RocketMQ源码解析：事务消息
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title: RocketMQ 源码分析 —— 事务消息
date: 2017-05-21
tags:
categories: RocketMQ
permalink: RocketMQ/message-transaction
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- 1. 概述
- 2. 事务消息发送
- 2.1 Producer 发送事务消息
- 2.2 Broker 处理结束事务请求
- 2.3 Broker 生成 ConsumeQueue
- 3. 事务消息回查
- 3.1 Broker 发起【事务消息回查】
- 3.1.1 官方V3.1.4：基于文件系统
- 3.1.1.1 存储消息到 CommitLog
- 3.1.1.2 写【事务消息】状态存储（TranStateTable）
- 3.1.1.3 【事务消息】回查
- 3.1.1.4 初始化【事务消息】状态存储（TranStateTable）
- 3.1.1.5 补充
- 3.1.2 官方V4.0.0：基于数据库
- 3.1.1 官方V3.1.4：基于文件系统
- 3.2 Producer 接收【事务消息回查】
- 3.1 Broker 发起【事务消息回查】
1. 概述
必须必须必须 前置阅读内容：
- 《事务消息（阿里云）》
2. 事务消息发送
2.1 Producer 发送事务消息
- 活动图如下（结合
核心代码理解）：
- 实现代码如下：
1: // ⬇️⬇️⬇️【DefaultMQProducerImpl.java】 2: /** 3: * 发送事务消息 4: * 5: * @param msg 消息 6: * @param tranExecuter 【本地事务】执行器 7: * @param arg 【本地事务】执行器参数 8: * @return 事务发送结果 9: * @throws MQClientException 当 Client 发生异常时 10: */ 11: public TransactionSendResult sendMessageInTransaction(final Message msg, final LocalTransactionExecuter tranExecuter, final Object arg) 12: throws MQClientException { 13: if (null == tranExecuter) { 14: throw new MQClientException("tranExecutor is null", null); 15: } 16: Validators.checkMessage(msg, this.defaultMQProducer); 17: 18: // 发送【Half消息】 19: SendResult sendResult; 20: MessageAccessor.putProperty(msg, MessageConst.PROPERTY_TRANSACTION_PREPARED, "true"); 21: MessageAccessor.putProperty(msg, MessageConst.PROPERTY_PRODUCER_GROUP, this.defaultMQProducer.getProducerGroup()); 22: try { 23: sendResult = this.send(msg); 24: } catch (Exception e) { 25: throw new MQClientException("send message Exception", e); 26: } 27: 28: // 处理发送【Half消息】结果 29: LocalTransactionState localTransactionState = LocalTransactionState.UNKNOW; 30: Throwable localException = null; 31: switch (sendResult.getSendStatus()) { 32: // 发送【Half消息】成功，执行【本地事务】逻辑 33: case SEND_OK: { 34: try { 35: if (sendResult.getTransactionId() != null) { // 事务编号。目前开源版本暂时没用到，猜想ONS在使用。 36: msg.putUserProperty("__transactionId__", sendResult.getTransactionId()); 37: } 38: 39: // 执行【本地事务】逻辑 40: localTransactionState = tranExecuter.executeLocalTransactionBranch(msg, arg); 41: if (null == localTransactionState) { 42: localTransactionState = LocalTransactionState.UNKNOW; 43: } 44: 45: if (localTransactionState != LocalTransactionState.COMMIT_MESSAGE) { 46: log.info("executeLocalTransactionBranch return {}", localTransactionState); 47: log.info(msg.toString()); 48: } 49: } catch (Throwable e) { 50: log.info("executeLocalTransactionBranch exception", e); 51: log.info(msg.toString()); 52: localException = e; 53: } 54: } 55: break; 56: // 发送【Half消息】失败，标记【本地事务】状态为回滚 57: case FLUSH_DISK_TIMEOUT: 58: case FLUSH_SLAVE_TIMEOUT: 59: case SLAVE_NOT_AVAILABLE: 60: localTransactionState = LocalTransactionState.ROLLBACK_MESSAGE; 61: break; 62: default: 63: break; 64: } 65: 66: // 结束事务：提交消息 COMMIT / ROLLBACK 67: try { 68: this.endTransaction(sendResult, localTransactionState, localException); 69: } catch (Exception e) { 70: log.warn("local transaction execute " + localTransactionState + ", but end broker transaction failed", e); 71: } 72: 73: // 返回【事务发送结果】 74: TransactionSendResult transactionSendResult = new TransactionSendResult(); 75: transactionSendResult.setSendStatus(sendResult.getSendStatus()); 76: transactionSendResult.setMessageQueue(sendResult.getMessageQueue()); 77: transactionSendResult.setMsgId(sendResult.getMsgId()); 78: transactionSendResult.setQueueOffset(sendResult.getQueueOffset()); 79: transactionSendResult.setTransactionId(sendResult.getTransactionId()); 80: transactionSendResult.setLocalTransactionState(localTransactionState); 81: return transactionSendResult; 82: } 83: 84: /** 85: * 结束事务：提交消息 COMMIT / ROLLBACK 86: * 87: * @param sendResult 发送【Half消息】结果 88: * @param localTransactionState 【本地事务】状态 89: * @param localException 