RocketMq 重置消费位点逻辑

系列

• RocketMq broker 配置文件
• RocketMq broker 启动流程
• RocketMq broker CommitLog介绍
• RocketMq broker consumeQueue介绍
• RocketMq broker 重试和死信队列
• RocketMq broker 延迟消息
• RocketMq IndexService介绍
• RocketMq 读写分离机制
• RocketMq Client管理
• RocketMq broker过期文件删除

开篇

• 这篇文章的主要目的是分析RocketMq根据时间戳重置某topic在某consumeGroup下的消费位点。

• 重置位点的执行顺序按照admin 到 broker 到 consumer的顺序依次触发，admin负责构建参数通知broker，broker负责查询consumeQueue的具体位移，broker负责通知consumer进行位移重置。

• 根据时间戳查找consumeQueue对应的位移，然后由broker通知consumer来持久化消费位移，最终会持久化到broker的消费位移。

• 重置位点操作本质上是在client端执行，consumer端负责持久化新的消费位移然后由定时任务通知broker更新消费位移。

• consumer在整个位移重置过程中会设置ProcessQueue的状态为Dropped，从而阻断消息拉取任务ConsumeRequest的执行阻断消息拉取，其次会在consumer侧修改消费位移通过心跳通知broker修改consumer的消费位移，最后通过重新的rebalance过程开始重新消费消息。

重置命令

public class ResetOffsetByTimeCommand implements SubCommand {

    @Override
    public String commandName() {
        return "resetOffsetByTime";
    }

    @Override
    public Options buildCommandlineOptions(Options options) {
        Option opt = new Option("g", "group", true, "set the consumer group");
        opt.setRequired(true);
        options.addOption(opt);

        opt = new Option("t", "topic", true, "set the topic");
        opt.setRequired(true);
        options.addOption(opt);

        opt = new Option("s", "timestamp", true, "set the timestamp[now|currentTimeMillis|yyyy-MM-dd#HH:mm:ss:SSS]");
        opt.setRequired(true);
        options.addOption(opt);

        opt = new Option("f", "force", true, "set the force rollback by timestamp switch[true|false]");
        opt.setRequired(false);
        options.addOption(opt);

        opt = new Option("c", "cplus", false, "reset c++ client offset");
        opt.setRequired(false);
        options.addOption(opt);
        return options;
    }

    @Override
    public void execute(CommandLine commandLine, Options options, RPCHook rpcHook) throws SubCommandException {
        DefaultMQAdminExt defaultMQAdminExt = new DefaultMQAdminExt(rpcHook);
        defaultMQAdminExt.setInstanceName(Long.toString(System.currentTimeMillis()));
        try {
            String group = commandLine.getOptionValue("g").trim();
            String topic = commandLine.getOptionValue("t").trim();
            String timeStampStr = commandLine.getOptionValue("s").trim();
            long timestamp = timeStampStr.equals("now") ? System.currentTimeMillis() : 0;

            try {
                if (timestamp == 0) {
                    timestamp = Long.parseLong(timeStampStr);
                }
            } catch (NumberFormatException e) {

                timestamp = UtilAll.parseDate(timeStampStr, UtilAll.YYYY_MM_DD_HH_MM_SS_SSS).getTime();
            }

            boolean force = true;
            if (commandLine.hasOption('f')) {
                force = Boolean.valueOf(commandLine.getOptionValue("f").trim());
            }

            boolean isC = false;
            if (commandLine.hasOption('c')) {
                isC = true;
            }

            defaultMQAdminExt.start();
            Map<MessageQueue, Long> offsetTable;
            try {
                // 通过defaultMQAdminExt#resetOffsetByTimestamp来执行
                offsetTable = defaultMQAdminExt.resetOffsetByTimestamp(topic, group, timestamp, force, isC);
            } catch (MQClientException e) {
                if (ResponseCode.CONSUMER_NOT_ONLINE == e.getResponseCode()) {
                    ResetOffsetByTimeOldCommand.resetOffset(defaultMQAdminExt, group, topic, timestamp, force, timeStampStr);
                    return;
                }
                throw e;
            }
        } catch (Exception e) {
            throw new SubCommandException(this.getClass().getSimpleName() + " command failed", e);
        } finally {
            defaultMQAdminExt.shutdown();
        }
    }
}

