rocketmq 之namesrv（十三）mqclient admin请求处理获取最早的消息存储时间

获取最早的消息存储时间AdminBrokerProcessor#getEarliestMsgStoretime

AdminBrokerProcessor#processRequest#this.getEarliestMsgStoretime(ctx, request)

private RemotingCommand getEarliestMsgStoretime(ChannelHandlerContext ctx,
        RemotingCommand request) throws RemotingCommandException {
        final RemotingCommand response = RemotingCommand.createResponseCommand(GetEarliestMsgStoretimeResponseHeader.class);
        final GetEarliestMsgStoretimeResponseHeader responseHeader = (GetEarliestMsgStoretimeResponseHeader) response.readCustomHeader();
        final GetEarliestMsgStoretimeRequestHeader requestHeader =
            (GetEarliestMsgStoretimeRequestHeader) request.decodeCommandCustomHeader(GetEarliestMsgStoretimeRequestHeader.class);

        //根据topic和queueId获取最早消息存储时间
        long timestamp =
            this.brokerController.getMessageStore().getEarliestMessageTime(requestHeader.getTopic(), requestHeader.getQueueId());

        responseHeader.setTimestamp(timestamp);
        response.setCode(ResponseCode.SUCCESS);
        response.setRemark(null);
        return response;
    }

DefaultMessageStore#getEarliestMessageTime

public long getEarliestMessageTime(String topic, int queueId) {
        //获取消费者队列
        ConsumeQueue logicQueue = this.findConsumeQueue(topic, queueId);
        if (logicQueue != null) {
            //获取最小的offset
            long minLogicOffset = logicQueue.getMinLogicOffset();
//            根据下标获取SelectMappedBufferResult
            SelectMappedBufferResult result = logicQueue.getIndexBuffer(minLogicOffset / ConsumeQueue.CQ_STORE_UNIT_SIZE);
            return getStoreTime(result);
        }

        return -1;
    }

ConsumeQueue#getIndexBuffer

logicQueue.getIndexBuffer(minLogicOffset / ConsumeQueue.CQ_STORE_UNIT_SIZE)

public SelectMappedBufferResult getIndexBuffer(final long startIndex) {
        int mappedFileSize = this.mappedFileSize;
        long offset = startIndex * CQ_STORE_UNIT_SIZE;
        if (offset >= this.getMinLogicOffset()) {
//            根据offset查询映射文件
            MappedFile mappedFile = this.mappedFileQueue.findMappedFileByOffset(offset);
            if (mappedFile != null) {
                SelectMappedBufferResult result = mappedFile.selectMappedBuffer((int) (offset % mappedFileSize));
                return result;
            }
        }
        return null;
    }

MappedFileQueue#findMappedFileByOffset

this.mappedFileQueue.findMappedFileByOffset(offset);

public MappedFile findMappedFileByOffset(final long offset, final boolean returnFirstOnNotFound) {
        try {
//            获取第一个映射文件
            MappedFile firstMappedFile = this.getFirstMappedFile();
//            获取最后一个映射文件
            MappedFile lastMappedFile = this.getLastMappedFile();
            if (firstMappedFile != null && lastMappedFile != null) {
                if (offset < firstMappedFile.getFileFromOffset() || offset >= lastMappedFile.getFileFromOffset() + this.mappedFileSize) {
                    LOG_ERROR.warn("Offset not matched. Request offset: {}, firstOffset: {}, lastOffset: {}, mappedFileSize: {}, mappedFiles count: {}",
                        offset,
                        firstMappedFile.getFileFromOffset(),
                        lastMappedFile.getFileFromOffset() + this.mappedFileSize,
                        this.mappedFileSize,
                        this.mappedFiles.size());
                } else {
//                    找到映射文件在队列中的索引位置
                    int index = (int) ((offset / this.mappedFileSize) - (firstMappedFile.getFileFromOffset() / this.mappedFileSize));
                    MappedFile targetFile = null;
                    try {
                        //获取offset对应的文件
                        targetFile = this.mappedFiles.get(index);
                    } catch (Exception ignored) {
                    }
//                    offset在目标文件的起始offset和结束offset范围内
                    if (targetFile != null && offset >= targetFile.getFileFromOffset()
                        && offset < targetFile.getFileFromOffset() + this.mappedFileSize) {
                        return targetFile;
                    }
//                    如果按索引在队列中找不到映射文件就遍历队列查找映射文件
                    for (MappedFile tmpMappedFile : this.mappedFiles) {
                        if (offset >= tmpMappedFile.getFileFromOffset()
                            && offset < tmpMappedFile.getFileFromOffset() + this.mappedFileSize) {
                            return tmpMappedFile;
                        }
                    }
                }

                if (returnFirstOnNotFound) {
                    return firstMappedFile;
                }
            }
        } catch (Exception e) {
            log.error("findMappedFileByOffset Exception", e);
        }

        return null;
    }

DefaultMessageStore#getStoreTime

DefaultMessageStore#getEarliestMessageTime#getStoreTime(result)

 private long getStoreTime(SelectMappedBufferResult result) {
        if (result != null) {
            try {
                final long phyOffset = result.getByteBuffer().getLong();
                final int size = result.getByteBuffer().getInt();
//                根据SelectMappedBufferResult的offset和大小查找存储时间
                long storeTime = this.getCommitLog().pickupStoreTimestamp(phyOffset, size);
                return storeTime;
            } catch (Exception e) {
            } finally {
                result.release();
            }
        }
        return -1;
    }

CommitLog#pickupStoreTimestamp

public long pickupStoreTimestamp(final long offset, final int size) {
        if (offset >= this.getMinOffset()) {
            SelectMappedBufferResult result = this.getMessage(offset, size);
            if (null != result) {
                try {
//                    获取消息存储时间
                    return result.getByteBuffer().getLong(MessageDecoder.MESSAGE_STORE_TIMESTAMP_POSTION);
                } finally {
                    result.release();
                }
            }
        }

        return -1;
    }

CommitLog#getMessage

public SelectMappedBufferResult getMessage(final long offset, final int size) {
        int mappedFileSize = this.defaultMessageStore.getMessageStoreConfig().getMapedFileSizeCommitLog();
//        根据offset找到映射文件
        MappedFile mappedFile = this.mappedFileQueue.findMappedFileByOffset(offset, offset == 0);
        if (mappedFile != null) {
            int pos = (int) (offset % mappedFileSize);
            return mappedFile.selectMappedBuffer(pos, size);
        }
        return null;
    }

来源：CSDN

作者：游语

链接：https://blog.csdn.net/qq_26400953/article/details/103245194