执行【本地事务】逻辑产生的异常 90: * @throws RemotingException 当远程调用发生异常时 91: * @throws MQBrokerException 当 Broker 发生异常时 92: * @throws InterruptedException 当线程中断时 93: * @throws UnknownHostException 当解码消息编号失败是 94: */ 95: public void endTransaction(// 96: final SendResult sendResult, // 97: final LocalTransactionState localTransactionState, // 98: final Throwable localException) throws RemotingException, MQBrokerException, InterruptedException, UnknownHostException { 99: // 解码消息编号100: final MessageId id;101: if (sendResult.getOffsetMsgId() != null) {102: id = MessageDecoder.decodeMessageId(sendResult.getOffsetMsgId());103: } else {104: id = MessageDecoder.decodeMessageId(sendResult.getMsgId());105: }106: 107: // 创建请求108: String transactionId = sendResult.getTransactionId();109: final String brokerAddr = this.mQClientFactory.findBrokerAddressInPublish(sendResult.getMessageQueue().getBrokerName());110: EndTransactionRequestHeader requestHeader = new EndTransactionRequestHeader();111: requestHeader.setTransactionId(transactionId);112: requestHeader.setCommitLogOffset(id.getOffset());113: switch (localTransactionState) {114: case COMMIT_MESSAGE:115: requestHeader.setCommitOrRollback(MessageSysFlag.TRANSACTION_COMMIT_TYPE);116: break;117: case ROLLBACK_MESSAGE:118: requestHeader.setCommitOrRollback(MessageSysFlag.TRANSACTION_ROLLBACK_TYPE);119: break;120: case UNKNOW:121: requestHeader.setCommitOrRollback(MessageSysFlag.TRANSACTION_NOT_TYPE);122: break;123: default:124: break;125: }126: requestHeader.setProducerGroup(this.defaultMQProducer.getProducerGroup());127: requestHeader.setTranStateTableOffset(sendResult.getQueueOffset());128: requestHeader.setMsgId(sendResult.getMsgId());129: String remark = localException != null ? ("executeLocalTransactionBranch exception: " + localException.toString()) : null;130: 131: // 提交消息 COMMIT / ROLLBACK。！！！通信方式为：Oneway！！！132: this.mQClientFactory.getMQClientAPIImpl().endTransactionOneway(brokerAddr, requestHeader, remark, this.defaultMQProducer.getSendMsgTimeout());133: }2.2 Broker 处理结束事务请求
- �� 查询请求的消息，进行提交 / 回滚。实现代码如下：
1: // ⬇️⬇️⬇️【EndTransactionProcessor.java】 2: public RemotingCommand processRequest(ChannelHandlerContext ctx, RemotingCommand request) throws RemotingCommandException { 3: final RemotingCommand response = RemotingCommand.createResponseCommand(null); 4: final EndTransactionRequestHeader requestHeader = (EndTransactionRequestHeader) request.decodeCommandCustomHeader(EndTransactionRequestHeader.class); 5: 6: // 省略代码 =》打印日志（只处理 COMMIT / ROLLBACK） 7: 8: // 查询提交的消息 9: final MessageExt msgExt = this.brokerController.getMessageStore().lookMessageByOffset(requestHeader.getCommitLogOffset()); 10: if (msgExt != null) { 11: // 省略代码 =》校验消息 12: 13: // 生成消息 14: MessageExtBrokerInner msgInner = this.endMessageTransaction(msgExt); 15: msgInner.setSysFlag(MessageSysFlag.resetTransactionValue(msgInner.getSysFlag(), requestHeader.getCommitOrRollback())); 16: msgInner.setQueueOffset(requestHeader.getTranStateTableOffset()); 17: msgInner.setPreparedTransactionOffset(requestHeader.getCommitLogOffset()); 18: msgInner.setStoreTimestamp(msgExt.getStoreTimestamp()); 19: if (MessageSysFlag.TRANSACTION_ROLLBACK_TYPE == requestHeader.getCommitOrRollback()) { 20: msgInner.setBody(null); 21: } 22: 23: // 存储生成消息 24: final MessageStore messageStore = this.brokerController.getMessageStore(); 25: final PutMessageResult putMessageResult = messageStore.putMessage(msgInner); 26: 27: // 处理存储结果 28: if (putMessageResult != null) { 29: switch (putMessageResult.getPutMessageStatus()) { 30: // Success 31: case PUT_OK: 32: case FLUSH_DISK_TIMEOUT: 33: case FLUSH_SLAVE_TIMEOUT: 34: case SLAVE_NOT_AVAILABLE: 35: response.setCode(ResponseCode.SUCCESS); 36: response.setRemark(null); 37: break; 38: // Failed 39: case CREATE_MAPEDFILE_FAILED: 40: response.setCode(ResponseCode.SYSTEM_ERROR); 41: response.setRemark("create