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DefaultMessageStore
接上文，SendMessageProcessor对象接收到消息之后，会把消息变成存储对象DefaultStoreMessage实例：
DefaultMessageStore的默认存储消息的方法asyncPutMessage如下：
@Override
public CompletableFuture<PutMessageResult> asyncPutMessage(MessageExtBrokerInner msg) {
PutMessageStatus checkStoreStatus = this.checkStoreStatus();
if (checkStoreStatus != PutMessageStatus.PUT_OK) {
return CompletableFuture.completedFuture(new PutMessageResult(checkStoreStatus, null));
}
PutMessageStatus msgCheckStatus = this.checkMessage(msg);
if (msgCheckStatus == PutMessageStatus.MESSAGE_ILLEGAL) {
return CompletableFuture.completedFuture(new PutMessageResult(msgCheckStatus, null));
}
long beginTime = this.getSystemClock().now();
CompletableFuture<PutMessageResult> putResultFuture = this.commitLog.asyncPutMessage(msg);
putResultFuture.thenAccept((result) -> {
long elapsedTime = this.getSystemClock().now() - beginTime;
if (elapsedTime > 500) {
log.warn("putMessage not in lock elapsed time(ms)={}, bodyLength={}", elapsedTime, msg.getBody().length);
}
this.storeStatsService.setPutMessageEntireTimeMax(elapsedTime);
if (null == result || !result.isOk()) {
this.storeStatsService.getPutMessageFailedTimes().incrementAndGet();
}
});
return putResultFuture;
}
整个存储流程的代码还是比较清晰的：
- 先判断消息是否投放成功 及 检查消息的格式
- 上述检查都没问题时就会把消息存储在
CommitLog里
CompletableFuture<PutMessageResult> putResultFuturethis.commitLog.asyncPutMessage(msg);
CommitLog
Broker接收到消息后，最终消息存储在Commitlog对象中，调用的是CommitLog的putMessage方法
public CompletableFuture<PutMessageResult> asyncPutMessage(final MessageExtBrokerInner msg) {
// Set the storage time
msg.setStoreTimestamp(System.currentTimeMillis());
// Set the message body BODY CRC (consider the most appropriate setting
// on the client)
msg.setBodyCRC(UtilAll.crc32(msg.getBody()));
// Back to Results
AppendMessageResult result = null;
StoreStatsService storeStatsService = this.defaultMessageStore.getStoreStatsService();
String topic = msg.getTopic();
int queueId = msg.getQueueId();
// 延时消息处理，事务为TRANSACTION_PREPARED_TYPE 和 TRANSACTION_ROLLBACK_TYPE 消息不支持延时投递
final int tranType = MessageSysFlag.getTransactionValue(msg.getSysFlag());
if (tranType == MessageSysFlag.TRANSACTION_NOT_TYPE
|| tranType == MessageSysFlag.TRANSACTION_COMMIT_TYPE) {
// Delay Delivery
if (msg.getDelayTimeLevel() > 0) {
if (msg.getDelayTimeLevel() > this.defaultMessageStore.getScheduleMessageService().getMaxDelayLevel()) {
msg.setDelayTimeLevel(this.defaultMessageStore.getScheduleMessageService().getMaxDelayLevel());
}
// 存储消息时，延时消息进入SCHEDULE_TOPIC_XXXX的主题下
topic = TopicValidator.RMQ_SYS_SCHEDULE_TOPIC;
// 消息队列编号 = 延迟级别 - 1
queueId = ScheduleMessageService.delayLevel2QueueId(msg.getDelayTimeLevel());
// Backup real topic, queueId
MessageAccessor.putProperty(msg, MessageConst.PROPERTY_REAL_TOPIC, msg.getTopic());
MessageAccessor.putProperty(msg, MessageConst.PROPERTY_REAL_QUEUE_ID, String.valueOf(msg.getQueueId()));
msg.setPropertiesString(MessageDecoder.messageProperties2String(msg.getProperties()));
msg.setTopic(topic);
msg.setQueueId(queueId);
}
}
InetSocketAddress bornSocketAddress = (InetSocketAddress) msg.getBornHost();
if (bornSocketAddress.getAddress() instanceof Inet6Address) {
msg.setBornHostV6Flag();
}
InetSocketAddress storeSocketAddress = (InetSocketAddress) msg.getStoreHost();
