前两章内容中，介绍了Producer的启动过程，然后是如何创建topic，本章内容将主要集中在如何发送消息到broker
一、消息的投递
消息的投递分为普通消息的投递和事务消息的投递
public class DefaultMQProducer extends ClientConfig implements MQProducer{
// 所有的实际操作委托给这个实现
protected final transient DefaultMQProducerImpl defaultMQProducerImpl;
// 默认topic队列数
private volatile int defaultTopicQueueNums = 4;
private int sendMsgTimeout = 3000;
private int compressMsgBodyOverHowmuch = 1024 * 4;
private int retryTimesWhenSendFailed = 2;
private int retryTimesWhenSendAsyncFailed = 2;
private boolean retryAnotherBrokerWhenNotStoreOK = false;
private int maxMessageSize = 1024 * 1024 * 4;
...
@Override
public SendResult send(Message msg) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
return this.defaultMQProducerImpl.send(msg);
}
@Override
public SendResult send(Message msg, long timeout) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
return this.defaultMQProducerImpl.send(msg, timeout);
}
@Override
public void send(Message msg, SendCallback sendCallback) throws MQClientException, RemotingException, InterruptedException {
this.defaultMQProducerImpl.send(msg, sendCallback);
}
@Override
public SendResult send(Message msg, MessageQueue mq, long timeout)
throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
return this.defaultMQProducerImpl.send(msg, mq, timeout);
}
@Override
public void send(Message msg, MessageQueue mq, SendCallback sendCallback, long timeout)
throws MQClientException, RemotingException, InterruptedException {
this.defaultMQProducerImpl.send(msg, mq, sendCallback, timeout);
}
@Override
public void send(Message msg, MessageQueueSelector selector, Object arg, SendCallback sendCallback, long timeout)
throws MQClientException, RemotingException, InterruptedException {
this.defaultMQProducerImpl.send(msg, selector, arg, sendCallback, timeout);
}
@Override
public void sendOneway(Message msg, MessageQueueSelector selector, Object arg)
throws MQClientException, RemotingException, InterruptedException {
this.defaultMQProducerImpl.sendOneway(msg, selector, arg);
}
@Override
public TransactionSendResult sendMessageInTransaction(Message msg, LocalTransactionExecuter tranExecuter, final Object arg)
throws MQClientException {
throw new RuntimeException("sendMessageInTransaction not implement, please use TransactionMQProducer class");
}
...
}二、消息投递的具体实现过程
1.、同样的方式，消息的具体投递是委托给DefaultMQProducer内部的DefaultMQProducerImpl
private SendResult sendDefaultImpl( Message msg, final CommunicationMode communicationMode,
final SendCallback sendCallback, final long timeout) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
// 校验 Producer 处于运行状态
this.makeSureStateOK();
// 校验消息格式
Validators.checkMessage(msg, this.defaultMQProducer);
final long invokeID = random.nextLong(); // 调用编号；用于下面打印日志，标记为同一次发送消息
long beginTimestampFirst = System.currentTimeMillis();
long beginTimestampPrev = beginTimestampFirst;
@SuppressWarnings("UnusedAssignment")
long endTimestamp = beginTimestampFirst;
// 获取 Topic路由信息
TopicPublishInfo topicPublishInfo = this.tryToFindTopicPublishInfo(msg.getTopic());
if (topicPublishInfo != null && topicPublishInfo.ok()) {
MessageQueue mq = null; // 最后选择消息要发送到的队列
Exception exception = null;
SendResult sendResult = null; // 最后一次发送结果
int timesTotal = communicationMode == CommunicationMode.SYNC ? 1 + this.defaultMQProducer.getRetryTimesWhenSendFailed() : 1; // 同步多次调用
int times = 0; // 第几次发送
String[] brokersSent = new String[timesTotal]; // 存储每次发送消息选择的broker名
// 循环调用发送消息，直到成功
for (; times < timesTotal; times++) {
String lastBrokerName = null == mq ? null : mq.getBrokerName();
@SuppressWarnings("SpellCheckingInspection")
MessageQueue tmpmq = this.selectOneMessageQueue(topicPublishInfo, lastBrokerName); // 选择消息要发送到的队列
if (tmpmq != null) {
mq = tmpmq;
brokersSent[times] = mq.getBrokerName();
try {
