/**
* Copyright (C) 2010-2013 Alibaba Group Holding Limited
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.alibaba.rocketmq.store.transaction;
import java.nio.ByteBuffer;
import java.util.Iterator;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;
import java.util.TreeSet;
import java.util.concurrent.atomic.AtomicLong;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.alibaba.rocketmq.common.constant.LoggerName;
import com.alibaba.rocketmq.common.message.MessageConst;
import com.alibaba.rocketmq.common.message.MessageExt;
import com.alibaba.rocketmq.common.sysflag.MessageSysFlag;
import com.alibaba.rocketmq.store.ConsumeQueue;
import com.alibaba.rocketmq.store.DefaultMessageStore;
import com.alibaba.rocketmq.store.MapedFile;
import com.alibaba.rocketmq.store.MapedFileQueue;
import com.alibaba.rocketmq.store.SelectMapedBufferResult;
import com.alibaba.rocketmq.store.config.BrokerRole;
/**
* 事务服务，存储每条事务的状态（Prepared，Commited，Rollbacked）<br>
* 名词解释：<br>
* clOffset - Commit Log Offset<br>
* tsOffset - Transaction State Table Offset
*
* @author shijia.wxr<vintage.wang@gmail.com>
* @since 2013-7-21
*/
public class TransactionStateService {
// 存储单元大小
public static final int TSStoreUnitSize = 24;
// 用来恢复事务状态表的redolog
public static final String TRANSACTION_REDOLOG_TOPIC = "TRANSACTION_REDOLOG_TOPIC_XXXX";
public static final int TRANSACTION_REDOLOG_TOPIC_QUEUEID = 0;
public final static long PreparedMessageTagsCode = -1;
private static final Logger log = LoggerFactory.getLogger(LoggerName.StoreLoggerName);
// 更改事务状态，具体更改位置
private final static int TS_STATE_POS = 20;
private static final Logger tranlog = LoggerFactory.getLogger(LoggerName.TransactionLoggerName);
// 存储顶层对象
private final DefaultMessageStore defaultMessageStore;
// 重复利用内存Buffer
private final ByteBuffer byteBufferAppend = ByteBuffer.allocate(TSStoreUnitSize);
// 事务状态的Redolog，当进程意外宕掉，可通过redolog恢复所有事务的状态
// Redolog的实现利用了消费队列，主要为了恢复方便
private final ConsumeQueue tranRedoLog;
// State Table Offset，重启时，必须纠正
private final AtomicLong tranStateTableOffset = new AtomicLong(0);
// 定时回查线程
private final Timer timer = new Timer("CheckTransactionMessageTimer", true);
// 存储事务状态的表格
private MapedFileQueue tranStateTable;
public TransactionStateService(final DefaultMessageStore defaultMessageStore) {
this.defaultMessageStore = defaultMessageStore;
this.tranStateTable =
new MapedFileQueue(defaultMessageStore.getMessageStoreConfig().getTranStateTableStorePath(),
defaultMessageStore.getMessageStoreConfig().getTranStateTableMapedFileSize(), null);
this.tranRedoLog = new ConsumeQueue(//
TRANSACTION_REDOLOG_TOPIC,//
TRANSACTION_REDOLOG_TOPIC_QUEUEID,//
defaultMessageStore.getMessageStoreConfig().getTranRedoLogStorePath(),//
defaultMessageStore.getMessageStoreConfig().getTranRedoLogMapedFileSize(),//
defaultMessageStore);
}
public boolean load() {
boolean result = this.tranRedoLog.load();
result = result && this.tranStateTable.load();
return result;
}
public void start() {
this.initTimerTask();
}
private void initTimerTask() {
final List<MapedFile> mapedFiles = this.tranStateTable.getMapedFiles();
for (MapedFile mf : mapedFiles) {
this.addTimerTask(mf);
}
}
private void addTimerTask(final MapedFile mf) {
this.timer.scheduleAtFixedRate(new TimerTask() {
private final MapedFile mapedFile = mf;
private final TransactionCheckExecuter transactionCheckExecuter =
TransactionStateService.this.defaultMessageStore.getTransactionCheckExecuter();
private final long checkTransactionMessageAtleastInterval =
TransactionStateService.this.defaultMessageStore.getMessageStoreConfig()
.getCheckTransactionMessageAtleastInterval();
private final boolean slave = TransactionStateService.this.defaultMessageStore
.getMessageStoreConfig().getBrokerRole() == BrokerRole.SLAVE;
@Override
public void run() {
// Slave不需要回查事务状态
if (slave)
