本章将简单分析下rocketmq的消息发送源码，如果错误的地方，欢迎指出！源码版本为release-5.2.0
一：整体概括
二：具体流程图
三：详细源码解析
以下是针对同步消息的发送的源码详细讲解
消息的发送类DefaultMQProducer
org.apache.rocketmq.client.producer.DefaultMQProducer#send(org.apache.rocketmq.common.message.Message)
@Override
public SendResult send(
Message msg) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
//withNamespace方法作用 为消息的topic添加命名空间
msg.setTopic(withNamespace(msg.getTopic()));
// 开启自动批处理
if (this.getAutoBatch() && !(msg instanceof MessageBatch)) {
return sendByAccumulator(msg, null, null);
} else {
//正常同步消息发送
return sendDirect(msg, null, null);
}
}
继续跟
org.apache.rocketmq.client.producer.DefaultMQProducer#sendDirect
public SendResult sendDirect(Message msg, MessageQueue mq,
SendCallback sendCallback) throws MQClientException, RemotingException, InterruptedException, MQBrokerException {
// send in sync mode
if (sendCallback == null) {
if (mq == null) {
//同步发送消息，不指定messagequeue
return this.defaultMQProducerImpl.send(msg);
} else {
//同步发送消息，不指定messagequeue
return this.defaultMQProducerImpl.send(msg, mq);
}
} else {
//异步消息
if (mq == null) {
this.defaultMQProducerImpl.send(msg, sendCallback);
} else {
this.defaultMQProducerImpl.send(msg, mq, sendCallback);
}
return null;
}
}
org.apache.rocketmq.client.impl.producer.DefaultMQProducerImpl#send(org.apache.rocketmq.common.message.Message)
public SendResult send(
Message msg) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
return send(msg, this.defaultMQProducer.getSendMsgTimeout());
}
```
public SendResult send(Message msg,
long timeout) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
return this.sendDefaultImpl(msg, CommunicationMode.SYNC, null, timeout);
}
```
org.apache.rocketmq.client.impl.producer.DefaultMQProducerImpl#sendDefaultImpl 发送消息的逻辑核心
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 不能为空 最大长度不超过127个字符 支持的符号 数字 字母 _ - | 不能包含其他字符
Validators.checkMessage(msg, this.defaultMQProducer);
final long invokeID = random.nextLong();
long beginTimestampFirst = System.currentTimeMillis();
long beginTimestampPrev = beginTimestampFirst;
long endTimestamp = beginTimestampFirst;
// 获取消息主题的路由信息 如果本地缓存没有 则从 NameServer 获取
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 同步发送默认3次 异步发送默认2次
int timesTotal = communicationMode == CommunicationMode.SYNC ? 1 + this.defaultMQProducer.getRetryTimesWhenSendFailed() : 1;
int times = 0;
String[] brokersSent = new String[timesTotal];
boolean resetIndex = false;
for (; times < timesTotal; times++) {
String lastBrokerName = null == mq ? null : mq.getBrokerName();
if (times > 0) {
resetIndex = true;
}
//获取topic下的messagequeue 详细规则下面讲解
MessageQueue mqSelected = this.selectOneMessageQueue(topicPublishInfo, lastBrokerName, resetIndex);
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;
}
// MQClientInstance 获取 MQClientAPIImpl 对象 通过网络模块发送消息
sendResult = this.sendKernelImpl(msg, mq, communicationMode, sendCallback, topicPublishInfo, timeout - costTime);
endTimestamp = System.currentTimeMillis();
// 更新broker故障信息
this.updateFaultItem(mq.getBrokerName(), endTimestamp - beginTimestampPrev, false, true);
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 (MQClientException e) {
endTimestamp = System.currentTimeMillis();
this.updateFaultItem(mq.getBrokerName(), endTimestamp - beginTimestampPrev, false, true);
log.warn("sendKernelImpl exception, resend at once, InvokeID: %s, RT: %sms, Broker: %s", invokeID, endTimestamp - beginTimestampPrev, mq, e);
log.warn(msg.toString());
exception = e;
continue;
} catch (RemotingException e) {
endTimestamp = System.currentTimeMillis();
if (this.mqFaultStrategy.isStartDetectorEnable()) {
// Set this broker unreachable when detecting schedule task is running for RemotingException.
this.updateFaultItem(mq.getBrokerName(), endTimestamp - beginTimestampPrev, true, false);
} else {
// Otherwise, isolate this broker.
this.updateFaultItem(mq.getBrokerName(), endTimestamp - beginTimestampPrev, true, true);
}
log.warn("sendKernelImpl exception, resend at once, InvokeID: %s, RT: %sms, Broker: %s", invokeID, endTimestamp - beginTimestampPrev, mq, e);
if (log.isDebugEnabled()) {
log.debug(msg.toString());
}
exception = e;
continue;
} catch (MQBrokerException e) {
endTimestamp = System.currentTimeMillis();
this.updateFaultItem(mq.getBrokerName(), endTimestamp - beginTimestampPrev, true, false);
log.warn("sendKernelImpl exception, resend at once, InvokeID: %s, RT: %sms, Broker: %s", invokeID, endTimestamp - beginTimestampPrev, mq, e);
if (log.isDebugEnabled()) {
log.debug(msg.toString());
}
exception = e;
if (this.defaultMQProducer.getRetryResponseCodes().contains(e.getResponseCode())) {
continue;
} else {
if (sendResult != null) {
return sendResult;
}
throw e;
}
} catch (InterruptedException e) {
endTimestamp = System.currentTimeMillis();
this.updateFaultItem(mq.getBrokerName(), endTimestamp - beginTimestampPrev, false, true);
log.warn("sendKernelImpl exception, throw exception, InvokeID: %s, RT: %sms, Broker: %s", invokeID, endTimestamp - beginTimestampPrev, mq, e);
if (log.isDebugEnabled()) {
log.debug(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);
获取topic下的messagequeue规则，selectOneMessageQueue分两种情况一种是开启故障延迟规避机制，一种是随机选择一个messagequeue；
public MessageQueue selectOneMessageQueue(final TopicPublishInfo tpInfo, final String lastBrokerName, final boolean resetIndex) {
// 获取当前线程的BrokerFilter
BrokerFilter brokerFilter = threadBrokerFilter.get();
brokerFilter.setLastBrokerName(lastBrokerName);
//sendLatencyFaultEnable配置的核心作用是实现消息发送端的故障延迟规避机制，
// 通过动态隔离高延迟或不可用的 Broker 节点，提升生产者的整体可用性与系统稳定性。
// 该机制通过实时监测 Broker 的响应状态，在特定时间段内自动规避异常节点，避免因单点故障或网络波动导致消息发送性能下降
if (this.sendLatencyFaultEnable) {
if (resetIndex) {
tpInfo.resetIndex();
}
//availableFilter 作用 通过latencyFaultTolerance.isAvailable(mq.getBrokerName())判断broker是否可用
MessageQueue mq = tpInfo.selectOneMessageQueue(availableFilter, brokerFilter);
if (mq != null) {
return mq;
}
mq = tpInfo.selectOneMessageQueue(reachableFilter, brokerFilter);
if (mq != null) {
return mq;
}
return tpInfo.selectOneMessageQueue();
}
//tpInfo.selectOneMessageQueue 作用是随机选择一个MessageQueue
MessageQueue mq = tpInfo.selectOneMessageQueue(brokerFilter);
if (mq != null) {
return mq;
}
return tpInfo.selectOneMessageQueue();
}
rocketmq同步消息比较简单，接下来会再讲解broker收到消息的储存以及消息的网络模块；
