RocketMQ-事务消息
来自官网：
rocketmq_design_10.png
上图说明了事务消息的大致方案，其中分为两个流程：正常事务消息的发送及提交、事务消息的补偿流程。
1.事务消息发送及提交：
(1) 发送消息（half消息）。
(2) 服务端响应消息写入结果。
(3) 根据发送结果执行本地事务（如果写入失败，此时half消息对业务不可见，本地逻辑不执行）。
(4) 根据本地事务状态执行Commit或者Rollback（Commit操作生成消息索引，消息对消费者可见）
2.补偿流程：
(1) 对没有Commit/Rollback的事务消息（pending状态的消息），从服务端发起一次“回查”
(2) Producer收到回查消息，检查回查消息对应的本地事务的状态
(3) 根据本地事务状态，重新Commit或者Rollback
其中，补偿阶段用于解决消息Commit或者Rollback发生超时或者失败的情况。
上面的图片添加上数据的存储流转：
image.png
RocketMQ 版本4.3.2
1.事务消息发送和提交
我们通过官网的例子来查看源码，官网例子如下：
public class TransactionProducer {
public static void main(String[] args) throws MQClientException, InterruptedException {
TransactionListener transactionListener = new TransactionListenerImpl();
TransactionMQProducer producer = new TransactionMQProducer("please_rename_unique_group_name");
ExecutorService executorService = new ThreadPoolExecutor(2, 5, 100, TimeUnit.SECONDS, new ArrayBlockingQueue<Runnable>(2000), new ThreadFactory() {
@Override
public Thread newThread(Runnable r) {
Thread thread = new Thread(r);
thread.setName("client-transaction-msg-check-thread");
return thread;
}
});
//设置线程池
producer.setExecutorService(executorService);
//设置本地事务的监听器，便于执行相关逻辑
producer.setTransactionListener(transactionListener);
producer.start();
String[] tags = new String[] {"TagA", "TagB", "TagC", "TagD", "TagE"};
for (int i = 0; i < 10; i++) {
try {
Message msg =
new Message("TopicTest1234", tags[i % tags.length], "KEY" + i,
("Hello RocketMQ " + i).getBytes(RemotingHelper.DEFAULT_CHARSET));
SendResult sendResult = producer.sendMessageInTransaction(msg, null);
System.out.printf("%s%n", sendResult);
Thread.sleep(10);
} catch (MQClientException | UnsupportedEncodingException e) {
e.printStackTrace();
}
}
for (int i = 0; i < 100000; i++) {
Thread.sleep(1000);
}
producer.shutdown();
}
}
public class TransactionListenerImpl implements TransactionListener {
private AtomicInteger transactionIndex = new AtomicInteger(0);
private ConcurrentHashMap<String, Integer> localTrans = new ConcurrentHashMap<>();
//这里是执行本地事务的方法
@Override
public LocalTransactionState executeLocalTransaction(Message msg, Object arg) {
int value = transactionIndex.getAndIncrement();
int status = value % 3;
localTrans.put(msg.getTransactionId(), status);
return LocalTransactionState.UNKNOW;
}
//这个是服务端回调本地事务成功的方法
@Override
public LocalTransactionState checkLocalTransaction(MessageExt msg) {
Integer status = localTrans.get(msg.getTransactionId());
if (null != status) {
switch (status) {
case 0:
return LocalTransactionState.UNKNOW;
case 1:
return LocalTransactionState.COMMIT_MESSAGE;
case 2:
return LocalTransactionState.ROLLBACK_MESSAGE;
default:
return LocalTransactionState.COMMIT_MESSAGE;
}
}
return LocalTransactionState.COMMIT_MESSAGE;
}
}
1）先看客户端发送逻辑流程
//客户端发送
TransactionMQProducer#sendMessageInTransaction
DefaultMQProducerImpl#sendMessageInTransaction
-DefaultMQProducerImpl#send
= NOTOK -> state = ROLLBACK_MESSAGE
= sendOk -> state = TransactionListener#executeLocalTransaction
-DefaultMQProducerImpl#endTransaction
-MQClientAPIImpl#endTransactionOneway
-RemotingClient#invokeOneway
核心源码 在DefaultMQProducerImpl#sendMessageInTransaction中具体看一下
public TransactionSendResult sendMessageInTransaction(final Message msg,
final LocalTransactionExecuter localTransactionExecuter, final Object arg)
throws MQClientException {
TransactionListener transactionListener = getCheckListener();
if (null == localTransactionExecuter && null == transactionListener) {
throw new MQClientException("tranExecutor is null", null);
}
Validators.checkMessage(msg, this.defaultMQProducer);
SendResult sendResult = null;
//这里添加了事务预消息的标识
