsumeReturnType returnType = ConsumeReturnType.SUCCESS;
                    boolean hasException = false;
                    try {
                        // 申请消费锁
                        this.processQueue.getLockConsume().lock();
                        if (this.processQueue.isDropped()) {
                            log.warn("consumeMessage, the message queue not be able to consume, because it's dropped. {}",
                                this.messageQueue);
                            break;
                        }

                        // 消费消息
                        status = messageListener.consumeMessage(Collections.unmodifiableList(msgs), context);
                    } catch (Throwable e) {
                        log.warn("consumeMessage exception: {} Group: {} Msgs: {} MQ: {}",
                            RemotingHelper.exceptionSimpleDesc(e),
                            ConsumeMessageOrderlyService.this.consumerGroup,
                            msgs,
                            messageQueue);
                        hasException = true;
                    } finally {
                        this.processQueue.getLockConsume().unlock();
                    }

                    if (null == status
                        || ConsumeOrderlyStatus.ROLLBACK == status
                        || ConsumeOrderlyStatus.SUSPEND_CURRENT_QUEUE_A_MOMENT == status) {
                        log.warn("consumeMessage Orderly return not OK, Group: {} Msgs: {} MQ: {}",
                            ConsumeMessageOrderlyService.this.consumerGroup,
                            msgs,
                            messageQueue);
                    }

                    long consumeRT = System.currentTimeMillis() - beginTimestamp;
                    if (null == status) {
                        if (hasException) {
                            returnType = ConsumeReturnType.EXCEPTION;
                        } else {
                            returnType = ConsumeReturnType.RETURNNULL;
                        }
                    } else if (consumeRT >= defaultMQPushConsumer.getConsumeTimeout() * 60 * 1000) {
                        returnType = ConsumeReturnType.TIME_OUT;
                    } else if (ConsumeOrderlyStatus.SUSPEND_CURRENT_QUEUE_A_MOMENT == status) {
                        returnType = ConsumeReturnType.FAILED;
                    } else if (ConsumeOrderlyStatus.SUCCESS == status) {
                        returnType = ConsumeReturnType.SUCCESS;
                    }

                    if (ConsumeMessageOrderlyService.this.defaultMQPushConsumerImpl.hasHook()) {
                        consumeMessageContext.getProps().put(MixAll.CONSUME_CONTEXT_TYPE, returnType.name());
                    }

                    if (null == status) {
                        status = ConsumeOrderlyStatus.SUSPEND_CURRENT_QUEUE_A_MOMENT;
                    }

                    // 钩子函数
                    if (ConsumeMessageOrderlyService.this.defaultMQPushConsumerImpl.hasHook()) {
                        consumeMessageContext.setStatus(status.toString());
                        consumeMessageContext
                            .setSuccess(ConsumeOrderlyStatus.SUCCESS == status || ConsumeOrderlyStatus.COMMIT == status);
                        ConsumeMessageOrderlyService.this.defaultMQPushConsumerImpl.executeHookAfter(consumeMessageContext);
                    }

                    ConsumeMessageOrderlyService.this.getConsumerStatsManager()
                        .incConsumeRT(ConsumeMessageOrderlyService.this.consumerGroup, messageQueue.getTopic(), consumeRT);

                    continueConsume = ConsumeMessageOrderlyService.this.processConsumeResult(msgs, status, context, this);
                } else {
                    continueConsume = false;
                }
            }
        } else {
            if (this.processQueue.isDropped()) {
                log.warn("the message queue not be able to consume, because it's dropped. {}", this.messageQueue);
                return;
            }

            ConsumeMessageOrderlyService.this.tryLockLaterAndReconsume(this.messageQueue, this.processQueue, 100);
        }
    }

更新消费进度

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public boolean processConsumeResult(
    final List<MessageExt> msgs,
    final ConsumeOrderlyStatus status,
    final ConsumeOrderlyContext context,
    final ConsumeRequest consumeRequest
) {
    boolean continueConsume = true;
    long commitOffset = -1L;
    if (context.isAutoCommit()) {
        switch (status) {
            case COMMIT:
            case ROLLBACK:
                log.warn("the message queue consume result is illegal, we think you want to ack these message {}",
                    consumeRequest.getMessageQueue());
            case SUCCESS:
                // commit
                commitOffset = consumeRequest.getProcessQueue().commit();
                this.getConsumerStatsManager().incConsumeOKTPS(consumerGroup, consumeRequest.getMessageQueue().getTopic(), msgs.size());
                break;
            case SUSPEND_CURRENT_QUEUE_A_MOMENT:
                this.getConsumerStatsManager().incConsumeFailedTPS(consumerGroup, consumeRequest.getMessageQueue().getTopic(), msgs.size());
                // 重试
                if (checkReconsumeTimes(msgs)) {
                    consumeRequest.getProcessQueue().makeMessageToCosumeAgain(msgs);
                    this.submitConsumeRequestLater(
                        consumeRequest.getProcessQueue(),
                        consumeRequest.getMessageQueue(),
                        context.getSuspendCurrentQueueTimeMillis());
                    continueConsume = false;
                } else {
                    commitOffset = consumeRequest.getProcessQueue().commit();
                }
                break;
            default:
                break;
        }
    } else {
        switch (status) {
            case SUCCESS:
                this.getConsumerStatsManager().incConsumeOKTPS(consumerGroup, consumeRequest.getMessageQueue().getTopic(), msgs.size());
                break;
            case COMMIT:
                commitOffset = consumeRequest.getProcessQueue().commit();
                break;
            case ROLLBACK:
                consumeRequest.getProcessQueue().rollback();
                this.submitConsumeRequestLater(
                    consumeRequest.getProcessQueue(),
                    consumeRequest.getMessageQueue(),
                    context.getSuspendCurrentQueueTimeMillis());
                continueConsume = false;
                break;
            case SUSPEND_CURRENT_QUEUE_A_MOMENT:
                this.getConsumerStatsManager().incConsumeFailedTPS(consumerGroup, consumeRequest.getMessageQueue().getTopic(), msgs.size());
                if (checkReconsumeTimes(msgs)) {
                    consumeRequest.getProcessQueue().makeMessageToCosumeAgain(msgs);
                    this.submitConsumeRequestLater(
                        consumeRequest.getProcessQueue(),
                        consumeRequest.getMessageQueue(),
                        context.getSuspendCurrentQueueTimeMillis());
                    continueConsume = false;
                }
                break;
            default:
                break;
        }
    }

    if (commitOffset >= 0 && !consumeRequest.getProcessQueue().isDropped()) {
        // 更新偏移量
        this.defaultMQPushConsumerImpl.getOffsetStore().updateOffset(consumeRequest.getMessageQueue(), commitOffset, false);
    }

    return continueConsume;
}

非顺序消息
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 public void run() {
    // ProcessQueue是否丢弃（例如当前消费者不负责消费当前消息的情况）
    if (this.processQueue.isDropped()) {
        log.info("the message queue not be able to consume, because it's dropped. group={} {}", ConsumeMessageConcurrentlyService.this.consumerGroup, this.messageQueue);
        return;
    }

