RocketMQ原理学习---生产者普通消息发送

迈不过友情╰ 2022-04-17 00:25 282阅读 0赞

上一篇博客[RocketMQ原理学习-- Name Server][RocketMQ_-- Name Server]中我们介绍了Name Server提供的相关功能，这篇博客我们来介绍一下生产者消息发送相关的内容。

消息发送示例：

public class Producer {
    
        public static void main(String[] args) throws MQClientException, InterruptedException {
            DefaultMQProducer producer = new DefaultMQProducer("rmq-group");
            producer.setNamesrvAddr("localhost:9876");
            producer.start();
            try {
                for (int i = 0; i < 3; i++) {
                    Message msg = new Message("TopicA-test",// topic
                            "TagA",// tag
                            (new Date() + "Hello RocketMQ ,QuickStart 11" + i)
                                    .getBytes()// body
                    );
                    SendResult sendResult = producer.send(msg);
                    System.out.println(sendResult);
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
           producer.shutdown();
        }
    
    }

在DefaultMQProducer中调用send方法发送消息

public SendResult send(Message msg) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
            return this.defaultMQProducerImpl.send(msg);
        }

最终是调用DefaultMQProducerImpl的send方法来发送消息

public SendResult send(Message msg) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
            return this.send(msg, (long)this.defaultMQProducer.getSendMsgTimeout());
        }

最终会调用sendDefaultImpl方法来发送消息：

（1）在发送消息时会根据消息的Topic名称从Name Server中根据Topic名称来获取Broker相关的地址信息TopicPublishInfo topicPublishInfo = this.tryToFindTopicPublishInfo(msg.getTopic());

（2）由于一个Broker中对于每个Topic会有多个MessageQueue，生产者默认选择MessageQueue策略为轮询MessageQueue mqSelected = this.selectOneMessageQueue(topicPublishInfo, info);

（3）选择了MessageQueue后，会根据MessageQueue中Broker信息调用sendResult = this.sendKernelImpl(msg, mq, communicationMode, sendCallback, topicPublishInfo, timeout);发送消息。

private SendResult sendDefaultImpl(Message msg, CommunicationMode communicationMode, SendCallback sendCallback, long timeout) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
            this.makeSureStateOK();
            Validators.checkMessage(msg, this.defaultMQProducer);
            long invokeID = this.random.nextLong();
            long beginTimestampFirst = System.currentTimeMillis();
            long beginTimestampPrev = beginTimestampFirst;
            TopicPublishInfo topicPublishInfo = this.tryToFindTopicPublishInfo(msg.getTopic());
            if (topicPublishInfo != null && topicPublishInfo.ok()) {
                MessageQueue mq = null;
                Exception exception = null;
                SendResult sendResult = null;
                int timesTotal = communicationMode == CommunicationMode.SYNC ? 1 + this.defaultMQProducer.getRetryTimesWhenSendFailed() : 1;
                int times = 0;
                String[] brokersSent = new String[timesTotal];
    
                while(true) {
                    String info;
                    if (times < timesTotal) {
                        info = null == mq ? null : mq.getBrokerName();
                        MessageQueue mqSelected = this.selectOneMessageQueue(topicPublishInfo, info);
                        if (mqSelected != null) {
                            mq = mqSelected;
                            brokersSent[times] = mqSelected.getBrokerName();
    