MessageAccessor.putProperty(msg, MessageConst.PROPERTY_TRANSACTION_PREPARED, "true");
MessageAccessor.putProperty(msg, MessageConst.PROPERTY_PRODUCER_GROUP, this.defaultMQProducer.getProducerGroup());
try {
//发送消息
sendResult = this.send(msg);
} catch (Exception e) {
throw new MQClientException("send message Exception", e);
}
LocalTransactionState localTransactionState = LocalTransactionState.UNKNOW;
Throwable localException = null;
switch (sendResult.getSendStatus()) {
case SEND_OK: { //发送到broker的消息发送ok时
try {
if (sendResult.getTransactionId() != null) {
msg.putUserProperty("__transactionId__", sendResult.getTransactionId());
}
String transactionId = msg.getProperty(MessageConst.PROPERTY_UNIQ_CLIENT_MESSAGE_ID_KEYIDX);
if (null != transactionId && !"".equals(transactionId)) {
msg.setTransactionId(transactionId);
}
//默认之类的localTransactionExecuter是空的
if (null != localTransactionExecuter) {
localTransactionState = localTransactionExecuter.executeLocalTransactionBranch(msg, arg);
} else if (transactionListener != null) {
log.debug("Used new transaction API");
//这里执行本地实现的listerner的本地事务
localTransactionState = transactionListener.executeLocalTransaction(msg, arg);
}
if (null == localTransactionState) {
localTransactionState = LocalTransactionState.UNKNOW;
}
if (localTransactionState != LocalTransactionState.COMMIT_MESSAGE) {
log.info("executeLocalTransactionBranch return {}", localTransactionState);
log.info(msg.toString());
}
} catch (Throwable e) {
log.info("executeLocalTransactionBranch exception", e);
log.info(msg.toString());
localException = e;
}
}
break; //下面其他状态设置rollback
case FLUSH_DISK_TIMEOUT:
case FLUSH_SLAVE_TIMEOUT:
case SLAVE_NOT_AVAILABLE:
localTransactionState = LocalTransactionState.ROLLBACK_MESSAGE;
break;
default:
break;
}
try {
//这里结束本地事务后的处理逻辑
this.endTransaction(sendResult, localTransactionState, localException);
} catch (Exception e) {
log.warn("local transaction execute " + localTransactionState + ", but end broker transaction failed", e);
}
TransactionSendResult transactionSendResult = new TransactionSendResult();
transactionSendResult.setSendStatus(sendResult.getSendStatus());
transactionSendResult.setMessageQueue(sendResult.getMessageQueue());
transactionSendResult.setMsgId(sendResult.getMsgId());
transactionSendResult.setQueueOffset(sendResult.getQueueOffset());
transactionSendResult.setTransactionId(sendResult.getTransactionId());
transactionSendResult.setLocalTransactionState(localTransactionState);
return transactionSendResult;
}
//在看看结束本地事务后消息怎么处理
public void endTransaction(
final SendResult sendResult,
final LocalTransactionState localTransactionState,
final Throwable localException) throws RemotingException, MQBrokerException, InterruptedException, UnknownHostException {
final MessageId id;
if (sendResult.getOffsetMsgId() != null) {
id = MessageDecoder.decodeMessageId(sendResult.getOffsetMsgId());
} else {
id = MessageDecoder.decodeMessageId(sendResult.getMsgId());
}
String transactionId = sendResult.getTransactionId();
final String brokerAddr = this.mQClientFactory.findBrokerAddressInPublish(sendResult.getMessageQueue().getBrokerName());
EndTransactionRequestHeader requestHeader = new EndTransactionRequestHeader();
requestHeader.setTransactionId(transactionId);
requestHeader.setCommitLogOffset(id.getOffset());
//根据本地事务执行状态设置请求头提交还是徽标标识
switch (localTransactionState) {
case COMMIT_MESSAGE:
requestHeader.setCommitOrRollback(MessageSysFlag.TRANSACTION_COMMIT_TYPE);
break;
case ROLLBACK_MESSAGE:
requestHeader.setCommitOrRollback(MessageSysFlag.TRANSACTION_ROLLBACK_TYPE);
break;
case UNKNOW:
requestHeader.setCommitOrRollback(MessageSysFlag.TRANSACTION_NOT_TYPE);
break;
default:
break;
}