    MessageListenerConcurrently listener = ConsumeMessageConcurrentlyService.this.messageListener;
    ConsumeConcurrentlyContext context = new ConsumeConcurrentlyContext(messageQueue);
    ConsumeConcurrentlyStatus status = null;
    // 恢复重试消息主题名
    defaultMQPushConsumerImpl.resetRetryAndNamespace(msgs, defaultMQPushConsumer.getConsumerGroup());

    ConsumeMessageContext consumeMessageContext = null;
    // 执行钩子函数
    if (ConsumeMessageConcurrentlyService.this.defaultMQPushConsumerImpl.hasHook()) {
        consumeMessageContext = new ConsumeMessageContext();
        consumeMessageContext.setNamespace(defaultMQPushConsumer.getNamespace());
        consumeMessageContext.setConsumerGroup(defaultMQPushConsumer.getConsumerGroup());
        consumeMessageContext.setProps(new HashMap<String, String>());
        consumeMessageContext.setMq(messageQueue);
        consumeMessageContext.setMsgList(msgs);
        consumeMessageContext.setSuccess(false);
        ConsumeMessageConcurrentlyService.this.defaultMQPushConsumerImpl.executeHookBefore(consumeMessageContext);
    }

    long beginTimestamp = System.currentTimeMillis();
    boolean hasException = false;
    ConsumeReturnType returnType = ConsumeReturnType.SUCCESS;
    try {
        if (msgs != null && !msgs.isEmpty()) {
            for (MessageExt msg : msgs) {
                MessageAccessor.setConsumeStartTimeStamp(msg, String.valueOf(System.currentTimeMillis()));
            }
        }
        // 具体消息消费业务逻辑
        status = listener.consumeMessage(Collections.unmodifiableList(msgs), context);
    } catch (Throwable e) {
        log.warn("consumeMessage exception: {} Group: {} Msgs: {} MQ: {}",
            RemotingHelper.exceptionSimpleDesc(e),
            ConsumeMessageConcurrentlyService.this.consumerGroup,
            msgs,
            messageQueue);
        hasException = true;
    }
    long consumeRT = System.currentTimeMillis() - beginTimestamp;
    if (null == status) {
        if (hasException) {
            returnType = ConsumeReturnType.EXCEPTION;
        } else {
            returnType = ConsumeReturnType.RETURNNULL;
        }
    } else if (consumeRT >= defaultMQPushConsumer.getConsumeTimeout() * 60 * 1000) {
        returnType = ConsumeReturnType.TIME_OUT;
    } else if (ConsumeConcurrentlyStatus.RECONSUME_LATER == status) {
        returnType = ConsumeReturnType.FAILED;
    } else if (ConsumeConcurrentlyStatus.CONSUME_SUCCESS == status) {
        returnType = ConsumeReturnType.SUCCESS;
    }

    if (ConsumeMessageConcurrentlyService.this.defaultMQPushConsumerImpl.hasHook()) {
        consumeMessageContext.getProps().put(MixAll.CONSUME_CONTEXT_TYPE, returnType.name());
    }

    if (null == status) {
        log.warn("consumeMessage return null, Group: {} Msgs: {} MQ: {}",
            ConsumeMessageConcurrentlyService.this.consumerGroup,
            msgs,
            messageQueue);
        status = ConsumeConcurrentlyStatus.RECONSUME_LATER;
    }

    // 钩子函数
    if (ConsumeMessageConcurrentlyService.this.defaultMQPushConsumerImpl.hasHook()) {
        consumeMessageContext.setStatus(status.toString());
        consumeMessageContext.setSuccess(ConsumeConcurrentlyStatus.CONSUME_SUCCESS == status);
        ConsumeMessageConcurrentlyService.this.defaultMQPushConsumerImpl.executeHookAfter(consumeMessageContext);
    }

    ConsumeMessageConcurrentlyService.this.getConsumerStatsManager()
        .incConsumeRT(ConsumeMessageConcurrentlyService.this.consumerGroup, messageQueue.getTopic(), consumeRT);

    // 处理结果前，再次验证下是否丢弃
    if (!processQueue.isDropped()) {
        ConsumeMessageConcurrentlyService.this.processConsumeResult(status, context, this);
    } else {
        log.warn("processQueue is dropped without process consume result. messageQueue={}, msgs={}", messageQueue, msgs);
    }
}

更新消费进度

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

    if (consumeRequest.getMsgs().isEmpty())
        return;

    switch (status) {
        case CONSUME_SUCCESS:
            // 消费成功的个数
            if (ackIndex >= consumeRequest.getMsgs().size()) {
                // 消费成功，ackIndex = msg.size - 1 即最后一条消息
                ackIndex = consumeRequest.getMsgs().size() - 1;
            }
            int ok = ackIndex + 1;
            int failed = consumeRequest.getMsgs().size() - ok;
            this.getConsumerStatsManager().incConsumeOKTPS(consumerGroup, consumeRequest.getMessageQueue().getTopic(), ok);
            this.getConsumerStatsManager().incConsumeFailedTPS(consumerGroup, consumeRequest.getMessageQueue().getTopic(), failed);
            break;
        case RECONSUME_LATER:
            ackIndex = -1;
            this.getConsumerStatsManager().incConsumeFailedTPS(consumerGroup, consumeRequest.getMessageQueue().getTopic(),
                consumeRequest.getMsgs().size());
            break;
        default:
            break;
    }

    switch (this.defaultMQPushConsumer.getMessageModel()) {
        case BROADCASTING:
            for (int i = ackIndex + 1; i < consumeRequest.getMsgs().size(); i++) {
                MessageExt msg = consumeRequest.getMsgs().get(i);
                // 广播模式，消息消费失败并不会重试
                log.warn("BROADCASTING, the message consume failed, drop it, {}", msg.toString());
            }
            break;
        case CLUSTERING:
            List<MessageExt> msgBackFailed = new ArrayList<MessageExt>(consumeRequest.getMsgs().size());
            // 与上面的ackIndex设置向对应，为0时，会去把这批消息重新调用sendMessageBack
            // 发送ack消息（发送给broker延迟消息）
            for (int i = ackIndex + 1; i < consumeRequest.getMsgs().size(); i++) {
                MessageExt msg = consumeRequest.getMsgs().get(i);
                // 将消费失败的消息发送到broker，进入重试队列或死信队列
                boolean result = this.sendMessageBack(msg, context);
                if (!result) {
                    // 假如丢入重试队列失败，则在本地重试消费
                    msg.setReconsumeTimes(msg.getReconsumeTimes() + 1);
                    msgBackFailed.add(msg);
                }
            }

            if (!msgBackFailed.isEmpty()) {
                consumeRequest.getMsgs().removeAll(msgBackFailed);