return;
// Check功能是否开启
if (!TransactionStateService.this.defaultMessageStore.getMessageStoreConfig()
.isCheckTransactionMessageEnable()) {
return;
}
try {
/**
* chen.si:这里会延迟执行，消息会先写进去，导致file的write position
*
* 这里做个同步是不是好点，加载完消息，再触发这里
*/
SelectMapedBufferResult selectMapedBufferResult = mapedFile.selectMapedBuffer(0);
if (selectMapedBufferResult != null) {
long preparedMessageCountInThisMapedFile = 0;
int i = 0;
try {
for (; i < selectMapedBufferResult.getSize(); i += TSStoreUnitSize) {
selectMapedBufferResult.getByteBuffer().position(i);
// Commit Log Offset
long clOffset = selectMapedBufferResult.getByteBuffer().getLong();
// Message Size
int msgSize = selectMapedBufferResult.getByteBuffer().getInt();
// Timestamp
int timestamp = selectMapedBufferResult.getByteBuffer().getInt();
// Producer Group Hashcode
int groupHashCode = selectMapedBufferResult.getByteBuffer().getInt();
// Transaction State
int tranType = selectMapedBufferResult.getByteBuffer().getInt();
/**
* chen.si:这里只需要处理超时的prepared消息，用于回查事务状态
*/
// 已经提交或者回滚的消息跳过
if (tranType != MessageSysFlag.TransactionPreparedType) {
continue;
}
// 遇到时间不符合，终止
long timestampLong = timestamp * 1000;
long diff = System.currentTimeMillis() - timestampLong;
if (diff < checkTransactionMessageAtleastInterval) {
/**
* chen.si 这里没法优化，本想记录 当前操作位置，后面继续处理。
* 但是，这里只是发事务确认消息，是oneway的， 可能会确认失败，或者 事务状态unknown
* 需要继续重新来查
*/
break;
}
preparedMessageCountInThisMapedFile++;
try {
this.transactionCheckExecuter.gotoCheck(//
groupHashCode,//
getTranStateOffset(i),//
clOffset,//
msgSize);
}
catch (Exception e) {
tranlog.warn("gotoCheck Exception", e);
}
}
// 无Prepared消息，且遍历完，则终止定时任务
if (0 == preparedMessageCountInThisMapedFile //
&& i == mapedFile.getFileSize()) {
tranlog
.info(
"remove the transaction timer task, because no prepared message in this mapedfile[{}]",
mapedFile.getFileName());
this.cancel();
}
}
finally {
selectMapedBufferResult.release();
}
tranlog
.info(
"the transaction timer task execute over in this period, {} Prepared Message: {} Check Progress: {}/{}",
mapedFile.getFileName(),//
preparedMessageCountInThisMapedFile,//
i / TSStoreUnitSize,//
mapedFile.getFileSize() / TSStoreUnitSize//
);
}
else if (mapedFile.isFull()) {
tranlog.info("the mapedfile[{}] maybe deleted, cancel check transaction timer task",
mapedFile.getFileName());
this.cancel();
return;
}
}
catch (Exception e) {
log.error("check transaction timer task Exception", e);
}
}
private long getTranStateOffset(final long currentIndex) {
long offset =
(this.mapedFile.getFileFromOffset() + currentIndex)
/ TransactionStateService.TSStoreUnitSize;
return offset;
}
}, 1000 * 60, this.defaultMessageStore.getMessageStoreConfig()
.getCheckTransactionMessageTimerInterval());
}
public void shutdown() {
this.timer.cancel();
}
public int deleteExpiredStateFile(long offset) {
int cnt = this.tranStateTable.deleteExpiredFileByOffset(offset, TSStoreUnitSize);
return cnt;
}
public void recoverStateTable(final boolean lastExitOK) {
if (lastExitOK) {
this.recoverStateTableNormal();
}
else {
// 第一步，删除State Table
/**
* chen.si：这里删除了所有的tran table
*/
this.tranStateTable.destroy();
// 第二步，通过RedoLog全量恢复StateTable
/**
* chen.si：重新生成tran table
*/
this.recreateStateTable();
}
}
private void recreateStateTable() {
this.tranStateTable =
new MapedFileQueue(defaultMessageStore.getMessageStoreConfig().getTranStateTableStorePath(),
defaultMessageStore.getMessageStoreConfig().getTranStateTableMapedFileSize(), null);
final TreeSet<Long> preparedItemSet = new TreeSet<Long>();
// 第一步，重头扫描RedoLog
final long minOffset = this.tranRedoLog.getMinOffsetInQuque();
long processOffset = minOffset;
while (true) {
SelectMapedBufferResult bufferConsumeQueue = this.tranRedoLog.getIndexBuffer(processOffset);
if (bufferConsumeQueue != null) {
try {
long i = 0;