if (storeSocketAddress.getAddress() instanceof Inet6Address) {
msg.setStoreHostAddressV6Flag();
}
PutMessageThreadLocal putMessageThreadLocal = this.putMessageThreadLocal.get();
PutMessageResult encodeResult = putMessageThreadLocal.getEncoder().encode(msg);
if (encodeResult != null) {
return CompletableFuture.completedFuture(encodeResult);
}
msg.setEncodedBuff(putMessageThreadLocal.getEncoder().encoderBuffer);
PutMessageContext putMessageContext = new PutMessageContext(generateKey(putMessageThreadLocal.getKeyBuilder(), msg));
long elapsedTimeInLock = 0;
MappedFile unlockMappedFile = null;
// 加锁，同一时刻只能有一个线程put消息
putMessageLock.lock(); //spin or ReentrantLock ,depending on store config
try {
MappedFile mappedFile = this.mappedFileQueue.getLastMappedFile();
long beginLockTimestamp = this.defaultMessageStore.getSystemClock().now();
this.beginTimeInLock = beginLockTimestamp;
// Here settings are stored timestamp, in order to ensure an orderly
// global
msg.setStoreTimestamp(beginLockTimestamp);
// 只有不存在映射文件或文件已存满，才进行创建
if (null == mappedFile || mappedFile.isFull()) {
mappedFile = this.mappedFileQueue.getLastMappedFile(0);
}
if (null == mappedFile) {
log.error("create mapped file1 error, topic: " + msg.getTopic() + " clientAddr: " + msg.getBornHostString());
beginTimeInLock = 0;
return CompletableFuture.completedFuture(new PutMessageResult(PutMessageStatus.CREATE_MAPEDFILE_FAILED, null));
}
// 追加消息至MappedFile的缓存中，更新写入位置wrotePosition
result = mappedFile.appendMessage(msg, this.appendMessageCallback, putMessageContext);
switch (result.getStatus()) {
case PUT_OK:
break;
// 当文件剩余空间不足时，创建新的MappedFile并写入
case END_OF_FILE:
unlockMappedFile = mappedFile;
// Create a new file, re-write the message
mappedFile = this.mappedFileQueue.getLastMappedFile(0);
if (null == mappedFile) {
// XXX: warn and notify me
log.error("create mapped file2 error, topic: " + msg.getTopic() + " clientAddr: " + msg.getBornHostString());
beginTimeInLock = 0;
return CompletableFuture.completedFuture(new PutMessageResult(PutMessageStatus.CREATE_MAPEDFILE_FAILED, result));
}
result = mappedFile.appendMessage(msg, this.appendMessageCallback, putMessageContext);
break;
case MESSAGE_SIZE_EXCEEDED:
case PROPERTIES_SIZE_EXCEEDED:
beginTimeInLock = 0;
return CompletableFuture.completedFuture(new PutMessageResult(PutMessageStatus.MESSAGE_ILLEGAL, result));
case UNKNOWN_ERROR:
beginTimeInLock = 0;
return CompletableFuture.completedFuture(new PutMessageResult(PutMessageStatus.UNKNOWN_ERROR, result));
default:
beginTimeInLock = 0;
return CompletableFuture.completedFuture(new PutMessageResult(PutMessageStatus.UNKNOWN_ERROR, result));
}
elapsedTimeInLock = this.defaultMessageStore.getSystemClock().now() - beginLockTimestamp;
beginTimeInLock = 0;
} finally {
// 释放锁
putMessageLock.unlock();
}
/** log **/
if (null != unlockMappedFile && this.defaultMessageStore.getMessageStoreConfig().isWarmMapedFileEnable()) {
this.defaultMessageStore.unlockMappedFile(unlockMappedFile);
}
PutMessageResult putMessageResult = new PutMessageResult(PutMessageStatus.PUT_OK, result);
// Statistics
storeStatsService.getSinglePutMessageTopicTimesTotal(msg.getTopic()).incrementAndGet();
storeStatsService.getSinglePutMessageTopicSizeTotal(topic).addAndGet(result.getWroteBytes());
