RocketMQ-broker存储机制-Index

RocketMQ-broker存储机制-Index

数据结构

 

 

 在indexFileHeader中存放着开始和结束的时间戳，开始和结束的物理点位，以及索引的个数。

索引文件加载

    public boolean load(final boolean lastExitOK) {
        File dir = new File(this.storePath);
        File[] files = dir.listFiles();
        if (files != null) {
            // ascending order
            Arrays.sort(files);
            for (File file : files) {
                try {
                    // 创建  IndexFile
                    IndexFile f = new IndexFile(file.getPath(), this.hashSlotNum, this.indexNum, 0, 0);
                    // 初始化 IndexFile中的 indexHeader 一些时间戳和点位信息
                    f.load();

                    if (!lastExitOK) {
                        // 在checkpoint之后写入的IndexFile   执行删除
                        if (f.getEndTimestamp() > this.defaultMessageStore.getStoreCheckpoint()
                            .getIndexMsgTimestamp()) {
                            f.destroy(0);
                            continue;
                        }
                    }

                    log.info("load index file OK, " + f.getFileName());
                    this.indexFileList.add(f);
                } catch (IOException e) {
                    log.error("load file {} error", file, e);
                    return false;
                } catch (NumberFormatException e) {
                    log.error("load file {} error", file, e);
                }
            }
        }

        return true;
    }

dispatch

 那么index文件是如何写入的呢？还是通过reputservice中CommitLogDispatcherBuildIndex的dispatch实现

 class CommitLogDispatcherBuildIndex implements CommitLogDispatcher {

        @Override
        public void dispatch(DispatchRequest request) {
            if (DefaultMessageStore.this.messageStoreConfig.isMessageIndexEnable()) {
                DefaultMessageStore.this.indexService.buildIndex(request);
            }
        }
    }

public void buildIndex(DispatchRequest req) {
        // 判断前一个indexfile有没有写满 没写满就返回当前的indexfile  如果写满了 创建下一个indexfile 并把上一个indexfile flush
        IndexFile indexFile = retryGetAndCreateIndexFile();
        if (indexFile != null) {
            long endPhyOffset = indexFile.getEndPhyOffset();
            DispatchRequest msg = req;
            String topic = msg.getTopic();
            String keys = msg.getKeys();
            // 已经put完成
            if (msg.getCommitLogOffset() < endPhyOffset) {
                return;
            }

            final int tranType = MessageSysFlag.getTransactionValue(msg.getSysFlag());
            switch (tranType) {
                case MessageSysFlag.TRANSACTION_NOT_TYPE:
                case MessageSysFlag.TRANSACTION_PREPARED_TYPE:
                case MessageSysFlag.TRANSACTION_COMMIT_TYPE:
                    break;
                case MessageSysFlag.TRANSACTION_ROLLBACK_TYPE:
                    return;
            }

            if (req.getUniqKey() != null) {  // topic + "#" + UniqKey;
                indexFile = putKey(indexFile, msg, buildKey(topic, req.getUniqKey()));
                if (indexFile == null) {
                    log.error("putKey error commitlog {} uniqkey {}", req.getCommitLogOffset(), req.getUniqKey());
                    return;
                }
            }

            if (keys != null && keys.length() > 0) {   // topic + "#" + key;
                String[] keyset = keys.split(MessageConst.KEY_SEPARATOR);
                for (int i = 0; i < keyset.length; i++) {
                    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();
            if (null == indexFile) {
                return null;
            }

            ok = indexFile.putKey(idxKey, msg.getCommitLogOffset(), msg.getStoreTimestamp());
        }

        return indexFile;
    }

实现putkey的真正逻辑

 public boolean putKey(final String key, final long phyOffset, final long storeTimestamp) {
        if (this.indexHeader.getIndexCount() < this.indexNum) {
            int keyHash = indexKeyHashMethod(key);
            int slotPos = keyHash % this.hashSlotNum;
            int absSlotPos = IndexHeader.INDEX_HEADER_SIZE + slotPos * hashSlotSize;

            FileLock fileLock = null;

            try {

                // fileLock = this.fileChannel.lock(absSlotPos, hashSlotSize,
                // false);
                // absSlotPos点位存放的是当前需要查询的数据处在第几个index上   
                int slotValue = this.mappedByteBuffer.getInt(absSlotPos);
                if (slotValue <= invalidIndex || slotValue > this.indexHeader.getIndexCount()) {
                    slotValue = invalidIndex;
                }

                long timeDiff = storeTimestamp - this.indexHeader.getBeginTimestamp();

                timeDiff = timeDiff / 1000;

                if (this.indexHeader.getBeginTimestamp() <= 0) {
                    timeDiff = 0;
                } else if (timeDiff > Integer.MAX_VALUE) {
                    timeDiff = Integer.MAX_VALUE;
                } else if (timeDiff < 0) {
                    timeDiff = 0;
                }

                // 目前最大索引值处在的点位
                int absIndexPos =
                    IndexHeader.INDEX_HEADER_SIZE + this.hashSlotNum * hashSlotSize
                        + this.indexHeader.getIndexCount() * indexSize;

                // 存放在indexfile最后
                this.mappedByteBuffer.putInt(absIndexPos, keyHash);
                this.mappedByteBuffer.putLong(absIndexPos + 4, phyOffset);
                this.mappedByteBuffer.putInt(absIndexPos + 4 + 8, (int) timeDiff);
                this.mappedByteBuffer.putInt(absIndexPos + 4 + 8 + 4, slotValue);

                // 并返回没写之前 index的总数   实际上最新的数据是放在最前面   相同哈希的数据作为作为下一个数据引用存放
                this.mappedByteBuffer.putInt(absSlotPos, this.indexHeader.getIndexCount());

                if (this.indexHeader.getIndexCount() <= 1) {
                    this.indexHeader.setBeginPhyOffset(phyOffset);
                    this.indexHeader.setBeginTimestamp(storeTimestamp);
                }
                
                // 更新indexHeader

                this.indexHeader.incHashSlotCount();
                this.indexHeader.incIndexCount();
                this.indexHeader.setEndPhyOffset(phyOffset);
                this.indexHeader.setEndTimestamp(storeTimestamp);

                return true;
            } catch (Exception e) {
                log.error("putKey exception, Key: " + key + " KeyHashCode: " + key.hashCode(), e);
            } finally {
                if (fileLock != null) {
                    try {
                        fileLock.release();
                    } catch (IOException e) {
                        log.error("Failed to release the lock", e);
                    }
                }
            }
        } else {
            log.warn("Over index file capacity: index count = " + this.indexHeader.getIndexCount()
                + "; index max num = " + this.indexNum);
        }

        return false;
    }