beginTimestampPrev = System.currentTimeMillis();
// 调用发送消息核心方法
sendResult = this.sendKernelImpl(msg, mq, communicationMode, sendCallback, topicPublishInfo, timeout);
endTimestamp = System.currentTimeMillis();
// 更新Broker可用性信息
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()) { // 同步发送成功但存储有问题时 && 配置存储异常时重新发送开关 时，进行重试
continue;
}
}
return sendResult;
default:
break;
}catch (RemotingException e) { // 打印异常，更新Broker可用性信息，更新继续循环
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 (MQClientException e) { // 打印异常，更新Broker可用性信息，继续循环
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) { // 打印异常，更新Broker可用性信息，部分情况下的异常，直接返回，结束循环
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()) {
// 如下异常continue，进行发送消息重试
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;
// 如果有发送结果，进行返回，否则，抛出异常；
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());
throw e;
}
} else {
break;
}
}
// 返回发送结果
if (sendResult != null) {
return sendResult;
}
// 根据不同情况，抛出不同的异常
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)) + FAQUrl.suggestTodo(FAQUrl.SEND_MSG_FAILED);
MQClientException mqClientException = new MQClientException(info, exception);
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;
}
// Namesrv找不到异常
List<String> nsList = this.getmQClientFactory().getMQClientAPIImpl().getNameServerAddressList();
if (null == nsList || nsList.isEmpty()) {
throw new MQClientException(
"No name server address, please set it." + FAQUrl.suggestTodo(FAQUrl.NAME_SERVER_ADDR_NOT_EXIST_URL), null).setResponseCode(ClientErrorCode.NO_NAME_SERVER_EXCEPTION);
}
// 消息路由找不到异常
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);
}2、关键函数获取topic的路由信息tryToFindTopicPublishInfo，因为在创建topic时，会将topic和broker的信息同步到NameSrv，所以这里可以从NameSrv获取发送消息的topic理由信息。
private TopicPublishInfo tryToFindTopicPublishInfo(final String topic) {
// 缓存中获取 Topic发布信息，在start的时候，只是放入了一个空的topicPublicInfo
TopicPublishInfo topicPublishInfo = this.topicPublishInfoTable.get(topic);
// 当无可用的 Topic发布信息时，从Namesrv获取一次
if (null == topicPublishInfo || !topicPublishInfo.ok()) {
this.topicPublishInfoTable.putIfAbsent(topic, new TopicPublishInfo());
this.mQClientFactory.updateTopicRouteInfoFromNameServer(topic);
topicPublishInfo = this.topicPublishInfoTable.get(topic);
}
// 若获取的 Topic发布信息时候可用，则返回
if (topicPublishInfo.isHaveTopicRouterInfo() || topicPublishInfo.ok()) {
return topicPublishInfo;
} else { // 使用 {@link DefaultMQProducer#createTopicKey} 对应的 Topic发布信息。用于 Topic发布信息不存在 && Broker支持自动创建Topic
this.mQClientFactory.updateTopicRouteInfoFromNameServer(topic, true, this.defaultMQProducer);
topicPublishInfo = this.topicPublishInfoTable.get(topic);
return topicPublishInfo;
}
}接着看更新topic的路由信息
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) {
// 使用默认TopicKey获取TopicRouteData。
// 当broker开启自动创建topic开关时，会使用MixAll.DEFAULT_TOPIC进行创建。
// 当producer的createTopic为MixAll.DEFAULT_TOPIC时，则可以获得TopicRouteData。
// 目的：用于新的topic，发送消息时，未创建路由信息，先使用createTopic的路由信息，等到发送到broker时，进行自动创建。
topicRouteData = this.mQClientAPIImpl.getDefaultTopicRouteInfoFromNameServer(defaultMQProducer.getCreateTopicKey(),1000 * 3);
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, 1000 * 3);
}
if (topicRouteData != null) {
TopicRouteData old = this.topicRouteTable.get(topic);
boolean changed = topicRouteDataIsChange(old, topicRouteData);
if (!changed) {
changed = this.isNeedUpdateTopicRouteInfo(topic);
} else {
log.info("the topic[{}] route info changed, old[{}] ,new[{}]", topic, old, topicRouteData);
}
if (changed) {
TopicRouteData cloneTopicRouteData = topicRouteData.cloneTopicRouteData(); // 克隆对象的原因：topicRouteData会被设置到下面的publishInfo/subscribeInfo
// 更新 Broker 地址相关信息
for (BrokerData bd : topicRouteData.getBrokerDatas()) {
this.brokerAddrTable.put(bd.getBrokerName(), bd.getBrokerAddrs());
}
// 更新发布topic的消息，这里可能涉及到创建MessageQueue