for (; i < bufferConsumeQueue.getSize(); i += ConsumeQueue.CQStoreUnitSize) {
long offsetMsg = bufferConsumeQueue.getByteBuffer().getLong();
int sizeMsg = bufferConsumeQueue.getByteBuffer().getInt();
long tagsCode = bufferConsumeQueue.getByteBuffer().getLong();
/**
* chen.si:redo 消息示例：
*
prepared:
1 commitLogOffset:3780
2 messageSize:195
3 tagsCode:-1
prepared:
1 commitLogOffset:3975
2 messageSize:195
3 tagsCode:-1
commit/rollback:
1 commitLogOffset:4170
2 messageSize:195
3 tagsCode:3975
*/
// Prepared
/**
* chen.si：根据tag code来区分redo消息类型
*/
if (TransactionStateService.PreparedMessageTagsCode == tagsCode) {
preparedItemSet.add(offsetMsg);
}
// Commit/Rollback
else {
/**
* chen.si: commit和rollback的消息，不需要继续处理，同时 要将对应的prepared消息移除掉
*/
preparedItemSet.remove(tagsCode);
}
}
processOffset += i;
}
finally {
// 必须释放资源
bufferConsumeQueue.release();
}
}
else {
break;
}
}
log.info("scan transaction redolog over, End offset: {}, Prepared Transaction Count: {}",
processOffset, preparedItemSet.size());
// 第二步，重建StateTable
Iterator<Long> it = preparedItemSet.iterator();
while (it.hasNext()) {
Long offset = it.next();
/**
* chen.si：根据redo消息，在commit log中找到对应的prepared消息
*/
MessageExt msgExt = this.defaultMessageStore.lookMessageByOffset(offset);
if (msgExt != null) {
/**
* chen.si:重建tran stat消息
*/
this.appendPreparedTransaction(msgExt.getCommitLogOffset(), msgExt.getStoreSize(),
(int) (msgExt.getStoreTimestamp() / 1000),
msgExt.getProperty(MessageConst.PROPERTY_PRODUCER_GROUP).hashCode());
this.tranStateTableOffset.incrementAndGet();
}
}
}
/**
* 单线程调用
*/
public boolean appendPreparedTransaction(//
final long clOffset,//
final int size,//
final int timestamp,//
final int groupHashCode//
) {
MapedFile mapedFile = this.tranStateTable.getLastMapedFile();
if (null == mapedFile) {
log.error("appendPreparedTransaction: create mapedfile error.");
return false;
}
/**
* chen.si:用来处理prepared tran消息，主要进行回查事务状态
*/
// 首次创建，加入定时任务中
if (0 == mapedFile.getWrotePostion()) {
this.addTimerTask(mapedFile);
}
/**
* chen.si：将redo中的prepared消息，重新写入tran stat文件
*/
this.byteBufferAppend.position(0);
this.byteBufferAppend.limit(TSStoreUnitSize);
// Commit Log Offset
this.byteBufferAppend.putLong(clOffset);
// Message Size
this.byteBufferAppend.putInt(size);
// Timestamp
this.byteBufferAppend.putInt(timestamp);
// Producer Group Hashcode
this.byteBufferAppend.putInt(groupHashCode);
// Transaction State
this.byteBufferAppend.putInt(MessageSysFlag.TransactionPreparedType);
return mapedFile.appendMessage(this.byteBufferAppend.array());
}
private void recoverStateTableNormal() {
/**
* chen.si：这个方法的主要任务如下：
*
* 1. 设置 tran log queue中的最后一个消息位置 ？ 这个版本为什么不设置？
*
* 2. 设置最后一个消息所在 log文件的commit 和 write position
*
* 3. 设置tran stat的事务消息的下一个序号
*
* 3. 删除多余的文件
*/
final List<MapedFile> mapedFiles = this.tranStateTable.getMapedFiles();
if (!mapedFiles.isEmpty()) {
/**
* chen.si:老路子了，依旧从最后的3个文件中找出 最后一个在用文件
*/
// 从倒数第三个文件开始恢复
int index = mapedFiles.size() - 3;
if (index < 0)
index = 0;
int mapedFileSizeLogics = this.tranStateTable.getMapedFileSize();
MapedFile mapedFile = mapedFiles.get(index);
ByteBuffer byteBuffer = mapedFile.sliceByteBuffer();
/*
* chen.si：queue offset(global offset)
*/
long processOffset = mapedFile.getFileFromOffset();
/*
* chen.si：file offset(local offset)
*/
long mapedFileOffset = 0;
while (true) {
/**
* chen.si：每个事务消息24个字节
*/
for (int i = 0; i < mapedFileSizeLogics; i += TSStoreUnitSize) {
final long clOffset_read = byteBuffer.getLong();
final int size_read = byteBuffer.getInt();
final int timestamp_read = byteBuffer.getInt();
final int groupHashCode_read = byteBuffer.getInt();
/**
* chen.si：事务状态：prepared/commit/rollback
*/
final int state_read = byteBuffer.getInt();
/**
* chen.si: 事务消息的示例
*
* 其中<>内的内容为时间转换后的
*
* prepared：
1 commitLogOffset:3780
2 messageSize:195
3 timestamp:1404354477 <1970-01-17 14:05:54>
4 groupHCode:1119945399