                            long endTimestamp;
                            try {
                                beginTimestampPrev = System.currentTimeMillis();
                                sendResult = this.sendKernelImpl(msg, mq, communicationMode, sendCallback, topicPublishInfo, timeout);
                                endTimestamp = System.currentTimeMillis();
                                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 || !this.defaultMQProducer.isRetryAnotherBrokerWhenNotStoreOK()) {
                                        return sendResult;
                                    }
                                }
                            } catch (RemotingException var24) {
                                endTimestamp = System.currentTimeMillis();
                                this.updateFaultItem(mqSelected.getBrokerName(), endTimestamp - beginTimestampPrev, true);
                                this.log.warn(String.format("sendKernelImpl exception, resend at once, InvokeID: %s, RT: %sms, Broker: %s", invokeID, endTimestamp - beginTimestampPrev, mqSelected), var24);
                                this.log.warn(msg.toString());
                                exception = var24;
                            } catch (MQClientException var25) {
                                endTimestamp = System.currentTimeMillis();
                                this.updateFaultItem(mqSelected.getBrokerName(), endTimestamp - beginTimestampPrev, true);
                                this.log.warn(String.format("sendKernelImpl exception, resend at once, InvokeID: %s, RT: %sms, Broker: %s", invokeID, endTimestamp - beginTimestampPrev, mqSelected), var25);
                                this.log.warn(msg.toString());
                                exception = var25;
                            } catch (MQBrokerException var26) {
                                endTimestamp = System.currentTimeMillis();
                                this.updateFaultItem(mqSelected.getBrokerName(), endTimestamp - beginTimestampPrev, true);
                                this.log.warn(String.format("sendKernelImpl exception, resend at once, InvokeID: %s, RT: %sms, Broker: %s", invokeID, endTimestamp - beginTimestampPrev, mqSelected), var26);
                                this.log.warn(msg.toString());
                                exception = var26;
                                switch(var26.getResponseCode()) {
                                case 1:
                                case 14:
                                case 16:
                                case 17:
                                case 204:
                                case 205:
                                    break;
                                default:
                                    if (sendResult != null) {
                                        return sendResult;
                                    }
    
                                    throw var26;
                                }
                            } catch (InterruptedException var27) {
                                endTimestamp = System.currentTimeMillis();
                                this.updateFaultItem(mqSelected.getBrokerName(), endTimestamp - beginTimestampPrev, false);
                                this.log.warn(String.format("sendKernelImpl exception, throw exception, InvokeID: %s, RT: %sms, Broker: %s", invokeID, endTimestamp - beginTimestampPrev, mqSelected), var27);
                                this.log.warn(msg.toString());
                                this.log.warn("sendKernelImpl exception", var27);
                                this.log.warn(msg.toString());
                                throw var27;
                            }
    
                            ++times;
                            continue;
                        }
                    }
    
                    if (sendResult != null) {
                        return sendResult;
                    }
    
                    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 = info + FAQUrl.suggestTodo("http://rocketmq.apache.org/docs/faq/");
                    MQClientException mqClientException = new MQClientException(info, (Throwable)exception);
                    if (exception instanceof MQBrokerException) {
                        mqClientException.setResponseCode(((MQBrokerException)exception).getResponseCode());
                    } else if (exception instanceof RemotingConnectException) {
                        mqClientException.setResponseCode(10001);
                    } else if (exception instanceof RemotingTimeoutException) {
                        mqClientException.setResponseCode(10002);
                    } else if (exception instanceof MQClientException) {
                        mqClientException.setResponseCode(10003);
                    }
    
                    throw mqClientException;
                }
            } else {
                List<String> nsList = this.getmQClientFactory().getMQClientAPIImpl().getNameServerAddressList();
                if (null != nsList && !nsList.isEmpty()) {
                    throw (new MQClientException("No route info of this topic, " + msg.getTopic() + FAQUrl.suggestTodo("http://rocketmq.apache.org/docs/faq/"), (Throwable)null)).setResponseCode(10005);
                } else {
                    throw (new MQClientException("No name server address, please set it." + FAQUrl.suggestTodo("http://rocketmq.apache.org/docs/faq/"), (Throwable)null)).setResponseCode(10004);
                }
            }
        }

在sendKernelImpl中会获取Broker的地址信息，然后组装消息信息，调用MQClientAPIImpl的sendMessage方法将消息发送到Broker中。

private SendResult sendKernelImpl(Message msg, MessageQueue mq, CommunicationMode communicationMode, SendCallback sendCallback, TopicPublishInfo topicPublishInfo, long timeout) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
            //获取Broker的地址信息
            String brokerAddr = this.mQClientFactory.findBrokerAddressInPublish(mq.getBrokerName());
            if (null == brokerAddr) {
                this.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();
    
