RocketMQ producer发送者浅析
作者:Acqierement
发送者其实比较简单,需要做的就是首先确定往哪里发送,其次怎么让消息发送顺畅。我们就看一下具体的代码吧。
首先调用start方法。完成各个类的初始化,启动多个定时任务,其中一个定时任务是updateTopicRouteInfoFromNameServer,这个方法里面和nameService建立长连接,同时维护了topicRouteTable和brokerAddrTable等缓存。topicRouteTable里面维护了这个topic包括有哪些queue和broker。这样producer才可以知道要发往哪里。
启动的流程主要在这个方法中:
MQClientInstance#start
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 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; } } }
其中启动了一系列定时任务,包括org.apache.rocketmq.client.impl.factory.MQClientInstance#updateTopicRouteInfoFromNameServer这个方法
public boolean updateTopicRouteInfoFromNameServer(final String topic, boolean isDefault, DefaultMQProducer defaultMQProducer) { try { if (this.lockNamesrv.tryLock(LOCK_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS)) { try { TopicRouteData topicRouteData; if (isDefault && defaultMQProducer != null) { // 从nameServer获取topciRouteData topicRouteData = this.mQClientAPIImpl.getDefaultTopicRouteInfoFromNameServer(defaultMQProducer.getCreateTopicKey(), clientConfig.getMqClientApiTimeout()); if (topicRouteData != null) { for (QueueData data : topicRouteData.getQueueDatas()) { int queueNums = Math.min(defaultMQProducer.getDefaultTopicQueueNums(), data.getReadQueueNums()); data.setReadQueueNums(queueNums); data.setWriteQueueNums(queueNums); } } } else { topicRouteData = this.mQClientAPIImpl.getTopicRouteInfoFromNameServer(topic, clientConfig.getMqClientApiTimeout()); } if (topicRouteData != null) { TopicRouteData old = this.topicRouteTable.get(topic); boolean changed = topicRouteData.topicRouteDataChanged(old); if (!changed) { changed = this.isNeedUpdateTopicRouteInfo(topic); } else { log.info("the topic[{}] route info changed, old[{}] ,new[{}]", topic, old, topicRouteData); } if (changed) { for (BrokerData bd : topicRouteData.getBrokerDatas()) { this.brokerAddrTable.put(bd.getBrokerName(), bd.getBrokerAddrs()); } // Update endpoint map { ConcurrentMap<MessageQueue, String> mqEndPoints = topicRouteData2EndpointsForStaticTopic(topic, topicRouteData); if (!mqEndPoints.isEmpty()) { topicEndPointsTable.put(topic, mqEndPoints); } } // Update Pub info { // 生成topicPublishInfo TopicPublishInfo publishInfo = topicRouteData2TopicPublishInfo(topic, topicRouteData); publishInfo.setHaveTopicRouterInfo(true); for (Entry<String, MQProducerInner> entry : this.producerTable.entrySet()) { MQProducerInner impl = entry.getValue(); if (impl != null) { // 更新 topicPublishInfo impl.updateTopicPublishInfo(topic, publishInfo); } } } // Update sub info if (!consumerTable.isEmpty()) { Set<MessageQueue> subscribeInfo = topicRouteData2TopicSubscribeInfo(topic, topicRouteData); for (Entry<String, MQConsumerInner> entry : this.consumerTable.entrySet()) { MQConsumerInner impl = entry.getValue(); if (impl != null) { impl.updateTopicSubscribeInfo(topic, subscribeInfo); } } } TopicRouteData cloneTopicRouteData = new TopicRouteData(topicRouteData); log.info("topicRouteTable.put. Topic = {}, TopicRouteData[{}]", topic, cloneTopicRouteData); this.topicRouteTable.put(topic, cloneTopicRouteData); return true; } } else { log.warn("updateTopicRouteInfoFromNameServer, getTopicRouteInfoFromNameServer return null, Topic: {}. [{}]", topic, this.clientId); } } catch (MQClientException e) { if (!topic.startsWith(MixAll.RETRY_GROUP_TOPIC_PREFIX) && !topic.equals(TopicValidator.AUTO_CREATE_TOPIC_KEY_TOPIC)) { log.warn("updateTopicRouteInfoFromNameServer Exception", e); } } catch (RemotingException e) { log.error("updateTopicRouteInfoFromNameServer Exception", e); throw new IllegalStateException(e); } finally { this.lockNamesrv.unlock(); } } else { log.warn("updateTopicRouteInfoFromNameServer tryLock timeout {}ms. [{}]", LOCK_TIMEOUT_MILLIS, this.clientId); } } catch (InterruptedException e) { log.warn("updateTopicRouteInfoFromNameServer Exception", e); } return false; }
通过方法名也知道是从nameServer获取这个topic相关的broke数据,拿到TopicRouteData数据。先更新brokerAddrTable,存储borker具体的地址。然后在org.apache.rocketmq.client.impl.factory.MQClientInstance#topicRouteData2TopicPublishInfo里面再进一步生成TopicPublishInfo数据。TopicPublishInfo是对TopicRouteData的一个封装,除了TopicRouteData,还有messageQueue数据,messageQueue是Queue和Borker的交集,会根据配置的queue数量,生成具体的messageQueue,queueId就是0,1,2,3,4他们自己的顺序。
所以有了TopicPublishInfo数据,就知道往哪里发了。
发送消息的过程。
- 先找到TopicPublishInfo。TopicPublishInfo里面有一个MessageQueue的list。
- 从MessageQueueList里面拿到一个messageQueue。 如果没有开启sendLatencyFaultEnable,默认就是采用轮询方法。具体的轮询方式就是,TopicPublishInfo里面维护了一个序号index,每次index自增1,然后通过index去MessageQueueList里面拿一个。
- 拿到了MessageQueue之后,里面有broker的name,根据name去找broker的ip地址,发送数据。这个ip地址就是前面提到的brokerAddrTable变量,在updateTopicRouteInfoFromNameServer方法里面维护的。
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