CompletableFuture<PutMessageStatus> flushResultFuture = submitFlushRequest(result, msg);
CompletableFuture<PutMessageStatus> replicaResultFuture = submitReplicaRequest(result, msg);
// 异步刷盘流程
return flushResultFuture.thenCombine(replicaResultFuture, (flushStatus, replicaStatus) -> {
if (flushStatus != PutMessageStatus.PUT_OK) {
putMessageResult.setPutMessageStatus(flushStatus);
}
if (replicaStatus != PutMessageStatus.PUT_OK) {
putMessageResult.setPutMessageStatus(replicaStatus);
if (replicaStatus == PutMessageStatus.FLUSH_SLAVE_TIMEOUT) {
log.error("do sync transfer other node, wait return, but failed, topic: {} tags: {} client address: {}",
msg.getTopic(), msg.getTags(), msg.getBornHostNameString());
}
}
return putMessageResult;
});
}
消息在
CommitLog文件中是顺序存储的
RocketMQ消息存储在CommitLog文件里，最终落盘，对应的类为MappedFile，它是从MappedFileQueue中获取的，如果对象不存在，就会创建：
MappedFile mappedFile = this.mappedFileQueue.getLastMappedFile();
// 只有不存在映射文件或文件已存满，才进行创建
if (null == mappedFile || mappedFile.isFull()) {
mappedFile = this.mappedFileQueue.getLastMappedFile(0);
}
创建（获取）完成对象之后就会把消息插入到mappedFile里，如果文件放不下了，则会重新创建一个mappedFile来对其进行写入，最后就是使用异步Future的方式把消息持久化到磁盘上。
MappedFileQueue
上面的源码里首先从MappedFileQueue映射队列尾部中获取MappedFile对象：
public MappedFile getLastMappedFile() {
MappedFile mappedFileLast = null;
while (!this.mappedFiles.isEmpty()) {
try {
mappedFileLast = this.mappedFiles.get(this.mappedFiles.size() - 1);
break;
} catch (IndexOutOfBoundsException e) {
//continue;
} catch (Exception e) {
log.error("getLastMappedFile has exception.", e);
break;
}
}
return mappedFileLast;
}
当MappedFile对象为空时，表示MappedFile对象不存在，此时就需要重新创建一个MappedFile对象，相应的方法在MappedFileQueue里
public class MappedFileQueue {
private static final InternalLogger log = InternalLoggerFactory.getLogger(LoggerName.STORE_LOGGER_NAME);
private static final InternalLogger LOG_ERROR = InternalLoggerFactory.getLogger(LoggerName.STORE_ERROR_LOGGER_NAME);
// 批量删除文件上限
private static final int DELETE_FILES_BATCH_MAX = 10;
// 目录
private final String storePath;
// 每个映射文件的大小
private final int mappedFileSize;
// 映射文件数组
private final CopyOnWriteArrayList<MappedFile> mappedFiles = new CopyOnWriteArrayList<MappedFile>();
// 分配MappedFile服务
private final AllocateMappedFileService allocateMappedFileService;
// 最后flush到的offset
private long flushedWhere = 0;
// 最后commit到的offset
private long committedWhere = 0;
// 最后保存的时间戳
private volatile long storeTimestamp = 0;
/**
* 获取最后一个可写入的映射文件
* 当最后一个文件已经满的时候，创建一个新的文件
*/
public MappedFile getLastMappedFile(final long startOffset, boolean needCreate) {
long createOffset = -1;
MappedFile mappedFileLast = getLastMappedFile();
// 不存在映射文件
if (mappedFileLast == null) {
// 计算从哪个offset开始
createOffset = startOffset - (startOffset % this.mappedFileSize);
}
// 最后一个文件已满
if (mappedFileLast != null && mappedFileLast.isFull()) {
createOffset = mappedFileLast.getFileFromOffset() + this.mappedFileSize;
}
// 创建文件
if (createOffset != -1 && needCreate) {
String nextFilePath = this.storePath + File.separator + UtilAll.offset2FileName(createOffset);
String nextNextFilePath = this.storePath + File.separator
+ UtilAll.offset2FileName(createOffset + this.mappedFileSize);
MappedFile mappedFile = null;
if (this.allocateMappedFileService != null) {
mappedFile = this.allocateMappedFileService.putRequestAndReturnMappedFile(nextFilePath,