                // 本地消费重试（延迟五秒后重试）
                this.submitConsumeRequestLater(msgBackFailed, consumeRequest.getProcessQueue(), consumeRequest.getMessageQueue());
            }
            break;
        default:
            break;
    }

    // 从 消息消费队列 中删除这批消息，获取 移除该批消息后最小的偏移量
    // 以便于消费者重启后能从上次消费的位置开始消费
    // 即使消费结果返回的是RECONSUME_LATER,消费偏移量也会发生改变,此时broker会创建出一条全新的但是内容一样的消息,放到commitLog中
    // increaseOnly 只有大于内存中当前的消费偏移量才更新
    long offset = consumeRequest.getProcessQueue().removeMessage(consumeRequest.getMsgs());
    if (offset >= 0 && !consumeRequest.getProcessQueue().isDropped()) {
        this.defaultMQPushConsumerImpl.getOffsetStore().updateOffset(consumeRequest.getMessageQueue(), offset, true);
    }
}

Broker

流程图

Broker消息消费流程.png

关键代码

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private RemotingCommand processRequest(final Channel channel, RemotingCommand request, boolean brokerAllowSuspend)
    throws RemotingCommandException {
    RemotingCommand response = RemotingCommand.createResponseCommand(PullMessageResponseHeader.class);
    final PullMessageResponseHeader responseHeader = (PullMessageResponseHeader) response.readCustomHeader();
    final PullMessageRequestHeader requestHeader =
        (PullMessageRequestHeader) request.decodeCommandCustomHeader(PullMessageRequestHeader.class);

    response.setOpaque(request.getOpaque());

    log.debug("receive PullMessage request command, {}", request);

    if (!PermName.isReadable(this.brokerController.getBrokerConfig().getBrokerPermission())) {
        response.setCode(ResponseCode.NO_PERMISSION);
        response.setRemark(String.format("the broker[%s] pulling message is forbidden", this.brokerController.getBrokerConfig().getBrokerIP1()));
        return response;
    }

    SubscriptionGroupConfig subscriptionGroupConfig =
        this.brokerController.getSubscriptionGroupManager().findSubscriptionGroupConfig(requestHeader.getConsumerGroup());
    if (null == subscriptionGroupConfig) {
        response.setCode(ResponseCode.SUBSCRIPTION_GROUP_NOT_EXIST);
        response.setRemark(String.format("subscription group [%s] does not exist, %s", requestHeader.getConsumerGroup(), FAQUrl.suggestTodo(FAQUrl.SUBSCRIPTION_GROUP_NOT_EXIST)));
        return response;
    }

    if (!subscriptionGroupConfig.isConsumeEnable()) {
        response.setCode(ResponseCode.NO_PERMISSION);
        response.setRemark("subscription group no permission, " + requestHeader.getConsumerGroup());
        return response;
    }

    final boolean hasSuspendFlag = PullSysFlag.hasSuspendFlag(requestHeader.getSysFlag());
    final boolean hasCommitOffsetFlag = PullSysFlag.hasCommitOffsetFlag(requestHeader.getSysFlag());
    final boolean hasSubscriptionFlag = PullSysFlag.hasSubscriptionFlag(requestHeader.getSysFlag());

    final long suspendTimeoutMillisLong = hasSuspendFlag ? requestHeader.getSuspendTimeoutMillis() : 0;

    TopicConfig topicConfig = this.brokerController.getTopicConfigManager().selectTopicConfig(requestHeader.getTopic());
    if (null == topicConfig) {
        log.error("the topic {} not exist, consumer: {}", requestHeader.getTopic(), RemotingHelper.parseChannelRemoteAddr(channel));
        response.setCode(ResponseCode.TOPIC_NOT_EXIST);
        response.setRemark(String.format("topic[%s] not exist, apply first please! %s", requestHeader.getTopic(), FAQUrl.suggestTodo(FAQUrl.APPLY_TOPIC_URL)));
        return response;
    }

    if (!PermName.isReadable(topicConfig.getPerm())) {
        response.setCode(ResponseCode.NO_PERMISSION);
        response.setRemark("the topic[" + requestHeader.getTopic() + "] pulling message is forbidden");
        return response;
    }

    if (requestHeader.getQueueId() < 0 || requestHeader.getQueueId() >= topicConfig.getReadQueueNums()) {
        String errorInfo = String.format("queueId[%d] is illegal, topic:[%s] topicConfig.readQueueNums:[%d] consumer:[%s]",
            requestHeader.getQueueId(), requestHeader.getTopic(), topicConfig.getReadQueueNums(), channel.remoteAddress());
        log.warn(errorInfo);
        response.setCode(ResponseCode.SYSTEM_ERROR);
        response.setRemark(errorInfo);
        return response;
    }

    SubscriptionData subscriptionData = null;
    ConsumerFilterData consumerFilterData = null;
    if (hasSubscriptionFlag) {
        try {
            subscriptionData = FilterAPI.build(
                requestHeader.getTopic(), requestHeader.getSubscription(), requestHeader.getExpressionType()
            );
            if (!ExpressionType.isTagType(subscriptionData.getExpressionType())) {
                // 不是TAG模式，构建过滤数据ConsumeFilterData
                consumerFilterData = ConsumerFilterManager.build(
                    requestHeader.getTopic(), requestHeader.getConsumerGroup(), requestHeader.getSubscription(),
                    requestHeader.getExpressionType(), requestHeader.getSubVersion()
                );
                assert consumerFilterData != null;
            }
        } catch (Exception e) {
            log.warn("Parse the consumer's subscription[{}] failed, group: {}", requestHeader.getSubscription(),
                requestHeader.getConsumerGroup());
            response.setCode(ResponseCode.SUBSCRIPTION_PARSE_FAILED);
            response.setRemark("parse the consumer's subscription failed");
            return response;
        }
    } else {
        ConsumerGroupInfo consumerGroupInfo =
            this.brokerController.getConsumerManager().getConsumerGroupInfo(requestHeader.getConsumerGroup());
        if (null == consumerGroupInfo) {
            log.warn("the consumer's group info not exist, group: {}", requestHeader.getConsumerGroup());
            response.setCode(ResponseCode.SUBSCRIPTION_NOT_EXIST);
            response.setRemark("the consumer's group info not exist" + FAQUrl.suggestTodo(FAQUrl.SAME_GROUP_DIFFERENT_TOPIC));
            return response;
        }

        if (!subscriptionGroupConfig.isConsumeBroadcastEnable()
            && consumerGroupInfo.getMessageModel() == MessageModel.BROADCASTING) {
            response.setCode(ResponseCode.NO_PERMISSION);
            response.setRemark("the consumer group[" + requestHeader.getConsumerGroup() + "] can not consume by broadcast way");
            return response;
        }