                SendResult var28;
                try {
                    if (!(msg instanceof MessageBatch)) {
                        MessageClientIDSetter.setUniqID(msg);
                    }
    
                    int sysFlag = 0;
                    if (this.tryToCompressMessage(msg)) {
                        sysFlag |= 1;
                    }
    
                    String tranMsg = msg.getProperty("TRAN_MSG");
                    if (tranMsg != null && Boolean.parseBoolean(tranMsg)) {
                        sysFlag |= 4;
                    }
    
                    if (this.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);
                    }
    
                    if (this.hasSendMessageHook()) {
                        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);
                        String isTrans = msg.getProperty("TRAN_MSG");
                        if (isTrans != null && isTrans.equals("true")) {
                            context.setMsgType(MessageType.Trans_Msg_Half);
                        }
    
                        if (msg.getProperty("__STARTDELIVERTIME") != null || msg.getProperty("DELAY") != null) {
                            context.setMsgType(MessageType.Delay_Msg);
                        }
    
                        this.executeSendMessageHookBefore(context);
                    }
                    //组装消息请求头信息
                    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("%RETRY%")) {
                        String reconsumeTimes = MessageAccessor.getReconsumeTime(msg);
                        if (reconsumeTimes != null) {
                            requestHeader.setReconsumeTimes(Integer.valueOf(reconsumeTimes));
                            MessageAccessor.clearProperty(msg, "RECONSUME_TIME");
                        }
    
                        String maxReconsumeTimes = MessageAccessor.getMaxReconsumeTimes(msg);
                        if (maxReconsumeTimes != null) {
                            requestHeader.setMaxReconsumeTimes(Integer.valueOf(maxReconsumeTimes));
                            MessageAccessor.clearProperty(msg, "MAX_RECONSUME_TIMES");
                        }
                    }
    
                    SendResult sendResult = null;
                    switch(communicationMode) {
                    //异步消息
                    case ASYNC:
                        sendResult = this.mQClientFactory.getMQClientAPIImpl().sendMessage(brokerAddr, mq.getBrokerName(), msg, requestHeader, timeout, communicationMode, sendCallback, topicPublishInfo, this.mQClientFactory, this.defaultMQProducer.getRetryTimesWhenSendAsyncFailed(), context, this);
                        break;
                    case ONEWAY:
                    //同步消息
                    case SYNC:
                        sendResult = this.mQClientFactory.getMQClientAPIImpl().sendMessage(brokerAddr, mq.getBrokerName(), msg, requestHeader, timeout, communicationMode, context, this);
                        break;
                    default:
                        assert false;
                    }
    
                    if (this.hasSendMessageHook()) {
                        context.setSendResult(sendResult);
                        this.executeSendMessageHookAfter(context);
                    }
    
                    var28 = sendResult;
                } catch (RemotingException var21) {
                    if (this.hasSendMessageHook()) {
                        context.setException(var21);
                        this.executeSendMessageHookAfter(context);
                    }
    
                    throw var21;
                } catch (MQBrokerException var22) {
                    if (this.hasSendMessageHook()) {
                        context.setException(var22);
                        this.executeSendMessageHookAfter(context);
                    }
    
                    throw var22;
                } catch (InterruptedException var23) {
                    if (this.hasSendMessageHook()) {
                        context.setException(var23);
                        this.executeSendMessageHookAfter(context);
                    }
    
                    throw var23;
                } finally {
                    msg.setBody(prevBody);
                }
    
                return var28;
            } else {
                throw new MQClientException("The broker[" + mq.getBrokerName() + "] not exist", (Throwable)null);
            }
        }