maped file failed."); 42: break; 43: case MESSAGE_ILLEGAL: 44: case PROPERTIES_SIZE_EXCEEDED: 45: response.setCode(ResponseCode.MESSAGE_ILLEGAL); 46: response.setRemark("the message is illegal, maybe msg body or properties length not matched. msg body length limit 128k, msg properties length limit 32k."); 47: break; 48: case SERVICE_NOT_AVAILABLE: 49: response.setCode(ResponseCode.SERVICE_NOT_AVAILABLE); 50: response.setRemark("service not available now."); 51: break; 52: case OS_PAGECACHE_BUSY: 53: response.setCode(ResponseCode.SYSTEM_ERROR); 54: response.setRemark("OS page cache busy, please try another machine"); 55: break; 56: case UNKNOWN_ERROR: 57: response.setCode(ResponseCode.SYSTEM_ERROR); 58: response.setRemark("UNKNOWN_ERROR"); 59: break; 60: default: 61: response.setCode(ResponseCode.SYSTEM_ERROR); 62: response.setRemark("UNKNOWN_ERROR DEFAULT"); 63: break; 64: } 65: 66: return response; 67: } else { 68: response.setCode(ResponseCode.SYSTEM_ERROR); 69: response.setRemark("store putMessage return null"); 70: } 71: } else { 72: response.setCode(ResponseCode.SYSTEM_ERROR); 73: response.setRemark("find prepared transaction message failed"); 74: return response; 75: } 76: 77: return response; 78: }2.3 Broker 生成 ConsumeQueue
- �� 事务消息，提交（
COMMIT）后才生成ConsumeQueue。
1: // ⬇️⬇️⬇️【DefaultMessageStore.java】 2: public void doDispatch(DispatchRequest req) { 3: // 非事务消息 或 事务提交消息 建立 消息位置信息 到 ConsumeQueue 4: final int tranType = MessageSysFlag.getTransactionValue(req.getSysFlag()); 5: switch (tranType) { 6: case MessageSysFlag.TRANSACTION_NOT_TYPE: // 非事务消息 7: case MessageSysFlag.TRANSACTION_COMMIT_TYPE: // 事务消息COMMIT 8: DefaultMessageStore.this.putMessagePositionInfo(req.getTopic(), req.getQueueId(), req.getCommitLogOffset(), req.getMsgSize(), 9: req.getTagsCode(), req.getStoreTimestamp(), req.getConsumeQueueOffset()); 10: break; 11: case MessageSysFlag.TRANSACTION_PREPARED_TYPE: // 事务消息PREPARED 12: case MessageSysFlag.TRANSACTION_ROLLBACK_TYPE: // 事务消息ROLLBACK 13: break; 14: } 15: // 省略代码 =》 建立 索引信息 到 IndexFile 16: }3. 事务消息回查
- 【事务消息回查】功能曾经开源过，目前（V4.0.0）暂未开源。如下是该功能的开源情况：
我们来看看两种情况下是怎么实现的。
3.1 Broker 发起【事务消息回查】
3.1.1 官方V3.1.4：基于文件系统
仓库地址：https://github.com/YunaiV/rocketmq-3.1.9/tree/release_3.1.4
相较于普通消息，【事务消息】多依赖如下三个组件：
- TransactionStateService ：事务状态服务，负责对【事务消息】进行管理，包括存储与更新事务消息状态、回查事务消息状态等等。
- TranStateTable ：【事务消息】状态存储。基于
MappedFileQueue实现，默认存储路径为~/store/transaction/statetable，每条【事务消息】状态存储结构如下：
* TranRedoLog ：TranStateTable 重放日志，每次写操作 TranStateTable 记录重放日志。当 Broker 异常关闭时，使用 TranRedoLog 恢复 TranStateTable。基于 ConsumeQueue 实现，Topic 为 TRANSACTION_REDOLOG_TOPIC_XXXX，默认存储路径为 ~/store/transaction/redolog。
简单手绘逻辑图如下��：
3.1.1.1 存储消息到 CommitLog
- ��存储【half消息】到
CommitLog时，消息队列位置（queueOffset）使用TranStateTable最大物理位置（可写入物理位置）。这样，消息可以索引到自己对应的TranStateTable的位置和记录。
核心代码如下：
1: // ⬇️⬇️⬇️【DefaultAppendMessageCallback.java】 2: class DefaultAppendMessageCallback implements AppendMessageCallback { 3: public AppendMessageResult doAppend(final long fileFromOffset, final ByteBuffer byteBuffer, final int maxBlank, final Object msg) { 4: // ...省略代码 5: 6: // 事务消息需要特殊处理 7: final int tranType = MessageSysFlag.getTransactionValue(msgInner.getSysFlag()); 8: switch (tranType) { 9: case MessageSysFlag.TransactionPreparedType: // 消息队列位置（queueOffset）使用 TranStateTable 最大物理位置（可写入物理位置） 10: queueOffset = CommitLog.this.defaultMessageStore.getTransactionStateService().getTranStateTableOffset().get(); 11: break; 12: case MessageSysFlag.TransactionRollbackType: 13: queueOffset = msgInner.getQueueOffset(); 14: break; 15: case MessageSysFlag.TransactionNotType: 16: case MessageSysFlag.TransactionCommitType: 17: default: 18: break; 19: } 20: 21: // ...省略代码 22: 23: switch (tranType) { 24: case MessageSysFlag.TransactionPreparedType: 25: // 更新 TranStateTable 最大物理位置（可写入物理位置） 26: CommitLog.this.defaultMessageStore.getTransactionStateService().getTranStateTableOffset().incrementAndGet(); 27: break; 28: case MessageSysFlag.TransactionRollbackType: 29: break; 30: case MessageSysFlag.TransactionNotType: 31: case MessageSysFlag.TransactionCommitType: 32: // 更新下一次的ConsumeQueue信息 33: CommitLog.this.topicQueueTable.put(key, ++queueOffset); 34: break; 35: default: 36: break; 37: } 38: 39: // 返回结果 40: return result; 41: } 42: }3.1.1.2 写【事务消息】状态存储（TranStateTable）