        subscriptionData = consumerGroupInfo.findSubscriptionData(requestHeader.getTopic());
        if (null == subscriptionData) {
            log.warn("the consumer's subscription not exist, group: {}, topic:{}", requestHeader.getConsumerGroup(), requestHeader.getTopic());
            response.setCode(ResponseCode.SUBSCRIPTION_NOT_EXIST);
            response.setRemark("the consumer's subscription not exist" + FAQUrl.suggestTodo(FAQUrl.SAME_GROUP_DIFFERENT_TOPIC));
            return response;
        }

        if (subscriptionData.getSubVersion() < requestHeader.getSubVersion()) {
            log.warn("The broker's subscription is not latest, group: {} {}", requestHeader.getConsumerGroup(),
                subscriptionData.getSubString());
            response.setCode(ResponseCode.SUBSCRIPTION_NOT_LATEST);
            response.setRemark("the consumer's subscription not latest");
            return response;
        }
        if (!ExpressionType.isTagType(subscriptionData.getExpressionType())) {
            consumerFilterData = this.brokerController.getConsumerFilterManager().get(requestHeader.getTopic(),
                requestHeader.getConsumerGroup());
            if (consumerFilterData == null) {
                response.setCode(ResponseCode.FILTER_DATA_NOT_EXIST);
                response.setRemark("The broker's consumer filter data is not exist!Your expression may be wrong!");
                return response;
            }
            if (consumerFilterData.getClientVersion() < requestHeader.getSubVersion()) {
                log.warn("The broker's consumer filter data is not latest, group: {}, topic: {}, serverV: {}, clientV: {}",
                    requestHeader.getConsumerGroup(), requestHeader.getTopic(), consumerFilterData.getClientVersion(), requestHeader.getSubVersion());
                response.setCode(ResponseCode.FILTER_DATA_NOT_LATEST);
                response.setRemark("the consumer's consumer filter data not latest");
                return response;
            }
        }
    }

    if (!ExpressionType.isTagType(subscriptionData.getExpressionType())
        && !this.brokerController.getBrokerConfig().isEnablePropertyFilter()) {
        response.setCode(ResponseCode.SYSTEM_ERROR);
        response.setRemark("The broker does not support consumer to filter message by " + subscriptionData.getExpressionType());
        return response;
    }

    MessageFilter messageFilter;
    if (this.brokerController.getBrokerConfig().isFilterSupportRetry()) {
        messageFilter = new ExpressionForRetryMessageFilter(subscriptionData, consumerFilterData,
            this.brokerController.getConsumerFilterManager());
    } else {
        messageFilter = new ExpressionMessageFilter(subscriptionData, consumerFilterData,
            this.brokerController.getConsumerFilterManager());
    }

    // 获取消息
    final GetMessageResult getMessageResult =
        this.brokerController.getMessageStore().getMessage(requestHeader.getConsumerGroup(), requestHeader.getTopic(),
            requestHeader.getQueueId(), requestHeader.getQueueOffset(), requestHeader.getMaxMsgNums(), messageFilter);
    if (getMessageResult != null) {
        response.setRemark(getMessageResult.getStatus().name());
        responseHeader.setNextBeginOffset(getMessageResult.getNextBeginOffset());
        responseHeader.setMinOffset(getMessageResult.getMinOffset());
        responseHeader.setMaxOffset(getMessageResult.getMaxOffset());

        if (getMessageResult.isSuggestPullingFromSlave()) {
            responseHeader.setSuggestWhichBrokerId(subscriptionGroupConfig.getWhichBrokerWhenConsumeSlowly());
        } else {
            responseHeader.setSuggestWhichBrokerId(MixAll.MASTER_ID);
        }

        switch (this.brokerController.getMessageStoreConfig().getBrokerRole()) {
            case ASYNC_MASTER:
            case SYNC_MASTER:
                break;
            case SLAVE:
                if (!this.brokerController.getBrokerConfig().isSlaveReadEnable()) {
                    response.setCode(ResponseCode.PULL_RETRY_IMMEDIATELY);
                    responseHeader.setSuggestWhichBrokerId(MixAll.MASTER_ID);
                }
                break;
        }

        if (this.brokerController.getBrokerConfig().isSlaveReadEnable()) {
            // consume too slow ,redirect to another machine
            if (getMessageResult.isSuggestPullingFromSlave()) {
                responseHeader.setSuggestWhichBrokerId(subscriptionGroupConfig.getWhichBrokerWhenConsumeSlowly());
            }
            // consume ok
            else {
                responseHeader.setSuggestWhichBrokerId(subscriptionGroupConfig.getBrokerId());
            }
        } else {
            responseHeader.setSuggestWhichBrokerId(MixAll.MASTER_ID);
        }

        switch (getMessageResult.getStatus()) {
            case FOUND:
                response.setCode(ResponseCode.SUCCESS);
                break;
            case MESSAGE_WAS_REMOVING:
                response.setCode(ResponseCode.PULL_RETRY_IMMEDIATELY);
                break;
            case NO_MATCHED_LOGIC_QUEUE:
            case NO_MESSAGE_IN_QUEUE:
                if (0 != requestHeader.getQueueOffset()) {
                    response.setCode(ResponseCode.PULL_OFFSET_MOVED);

                    // XXX: warn and notify me
                    log.info("the broker store no queue data, fix the request offset {} to {}, Topic: {} QueueId: {} Consumer Group: {}",
                        requestHeader.getQueueOffset(),
                        getMessageResult.getNextBeginOffset(),
                        requestHeader.getTopic(),
                        requestHeader.getQueueId(),
                        requestHeader.getConsumerGroup()
                    );
                } else {
                    response.setCode(ResponseCode.PULL_NOT_FOUND);
                }
                break;
            case NO_MATCHED_MESSAGE:
                response.setCode(ResponseCode.PULL_RETRY_IMMEDIATELY);
                break;
            case OFFSET_FOUND_NULL:
                response.setCode(ResponseCode.PULL_NOT_FOUND);
                break;
            case OFFSET_OVERFLOW_BADLY:
                response.setCode(ResponseCode.PULL_OFFSET_MOVED);
                // XXX: warn and notify me
                log.info("the request offset: {} over flow badly, broker max offset: {}, consumer: {}",
                    requestHeader.getQueueOffset(), getMessageResult.getMaxOffset(), channel.remoteAddress());
                break;
            case OFFSET_OVERFLOW_ONE:
                response.setCode(ResponseCode.PULL_NOT_FOUND);
                break;
            case OFFSET_TOO_SMALL:
                response.setCode(ResponseCode.PULL_OFFSET_MOVED);
                log.info("the request offset too small. group={}, topic={}, requestOffset={}, brokerMinOffset={}, clientIp={}",
                    requestHeader.getConsumerGroup(), requestHeader.getTopic(), requestHeader.getQueueOffset(),
                    getMessageResult.getMinOffset(), channel.remoteAddress());
                break;
            default:
                assert false;
                break;
        }

        if (this.hasConsumeMessageHook()) {
            ConsumeMessageContext context = new ConsumeMessageContext();
            context.setConsumerGroup(requestHeader.getConsumerGroup());
            context.setTopic(requestHeader.getTopic());
            context.setQueueId(requestHeader.getQueueId());

