RocketMq
发送端启动过程
- 通过一个单例模式（Singleton Pattern）的 MQClientManager 获取 MQClientInstance 的实例 mQClientFactory，没有则自动创建新的实例；
- 在 mQClientFactory 中注册自己；
- 启动 mQClientFactory；
- 给所有 Broker 发送心跳。
public void start(final boolean startFactory) throws MQClientException {
switch (this.serviceState) {
case CREATE_JUST:
this.serviceState = ServiceState.START_FAILED;
// 省略参数检查和异常情况处理的代码
// 1. 获取MQClientInstance的实例mQClientFactory，没有则自动创建新的实例
// 此处通过 一个concurrentMap factoryTable 保证单例
this.mQClientFactory = MQClientManager.getInstance().getAndCreateMQClientInstance(this.defaultMQProducer, rpcHook);
// 2. 在mQClientFactory中注册自己 最终是放入一个concurrentMap中
boolean registerOK = mQClientFactory.registerProducer(this.defaultMQProducer.getProducerGroup(), this);
// 省略异常处理代码
// 3. 启动mQClientFactory
if (startFactory) {
mQClientFactory.start();
}
this.serviceState = ServiceState.RUNNING;
break;
case RUNNING:
case START_FAILED:
case SHUTDOWN_ALREADY:
// 省略异常处理代码
default:
break;
}
// 4. 给所有Broker发送心跳
this.mQClientFactory.sendHeartbeatToAllBrokerWithLock();
}
其中，第三步的具体逻辑为：
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();
}
// 1. 启动请求响应通道
this.mQClientAPIImpl.start();
// 2.启动定时任务
this.startScheduledTask();
// 3.开启拉消息服务 暂时不理解为什么producer要pull service
this.pullMessageService.start();
// 4. rebalanceService服务启动
this.rebalanceService.start();
// 5.启动发送实例
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;
}
}
}
- DefaultMQProducerImpl：Producer 的内部实现类，大部分 Producer 的业务逻辑，也就是发消息的逻辑，都在这个类中。
- MQClientInstance：这个类中封装了客户端一些通用的业务逻辑，无论是 Producer 还是 Consumer，最终需要与服务端交互时，都需要调用这个类中的方法；
- MQClientAPIImpl：这个类中封装了客户端服务端的 RPC，对调用者隐藏了真正网络通信部分的具体实现；
- NettyRemotingClient：RocketMQ 各进程之间网络通信的底层实现类。
发送端发送过程
private SendResult sendSelectImpl(
Message msg,
MessageQueueSelector selector,
Object arg,
final CommunicationMode communicationMode,
final SendCallback sendCallback, final long timeout
) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
long beginStartTime = System.currentTimeMillis();
this.makeSureStateOK();
Validators.checkMessage(msg, this.defaultMQProducer);
// 获取topic信息
TopicPublishInfo topicPublishInfo = this.tryToFindTopicPublishInfo(msg.getTopic());
if (topicPublishInfo != null && topicPublishInfo.ok()) {
MessageQueue mq = null;
// 选择将消息发送到哪个队列（Queue）中
try {
List messageQueueList =
mQClientFactory.getMQAdminImpl().parsePublishMessageQueues(topicPublishInfo.getMessageQueueList());
Message userMessage = MessageAccessor.cloneMessage(msg);
String userTopic = NamespaceUtil.withoutNamespace(userMessage.getTopic(), mQClientFactory.getClientConfig().getNamespace());
userMessage.setTopic(userTopic);
mq = mQClientFactory.getClientConfig().queueWithNamespace(selector.select(messageQueueList, userMessage, arg));
} catch (Throwable e) {
throw new MQClientException("select message queue throwed exception.", e);
}
long costTime = System.currentTimeMillis() - beginStartTime;
if (timeout < costTime) {
throw new RemotingTooMuchRequestException("sendSelectImpl call timeout");
}
// 真正的发送消息
if (mq != null) {
return this.sendKernelImpl(msg, mq, communicationMode, sendCallback, null, timeout - costTime);
} else {
throw new MQClientException("select message queue return null.", null);
}
}
validateNameServerSetting();
throw new MQClientException("No route info for this topic, " + msg.getTopic(), null);
}
sendKernelImpl为最核心的内容
private SendResult sendKernelImpl(
// 待发送的消息
final Message msg,
// 消息发送对应的消息队列
final MessageQueue mq,
//消息发送模式
final CommunicationMode communicationMode,
// 异步发送使用
final SendCallback sendCallback,
// topic 路由信息表
final TopicPublishInfo topicPublishInfo,
// 超时时间
final long timeout) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
long beginStartTime = System.currentTimeMillis();
// 获取broker的地址
String brokerAddr = this.mQClientFactory.findBrokerAddressInPublish(mq.getBrokerName());
if (null == brokerAddr) {
tryToFindTopicPublishInfo(mq.getTopic());
brokerAddr = this.mQClientFactory.findBrokerAddressInPublish(mq.getBrokerName());
}
SendMessageContext context = null;
// 计算得到 broker的 VIP channel ?