- ��处理【Half消息】时，新增【事务消息】状态存储（
TranStateTable）。 - ��处理【Commit / Rollback消息】时，更新 【事务消息】状态存储（
TranStateTable） COMMIT / ROLLBACK。 - ��每次写操作【事务消息】状态存储（
TranStateTable），记录重放日志（TranRedoLog）。
核心代码如下：
1: // ⬇️⬇️⬇️【DispatchMessageService.java】 2: private void doDispatch() { 3: if (!this.requestsRead.isEmpty()) { 4: for (DispatchRequest req : this.requestsRead) { 5: 6: // ...省略代码 7: 8: // 2、写【事务消息】状态存储（TranStateTable） 9: if (req.getProducerGroup() != null) { 10: switch (tranType) { 11: case MessageSysFlag.TransactionNotType: 12: break; 13: case MessageSysFlag.TransactionPreparedType: 14: // 新增 【事务消息】状态存储（TranStateTable） 15: DefaultMessageStore.this.getTransactionStateService().appendPreparedTransaction( 16: req.getCommitLogOffset(), req.getMsgSize(), (int) (req.getStoreTimestamp() / 1000), req.getProducerGroup().hashCode()); 17: break; 18: case MessageSysFlag.TransactionCommitType: 19: case MessageSysFlag.TransactionRollbackType: 20: // 更新 【事务消息】状态存储（TranStateTable） COMMIT / ROLLBACK 21: DefaultMessageStore.this.getTransactionStateService().updateTransactionState( 22: req.getTranStateTableOffset(), req.getPreparedTransactionOffset(), req.getProducerGroup().hashCode(), tranType); 23: break; 24: } 25: } 26: // 3、记录 TranRedoLog 27: switch (tranType) { 28: case MessageSysFlag.TransactionNotType: 29: break; 30: case MessageSysFlag.TransactionPreparedType: 31: // 记录 TranRedoLog 32: DefaultMessageStore.this.getTransactionStateService().getTranRedoLog().putMessagePostionInfoWrapper( 33: req.getCommitLogOffset(), req.getMsgSize(), TransactionStateService.PreparedMessageTagsCode, 34: req.getStoreTimestamp(), 0L); 35: break; 36: case MessageSysFlag.TransactionCommitType: 37: case MessageSysFlag.TransactionRollbackType: 38: // 记录 TranRedoLog 39: DefaultMessageStore.this.getTransactionStateService().getTranRedoLog().putMessagePostionInfoWrapper( 40: req.getCommitLogOffset(), req.getMsgSize(), req.getPreparedTransactionOffset(), 41: req.getStoreTimestamp(), 0L); 42: break; 43: } 44: } 45: 46: // ...省略代码 47: } 48: } 49: // ⬇️⬇️⬇️【TransactionStateService.java】 50: /** 51: * 新增事务状态 52: * 53: * @param clOffset commitLog 物理位置 54: * @param size 消息长度 55: * @param timestamp 消息存储时间 56: * @param groupHashCode groupHashCode 57: * @return 是否成功 58: */ 59: public boolean appendPreparedTransaction(// 60: final long clOffset,// 61: final int size,// 62: final int timestamp,// 63: final int groupHashCode// 64: ) { 65: MapedFile mapedFile = this.tranStateTable.getLastMapedFile(); 66: if (null == mapedFile) { 67: log.error("appendPreparedTransaction: create mapedfile error."); 68: return false; 69: } 70: 71: // 首次创建，加入定时任务中 72: if (0 == mapedFile.getWrotePostion()) { 73: this.addTimerTask(mapedFile); 74: } 75: 76: this.byteBufferAppend.position(0); 77: this.byteBufferAppend.limit(TSStoreUnitSize); 78: 79: // Commit Log Offset 80: this.byteBufferAppend.putLong(clOffset); 81: // Message Size 82: this.byteBufferAppend.putInt(size); 83: // Timestamp 84: this.byteBufferAppend.putInt(timestamp); 85: // Producer Group Hashcode 86: this.byteBufferAppend.putInt(groupHashCode); 87: // Transaction State 88: this.byteBufferAppend.putInt(MessageSysFlag.TransactionPreparedType); 89: 90: return mapedFile.appendMessage(this.byteBufferAppend.array()); 91: } 92: 93: /** 94: * 更新事务状态 95: * 96: * @param tsOffset tranStateTable 物理位置 97: * @param clOffset commitLog 物理位置 98: * @param groupHashCode groupHashCode 99: * @param state 事务状态100: * @return 是否成功101: */102: public boolean updateTransactionState(103: final long tsOffset,104: final long clOffset,105: final int groupHashCode,106: final int state) {107: SelectMapedBufferResult selectMapedBufferResult = this.findTransactionBuffer(tsOffset);108: if (selectMapedBufferResult != null) {109: try {110: 111: // ....