requestHeader.setProducerGroup(this.defaultMQProducer.getProducerGroup());
requestHeader.setTranStateTableOffset(sendResult.getQueueOffset());
requestHeader.setMsgId(sendResult.getMsgId());
String remark = localException != null ? ("executeLocalTransactionBranch exception: " + localException.toString()) : null;
//发送oneWay 单项一次性消息，消息code时事务的code；(便于不同的处理器处理)
this.mQClientFactory.getMQClientAPIImpl().endTransactionOneway(brokerAddr, requestHeader, remark,
this.defaultMQProducer.getSendMsgTimeout());
}
2）服务端第一次接受事务消息
// broker端处理
NettyServerHandler#channelRead0
NettyRemotingAbstract#processMessageReceived
#processRequestCommand
-SendMessageProcessor#processRequest
-SendMessageProcessor#sendMessage
-TransactionalMessageServiceImpl#prepareMessage
-TransactionalMessageBridge#putHalfMessage
-DefaultMessageStore#putMessage
整个流程我们从SendMessageProcessor看看
private RemotingCommand sendMessage(final ChannelHandlerContext ctx,
final RemotingCommand request,
final SendMessageContext sendMessageContext,
final SendMessageRequestHeader requestHeader) throws RemotingCommandException {
final RemotingCommand response = RemotingCommand.createResponseCommand(SendMessageResponseHeader.class);
final SendMessageResponseHeader responseHeader = (SendMessageResponseHeader)response.readCustomHeader();
response.setOpaque(request.getOpaque());
//...部分逻辑省略
MessageExtBrokerInner msgInner = new MessageExtBrokerInner();
msgInner.setTopic(requestHeader.getTopic());
msgInner.setQueueId(queueIdInt);
if (!handleRetryAndDLQ(requestHeader, response, request, msgInner, topicConfig)) {
return response;
}
msgInner.setBody(body);
msgInner.setFlag(requestHeader.getFlag());
MessageAccessor.setProperties(msgInner, MessageDecoder.string2messageProperties(requestHeader.getProperties()));
msgInner.setPropertiesString(requestHeader.getProperties());
msgInner.setBornTimestamp(requestHeader.getBornTimestamp());
msgInner.setBornHost(ctx.channel().remoteAddress());
msgInner.setStoreHost(this.getStoreHost());
msgInner.setReconsumeTimes(requestHeader.getReconsumeTimes() == null ? 0 : requestHeader.getReconsumeTimes());
PutMessageResult putMessageResult = null;
Map<String, String> oriProps = MessageDecoder.string2messageProperties(requestHeader.getProperties());
//获取是否是事务消息的标识
String traFlag = oriProps.get(MessageConst.PROPERTY_TRANSACTION_PREPARED);
if (traFlag != null && Boolean.parseBoolean(traFlag)) {
if (this.brokerController.getBrokerConfig().isRejectTransactionMessage()) {
response.setCode(ResponseCode.NO_PERMISSION);
response.setRemark(
"the broker[" + this.brokerController.getBrokerConfig().getBrokerIP1()
+ "] sending transaction message is forbidden");
return response;
}
putMessageResult = this.brokerController.getTransactionalMessageService().prepareMessage(msgInner);
} else {
//非事务消息的处理，直接存储
putMessageResult = this.brokerController.getMessageStore().putMessage(msgInner);
}
//结果处理返回
return handlePutMessageResult(putMessageResult, response, request, msgInner, responseHeader, sendMessageContext, ctx, queueIdInt);
}
//TransactionalMessageBridge#putHalfMessage 存储半消息瞧瞧
public PutMessageResult putHalfMessage(MessageExtBrokerInner messageInner) {
//存储消息
return store.putMessage(parseHalfMessageInner(messageInner));
}
//这里对于消息做了重新的封装
private MessageExtBrokerInner parseHalfMessageInner(MessageExtBrokerInner msgInner) {
//设置真实topic和queueId的 原始信息
MessageAccessor.putProperty(msgInner, MessageConst.PROPERTY_REAL_TOPIC, msgInner.getTopic());
MessageAccessor.putProperty(msgInner, MessageConst.PROPERTY_REAL_QUEUE_ID,
String.valueOf(msgInner.getQueueId()));
msgInner.setSysFlag(
MessageSysFlag.resetTransactionValue(msgInner.getSysFlag(), MessageSysFlag.TRANSACTION_NOT_TYPE));