5 tranType:4
commit：
1 commitLogOffset:3975
2 messageSize:195
3 timestamp:1404355385 <1970-01-17 14:05:55>
4 groupHCode:1119945399
5 tranType:8
*/
boolean stateOK = false;
switch (state_read) {
case MessageSysFlag.TransactionPreparedType:
case MessageSysFlag.TransactionCommitType:
case MessageSysFlag.TransactionRollbackType:
stateOK = true;
break;
default:
break;
}
// 说明当前存储单元有效
// TODO 这样判断有效是否合理？
if (clOffset_read >= 0 && size_read > 0 && stateOK) {
/**
* chen.si：消息合法，增加 file offset
*/
mapedFileOffset = i + TSStoreUnitSize;
}
else {
log.info("recover current transaction state table file over, "
+ mapedFile.getFileName() + " " + clOffset_read + " " + size_read + " "
+ timestamp_read);
break;
}
}
// 走到文件末尾，切换至下一个文件
if (mapedFileOffset == mapedFileSizeLogics) {
index++;
if (index >= mapedFiles.size()) {
// 当前条件分支不可能发生
log.info("recover last transaction state table file over, last maped file "
+ mapedFile.getFileName());
break;
}
else {
/**
* chen.si：继续解析下一个文件
*/
mapedFile = mapedFiles.get(index);
byteBuffer = mapedFile.sliceByteBuffer();
/**
* chen.si：queue offset直接更新为 file的名字对应的offset
*/
processOffset = mapedFile.getFileFromOffset();
mapedFileOffset = 0;
log.info("recover next transaction state table file, " + mapedFile.getFileName());
}
}
else {
log.info("recover current transaction state table queue over " + mapedFile.getFileName()
+ " " + (processOffset + mapedFileOffset));
break;
}
}
processOffset += mapedFileOffset;
/**
* chen.si：
* 1. 设置 代写文件 的commit 和 write position
* 2. 删除多余的文件
*/
this.tranStateTable.truncateDirtyFiles(processOffset);
/**
* chen.si:这个很重要，基于事务消息个数，来设置 事务的ID
*/
this.tranStateTableOffset.set(this.tranStateTable.getMaxOffset() / TSStoreUnitSize);
log.info("recover normal over, transaction state table max offset: {}",
this.tranStateTableOffset.get());
}
}
/**
* 单线程调用
*/
public boolean updateTransactionState(//
final long tsOffset,//
final long clOffset,//
final int groupHashCode,//
final int state//
) {
SelectMapedBufferResult selectMapedBufferResult = this.findTransactionBuffer(tsOffset);
if (selectMapedBufferResult != null) {
try {
final long clOffset_read = selectMapedBufferResult.getByteBuffer().getLong();
final int size_read = selectMapedBufferResult.getByteBuffer().getInt();
final int timestamp_read = selectMapedBufferResult.getByteBuffer().getInt();
final int groupHashCode_read = selectMapedBufferResult.getByteBuffer().getInt();
final int state_read = selectMapedBufferResult.getByteBuffer().getInt();
// 校验数据正确性
if (clOffset != clOffset_read) {
log.error("updateTransactionState error clOffset: {} clOffset_read: {}", clOffset,
clOffset_read);
return false;
}
// 校验数据正确性
if (groupHashCode != groupHashCode_read) {
log.error("updateTransactionState error groupHashCode: {} groupHashCode_read: {}",
groupHashCode, groupHashCode_read);
return false;
}
// 判断是否已经更新过
if (MessageSysFlag.TransactionPreparedType != state_read) {
log.warn("updateTransactionState error, the transaction is updated before.");
return true;
}
// 更新事务状态
selectMapedBufferResult.getByteBuffer().putInt(TS_STATE_POS, state);
}
catch (Exception e) {
log.error("updateTransactionState exception", e);
}
finally {
selectMapedBufferResult.release();
}
}
return false;
}
private SelectMapedBufferResult findTransactionBuffer(final long tsOffset) {
final int mapedFileSize =
this.defaultMessageStore.getMessageStoreConfig().getTranStateTableMapedFileSize();
final long offset = tsOffset * TSStoreUnitSize;
MapedFile mapedFile = this.tranStateTable.findMapedFileByOffset(offset);
if (mapedFile != null) {
SelectMapedBufferResult result = mapedFile.selectMapedBuffer((int) (offset % mapedFileSize));
return result;
}
return null;
}
public AtomicLong getTranStateTableOffset() {
return tranStateTableOffset;
}
public ConsumeQueue getTranRedoLog() {
return tranRedoLog;
}
}