if (brokerAddr != null) {
brokerAddr = MixAll.brokerVIPChannel(this.defaultMQProducer.isSendMessageWithVIPChannel(), brokerAddr);
// 获得消息体的字节数组
byte[] prevBody = msg.getBody();
try {
// 对每一批消息，在此放入唯一的消息id
if (!(msg instanceof MessageBatch)) {
MessageClientIDSetter.setUniqID(msg);
}
// 判断是否有namespace
boolean topicWithNamespace = false;
if (null != this.mQClientFactory.getClientConfig().getNamespace()) {
msg.setInstanceId(this.mQClientFactory.getClientConfig().getNamespace());
topicWithNamespace = true;
}
int sysFlag = 0;
boolean msgBodyCompressed = false;
// 如果消息不为批消息 且大于设置的阈值，则进行压缩
if (this.tryToCompressMessage(msg)) {
sysFlag |= MessageSysFlag.COMPRESSED_FLAG;
msgBodyCompressed = true;
}
// 判断是否为事务消息 并计算syFlag
final String tranMsg = msg.getProperty(MessageConst.PROPERTY_TRANSACTION_PREPARED);
if (tranMsg != null && Boolean.parseBoolean(tranMsg)) {
sysFlag |= MessageSysFlag.TRANSACTION_PREPARED_TYPE;
}
// 若有 checkForbiddenHook 进行处理
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);
}
// 若有发送消息hook 进行处理
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);
context.setNamespace(this.defaultMQProducer.getNamespace());
// 是否事务处理
String isTrans = msg.getProperty(MessageConst.PROPERTY_TRANSACTION_PREPARED);
if (isTrans != null && isTrans.equals("true")) {
context.setMsgType(MessageType.Trans_Msg_Half);
}
// 是否延时消息
if (msg.getProperty("__STARTDELIVERTIME") != null || msg.getProperty(MessageConst.PROPERTY_DELAY_TIME_LEVEL) != null) {
context.setMsgType(MessageType.Delay_Msg);
}
// 执行hook方法
this.executeSendMessageHookBefore(context);
}
// 以上 消息发送hook处理结束
// 组装发送消息request header开始
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()));
// 由于是发送消息，所以设置为0
requestHeader.setReconsumeTimes(0);
requestHeader.setUnitMode(this.isUnitMode());
requestHeader.setBatch(msg instanceof MessageBatch);
// 如果当前消息topic为重试topic
if (requestHeader.getTopic().startsWith(MixAll.RETRY_GROUP_TOPIC_PREFIX)) {
// 获取重试次数
// 重试次数不为null则清除重试次数
String reconsumeTimes = MessageAccessor.getReconsumeTime(msg);
if (reconsumeTimes != null) {
requestHeader.setReconsumeTimes(Integer.valueOf(reconsumeTimes));
MessageAccessor.clearProperty(msg, MessageConst.PROPERTY_RECONSUME_TIME);
}
// 最大重试次数
String maxReconsumeTimes = MessageAccessor.getMaxReconsumeTimes(msg);
if (maxReconsumeTimes != null) {
requestHeader.setMaxReconsumeTimes(Integer.valueOf(maxReconsumeTimes));
MessageAccessor.clearProperty(msg, MessageConst.PROPERTY_MAX_RECONSUME_TIMES);
}
}
SendResult sendResult = null;
// 根据不同的模式 进行发送
switch (communicationMode) {
case ASYNC:
Message tmpMessage = msg;
boolean messageCloned = false;
if (msgBodyCompressed) {
// 如果消息body是压缩的，则使用prevBody，prevBody就是真实的msgBody对应的byte[]
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 ...(省略异常获取)
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