//设置消息的topic为 "RMQ_SYS_TRANS_HALF_TOPIC"
msgInner.setTopic(TransactionalMessageUtil.buildHalfTopic());
msgInner.setQueueId(0); //队列使用0号
msgInner.setPropertiesString(MessageDecoder.messageProperties2String(msgInner.getProperties()));
return msgInner;
}
3）服务端处理二段事务结果
//client发送消息RemoteCommand.setCode(RequestCode.END_TRANSACTION)
// broker端处理
NettyServerHandler#channelRead0
NettyRemotingAbstract#processMessageReceived
#processRequestCommand
-EndTransactionProcessor#processRequest
//总结：事务消息commit相对rollback 就多一个添加到原来的topic消息的逻辑
// 查看EndTransactionProcessor#processRequest
public RemotingCommand processRequest(ChannelHandlerContext ctx, RemotingCommand request) throws
RemotingCommandException {
final RemotingCommand response = RemotingCommand.createResponseCommand(null);
final EndTransactionRequestHeader requestHeader =
(EndTransactionRequestHeader)request.decodeCommandCustomHeader(EndTransactionRequestHeader.class);
LOGGER.info("Transaction request:{}", requestHeader);
if (BrokerRole.SLAVE == brokerController.getMessageStoreConfig().getBrokerRole()) {
response.setCode(ResponseCode.SLAVE_NOT_AVAILABLE);
LOGGER.warn("Message store is slave mode, so end transaction is forbidden. ");
return response;
}
//... 省略掉不必要的代码
OperationResult result = new OperationResult();
//消息提交
if (MessageSysFlag.TRANSACTION_COMMIT_TYPE == requestHeader.getCommitOrRollback()) {
//获取之前存储的半消息
result = this.brokerController.getTransactionalMessageService().commitMessage(requestHeader);
if (result.getResponseCode() == ResponseCode.SUCCESS) {
//校验消息是否正确
RemotingCommand res = checkPrepareMessage(result.getPrepareMessage(), requestHeader);
if (res.getCode() == ResponseCode.SUCCESS) {
//构建原来topic的消息
MessageExtBrokerInner msgInner = endMessageTransaction(result.getPrepareMessage());
msgInner.setSysFlag(MessageSysFlag.resetTransactionValue(msgInner.getSysFlag(), requestHeader.getCommitOrRollback()));
msgInner.setQueueOffset(requestHeader.getTranStateTableOffset());
msgInner.setPreparedTransactionOffset(requestHeader.getCommitLogOffset());
msgInner.setStoreTimestamp(result.getPrepareMessage().getStoreTimestamp());
//消息存储
RemotingCommand sendResult = sendFinalMessage(msgInner);
if (sendResult.getCode() == ResponseCode.SUCCESS) {
//”删除“ 原来的半消息
this.brokerController.getTransactionalMessageService().deletePrepareMessage(result.getPrepareMessage());
}
return sendResult;
}
return res;
}
// 消息回滚
} else if (MessageSysFlag.TRANSACTION_ROLLBACK_TYPE == requestHeader.getCommitOrRollback()) {
//获取原来的半消息
result = this.brokerController.getTransactionalMessageService().rollbackMessage(requestHeader);
if (result.getResponseCode() == ResponseCode.SUCCESS) {
//校验消息是否正确
RemotingCommand res = checkPrepareMessage(result.getPrepareMessage(), requestHeader);
if (res.getCode() == ResponseCode.SUCCESS) {
//”删除“ 原来的半消息
this.brokerController.getTransactionalMessageService().deletePrepareMessage(result.getPrepareMessage());
}
return res;
}
}
response.setCode(result.getResponseCode());
response.setRemark(result.getResponseRemark());
return response;
}
//TransactionalMessageServiceImpl# deletePrepareMessage
public boolean deletePrepareMessage(MessageExt msgExt) {
if (this.transactionalMessageBridge.putOpMessage(msgExt, TransactionalMessageUtil.REMOVETAG)) {
log.info("Transaction op message write successfully. messageId={}, queueId={} msgExt:{}", msgExt.getMsgId(), msgExt.getQueueId(), msgExt);
return true;
} else {
log.error("Transaction op message write failed. messageId is {}, queueId is {}", msgExt.getMsgId(), msgExt.getQueueId());
return false;
}
}
// TransactionalMessageBridge#putOpMessage