            String owner = request.getExtFields().get(BrokerStatsManager.COMMERCIAL_OWNER);

            switch (response.getCode()) {
                case ResponseCode.SUCCESS:
                    int commercialBaseCount = brokerController.getBrokerConfig().getCommercialBaseCount();
                    int incValue = getMessageResult.getMsgCount4Commercial() * commercialBaseCount;

                    context.setCommercialRcvStats(BrokerStatsManager.StatsType.RCV_SUCCESS);
                    context.setCommercialRcvTimes(incValue);
                    context.setCommercialRcvSize(getMessageResult.getBufferTotalSize());
                    context.setCommercialOwner(owner);

                    break;
                case ResponseCode.PULL_NOT_FOUND:
                    if (!brokerAllowSuspend) {

                        context.setCommercialRcvStats(BrokerStatsManager.StatsType.RCV_EPOLLS);
                        context.setCommercialRcvTimes(1);
                        context.setCommercialOwner(owner);

                    }
                    break;
                case ResponseCode.PULL_RETRY_IMMEDIATELY:
                case ResponseCode.PULL_OFFSET_MOVED:
                    context.setCommercialRcvStats(BrokerStatsManager.StatsType.RCV_EPOLLS);
                    context.setCommercialRcvTimes(1);
                    context.setCommercialOwner(owner);
                    break;
                default:
                    assert false;
                    break;
            }

            this.executeConsumeMessageHookBefore(context);
        }

        switch (response.getCode()) {
            case ResponseCode.SUCCESS:

                this.brokerController.getBrokerStatsManager().incGroupGetNums(requestHeader.getConsumerGroup(), requestHeader.getTopic(),
                    getMessageResult.getMessageCount());

                this.brokerController.getBrokerStatsManager().incGroupGetSize(requestHeader.getConsumerGroup(), requestHeader.getTopic(),
                    getMessageResult.getBufferTotalSize());

                this.brokerController.getBrokerStatsManager().incBrokerGetNums(getMessageResult.getMessageCount());
                if (this.brokerController.getBrokerConfig().isTransferMsgByHeap()) {
                    final long beginTimeMills = this.brokerController.getMessageStore().now();
                    final byte[] r = this.readGetMessageResult(getMessageResult, requestHeader.getConsumerGroup(), requestHeader.getTopic(), requestHeader.getQueueId());
                    this.brokerController.getBrokerStatsManager().incGroupGetLatency(requestHeader.getConsumerGroup(),
                        requestHeader.getTopic(), requestHeader.getQueueId(),
                        (int) (this.brokerController.getMessageStore().now() - beginTimeMills));
                    response.setBody(r);
                } else {
                    try {
                        FileRegion fileRegion =
                            new ManyMessageTransfer(response.encodeHeader(getMessageResult.getBufferTotalSize()), getMessageResult);
                        channel.writeAndFlush(fileRegion).addListener(new ChannelFutureListener() {
                            @Override
                            public void operationComplete(ChannelFuture future) throws Exception {
                                getMessageResult.release();
                                if (!future.isSuccess()) {
                                    log.error("transfer many message by pagecache failed, {}", channel.remoteAddress(), future.cause());
                                }
                            }
                        });
                    } catch (Throwable e) {
                        log.error("transfer many message by pagecache exception", e);
                        getMessageResult.release();
                    }

                    response = null;
                }
                break;
            case ResponseCode.PULL_NOT_FOUND:

                if (brokerAllowSuspend && hasSuspendFlag) {
                    long pollingTimeMills = suspendTimeoutMillisLong;
                    // 长轮询模式
                    if (!this.brokerController.getBrokerConfig().isLongPollingEnable()) {
                        pollingTimeMills = this.brokerController.getBrokerConfig().getShortPollingTimeMills();
                    }

                    String topic = requestHeader.getTopic();
                    long offset = requestHeader.getQueueOffset();
                    int queueId = requestHeader.getQueueId();
                    // channel 网络通道，通过该通道向消息拉取客户端发送响应结果
                    PullRequest pullRequest = new PullRequest(request, channel, pollingTimeMills,
                        this.brokerController.getMessageStore().now(), offset, subscriptionData, messageFilter);
                    // 提交到PullRequestsHoldService线程中
                    this.brokerController.getPullRequestHoldService().suspendPullRequest(topic, queueId, pullRequest);
                    response = null;
                    break;
                }

            case ResponseCode.PULL_RETRY_IMMEDIATELY:
                break;
            case ResponseCode.PULL_OFFSET_MOVED:
                if (this.brokerController.getMessageStoreConfig().getBrokerRole() != BrokerRole.SLAVE
                    || this.brokerController.getMessageStoreConfig().isOffsetCheckInSlave()) {
                    MessageQueue mq = new MessageQueue();
                    mq.setTopic(requestHeader.getTopic());
                    mq.setQueueId(requestHeader.getQueueId());
                    mq.setBrokerName(this.brokerController.getBrokerConfig().getBrokerName());

                    OffsetMovedEvent event = new OffsetMovedEvent();
                    event.setConsumerGroup(requestHeader.getConsumerGroup());
                    event.setMessageQueue(mq);
                    event.setOffsetRequest(requestHeader.getQueueOffset());
                    event.setOffsetNew(getMessageResult.getNextBeginOffset());
                    this.generateOffsetMovedEvent(event);
                    log.warn(
                        "PULL_OFFSET_MOVED:correction offset. topic={}, groupId={}, requestOffset={}, newOffset={}, suggestBrokerId={}",
                        requestHeader.getTopic(), requestHeader.getConsumerGroup(), event.getOffsetRequest(), event.getOffsetNew(),
                        responseHeader.getSuggestWhichBrokerId());
                } else {
                    responseHeader.setSuggestWhichBrokerId(subscriptionGroupConfig.getBrokerId());
                    response.setCode(ResponseCode.PULL_RETRY_IMMEDIATELY);
                    log.warn("PULL_OFFSET_MOVED:none correction. topic={}, groupId={}, requestOffset={}, suggestBrokerId={}",
                        requestHeader.getTopic(), requestHeader.getConsumerGroup(), requestHeader.getQueueOffset(),
                        responseHeader.getSuggestWhichBrokerId());
                }

                break;
            default:
                assert false;
        }
    } else {
        response.setCode(ResponseCode.SYSTEM_ERROR);
        response.setRemark("store getMessage return null");
    }

    boolean storeOffsetEnable = brokerAllowSuspend;
    storeOffsetEnable = storeOffsetEnable && hasCommitOffsetFlag;
    storeOffsetEnable = storeOffsetEnable
        && this.brokerController.getMessageStoreConfig().getBrokerRole() != BrokerRole.SLAVE;
    if (storeOffsetEnable) {
        this.brokerController.getConsumerOffsetManager().commitOffset(RemotingHelper.parseChannelRemoteAddr(channel),
            requestHeader.getConsumerGroup(), requestHeader.getTopic(), requestHeader.getQueueId(), requestHeader.getCommitOffset());
    }
    return response;
}