{
TopicPublishInfo publishInfo = topicRouteData2TopicPublishInfo(topic, topicRouteData);
publishInfo.setHaveTopicRouterInfo(true);
for (Entry<String, MQProducerInner> entry : this.producerTable.entrySet()) {
MQProducerInner impl = entry.getValue();
if (impl != null) {
impl.updateTopicPublishInfo(topic, publishInfo);
}
}
}
// 这里会更新一次consumer的信息
{
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);
}
}
}
log.info("topicRouteTable.put TopicRouteData[{}]", cloneTopicRouteData);
this.topicRouteTable.put(topic, cloneTopicRouteData);
return true;
}
} else {
log.warn("updateTopicRouteInfoFromNameServer, getTopicRouteInfoFromNameServer return null, Topic: {}", topic);
}
} catch (Exception e) {
if (!topic.startsWith(MixAll.RETRY_GROUP_TOPIC_PREFIX) && !topic.equals(MixAll.DEFAULT_TOPIC)) {
log.warn("updateTopicRouteInfoFromNameServer Exception", e);
}
} finally {
this.lockNamesrv.unlock();
}
} else {
log.warn("updateTopicRouteInfoFromNameServer tryLock timeout {}ms", LOCK_TIMEOUT_MILLIS);
}
} catch (InterruptedException e) {
log.warn("updateTopicRouteInfoFromNameServer Exception", e);
}
return false;
}3、因为一个topic可能有很多的消息队列MessageQueue，如何选取MessageQueue路由呢？这里会通过一种容错机制选取出最优的MessageQueue。默认的MQFaultStrategy实现
// MQ 故障策略
public class MQFaultStrategy {
/**
* 延迟故障容错，维护每个Broker的发送消息的延迟
* key：brokerName
*/
private final LatencyFaultTolerance<String> latencyFaultTolerance = new LatencyFaultToleranceImpl();
/**
* 发送消息延迟容错开关
*/
private boolean sendLatencyFaultEnable = false;
/**
* 延迟级别数组
*/
private long[] latencyMax = {50L, 100L, 550L, 1000L, 2000L, 3000L, 15000L};
/**
* 不可用时长数组
*/
private long[] notAvailableDuration = {0L, 0L, 30000L, 60000L, 120000L, 180000L, 600000L};
public MessageQueue selectOneMessageQueue(final TopicPublishInfo tpInfo, final String lastBrokerName) {
if (this.sendLatencyFaultEnable) {
try {
// 感觉是在MessageQueue中轮流选取
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);
if (latencyFaultTolerance.isAvailable(mq.getBrokerName())) {
if (null == lastBrokerName || mq.getBrokerName().equals(lastBrokerName))
return mq;
}
}
// 选择一个相对好的broker，并获得其对应的一个消息队列，不考虑该队列的可用性
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);
}
// 选择一个消息队列，不考虑队列的可用性
return tpInfo.selectOneMessageQueue();
}
// 获得 lastBrokerName 对应的一个消息队列，不考虑该队列的可用性
return tpInfo.selectOneMessageQueue(lastBrokerName);
}
}4、发送消息的核心：非常主要一点，因为MessageQueue可能在不同的broker上，每一个brokerName可能有一组broker，所以这个时候会向这组broker的主broker投递消息。
//发送消息的实际操作者
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();
//获得需要发送的broker地址，主要是发送给master
String brokerAddr = this.mQClientFactory.findBrokerAddressInPublish(mq.getBrokerName());
if (null == brokerAddr) {
//重新拉取topic信息
tryToFindTopicPublishInfo(mq.getTopic());
brokerAddr = this.mQClientFactory.findBrokerAddressInPublish(mq.getBrokerName());
}
SendMessageContext context = null;
if (brokerAddr != null) {
//是否是vip的操作，主要是端口-2的操作，然后重新拼接addr
brokerAddr = MixAll.brokerVIPChannel(this.defaultMQProducer.isSendMessageWithVIPChannel(), brokerAddr);
//发送的消息体
byte[] prevBody = msg.getBody();
try {
//for MessageBatch,ID has been set in the generating process
//是否是批量消息体
if (!(msg instanceof MessageBatch)) {
MessageClientIDSetter.setUniqID(msg);
}
int sysFlag = 0;
boolean msgBodyCompressed = false;
//压缩消息体
if (this.tryToCompressMessage(msg)) {
sysFlag |= MessageSysFlag.COMPRESSED_FLAG;
msgBodyCompressed = true;
}
//判断是否是事务消息，设置事务属性
final String tranMsg = msg.getProperty(MessageConst.PROPERTY_TRANSACTION_PREPARED);
if (tranMsg != null && Boolean.parseBoolean(tranMsg)) {
sysFlag |= MessageSysFlag.TRANSACTION_PREPARED_TYPE;
}
//验证自定义的hook
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);
}
//验证发送消息的hook
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(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);
}
//消息头的封装