public boolean putOpMessage(MessageExt messageExt, String opType) {
MessageQueue messageQueue = new MessageQueue(messageExt.getTopic(),
this.brokerController.getBrokerConfig().getBrokerName(), messageExt.getQueueId());
if (TransactionalMessageUtil.REMOVETAG.equals(opType)) {
return addRemoveTagInTransactionOp(messageExt, messageQueue);
}
return true;
}
private boolean addRemoveTagInTransactionOp(MessageExt messageExt, MessageQueue messageQueue) {
//构建 ”RMQ_SYS_TRANS_OP_HALF_TOPIC“ topic的消息，值为queueOffset
Message message = new Message(TransactionalMessageUtil.buildOpTopic(), TransactionalMessageUtil.REMOVETAG,
String.valueOf(messageExt.getQueueOffset()).getBytes(TransactionalMessageUtil.charset));
writeOp(message, messageQueue);
return true;
}
private void writeOp(Message message, MessageQueue mq) {
MessageQueue opQueue;
if (opQueueMap.containsKey(mq)) {
opQueue = opQueueMap.get(mq);
} else {
opQueue = getOpQueueByHalf(mq);
MessageQueue oldQueue = opQueueMap.putIfAbsent(mq, opQueue);
if (oldQueue != null) {
opQueue = oldQueue;
}
}
if (opQueue == null) {
opQueue = new MessageQueue(TransactionalMessageUtil.buildOpTopic(), mq.getBrokerName(), mq.getQueueId());
}
//存储消息
putMessage(makeOpMessageInner(message, opQueue));
}
2.补偿流程
补偿流程主要是broker端通过定时任务 TransactionalMessageCheckService 来回查事务状态
//入手流程
BrokerController#initialize 构建TransactionalMessageCheckService
BrokerController#start 启动TransactionalMessageCheckService#run方法
TransactionalMessageCheckService#check 真实的业务逻辑
@Override
public void run() {
log.info("Start transaction check service thread!");
long checkInterval = brokerController.getBrokerConfig().getTradiaonsactionCheckInterval();
while (!this.isStopped()) {
//这个调用父类方法，然后父类使用模板调用如下onWaitEnd方法
this.waitForRunning(checkInterval);
}
log.info("End transaction check service thread!");
}
@Override
protected void onWaitEnd() {
long timeout = brokerController.getBrokerConfig().getTransactionTimeOut();
int checkMax = brokerController.getBrokerConfig().getTransactionCheckMax();
long begin = System.currentTimeMillis();
log.info("Begin to check prepare message, begin time:{}", begin);
this.brokerController.getTransactionalMessageService().check(timeout, checkMax, this.brokerController.getTransactionalMessageCheckListener());
log.info("End to check prepare message, consumed time:{}", System.currentTimeMillis() - begin);
}
这里先看看主要的逻辑
@Override
public void check(long transactionTimeout, int transactionCheckMax,
AbstractTransactionalMessageCheckListener listener) {
try {
//获取半消息的队列
String topic = MixAll.RMQ_SYS_TRANS_HALF_TOPIC;
Set<MessageQueue> msgQueues = transactionalMessageBridge.fetchMessageQueues(topic);
if (msgQueues == null || msgQueues.size() == 0) {
log.warn("The queue of topic is empty :" + topic);
return;
}
log.info("Check topic={}, queues={}", topic, msgQueues);
for (MessageQueue messageQueue : msgQueues) {
long startTime = System.currentTimeMillis();
//根据半消息队列，组装获取op_半消息(删除的标识) 队列
MessageQueue opQueue = getOpQueue(messageQueue);
//分别获取两者的消费偏移量
long halfOffset = transactionalMessageBridge.fetchConsumeOffset(messageQueue);
long opOffset = transactionalMessageBridge.fetchConsumeOffset(opQueue);
log.info("Before check, the queue={} msgOffset={} opOffset={}", messageQueue, halfOffset, opOffset);
if (halfOffset < 0 || opOffset < 0) {
log.error("MessageQueue: {} illegal offset read: {}, op offset: {},skip this queue", messageQueue,
halfOffset, opOffset);
continue;
}
List<Long> doneOpOffset = new ArrayList<>();
HashMap<Long, Long> removeMap = new HashMap<>();
//将需要移除的放入 removeMap，已经过期或者完成的消息放入doneOpOffSet中， key是半消息的offset
PullResult pullResult = fillOpRemoveMap(removeMap, opQueue, opOffset, halfOffset, doneOpOffset);