省略代码：校验是否能够更新112: 113: // 更新事务状态114: selectMapedBufferResult.getByteBuffer().putInt(TS_STATE_POS, state);115: }116: catch (Exception e) {117: log.error("updateTransactionState exception", e);118: }119: finally {120: selectMapedBufferResult.release();121: }122: }123: 124: return false;125: }3.1.1.3 【事务消息】回查
- ��
TranStateTable每个MappedFile都对应一个Timer。Timer固定周期（默认：60s）遍历MappedFile，查找【half消息】，向Producer发起【事务消息】回查请求。【事务消息】回查结果的逻辑不在此处进行，在 CommitLog dispatch时执行。
实现代码如下：
1: // ⬇️⬇️⬇️【TransactionStateService.java】 2: /** 3: * 初始化定时任务 4: */ 5: private void initTimerTask() { 6: // 7: final List<MapedFile> mapedFiles = this.tranStateTable.getMapedFiles(); 8: for (MapedFile mf : mapedFiles) { 9: this.addTimerTask(mf); 10: } 11: } 12: 13: /** 14: * 每个文件初始化定时任务 15: * @param mf 文件 16: */ 17: private void addTimerTask(final MapedFile mf) { 18: this.timer.scheduleAtFixedRate(new TimerTask() { 19: private final MapedFile mapedFile = mf; 20: private final TransactionCheckExecuter transactionCheckExecuter = TransactionStateService.this.defaultMessageStore.getTransactionCheckExecuter(); 21: private final long checkTransactionMessageAtleastInterval = TransactionStateService.this.defaultMessageStore.getMessageStoreConfig() 22: .getCheckTransactionMessageAtleastInterval(); 23: private final boolean slave = TransactionStateService.this.defaultMessageStore.getMessageStoreConfig().getBrokerRole() == BrokerRole.SLAVE; 24: 25: @Override 26: public void run() { 27: // Slave不需要回查事务状态 28: if (slave) { 29: return; 30: } 31: // Check功能是否开启 32: if (!TransactionStateService.this.defaultMessageStore.getMessageStoreConfig() 33: .isCheckTransactionMessageEnable()) { 34: return; 35: } 36: 37: try { 38: SelectMapedBufferResult selectMapedBufferResult = mapedFile.selectMapedBuffer(0); 39: if (selectMapedBufferResult != null) { 40: long preparedMessageCountInThisMapedFile = 0; // 回查的【half消息】数量 41: int i = 0; 42: try { 43: // 循环每条【事务消息】状态，对【half消息】进行回查 44: for (; i < selectMapedBufferResult.getSize(); i += TSStoreUnitSize) { 45: selectMapedBufferResult.getByteBuffer().position(i); 46: 47: // Commit Log Offset 48: long clOffset = selectMapedBufferResult.getByteBuffer().getLong(); 49: // Message Size 50: int msgSize = selectMapedBufferResult.getByteBuffer().getInt(); 51: // Timestamp 52: int timestamp = selectMapedBufferResult.getByteBuffer().getInt(); 53: // Producer Group Hashcode 54: int groupHashCode = selectMapedBufferResult.getByteBuffer().getInt(); 55: // Transaction State 56: int tranType = selectMapedBufferResult.getByteBuffer().getInt(); 57: 58: // 已经提交或者回滚的消息跳过 59: if (tranType != MessageSysFlag.TransactionPreparedType) { 60: continue; 61: } 62: 63: // 遇到时间不符合最小轮询间隔，终止 64: long timestampLong = timestamp * 1000; 65: long diff = System.currentTimeMillis() - timestampLong; 66: if (diff < checkTransactionMessageAtleastInterval) { 67: break; 68: } 69: 70: preparedMessageCountInThisMapedFile++; 71: 72: // 回查Producer 73: try { 74: this.transactionCheckExecuter.gotoCheck(groupHashCode, getTranStateOffset(i), clOffset, msgSize); 75: } catch (Exception e) { 76: tranlog.warn("gotoCheck Exception", e); 77: } 78: } 79: 80: // 无回查的【half消息】数量，且遍历完，则终止定时任务 81: if (0 == preparedMessageCountInThisMapedFile // 82: && i == mapedFile.getFileSize()) { 83: tranlog.info("remove the transaction timer task, because no prepared message in this mapedfile[{}]", mapedFile.getFileName()); 84: this.cancel(); 85: } 86: } finally { 87: selectMapedBufferResult.release(); 88: } 89: 90: tranlog.info("the transaction timer task execute over in this