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public GetMessageResult getMessage(final String group, final String topic, final int queueId, final long offset,
    final int maxMsgNums,
    final MessageFilter messageFilter) {
    if (this.shutdown) {
        log.warn("message store has shutdown, so getMessage is forbidden");
        return null;
    }

    if (!this.runningFlags.isReadable()) {
        log.warn("message store is not readable, so getMessage is forbidden " + this.runningFlags.getFlagBits());
        return null;
    }

    long beginTime = this.getSystemClock().now();

    GetMessageStatus status = GetMessageStatus.NO_MESSAGE_IN_QUEUE;
    // 待查找队列的偏移量
    long nextBeginOffset = offset;
    // 当前消息队列的最小偏移量
    long minOffset = 0;
    // 当前消息队列的最大偏移量
    long maxOffset = 0;

    GetMessageResult getResult = new GetMessageResult();

    // 当前CommitLog文件的最大偏移量
    final long maxOffsetPy = this.commitLog.getMaxOffset();

    // 根据topic与队列id获取对应的ConsumeQueue文件
    ConsumeQueue consumeQueue = findConsumeQueue(topic, queueId);
    if (consumeQueue != null) {
        minOffset = consumeQueue.getMinOffsetInQueue();
        maxOffset = consumeQueue.getMaxOffsetInQueue();

        if (maxOffset == 0) {
            // 代表当前消息队列没有消息
            status = GetMessageStatus.NO_MESSAGE_IN_QUEUE;
            nextBeginOffset = nextOffsetCorrection(offset, 0);
        } else if (offset < minOffset) {
            // 待拉取消息偏移量小于队列的起始偏移量
            status = GetMessageStatus.OFFSET_TOO_SMALL;
            nextBeginOffset = nextOffsetCorrection(offset, minOffset);
        } else if (offset == maxOffset) {
            // 待拉取消息偏移量等于队列的起始偏移量
            status = GetMessageStatus.OFFSET_OVERFLOW_ONE;
            nextBeginOffset = nextOffsetCorrection(offset, offset);
        } else if (offset > maxOffset) {
            // 带拉取消息偏移量大于队列的其实偏移量
            status = GetMessageStatus.OFFSET_OVERFLOW_BADLY;
            if (0 == minOffset) {
                nextBeginOffset = nextOffsetCorrection(offset, minOffset);
            } else {
                nextBeginOffset = nextOffsetCorrection(offset, maxOffset);
            }
        } else {
            // 偏移量合法
            SelectMappedBufferResult bufferConsumeQueue = consumeQueue.getIndexBuffer(offset);
            if (bufferConsumeQueue != null) {
                try {
                    status = GetMessageStatus.NO_MATCHED_MESSAGE;

                    long nextPhyFileStartOffset = Long.MIN_VALUE;
                    long maxPhyOffsetPulling = 0;

                    int i = 0;
                    // 客户端传过来的拉取消息条数限制
                    final int maxFilterMessageCount = Math.max(16000, maxMsgNums * ConsumeQueue.CQ_STORE_UNIT_SIZE);
                    final boolean diskFallRecorded = this.messageStoreConfig.isDiskFallRecorded();
                    ConsumeQueueExt.CqExtUnit cqExtUnit = new ConsumeQueueExt.CqExtUnit();
                    for (; i < bufferConsumeQueue.getSize() && i < maxFilterMessageCount; i += ConsumeQueue.CQ_STORE_UNIT_SIZE) {
                        long offsetPy = bufferConsumeQueue.getByteBuffer().getLong();
                        int sizePy = bufferConsumeQueue.getByteBuffer().getInt();
                        long tagsCode = bufferConsumeQueue.getByteBuffer().getLong();

                        maxPhyOffsetPulling = offsetPy;

                        if (nextPhyFileStartOffset != Long.MIN_VALUE) {
                            if (offsetPy < nextPhyFileStartOffset)
                                continue;
                        }

                        boolean isInDisk = checkInDiskByCommitOffset(offsetPy, maxOffsetPy);

                        if (this.isTheBatchFull(sizePy, maxMsgNums, getResult.getBufferTotalSize(), getResult.getMessageCount(),
                            isInDisk)) {
                            break;
                        }

                        boolean extRet = false, isTagsCodeLegal = true;
                        if (consumeQueue.isExtAddr(tagsCode)) {
                            extRet = consumeQueue.getExt(tagsCode, cqExtUnit);
                            if (extRet) {
                                tagsCode = cqExtUnit.getTagsCode();
                            } else {
                                // can't find ext content.Client will filter messages by tag also.
                                log.error("[BUG] can't find consume queue extend file content!addr={}, offsetPy={}, sizePy={}, topic={}, group={}",
                                    tagsCode, offsetPy, sizePy, topic, group);
                                isTagsCodeLegal = false;
                            }
                        }

                        if (messageFilter != null
                            // 根据tag hash码过滤
                            && !messageFilter.isMatchedByConsumeQueue(isTagsCodeLegal ? tagsCode : null, extRet ? cqExtUnit : null)) {
                            if (getResult.getBufferTotalSize() == 0) {
                                status = GetMessageStatus.NO_MATCHED_MESSAGE;
                            }

                            continue;
                        }

                        // 以上为从ConsumeQueue中获取消息在CommitLog中的偏移量及大小
                        // 以下为从CommitLog中获取对应的消息内容
                        SelectMappedBufferResult selectResult = this.commitLog.getMessage(offsetPy, sizePy);
                        if (null == selectResult) {
                            if (getResult.getBufferTotalSize() == 0) {
                                status = GetMessageStatus.MESSAGE_WAS_REMOVING;
                            }

                            nextPhyFileStartOffset = this.commitLog.rollNextFile(offsetPy);
                            continue;
                        }

                        if (messageFilter != null
                            && !messageFilter.isMatchedByCommitLog(selectResult.getByteBuffer().slice(), null)) {
                            if (getResult.getBufferTotalSize() == 0) {
                                status = GetMessageStatus.NO_MATCHED_MESSAGE;
                            }
                            // release...
                            selectResult.release();
                            continue;
                        }