• ResetOffsetByTimeCommand的命令格式如上代码所示，核心调用DefaultMQAdminExt#resetOffsetByTimestamp来重置。

admin

public class DefaultMQAdminExt extends ClientConfig implements MQAdminExt {

    public Map<MessageQueue, Long> resetOffsetByTimestamp(String topic, String group, long timestamp, boolean isForce,
        boolean isC)
        throws RemotingException, MQBrokerException, InterruptedException, MQClientException {
        // 通过defaultMQAdminExtImpl#resetOffsetByTimestamp重置位移
        return defaultMQAdminExtImpl.resetOffsetByTimestamp(topic, group, timestamp, isForce, isC);
    }
}


public class DefaultMQAdminExtImpl implements MQAdminExt, MQAdminExtInner {

    public Map<MessageQueue, Long> resetOffsetByTimestamp(String topic, String group, long timestamp, boolean isForce,
        boolean isC)
        throws RemotingException, MQBrokerException, InterruptedException, MQClientException {

        // 1、获取topic对应的TopicRouteData信息，进而获取对应的BrokerData信息
        TopicRouteData topicRouteData = this.examineTopicRouteInfo(topic);
        List<BrokerData> brokerDatas = topicRouteData.getBrokerDatas();
        Map<MessageQueue, Long> allOffsetTable = new HashMap<MessageQueue, Long>();
        if (brokerDatas != null) {
            // 2、遍历topic所在的broker节点信息
            for (BrokerData brokerData : brokerDatas) {
                String addr = brokerData.selectBrokerAddr();
                if (addr != null) {
                    // 2、远程调用broker来执行重置操作
                    Map<MessageQueue, Long> offsetTable =
                        this.mqClientInstance.getMQClientAPIImpl().invokeBrokerToResetOffset(addr, topic, group, timestamp, isForce,
                            timeoutMillis, isC);
                    if (offsetTable != null) {
                        allOffsetTable.putAll(offsetTable);
                    }
                }
            }
        }
        return allOffsetTable;
    }
}

• 获取topic对应的TopicRouteData信息，进而获取对应的BrokerData信息。
• 遍历topic所在的broker节点信息，远程调用broker来执行重置操作。

public class MQClientAPIImpl {

    public Map<MessageQueue, Long> invokeBrokerToResetOffset(final String addr, final String topic, final String group,
        final long timestamp, final boolean isForce, final long timeoutMillis, boolean isC)
        throws RemotingException, MQClientException, InterruptedException {
        ResetOffsetRequestHeader requestHeader = new ResetOffsetRequestHeader();
        requestHeader.setTopic(topic);
        requestHeader.setGroup(group);
        requestHeader.setTimestamp(timestamp);
        requestHeader.setForce(isForce);

        RemotingCommand request = RemotingCommand.createRequestCommand(RequestCode.INVOKE_BROKER_TO_RESET_OFFSET, requestHeader);
        if (isC) {
            request.setLanguage(LanguageCode.CPP);
        }

        RemotingCommand response = this.remotingClient.invokeSync(MixAll.brokerVIPChannel(this.clientConfig.isVipChannelEnabled(), addr),
            request, timeoutMillis);
        assert response != null;
        switch (response.getCode()) {
            case ResponseCode.SUCCESS: {
                if (response.getBody() != null) {
                    ResetOffsetBody body = ResetOffsetBody.decode(response.getBody(), ResetOffsetBody.class);
                    return body.getOffsetTable();
                }
            }
            default:
                break;
        }

        throw new MQClientException(response.getCode(), response.getRemark());
    }
}

• 远程调用的RequestCode为INVOKE_BROKER_TO_RESET_OFFSET。
• 通过RequestCode可以方便查找BrokerProcessor便于分析。

broker

public class AdminBrokerProcessor extends AsyncNettyRequestProcessor implements NettyRequestProcessor {