if (null == pullResult) {
log.error("The queue={} check msgOffset={} with opOffset={} failed, pullResult is null",
messageQueue, halfOffset, opOffset);
continue;
}
// single thread
int getMessageNullCount = 1;
long newOffset = halfOffset;
long i = halfOffset;
//具体的业务逻辑
while (true) {...}
//更新半消息的消费offset
if (newOffset != halfOffset) {
transactionalMessageBridge.updateConsumeOffset(messageQueue, newOffset);
}
//更新op_半消息的消费offset
long newOpOffset = calculateOpOffset(doneOpOffset, opOffset);
if (newOpOffset != opOffset) {
transactionalMessageBridge.updateConsumeOffset(opQueue, newOpOffset);
}
}
} catch (Exception e) {
e.printStackTrace();
log.error("Check error", e);
}
}
我们继续看while里面的具体业务逻辑
while (true) {
//处理时间超时退出处理
if (System.currentTimeMillis() - startTime > MAX_PROCESS_TIME_LIMIT) {
log.info("Queue={} process time reach max={}", messageQueue, MAX_PROCESS_TIME_LIMIT);
break;
}
//removeMap中存储的消息是已经被commit或者rollback,有删除标识的，所以这里存在需要移除
if (removeMap.containsKey(i)) {
log.info("Half offset {} has been committed/rolled back", i);
removeMap.remove(i);
} else {
GetResult getResult = getHalfMsg(messageQueue, i);
MessageExt msgExt = getResult.getMsg();
if (msgExt == null) {
if (getMessageNullCount++ > MAX_RETRY_COUNT_WHEN_HALF_NULL) {
break;
}
if (getResult.getPullResult().getPullStatus() == PullStatus.NO_NEW_MSG) {
log.info("No new msg, the miss offset={} in={}, continue check={}, pull result={}", i,
messageQueue, getMessageNullCount, getResult.getPullResult());
break;
} else {
log.info("Illegal offset, the miss offset={} in={}, continue check={}, pull result={}",
i, messageQueue, getMessageNullCount, getResult.getPullResult());
i = getResult.getPullResult().getNextBeginOffset();
newOffset = i;
continue;
}
}
//needDiscard 查过最多几次检查次数需要抛弃，needSkip消息存储超过三天也是需要抛弃
if (needDiscard(msgExt, transactionCheckMax) || needSkip(msgExt)) {
listener.resolveDiscardMsg(msgExt);
newOffset = i + 1;
i++;
continue;
}
//如果消息存储时间超过当前时间，那么退出当前逻辑
if (msgExt.getStoreTimestamp() >= startTime) {
log.info("Fresh stored. the miss offset={}, check it later, store={}", i,
new Date(msgExt.getStoreTimestamp()));
break;
}
long valueOfCurrentMinusBorn = System.currentTimeMillis() - msgExt.getBornTimestamp();
long checkImmunityTime = transactionTimeout;
String checkImmunityTimeStr = msgExt.getUserProperty(MessageConst.PROPERTY_CHECK_IMMUNITY_TIME_IN_SECONDS);
if (null != checkImmunityTimeStr) {
checkImmunityTime = getImmunityTime(checkImmunityTimeStr, transactionTimeout);
if (valueOfCurrentMinusBorn < checkImmunityTime) {
if (checkPrepareQueueOffset(removeMap, doneOpOffset, msgExt, checkImmunityTime)) {
newOffset = i + 1;
i++;
continue;
}
}
} else {
if ((0 <= valueOfCurrentMinusBorn) && (valueOfCurrentMinusBorn < checkImmunityTime)) {
log.info("New arrived, the miss offset={}, check it later checkImmunity={}, born={}", i,
checkImmunityTime, new Date(msgExt.getBornTimestamp()));
break;
}
}
List<MessageExt> opMsg = pullResult.getMsgFoundList();
//判断当前消息是否可以回查，有三个条件
boolean isNeedCheck = (opMsg == null && valueOfCurrentMinusBorn > checkImmunityTime)
|| (opMsg != null && (opMsg.get(opMsg.size() - 1).getBornTimestamp() - startTime > transactionTimeout))
|| (valueOfCurrentMinusBorn <= -1);
if (isNeedCheck) {
//将Half消息再次写入到commitlog中
if (!putBackHalfMsgQueue(msgExt, i)) {
continue;
}
//处理半消息，回查请求，单独的线程池处理
listener.resolveHalfMsg(msgExt);
} else {
pullResult = fillOpRemoveMap(removeMap, opQueue, pullResult.getNextBeginOffset(), halfOffset, doneOpOffset);
log.info("The miss offset:{} in messageQueue:{} need to get more opMsg, result is:{}", i,
messageQueue, pullResult);
continue;
}
}
//继续处理下一条消息
newOffset = i + 1;
i++;
}