SendMessageRequestHeader requestHeader = new SendMessageRequestHeader();
//消息发送组
requestHeader.setProducerGroup(this.defaultMQProducer.getProducerGroup());
//消息的topic
requestHeader.setTopic(msg.getTopic());
//消息的默认topic
requestHeader.setDefaultTopic(this.defaultMQProducer.getCreateTopicKey());
//消息的默认queue数量
requestHeader.setDefaultTopicQueueNums(this.defaultMQProducer.getDefaultTopicQueueNums());
//消息发送的queueid
requestHeader.setQueueId(mq.getQueueId());
//特殊标识
requestHeader.setSysFlag(sysFlag);
//消息创建的时间戳
requestHeader.setBornTimestamp(System.currentTimeMillis());
//标识
requestHeader.setFlag(msg.getFlag());
//消息的扩展属性
requestHeader.setProperties(MessageDecoder.messageProperties2String(msg.getProperties()));
//消息的消费
requestHeader.setReconsumeTimes(0);
//模型
requestHeader.setUnitMode(this.isUnitMode());
//批量
requestHeader.setBatch(msg instanceof MessageBatch);
//特殊标记的处理
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;
//消息发送的模型
switch (communicationMode) {
//异步发送
case ASYNC:
Message tmpMessage = msg;
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);
msg.setBody(prevBody);
}
long costTimeAsync = System.currentTimeMillis() - beginStartTime;
if (timeout < costTimeAsync) {
throw new RemotingTooMuchRequestException("sendKernelImpl call timeout");
}
//参数区别主要是回调相关的配置
sendResult = this.mQClientFactory.getMQClientAPIImpl().sendMessage(
brokerAddr,
mq.getBrokerName(),
tmpMessage,
requestHeader,
timeout - costTimeAsync,
communicationMode,
sendCallback,
topicPublishInfo,
this.mQClientFactory,
this.defaultMQProducer.getRetryTimesWhenSendAsyncFailed(),
context,
this);
break;
//同步及单发
case ONEWAY:
case SYNC:
long costTimeSync = System.currentTimeMillis() - beginStartTime;
if (timeout < costTimeSync) {
throw new RemotingTooMuchRequestException("sendKernelImpl call timeout");
}
//消息的最终发送
sendResult = this.mQClientFactory.getMQClientAPIImpl().sendMessage(
brokerAddr,
mq.getBrokerName(),
msg,
requestHeader,
timeout - costTimeSync,
communicationMode,
context,
this);
break;
default:
assert false;
break;
}
//是否有发送消息hook
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);
}
}
throw new MQClientException("The broker[" + mq.getBrokerName() + "] not exist", null);
}6、组装netty的发送指令，开始消息的最终发送：
//发送消息的核心操作实现
public SendResult sendMessage(
final String addr,//地址
final String brokerName,//broker名称
final Message msg,//消息
final SendMessageRequestHeader requestHeader,//消息头
final long timeoutMillis,//超时
final CommunicationMode communicationMode,//发送模式
final SendCallback sendCallback,//发送后的回调
final TopicPublishInfo topicPublishInfo,//topic的配置
final MQClientInstance instance,//基于client的发送实例
final int retryTimesWhenSendFailed,//重试次数
final SendMessageContext context,//发送消息的上下文信息
final DefaultMQProducerImpl producer//发送消息者
) throws RemotingException, MQBrokerException, InterruptedException {
long beginStartTime = System.currentTimeMillis();
RemotingCommand request = null;
//协议转换
if (sendSmartMsg || msg instanceof MessageBatch) {
SendMessageRequestHeaderV2 requestHeaderV2 = SendMessageRequestHeaderV2.createSendMessageRequestHeaderV2(requestHeader);
request = RemotingCommand.createRequestCommand(msg instanceof MessageBatch ? RequestCode.SEND_BATCH_MESSAGE : RequestCode.SEND_MESSAGE_V2, requestHeaderV2);
} else {
request = RemotingCommand.createRequestCommand(RequestCode.SEND_MESSAGE, requestHeader);
}
request.setBody(msg.getBody());
switch (communicationMode) {
case ONEWAY:
this.remotingClient.invokeOneway(addr, request, timeoutMillis);
return null;
case ASYNC:
final AtomicInteger times = new AtomicInteger();
long costTimeAsync = System.currentTimeMillis() - beginStartTime;
if (timeoutMillis < costTimeAsync) {
throw new RemotingTooMuchRequestException("sendMessage call timeout");
}
