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小编给大家分享一下RocketMQ中broker消息存储之如何实现消息转储,希望大家阅读完这篇文章之后都有所收获,下面让我们一起去探讨吧!
broker在接收到producer发送的消息之后,首先会将消息存储到CommitLog的末尾,然后通过一个异步的分发线程ReputMessageService将消息转储到ConsumeQueue以及IndexFile中。
转储的核心逻辑在ReputMessageService.doReput中:
// DefaultMessageStore.ReputMessageService private void doReput() { if (this.reputFromOffset < DefaultMessageStore.this.commitLog.getMinOffset()) { log.warn("The reputFromOffset={} is smaller than minPyOffset={}, this usually indicate that the dispatch behind too much and the commitlog has expired.", this.reputFromOffset, DefaultMessageStore.this.commitLog.getMinOffset()); this.reputFromOffset = DefaultMessageStore.this.commitLog.getMinOffset(); } for (boolean doNext = true; this.isCommitLogAvailable() && doNext; ) { if (DefaultMessageStore.this.getMessageStoreConfig().isDuplicationEnable() && this.reputFromOffset >= DefaultMessageStore.this.getConfirmOffset()) { break; } // 1. 获取reputFromOffset偏移所指向的数据 SelectMappedBufferResult result = DefaultMessageStore.this.commitLog.getData(reputFromOffset); if (result != null) { try { this.reputFromOffset = result.getStartOffset(); for (int readSize = 0; readSize < result.getSize() && doNext; ) { // 2. 解析消息体 DispatchRequest dispatchRequest = DefaultMessageStore.this.commitLog.checkMessageAndReturnSize(result.getByteBuffer(), false, false); int size = dispatchRequest.getBufferSize() == -1 ? dispatchRequest.getMsgSize() : dispatchRequest.getBufferSize(); if (dispatchRequest.isSuccess()) { if (size > 0) { // 3. 执行分发 DefaultMessageStore.this.doDispatch(dispatchRequest); // ... this.reputFromOffset += size; readSize += size; // ... } else if (size == 0) { this.reputFromOffset = DefaultMessageStore.this.commitLog.rollNextFile(this.reputFromOffset); readSize = result.getSize(); } } else if (!dispatchRequest.isSuccess()) { // ... } } } finally { result.release(); } } else { doNext = false; } } }
ConsumeQueue的插入操作如下:
// ConsumeQueue.java private boolean putMessagePositionInfo(final long offset, final int size, final long tagsCode, final long cqOffset) { if (offset + size <= this.maxPhysicOffset) { log.warn("Maybe try to build consume queue repeatedly maxPhysicOffset={} phyOffset={}", maxPhysicOffset, offset); return true; } // 1. 将commitlog offset/msg size/tags code写到内存缓存 this.byteBufferIndex.flip(); this.byteBufferIndex.limit(CQ_STORE_UNIT_SIZE); this.byteBufferIndex.putLong(offset); this.byteBufferIndex.putInt(size); this.byteBufferIndex.putLong(tagsCode); final long expectLogicOffset = cqOffset * CQ_STORE_UNIT_SIZE; // ConsumeQueue中偏移 // 2. 获取最后一个MappedFile MappedFile mappedFile = this.mappedFileQueue.getLastMappedFile(expectLogicOffset); if (mappedFile != null) { // ... this.maxPhysicOffset = offset + size; // 3. 写入索引数据 return mappedFile.appendMessage(this.byteBufferIndex.array()); } return false; }
IndexFile的写入逻辑如下:
// IndexService.java public void buildIndex(DispatchRequest req) { IndexFile indexFile = retryGetAndCreateIndexFile(); if (indexFile != null) { long endPhyOffset = indexFile.getEndPhyOffset(); DispatchRequest msg = req; String topic = msg.getTopic(); String keys = msg.getKeys(); if (msg.getCommitLogOffset() < endPhyOffset) { return; } // ... if (keys != null && keys.length() > 0) { String[] keyset = keys.split(MessageConst.KEY_SEPARATOR); for (int i = 0; i < keyset.length; i++) { // 为每个key执行写入 String key = keyset[i]; if (key.length() > 0) { indexFile = putKey(indexFile, msg, buildKey(topic, key)); if (indexFile == null) { log.error("putKey error commitlog {} uniqkey {}", req.getCommitLogOffset(), req.getUniqKey()); return; } } } } } else { log.error("build index error, stop building index"); } } private IndexFile putKey(IndexFile indexFile, DispatchRequest msg, String idxKey) { for (boolean ok = indexFile.putKey(idxKey, msg.getCommitLogOffset(), msg.getStoreTimestamp()); !ok; ) { log.warn("Index file [" + indexFile.getFileName() + "] is full, trying to create another one"); indexFile = retryGetAndCreateIndexFile(); // 文件已满,重试 if (null == indexFile) { return null; } ok = indexFile.putKey(idxKey, msg.getCommitLogOffset(), msg.getStoreTimestamp()); } return indexFile; }
消息转储的整体流程如下图:
看完了这篇文章,相信你对“RocketMQ中broker消息存储之如何实现消息转储”有了一定的了解,如果想了解更多相关知识,欢迎关注亿速云行业资讯频道,感谢各位的阅读!
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