后续的逻辑就是
服务端：
1.AbstractTransactionalMessageCheckListener#resolveHalfMsg //处理，向客户端发起请求
2.AbstractTransactionalMessageCheckListener#sendCheckMessage
3.Broker2Client#checkProducerTransactionState //通过invokeOneWay 发起请求check
客户端：
2.ClientRemotingProcessor#checkTransactionState
3.DefaultMQProducerImpl#checkTransactionState //本地逻辑处理
4.transactionListener.checkLocalTransaction //checkExecutor线程池 执行本地listener 事务结果
5.MQClientAPIImpl#endTransactionOneway //本地事务状态结果再次向服务端发起回传，服务端再重复之前的事务执行逻辑
//服务端代码
public void resolveHalfMsg(final MessageExt msgExt) {
executorService.execute(new Runnable() {
@Override
public void run() {
try {
//业务线程执行
sendCheckMessage(msgExt);
} catch (Exception e) {
LOGGER.error("Send check message error!", e);
}
}
});
}
public void sendCheckMessage(MessageExt msgExt) throws Exception {
CheckTransactionStateRequestHeader checkTransactionStateRequestHeader = new CheckTransactionStateRequestHeader();
checkTransactionStateRequestHeader.setCommitLogOffset(msgExt.getCommitLogOffset());
checkTransactionStateRequestHeader.setOffsetMsgId(msgExt.getMsgId());
checkTransactionStateRequestHeader.setMsgId(msgExt.getUserProperty(MessageConst.PROPERTY_UNIQ_CLIENT_MESSAGE_ID_KEYIDX));
checkTransactionStateRequestHeader.setTransactionId(checkTransactionStateRequestHeader.getMsgId());
checkTransactionStateRequestHeader.setTranStateTableOffset(msgExt.getQueueOffset());
msgExt.setTopic(msgExt.getUserProperty(MessageConst.PROPERTY_REAL_TOPIC));
msgExt.setQueueId(Integer.parseInt(msgExt.getUserProperty(MessageConst.PROPERTY_REAL_QUEUE_ID)));
msgExt.setStoreSize(0);
//从消息中获取生产组的一员发起请i去
String groupId = msgExt.getProperty(MessageConst.PROPERTY_PRODUCER_GROUP);
Channel channel = brokerController.getProducerManager().getAvaliableChannel(groupId);
if (channel != null) {
brokerController.getBroker2Client().checkProducerTransactionState(groupId, channel, checkTransactionStateRequestHeader, msgExt);
} else {
LOGGER.warn("Check transaction failed, channel is null. groupId={}", groupId);
}
}
//Broker2Client#checkProducerTransactionState
public void checkProducerTransactionState(
final String group,
final Channel channel,
final CheckTransactionStateRequestHeader requestHeader,
final MessageExt messageExt) throws Exception {
RemotingCommand request =
RemotingCommand.createRequestCommand(RequestCode.CHECK_TRANSACTION_STATE, requestHeader);
request.setBody(MessageDecoder.encode(messageExt, false));
try {
//单次发起请求处理
this.brokerController.getRemotingServer().invokeOneway(channel, request, 10);
} catch (Exception e) {
log.error("Check transaction failed because invoke producer exception. group={}, msgId={}", group, messageExt.getMsgId(), e.getMessage());
}
}
客户端的简单逻辑代码如下：
ClientRemotingProcessor#checkTransactionState
//
public RemotingCommand checkTransactionState(ChannelHandlerContext ctx,
RemotingCommand request) throws RemotingCommandException {
final CheckTransactionStateRequestHeader requestHeader =
(CheckTransactionStateRequestHeader) request.decodeCommandCustomHeader(CheckTransactionStateRequestHeader.class);
final ByteBuffer byteBuffer = ByteBuffer.wrap(request.getBody());
final MessageExt messageExt = MessageDecoder.decode(byteBuffer);
if (messageExt != null) {
String transactionId = messageExt.getProperty(MessageConst.PROPERTY_UNIQ_CLIENT_MESSAGE_ID_KEYIDX);
if (null != transactionId && !"".equals(transactionId)) {
messageExt.setTransactionId(transactionId);
}
final String group = messageExt.getProperty(MessageConst.PROPERTY_PRODUCER_GROUP);
if (group != null) {
MQProducerInner producer = this.mqClientFactory.selectProducer(group);
//找到当前生产组实例 做本地check
if (producer != null) {