period, {} Prepared Message: {} Check Progress: {}/{}", mapedFile.getFileName(),// 91: preparedMessageCountInThisMapedFile, i / TSStoreUnitSize, mapedFile.getFileSize() / TSStoreUnitSize); 92: } else if (mapedFile.isFull()) { 93: tranlog.info("the mapedfile[{}] maybe deleted, cancel check transaction timer task", mapedFile.getFileName()); 94: this.cancel(); 95: return; 96: } 97: } catch (Exception e) { 98: log.error("check transaction timer task Exception", e); 99: }100: }101: 102: 103: private long getTranStateOffset(final long currentIndex) {104: long offset = (this.mapedFile.getFileFromOffset() + currentIndex) / TransactionStateService.TSStoreUnitSize;105: return offset;106: }107: }, 1000 * 60, this.defaultMessageStore.getMessageStoreConfig().getCheckTransactionMessageTimerInterval());108: }109: 110: // 【DefaultTransactionCheckExecuter.java】111: @Override112: public void gotoCheck(int producerGroupHashCode, long tranStateTableOffset, long commitLogOffset,113: int msgSize) {114: // 第一步、查询Producer115: final ClientChannelInfo clientChannelInfo = this.brokerController.getProducerManager().pickProducerChannelRandomly(producerGroupHashCode);116: if (null == clientChannelInfo) {117: log.warn("check a producer transaction state, but not find any channel of this group[{}]", producerGroupHashCode);118: return;119: }120: 121: // 第二步、查询消息122: SelectMapedBufferResult selectMapedBufferResult = this.brokerController.getMessageStore().selectOneMessageByOffset(commitLogOffset, msgSize);123: if (null == selectMapedBufferResult) {124: log.warn("check a producer transaction state, but not find message by commitLogOffset: {}, msgSize: ", commitLogOffset, msgSize);125: return;126: }127: 128: // 第三步、向Producer发起请求129: final CheckTransactionStateRequestHeader requestHeader = new CheckTransactionStateRequestHeader();130: requestHeader.setCommitLogOffset(commitLogOffset);131: requestHeader.setTranStateTableOffset(tranStateTableOffset);132: this.brokerController.getBroker2Client().checkProducerTransactionState(clientChannelInfo.getChannel(), requestHeader, selectMapedBufferResult);133: }3.1.1.4 初始化【事务消息】状态存储（TranStateTable）
- ��根据最后 Broker 关闭是否正常，会有不同的初始化方式。
核心代码如下：
1: // ⬇️⬇️⬇️【TransactionStateService.java】 2: /** 3: * 初始化 TranRedoLog 4: * @param lastExitOK 是否正常退出 5: */ 6: public void recoverStateTable(final boolean lastExitOK) { 7: if (lastExitOK) { 8: this.recoverStateTableNormal(); 9: } else { 10: // 第一步，删除State Table 11: this.tranStateTable.destroy(); 12: // 第二步，通过RedoLog全量恢复StateTable 13: this.recreateStateTable(); 14: } 15: } 16: 17: /** 18: * 扫描 TranRedoLog 重建 StateTable 19: */ 20: private void recreateStateTable() { 21: this.tranStateTable = new MapedFileQueue(StorePathConfigHelper.getTranStateTableStorePath(defaultMessageStore 22: .getMessageStoreConfig().getStorePathRootDir()), defaultMessageStore 23: .getMessageStoreConfig().getTranStateTableMapedFileSize(), null); 24: 25: final TreeSet<Long> preparedItemSet = new TreeSet<Long>(); 26: 27: // 第一步，从头扫描RedoLog 28: final long minOffset = this.tranRedoLog.getMinOffsetInQuque(); 29: long processOffset = minOffset; 30: while (true) { 31: SelectMapedBufferResult bufferConsumeQueue = this.tranRedoLog.getIndexBuffer(processOffset); 32: if (bufferConsumeQueue != null) { 33: try { 34: long i = 0; 35: for (; i < bufferConsumeQueue.getSize(); i += ConsumeQueue.CQStoreUnitSize) { 36: long offsetMsg = bufferConsumeQueue.getByteBuffer().getLong(); 37: int sizeMsg = bufferConsumeQueue.getByteBuffer().getInt(); 38: long tagsCode = bufferConsumeQueue.getByteBuffer().getLong(); 39: 40: if (TransactionStateService.PreparedMessageTagsCode == tagsCode) { // Prepared 41: preparedItemSet.add(offsetMsg); 42: } else { // Commit/Rollback 43: preparedItemSet.remove(tagsCode); 44: } 45: } 46: 47: processOffset += i; 48: } finally { // 必须释放资源 49: bufferConsumeQueue.release(); 50: } 51: } else { 52: break; 53: } 54: } 55: log.info("scan transaction redolog over, End offset: {}, Prepared Transaction Count: {}", processOffset, preparedItemSet.size()); 56: 57: // 第二步，重建StateTable 58: Iterator<Long> it = preparedItemSet.iterator(); 59: while (it.hasNext()) { 60: Long offset = it.next(); 61: MessageExt msgExt = this.defaultMessageStore.lookMessageByOffset(offset); 62: if (msgExt != null) { 63: this.appendPreparedTransaction(msgExt.getCommitLogOffset(), msgExt.getStoreSize(), 64: (int) (msgExt.getStoreTimestamp() / 1000), 65: msgExt.getProperty(MessageConst.PROPERTY_PRODUCER_GROUP).hashCode()); 66: this.tranStateTableOffset.incrementAndGet(); 67: } 68: } 69: } 70: 71: /** 72: * 加载（解析）TranStateTable 的 MappedFile 73: * 1. 清理多余 MappedFile，设置最后一个 MappedFile的写入位置(position 74: * 2. 设置 TanStateTable 最大物理位置（可写入位置） 75: */ 76: private void recoverStateTableNormal() { 77: final List<MapedFile> mapedFiles = this.tranStateTable.getMapedFiles(); 78: if (!mapedFiles.isEmpty()) { 79: // 从倒数第三个文件开始恢复 80: int index = mapedFiles.size() - 3; 81: if (index < 0) { 82: index = 0; 83: } 84: 85: int mapedFileSizeLogics = this.tranStateTable.getMapedFileSize(); 86: MapedFile mapedFile = mapedFiles.get(index); 87: ByteBuffer byteBuffer = mapedFile.sliceByteBuffer(); 88: long processOffset = mapedFile.getFileFromOffset(); 89: long mapedFileOffset = 0; 90: while (true) { 91: for (int i = 0; i < mapedFileSizeLogics; i += TSStoreUnitSize) { 92: 93: final long clOffset_read = byteBuffer.getLong(); 94: final int size_read = byteBuffer.getInt(); 95: final int timestamp_read = byteBuffer.getInt(); 96: final int groupHashCode_read = byteBuffer.getInt(); 97: final int state_read = byteBuffer.getInt(); 98: 99: boolean stateOK = false;100: switch (state_read) {101: case MessageSysFlag.TransactionPreparedType:102: case MessageSysFlag.TransactionCommitType:103: case MessageSysFlag.TransactionRollbackType:104: stateOK = true;105: break;106: default:107: break;108: }109: 110: // 说明当前存储单元有效111: if (clOffset_read >= 0 && size_read > 0 && stateOK) {112: mapedFileOffset = i + TSStoreUnitSize;113: } else {114: log.info("recover current transaction state table file over, " + mapedFile.getFileName() + " "115: + clOffset_read + " " + size_read + " " + timestamp_read);116: break;117: }118: }119: 120: // 走到文件末尾，切换至下一个文件121: if (mapedFileOffset == mapedFileSizeLogics) {122: index++;123: if (index >= mapedFiles.size()) { // 循环while结束124: log.info("recover last transaction state table file over, last maped file " + mapedFile.getFileName());125: break;126: } else { // 切换下一个文件127: mapedFile = mapedFiles.get(index);128: byteBuffer = mapedFile.sliceByteBuffer();129: processOffset = mapedFile.getFileFromOffset();130: mapedFileOffset = 0;131: log.info("recover next transaction state table file, " + mapedFile.getFileName());132: }133: } else {134: log.info("recover current transaction state table queue over " + mapedFile.getFileName() + " " + (processOffset + mapedFileOffset));135: break;136: }137: }138: 139: // 清理多余 MappedFile，设置最后一个 MappedFile的写入位置(position140: processOffset += mapedFileOffset;141: this.tranStateTable.truncateDirtyFiles(processOffset);142: 143: // 设置 TanStateTable 最大物理位置（可写入位置）144: this.tranStateTableOffset.set(this.tranStateTable.getMaxOffset() / TSStoreUnitSize);145: log.info("recover normal over, transaction state table max offset: {}", this.tranStateTableOffset.get());146: }147: }3.1.1.5 补充
- 为什么 V3.1.5 开始，使用 数据库 实现【事务状态】的存储？如下是来自官方文档的说明，可能是一部分原因：
RocketMQ 这种实现事务方式，没有通过 KV 存储做，而是通过 Offset 方式，存在一个显著缺陷，即通过 Offset 更改数据，会令系统的脏页过多，需要特别关注。
3.1.2 官方V4.0.0：基于数据库
仓库地址：https://github.com/apache/incubator-rocketmq
官方V4.0.0 暂时未完全开源【事务消息回查】功能，So 我们需要进行一些猜想，可能不一定正确��。
��我们来对比【官方V3.1.4：基于文件】的实现。
- TransactionRecord ：记录每条【事务消息】。类似
TranStateTable。
另外，数据库本身保证了数据存储的可靠性，无需 TranRedoLog。
简单手绘逻辑图如下��：
3.2 Producer 接收【事务消息回查】
- 顺序图如下：
- 核心代码如下：