nextNextFilePath, this.mappedFileSize);
} else {
try {
mappedFile = new MappedFile(nextFilePath, this.mappedFileSize);
} catch (IOException e) {
log.error("create mappedFile exception", e);
}
}
if (mappedFile != null) {
if (this.mappedFiles.isEmpty()) {
mappedFile.setFirstCreateInQueue(true);
}
this.mappedFiles.add(mappedFile);
}
return mappedFile;
}
return mappedFileLast;
}
public MappedFile getLastMappedFile(final long startOffset) {
return getLastMappedFile(startOffset, true);
}
}
当获取到的“最后一个”MappedFile不存在或文件已满时，则新建一个，并计算新文件的createOffset
MappedFile
在CommitLog的代码中，最终把消息追加到MappedFile文件的缓冲区中，同时更新其写入位置writePosition，但是还没有刷盘：
result = mappedFile.appendMessages(messageExtBatch, this.appendMessageCallback, putMessageContext);
其中调用了MappedFile的appendMessage方法实现添加消息到消息映射文件：
public AppendMessageResult appendMessagesInner(final MessageExt messageExt, final AppendMessageCallback cb,
PutMessageContext putMessageContext) {
assert messageExt != null;
assert cb != null;
int currentPos = this.wrotePosition.get();
if (currentPos < this.fileSize) {
// 缓冲区
ByteBuffer byteBuffer = writeBuffer != null ? writeBuffer.slice() : this.mappedByteBuffer.slice();
byteBuffer.position(currentPos);
AppendMessageResult result;
// 判断是否是批量操作
if (messageExt instanceof MessageExtBrokerInner) {
result = cb.doAppend(this.getFileFromOffset(), byteBuffer, this.fileSize - currentPos,
(MessageExtBrokerInner) messageExt, putMessageContext);
} else if (messageExt instanceof MessageExtBatch) {
result = cb.doAppend(this.getFileFromOffset(), byteBuffer, this.fileSize - currentPos,
(MessageExtBatch) messageExt, putMessageContext);
} else {
return new AppendMessageResult(AppendMessageStatus.UNKNOWN_ERROR);
}
// 更新写入位置 + 写入偏移量
this.wrotePosition.addAndGet(result.getWroteBytes());
this.storeTimestamp = result.getStoreTimestamp();
return result;
}
log.error("MappedFile.appendMessage return null, wrotePosition: {} fileSize: {}", currentPos, this.fileSize);
return new AppendMessageResult(AppendMessageStatus.UNKNOWN_ERROR);
}
通过源码可以看到，实际上是吧消息放入ByteBuffer，同时更新写入位置和偏移量
submitFlushRequest
提交刷盘请求的源码如下：
public CompletableFuture<PutMessageStatus> submitFlushRequest(AppendMessageResult result, MessageExt messageExt) {
// 异步flush
if (FlushDiskType.SYNC_FLUSH == this.defaultMessageStore.getMessageStoreConfig().getFlushDiskType()) {
final GroupCommitService service = (GroupCommitService) this.flushCommitLogService;
if (messageExt.isWaitStoreMsgOK()) {
GroupCommitRequest request = new GroupCommitRequest(result.getWroteOffset() + result.getWroteBytes(),
this.defaultMessageStore.getMessageStoreConfig().getSyncFlushTimeout());
service.putRequest(request);
return request.future();
} else {
service.wakeup();
return CompletableFuture.completedFuture(PutMessageStatus.PUT_OK);
}
}
// 同步flush
else {
if (!this.defaultMessageStore.getMessageStoreConfig().isTransientStorePoolEnable()) {
flushCommitLogService.wakeup(); // 异步，使用MappedByteBuffer（默认策略）
} else {
commitLogService.wakeup(); // 异步，使用字节缓冲区 + FileChannel
}
return CompletableFuture.completedFuture(PutMessageStatus.PUT_OK);
}
}
CommitLog文件刷盘是由FlushCommitLogService服务具体执行，一共有两种刷盘策略：
-
FlushDiskType.SYNC_FLUSH：同步刷盘 -
FlushDiskType.ASYNC_FLUSH：异步刷盘
同步刷盘的情况下，必须要等到数据刷盘成功后才会有返回结果；如果是异步刷盘，只需要把消息放入内存之后即可返回。
上述策略可以在broker.conf配置文件中进行配置