final String addr = RemotingHelper.parseChannelRemoteAddr(ctx.channel());
producer.checkTransactionState(addr, messageExt, requestHeader);
} else {
log.debug("checkTransactionState, pick producer by group[{}] failed", group);
}
} else {
log.warn("checkTransactionState, pick producer group failed");
}
} else {
log.warn("checkTransactionState, decode message failed");
}
return null;
}
//DefaultMQProductImpl#checkTransactionState
@Override
public void checkTransactionState(final String addr, final MessageExt msg,
final CheckTransactionStateRequestHeader header) {
Runnable request = new Runnable() {
private final String brokerAddr = addr;
private final MessageExt message = msg;
private final CheckTransactionStateRequestHeader checkRequestHeader = header;
private final String group = DefaultMQProducerImpl.this.defaultMQProducer.getProducerGroup();
@Override
public void run() {
TransactionCheckListener transactionCheckListener = DefaultMQProducerImpl.this.checkListener();
TransactionListener transactionListener = getCheckListener();
if (transactionCheckListener != null || transactionListener != null) {
LocalTransactionState localTransactionState = LocalTransactionState.UNKNOW;
Throwable exception = null;
try {
//调用本地自定义的listerner 方法执行
if (transactionCheckListener != null) {
localTransactionState = transactionCheckListener.checkLocalTransactionState(message);
} else if (transactionListener != null) {
log.debug("Used new check API in transaction message");
localTransactionState = transactionListener.checkLocalTransaction(message);
} else {
log.warn("CheckTransactionState, pick transactionListener by group[{}] failed", group);
}
} catch (Throwable e) {
log.error("Broker call checkTransactionState, but checkLocalTransactionState exception", e);
exception = e;
}
//通过查询事务执行结果做后续处理
this.processTransactionState(
localTransactionState,
group,
exception);
} else {
log.warn("CheckTransactionState, pick transactionCheckListener by group[{}] failed", group);
}
}
private void processTransactionState(
final LocalTransactionState localTransactionState,
final String producerGroup,
final Throwable exception) {
final EndTransactionRequestHeader thisHeader = new EndTransactionRequestHeader();
thisHeader.setCommitLogOffset(checkRequestHeader.getCommitLogOffset());
thisHeader.setProducerGroup(producerGroup);
thisHeader.setTranStateTableOffset(checkRequestHeader.getTranStateTableOffset());
thisHeader.setFromTransactionCheck(true);
String uniqueKey = message.getProperties().get(MessageConst.PROPERTY_UNIQ_CLIENT_MESSAGE_ID_KEYIDX);
if (uniqueKey == null) {
uniqueKey = message.getMsgId();
}
thisHeader.setMsgId(uniqueKey);
thisHeader.setTransactionId(checkRequestHeader.getTransactionId());
switch (localTransactionState) {
case COMMIT_MESSAGE:
thisHeader.setCommitOrRollback(MessageSysFlag.TRANSACTION_COMMIT_TYPE);
break;
case ROLLBACK_MESSAGE:
thisHeader.setCommitOrRollback(MessageSysFlag.TRANSACTION_ROLLBACK_TYPE);
log.warn("when broker check, client rollback this transaction, {}", thisHeader);
break;
case UNKNOW:
thisHeader.setCommitOrRollback(MessageSysFlag.TRANSACTION_NOT_TYPE);
log.warn("when broker check, client does not know this transaction state, {}", thisHeader);
break;
default:
break;
}
String remark = null;
if (exception != null) {
remark = "checkLocalTransactionState Exception: " + RemotingHelper.exceptionSimpleDesc(exception);
}
try {
//继续通过获取到的事务结果 再次向服务端发起请求
DefaultMQProducerImpl.this.mQClientFactory.getMQClientAPIImpl().endTransactionOneway(brokerAddr, thisHeader, remark,
3000);
} catch (Exception e) {
log.error("endTransactionOneway exception", e);
}
}
};
//业务线程 处理本地事务结果查询
this.checkExecutor.submit(request);
}