1: // ⬇️⬇️⬇️【DefaultMQProducerImpl.java】 2: /** 3: * 检查【事务状态】状态 4: * 5: * @param addr broker地址 6: * @param msg 消息 7: * @param header 请求 8: */ 9: @Override 10: public void checkTransactionState(final String addr, final MessageExt msg, final CheckTransactionStateRequestHeader header) { 11: Runnable request = new Runnable() { 12: private final String brokerAddr = addr; 13: private final MessageExt message = msg; 14: private final CheckTransactionStateRequestHeader checkRequestHeader = header; 15: private final String group = DefaultMQProducerImpl.this.defaultMQProducer.getProducerGroup(); 16: 17: @Override 18: public void run() { 19: TransactionCheckListener transactionCheckListener = DefaultMQProducerImpl.this.checkListener(); 20: if (transactionCheckListener != null) { 21: // 获取事务执行状态 22: LocalTransactionState localTransactionState = LocalTransactionState.UNKNOW; 23: Throwable exception = null; 24: try { 25: localTransactionState = transactionCheckListener.checkLocalTransactionState(message); 26: } catch (Throwable e) { 27: log.error("Broker call checkTransactionState, but checkLocalTransactionState exception", e); 28: exception = e; 29: } 30: 31: // 处理事务结果，提交消息 COMMIT / ROLLBACK 32: this.processTransactionState(// 33: localTransactionState, // 34: group, // 35: exception); 36: } else { 37: log.warn("checkTransactionState, pick transactionCheckListener by group[{}] failed", group); 38: } 39: } 40: 41: /** 42: * 处理事务结果，提交消息 COMMIT / ROLLBACK 43: * 44: * @param localTransactionState 【本地事务】状态 45: * @param producerGroup producerGroup 46: * @param exception 检查【本地事务】状态发生的异常 47: */ 48: private void processTransactionState(// 49: final LocalTransactionState localTransactionState, // 50: final String producerGroup, // 51: final Throwable exception) { 52: final EndTransactionRequestHeader thisHeader = new EndTransactionRequestHeader(); 53: thisHeader.setCommitLogOffset(checkRequestHeader.getCommitLogOffset()); 54: thisHeader.setProducerGroup(producerGroup); 55: thisHeader.setTranStateTableOffset(checkRequestHeader.getTranStateTableOffset()); 56: thisHeader.setFromTransactionCheck(true); 57: 58: // 设置消息编号 59: String uniqueKey = message.getProperties().get(MessageConst.PROPERTY_UNIQ_CLIENT_MESSAGE_ID_KEYIDX); 60: if (uniqueKey == null) { 61: uniqueKey = message.getMsgId(); 62: } 63: thisHeader.setMsgId(uniqueKey); 64: 65: thisHeader.setTransactionId(checkRequestHeader.getTransactionId()); 66: switch (localTransactionState) { 67: case COMMIT_MESSAGE: 68: thisHeader.setCommitOrRollback(MessageSysFlag.TRANSACTION_COMMIT_TYPE); 69: break; 70: case ROLLBACK_MESSAGE: 71: thisHeader.setCommitOrRollback(MessageSysFlag.TRANSACTION_ROLLBACK_TYPE); 72: log.warn("when broker check, client rollback this transaction, {}", thisHeader); 73: break; 74: case UNKNOW: 75: thisHeader.setCommitOrRollback(MessageSysFlag.TRANSACTION_NOT_TYPE); 76: log.warn("when broker check, client does not know this transaction state, {}", thisHeader); 77: break; 78: default: 79: break; 80: } 81: 82: String remark = null; 83: if (exception != null) { 84: remark = "checkLocalTransactionState Exception: " + RemotingHelper.exceptionSimpleDesc(exception); 85: } 86: 87: try { 88: // 提交消息 COMMIT / ROLLBACK 89: DefaultMQProducerImpl.this.mQClientFactory.getMQClientAPIImpl().endTransactionOneway(brokerAddr, thisHeader, remark, 90: 3000); 91: } catch (Exception e) { 92: log.error("endTransactionOneway exception", e); 93: } 94: } 95: }; 96: 97: // 提交执行 98: this.checkExecutor.submit(request); 99: }100: 101: // ⬇️⬇️⬇️【DefaultMQProducerImpl.java】102: /**103: * 【事务消息回查】检查监听器104: */105: public interface TransactionCheckListener {106: 107: /**108: * 获取（检查）【本地事务】状态109: *110: * @param msg 消息111: * @return 事务状态112: */113: LocalTransactionState checkLocalTransactionState(final MessageExt msg);114: 115: }阅读全文
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