                        this.storeStatsService.getGetMessageTransferedMsgCount().incrementAndGet();
                        getResult.addMessage(selectResult);
                        status = GetMessageStatus.FOUND;
                        nextPhyFileStartOffset = Long.MIN_VALUE;
                    }

                    if (diskFallRecorded) {
                        long fallBehind = maxOffsetPy - maxPhyOffsetPulling;
                        brokerStatsManager.recordDiskFallBehindSize(group, topic, queueId, fallBehind);
                    }

                    nextBeginOffset = offset + (i / ConsumeQueue.CQ_STORE_UNIT_SIZE);

                    long diff = maxOffsetPy - maxPhyOffsetPulling;
                    long memory = (long) (StoreUtil.TOTAL_PHYSICAL_MEMORY_SIZE
                        * (this.messageStoreConfig.getAccessMessageInMemoryMaxRatio() / 100.0));
                    getResult.setSuggestPullingFromSlave(diff > memory);
                } finally {

                    bufferConsumeQueue.release();
                }
            } else {
                status = GetMessageStatus.OFFSET_FOUND_NULL;
                nextBeginOffset = nextOffsetCorrection(offset, consumeQueue.rollNextFile(offset));
                log.warn("consumer request topic: " + topic + "offset: " + offset + " minOffset: " + minOffset + " maxOffset: "
                    + maxOffset + ", but access logic queue failed.");
            }
        }
    } else {
        status = GetMessageStatus.NO_MATCHED_LOGIC_QUEUE;
        nextBeginOffset = nextOffsetCorrection(offset, 0);
    }

    if (GetMessageStatus.FOUND == status) {
        this.storeStatsService.getGetMessageTimesTotalFound().incrementAndGet();
    } else {
        this.storeStatsService.getGetMessageTimesTotalMiss().incrementAndGet();
    }
    long elapsedTime = this.getSystemClock().now() - beginTime;
    this.storeStatsService.setGetMessageEntireTimeMax(elapsedTime);

    getResult.setStatus(status);
    getResult.setNextBeginOffset(nextBeginOffset);
    getResult.setMaxOffset(maxOffset);
    getResult.setMinOffset(minOffset);
    return getResult;
}

消息消费失败处理

非顺序消息 => CONSUMER_SEND_MSG_BACK
丢入重试队列或死信队列

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

    String namespace = NamespaceUtil.getNamespaceFromResource(requestHeader.getGroup());
    if (this.hasConsumeMessageHook() && !UtilAll.isBlank(requestHeader.getOriginMsgId())) {

        ConsumeMessageContext context = new ConsumeMessageContext();
        context.setNamespace(namespace);
        context.setConsumerGroup(requestHeader.getGroup());
        context.setTopic(requestHeader.getOriginTopic());
        context.setCommercialRcvStats(BrokerStatsManager.StatsType.SEND_BACK);
        context.setCommercialRcvTimes(1);
        context.setCommercialOwner(request.getExtFields().get(BrokerStatsManager.COMMERCIAL_OWNER));

        this.executeConsumeMessageHookAfter(context);
    }

    // 获取消费组的订阅配置信息
    SubscriptionGroupConfig subscriptionGroupConfig =
        this.brokerController.getSubscriptionGroupManager().findSubscriptionGroupConfig(requestHeader.getGroup());
    if (null == subscriptionGroupConfig) {
        response.setCode(ResponseCode.SUBSCRIPTION_GROUP_NOT_EXIST);
        response.setRemark("subscription group not exist, " + requestHeader.getGroup() + " "
            + FAQUrl.suggestTodo(FAQUrl.SUBSCRIPTION_GROUP_NOT_EXIST));
        return response;
    }

    if (!PermName.isWriteable(this.brokerController.getBrokerConfig().getBrokerPermission())) {
        response.setCode(ResponseCode.NO_PERMISSION);
        response.setRemark("the broker[" + this.brokerController.getBrokerConfig().getBrokerIP1() + "] sending message is forbidden");
        return response;
    }

    // 重试队列数量小于1
    if (subscriptionGroupConfig.getRetryQueueNums() <= 0) {
        response.setCode(ResponseCode.SUCCESS);
        response.setRemark(null);
        return response;
    }

    String newTopic = MixAll.getRetryTopic(requestHeader.getGroup());
    int queueIdInt = Math.abs(this.random.nextInt() % 99999999) % subscriptionGroupConfig.getRetryQueueNums();

    int topicSysFlag = 0;
    if (requestHeader.isUnitMode()) {
        topicSysFlag = TopicSysFlag.buildSysFlag(false, true);
    }

    // 创建重试队列
    TopicConfig topicConfig = this.brokerController.getTopicConfigManager().createTopicInSendMessageBackMethod(
        newTopic,
        subscriptionGroupConfig.getRetryQueueNums(),
        PermName.PERM_WRITE | PermName.PERM_READ, topicSysFlag);
    if (null == topicConfig) {
        response.setCode(ResponseCode.SYSTEM_ERROR);
        response.setRemark("topic[" + newTopic + "] not exist");
        return response;
    }

    if (!PermName.isWriteable(topicConfig.getPerm())) {
        response.setCode(ResponseCode.NO_PERMISSION);
        response.setRemark(String.format("the topic[%s] sending message is forbidden", newTopic));
        return response;
    }

    MessageExt msgExt = this.brokerController.getMessageStore().lookMessageByOffset(requestHeader.getOffset());
    if (null == msgExt) {
        response.setCode(ResponseCode.SYSTEM_ERROR);
        response.setRemark("look message by offset failed, " + requestHeader.getOffset());
        return response;
    }

    final String retryTopic = msgExt.getProperty(MessageConst.PROPERTY_RETRY_TOPIC);
    if (null == retryTopic) {
        MessageAccessor.putProperty(msgExt, MessageConst.PROPERTY_RETRY_TOPIC, msgExt.getTopic());
    }
    msgExt.setWaitStoreMsgOK(false);

    int delayLevel = requestHeader.getDelayLevel();

    int maxReconsumeTimes = subscriptionGroupConfig.getRetryMaxTimes();
    if (request.getVersion() >= MQVersion.Version.V3_4_9.ordinal()) {
        maxReconsumeTimes = requestHeader.getMaxReconsumeTimes();
    }

    if (msgExt.getReconsumeTimes() >= maxReconsumeTimes
        || delayLevel < 0) {
        newTopic = MixAll.getDLQTopic(requestHeader.getGroup());
        // 超出重试次数，丢到死信队列中
        queueIdInt = Math.abs(this.random.nextInt() % 99999999) % DLQ_NUMS_PER_GROUP;