在MQClientAPIImpl中会调用底层通信模块NettyRemotingClient的invokeSync方法将消息信息发送到Broker中。

public SendResult sendMessage(String addr, String brokerName, Message msg, SendMessageRequestHeader requestHeader, long timeoutMillis, CommunicationMode communicationMode, SendCallback sendCallback, TopicPublishInfo topicPublishInfo, MQClientInstance instance, int retryTimesWhenSendFailed, SendMessageContext context, DefaultMQProducerImpl producer) throws RemotingException, MQBrokerException, InterruptedException {
            RemotingCommand request = null;
    		//创建消息
            if (!sendSmartMsg && !(msg instanceof MessageBatch)) {
                request = RemotingCommand.createRequestCommand(10, requestHeader);
            } else {
                SendMessageRequestHeaderV2 requestHeaderV2 = SendMessageRequestHeaderV2.createSendMessageRequestHeaderV2(requestHeader);
                request = RemotingCommand.createRequestCommand(msg instanceof MessageBatch ? 320 : 310, requestHeaderV2);
            }
    		//添加消息请求体
            request.setBody(msg.getBody());
            switch(communicationMode) {
            case ONEWAY:
                this.remotingClient.invokeOneway(addr, request, timeoutMillis);
                return null;
            case ASYNC:
                AtomicInteger times = new AtomicInteger();
                this.sendMessageAsync(addr, brokerName, msg, timeoutMillis, request, sendCallback, topicPublishInfo, instance, retryTimesWhenSendFailed, times, context, producer);
                return null;
            case SYNC:
                return this.sendMessageSync(addr, brokerName, msg, timeoutMillis, request);
            default:
                assert false;
    
                return null;
            }
    }

在NettyRemotingClient中调用invokeSync方法根据Broker地址信息创建Channel，然后根据request请求信息发起消息，并获取返回值RemotingCommand。

public RemotingCommand invokeSync(String addr, RemotingCommand request, long timeoutMillis) throws InterruptedException, RemotingConnectException, RemotingSendRequestException, RemotingTimeoutException {
            Channel channel = this.getAndCreateChannel(addr);
            if (channel != null && channel.isActive()) {
                try {
                    if (this.rpcHook != null) {
                        this.rpcHook.doBeforeRequest(addr, request);
                    }
    
                    RemotingCommand response = this.invokeSyncImpl(channel, request, timeoutMillis);
                    if (this.rpcHook != null) {
                        this.rpcHook.doAfterResponse(RemotingHelper.parseChannelRemoteAddr(channel), request, response);
                    }
    
                    return response;
                } catch (RemotingSendRequestException var7) {
                    log.warn("invokeSync: send request exception, so close the channel[{}]", addr);
                    this.closeChannel(addr, channel);
                    throw var7;
                } catch (RemotingTimeoutException var8) {
                    if (this.nettyClientConfig.isClientCloseSocketIfTimeout()) {
                        this.closeChannel(addr, channel);
                        log.warn("invokeSync: close socket because of timeout, {}ms, {}", timeoutMillis, addr);
                    }
    
                    log.warn("invokeSync: wait response timeout exception, the channel[{}]", addr);
                    throw var8;
                }
            } else {
                this.closeChannel(addr, channel);
                throw new RemotingConnectException(addr);
            }
        }

总结：

（1）生产者根据Topic名称从Name Server中获取相关Broker信息，根据Broker的地址信息将消息发送到对应Broker地址中

（2）对于同一个Topic，一个Broker对应多个MessageQueue(Topic可以在多个Broker中)，生产者默认通过取模轮询方式将消息发送到对应的MessageQueue中。

（3）生产者提供了接口send(Message msg, MessageQueueSelector selector, Object arg)，我们可以通过实现MessageQueueSelector接口可以实现选取MessageQueue的方法，例如实现有序消息就可以将需要有序的消息发送到同一个MessageQueue即可。

[RocketMQ_-- Name Server]: https://blog.csdn.net/qq924862077/article/details/84672586