    public RemotingCommand resetOffset(ChannelHandlerContext ctx,
        RemotingCommand request) throws RemotingCommandException {
        // 解析requestHeader的信息
        final ResetOffsetRequestHeader requestHeader =
            (ResetOffsetRequestHeader) request.decodeCommandCustomHeader(ResetOffsetRequestHeader.class);

        boolean isC = false;
        LanguageCode language = request.getLanguage();
        switch (language) {
            case CPP:
                isC = true;
                break;
        }
        // 通过Broker2Client#resetOffset重置位移
        return this.brokerController.getBroker2Client().resetOffset(requestHeader.getTopic(), requestHeader.getGroup(),
            requestHeader.getTimestamp(), requestHeader.isForce(), isC);
    }
}

public class Broker2Client {

    public RemotingCommand resetOffset(String topic, String group, long timeStamp, boolean isForce,
                                       boolean isC) {
        final RemotingCommand response = RemotingCommand.createResponseCommand(null);
        // 获取TopicConfig相关信息
        TopicConfig topicConfig = this.brokerController.getTopicConfigManager().selectTopicConfig(topic);
        if (null == topicConfig) {
            response.setCode(ResponseCode.SYSTEM_ERROR);
            response.setRemark("[reset-offset] reset offset failed, no topic in this broker. topic=" + topic);
            return response;
        }

        Map<MessageQueue, Long> offsetTable = new HashMap<MessageQueue, Long>();
        // 遍历所有的写队列并获取每个MessageQueue的消费位移
        for (int i = 0; i < topicConfig.getWriteQueueNums(); i++) {
            MessageQueue mq = new MessageQueue();
            mq.setBrokerName(this.brokerController.getBrokerConfig().getBrokerName());
            mq.setTopic(topic);
            mq.setQueueId(i);
            // 查询每个messageQueue查询对应的consumeQueue的消费位移consumerOffset
            long consumerOffset =
                this.brokerController.getConsumerOffsetManager().queryOffset(group, topic, i);
            if (-1 == consumerOffset) {
                response.setCode(ResponseCode.SYSTEM_ERROR);
                response.setRemark(String.format("THe consumer group <%s> not exist", group));
                return response;
            }
            
            // 根据时间戳查询consumeQueue的位移
            long timeStampOffset;
            if (timeStamp == -1) {
                // 没时间戳就获取consumeQueue的最大位移
                timeStampOffset = this.brokerController.getMessageStore().getMaxOffsetInQueue(topic, i);
            } else {
                // 根据时间戳查找consumeQueue的最大位移
                timeStampOffset = this.brokerController.getMessageStore().getOffsetInQueueByTime(topic, i, timeStamp);
            }

            if (timeStampOffset < 0) {
                log.warn("reset offset is invalid. topic={}, queueId={}, timeStampOffset={}", topic, i, timeStampOffset);
                timeStampOffset = 0;
            }

            if (isForce || timeStampOffset < consumerOffset) {
                offsetTable.put(mq, timeStampOffset);
            } else {
                offsetTable.put(mq, consumerOffset);
            }
        }
        // RequestCode 为 RESET_CONSUMER_CLIENT_OFFSET
        ResetOffsetRequestHeader requestHeader = new ResetOffsetRequestHeader();
        requestHeader.setTopic(topic);
        requestHeader.setGroup(group);
        requestHeader.setTimestamp(timeStamp);
        RemotingCommand request =
            RemotingCommand.createRequestCommand(RequestCode.RESET_CONSUMER_CLIENT_OFFSET, requestHeader);
        if (isC) {
            // c++ language
            ResetOffsetBodyForC body = new ResetOffsetBodyForC();
            List<MessageQueueForC> offsetList = convertOffsetTable2OffsetList(offsetTable);
            body.setOffsetTable(offsetList);
            request.setBody(body.encode());
        } else {
            // other language
            ResetOffsetBody body = new ResetOffsetBody();
            body.setOffsetTable(offsetTable);
            request.setBody(body.encode());
        }
        // 获取consumeGroup的所有consumer信息并通知位移重置
        ConsumerGroupInfo consumerGroupInfo =
            this.brokerController.getConsumerManager().getConsumerGroupInfo(group);