        topicConfig = this.brokerController.getTopicConfigManager().createTopicInSendMessageBackMethod(newTopic,
            DLQ_NUMS_PER_GROUP,
            PermName.PERM_WRITE, 0
        );
        if (null == topicConfig) {
            response.setCode(ResponseCode.SYSTEM_ERROR);
            response.setRemark("topic[" + newTopic + "] not exist");
            return response;
        }
    } else {
        // 根据重试次数设置延迟级别
        if (0 == delayLevel) {
            delayLevel = 3 + msgExt.getReconsumeTimes();
        }

        msgExt.setDelayTimeLevel(delayLevel);
    }

    MessageExtBrokerInner msgInner = new MessageExtBrokerInner();
    msgInner.setTopic(newTopic);
    msgInner.setBody(msgExt.getBody());
    msgInner.setFlag(msgExt.getFlag());
    MessageAccessor.setProperties(msgInner, msgExt.getProperties());
    msgInner.setPropertiesString(MessageDecoder.messageProperties2String(msgExt.getProperties()));
    msgInner.setTagsCode(MessageExtBrokerInner.tagsString2tagsCode(null, msgExt.getTags()));

    msgInner.setQueueId(queueIdInt);
    msgInner.setSysFlag(msgExt.getSysFlag());
    msgInner.setBornTimestamp(msgExt.getBornTimestamp());
    msgInner.setBornHost(msgExt.getBornHost());
    msgInner.setStoreHost(this.getStoreHost());
    msgInner.setReconsumeTimes(msgExt.getReconsumeTimes() + 1);

    String originMsgId = MessageAccessor.getOriginMessageId(msgExt);
    MessageAccessor.setOriginMessageId(msgInner, UtilAll.isBlank(originMsgId) ? msgExt.getMsgId() : originMsgId);

    PutMessageResult putMessageResult = this.brokerController.getMessageStore().putMessage(msgInner);
    if (putMessageResult != null) {
        switch (putMessageResult.getPutMessageStatus()) {
            case PUT_OK:
                String backTopic = msgExt.getTopic();
                String correctTopic = msgExt.getProperty(MessageConst.PROPERTY_RETRY_TOPIC);
                if (correctTopic != null) {
                    backTopic = correctTopic;
                }

                this.brokerController.getBrokerStatsManager().incSendBackNums(requestHeader.getGroup(), backTopic);

                response.setCode(ResponseCode.SUCCESS);
                response.setRemark(null);

                return response;
            default:
                break;
        }

        response.setCode(ResponseCode.SYSTEM_ERROR);
        response.setRemark(putMessageResult.getPutMessageStatus().name());
        return response;
    }

    response.setCode(ResponseCode.SYSTEM_ERROR);
    response.setRemark("putMessageResult is null");
    return response;
}

消息长轮询

假如消息拉取开启了长轮询，服务端在没有新消息的时候，会将客户端的请求hold住（直至超时），然后等有新消息时再激活客户端请求，给客户端传输数据

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case ResponseCode.PULL_NOT_FOUND:

    if (brokerAllowSuspend && hasSuspendFlag) {
        long pollingTimeMills = suspendTimeoutMillisLong;
        // 长轮询模式
        if (!this.brokerController.getBrokerConfig().isLongPollingEnable()) {
            pollingTimeMills = this.brokerController.getBrokerConfig().getShortPollingTimeMills();
        }

        String topic = requestHeader.getTopic();
        long offset = requestHeader.getQueueOffset();
        int queueId = requestHeader.getQueueId();
        // channel 网络通道，通过该通道向消息拉取客户端发送响应结果
        PullRequest pullRequest = new PullRequest(request, channel, pollingTimeMills,
            this.brokerController.getMessageStore().now(), offset, subscriptionData, messageFilter);
        // 提交到PullRequestsHoldService线程中
        this.brokerController.getPullRequestHoldService().suspendPullRequest(topic, queueId, pullRequest);
        response = null;
        break;
    }

PullRequestHoldService定时执行

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@Override
public void run() {
    log.info("{} service started", this.getServiceName());
    while (!this.isStopped()) {
        try {
            if (this.brokerController.getBrokerConfig().isLongPollingEnable()) {
                this.waitForRunning(5 * 1000);
            } else {
                this.waitForRunning(this.brokerController.getBrokerConfig().getShortPollingTimeMills());
            }

            long beginLockTimestamp = this.systemClock.now();
            this.checkHoldRequest();
            long costTime = this.systemClock.now() - beginLockTimestamp;
            if (costTime > 5 * 1000) {
                log.info("[NOTIFYME] check hold request cost {} ms.", costTime);
            }
        } catch (Throwable e) {
            log.warn(this.getServiceName() + " service has exception. ", e);
        }
    }

    log.info("{} service end", this.getServiceName());
}

public void notifyMessageArriving(final String topic, final int queueId, final long maxOffset, final Long tagsCode,
    long msgStoreTime, byte[] filterBitMap, Map<String, String> properties) {
    String key = this.buildKey(topic, queueId);
    ManyPullRequest mpr = this.pullRequestTable.get(key);
    if (mpr != null) {
        List<PullRequest> requestList = mpr.cloneListAndClear();
        if (requestList != null) {
            List<PullRequest> replayList = new ArrayList<PullRequest>();

            for (PullRequest request : requestList) {
                long newestOffset = maxOffset;
                if (newestOffset <= request.getPullFromThisOffset()) {
                    newestOffset = this.brokerController.getMessageStore().getMaxOffsetInQueue(topic, queueId);
                }

                if (newestOffset > request.getPullFromThisOffset()) {
                    boolean match = request.getMessageFilter().isMatchedByConsumeQueue(tagsCode,
                        new ConsumeQueueExt.CqExtUnit(tagsCode, msgStoreTime, filterBitMap));
                    // match by bit map, need eval again when properties is not null.
                    if (match && properties != null) {
                        match = request.getMessageFilter().isMatchedByCommitLog(null, properties);
                    }

                    if (match) {
                        try {
                            this.brokerController.getPullMessageProcessor().executeRequestWhenWakeup(request.getClientChannel(),
                                request.getRequestCommand());
                        } catch (Throwable e) {
                            log.error("execute request when wakeup failed.", e);
                        }
                        continue;
                    }
                }

                if (System.currentTimeMillis() >= (request.getSuspendTimestamp() + request.getTimeoutMillis())) {
                    try {
                        this.brokerController.getPullMessageProcessor().executeRequestWhenWakeup(request.getClientChannel(),
                            request.getRequestCommand());
                    } catch (Throwable e) {
                        log.error("execute request when wakeup failed.", e);
                    }
                    continue;
                }

                replayList.add(request);
            }

            if (!replayList.isEmpty()) {
                mpr.addPullRequest(replayList);
            }
        }
    }
}
  • Post title：RocketMQ流程
  • Post author：大黄
  • Create time：2023-04-06 11:14:15
  • Post link：https://huangbangjing.cn/2023/04/06/RocketMQ流程/
  • Copyright Notice：All articles in this blog are licensed under BY-NC-SA unless stating additionally.