this.sendMessageAsync(addr, brokerName, msg, timeoutMillis - costTimeAsync, request, sendCallback, topicPublishInfo, instance,
retryTimesWhenSendFailed, times, context, producer);
return null;
case SYNC:
long costTimeSync = System.currentTimeMillis() - beginStartTime;
if (timeoutMillis < costTimeSync) {
throw new RemotingTooMuchRequestException("sendMessage call timeout");
}
return this.sendMessageSync(addr, brokerName, msg, timeoutMillis - costTimeSync, request);
default:
assert false;
break;
}
return null;
}
// 同步调用发送方法
private SendResult sendMessageSync(
final String addr,
final String brokerName,
final Message msg,
final long timeoutMillis,
final RemotingCommand request
) throws RemotingException, MQBrokerException, InterruptedException {
//同步发送消息
RemotingCommand response = this.remotingClient.invokeSync(addr, request, timeoutMillis);
assert response != null;
//处理请求的相应结果
return this.processSendResponse(brokerName, msg, response);
}
//网络通信的核心方法实现，同步
@Override
public RemotingCommand invokeSync(String addr, final RemotingCommand request, long timeoutMillis)
throws InterruptedException, RemotingConnectException, RemotingSendRequestException, RemotingTimeoutException {
long beginStartTime = System.currentTimeMillis();
//获得通信的channel
final Channel channel = this.getAndCreateChannel(addr);
//验证channel的有效性
if (channel != null && channel.isActive()) {
try {
//前置处理
doBeforeRpcHooks(addr, request);
long costTime = System.currentTimeMillis() - beginStartTime;
if (timeoutMillis < costTime) {
throw new RemotingTimeoutException("invokeSync call timeout");
}
//执行方法调用
RemotingCommand response = this.invokeSyncImpl(channel, request, timeoutMillis - costTime);
//后置处理
doAfterRpcHooks(RemotingHelper.parseChannelRemoteAddr(channel), request, response);
return response;
} catch (RemotingSendRequestException e) {
log.warn("invokeSync: send request exception, so close the channel[{}]", addr);
this.closeChannel(addr, channel);
throw e;
} catch (RemotingTimeoutException e) {
if (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 e;
}
} else {
//如果异常则删除执行的channel的操作
this.closeChannel(addr, channel);
throw new RemotingConnectException(addr);
}
}
//同步操作的核心
public RemotingCommand invokeSyncImpl(final Channel channel, final RemotingCommand request,
final long timeoutMillis)
throws InterruptedException, RemotingSendRequestException, RemotingTimeoutException {
final int opaque = request.getOpaque();
try {
//异步调用封装，处理netty通信后的结果
final ResponseFuture responseFuture = new ResponseFuture(channel, opaque, timeoutMillis, null, null);
//结果的并发处理及通知，及后续的异常处理收集
this.responseTable.put(opaque, responseFuture);
final SocketAddress addr = channel.remoteAddress();
//netty的消息发送，只负责发送
channel.writeAndFlush(request).addListener(new ChannelFutureListener() {
@Override
public void operationComplete(ChannelFuture f) throws Exception {
//操作成功后马上返回
if (f.isSuccess()) {
responseFuture.setSendRequestOK(true);
return;
} else {
responseFuture.setSendRequestOK(false);
}
//同步处理后删除对应的请求对象
responseTable.remove(opaque);
responseFuture.setCause(f.cause());
responseFuture.putResponse(null);
log.warn("send a request command to channel <" + addr + "> failed.");
}
});
//相应结果的处理，实际的操作在NettyClientHandler中实现，根据opaque来更新结果
RemotingCommand responseCommand = responseFuture.waitResponse(timeoutMillis);
if (null == responseCommand) {
if (responseFuture.isSendRequestOK()) {
throw new RemotingTimeoutException(RemotingHelper.parseSocketAddressAddr(addr), timeoutMillis,
responseFuture.getCause());
} else {
throw new RemotingSendRequestException(RemotingHelper.parseSocketAddressAddr(addr), responseFuture.getCause());
}
}
return responseCommand;
} finally {
this.responseTable.remove(opaque);
}
}如果消息是异步发送机制，会通过sendCallBack进行回调处理。
7、broker接收到消息发送的指令后，会做消息的持久化处理，后面在broker环节将重要介绍。
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