        if (consumerGroupInfo != null && !consumerGroupInfo.getAllChannel().isEmpty()) {
            ConcurrentMap<Channel, ClientChannelInfo> channelInfoTable =
                consumerGroupInfo.getChannelInfoTable();
            for (Map.Entry<Channel, ClientChannelInfo> entry : channelInfoTable.entrySet()) {
                int version = entry.getValue().getVersion();
                if (version >= MQVersion.Version.V3_0_7_SNAPSHOT.ordinal()) {
                    try {
                        this.brokerController.getRemotingServer().invokeOneway(entry.getKey(), request, 5000);
                    } catch (Exception e) {
                    }
                } else {
                    response.setCode(ResponseCode.SYSTEM_ERROR);
                    response.setRemark("the client does not support this feature. version="
                        + MQVersion.getVersionDesc(version));
                    
                    return response;
                }
            }
        } else {
            String errorInfo =
                String.format("Consumer not online, so can not reset offset, Group: %s Topic: %s Timestamp: %d",
                    requestHeader.getGroup(),
                    requestHeader.getTopic(),
                    requestHeader.getTimestamp());
            log.error(errorInfo);
            response.setCode(ResponseCode.CONSUMER_NOT_ONLINE);
            response.setRemark(errorInfo);
            return response;
        }
        response.setCode(ResponseCode.SUCCESS);
        ResetOffsetBody resBody = new ResetOffsetBody();
        resBody.setOffsetTable(offsetTable);
        response.setBody(resBody.encode());
        return response;
    }
}

• Broker2Client#resetOffset负责执行broker侧的消费位点的流程。
• 获取topic对应TopicConfig，进而获取topic的所有写队列，
• 遍历所有的写队列，结合consumeGroup和topic获取该topic在consumeGroup下所有的队列的根据时间戳查找的消费位移。
• 获取consumeGroup下所有的client端信息，依次调用client通知消费位移。

public class DefaultMessageStore implements MessageStore {

    public long getOffsetInQueueByTime(String topic, int queueId, long timestamp) {
        // 先根据topic和queueId查找对应的ConsumeQueue对象
        ConsumeQueue logic = this.findConsumeQueue(topic, queueId);
        if (logic != null) {
            // 针对ConsumeQueue对象根据时间戳进行查找返回对应的位移
            return logic.getOffsetInQueueByTime(timestamp);
        }

        return 0;
    }

    public ConsumeQueue findConsumeQueue(String topic, int queueId) {
        ConcurrentMap<Integer, ConsumeQueue> map = consumeQueueTable.get(topic);
        if (null == map) {
            ConcurrentMap<Integer, ConsumeQueue> newMap = new ConcurrentHashMap<Integer, ConsumeQueue>(128);
            ConcurrentMap<Integer, ConsumeQueue> oldMap = consumeQueueTable.putIfAbsent(topic, newMap);
            if (oldMap != null) {
                map = oldMap;
            } else {
                map = newMap;
            }
        }

        ConsumeQueue logic = map.get(queueId);
        if (null == logic) {
            ConsumeQueue newLogic = new ConsumeQueue(
                topic,
                queueId,
                StorePathConfigHelper.getStorePathConsumeQueue(this.messageStoreConfig.getStorePathRootDir()),
                this.getMessageStoreConfig().getMappedFileSizeConsumeQueue(),
                this);
            ConsumeQueue oldLogic = map.putIfAbsent(queueId, newLogic);
            if (oldLogic != null) {
                logic = oldLogic;
            } else {
                logic = newLogic;
            }
        }

        return logic;
    }
}

• 根据topic和queueId查找对应的ConsumeQueue对象。

public class ConsumeQueue {

    public long getOffsetInQueueByTime(final long timestamp) {
        // 根据timestamp查找ConsumeQueue，文件最后更新时间戳大于该timestamp的文件
        MappedFile mappedFile = this.mappedFileQueue.getMappedFileByTime(timestamp);
        if (mappedFile != null) {
            long offset = 0;
            int low = minLogicOffset > mappedFile.getFileFromOffset() ? (int) (minLogicOffset - mappedFile.getFileFromOffset()) : 0;
            int high = 0;
            int midOffset = -1, targetOffset = -1, leftOffset = -1, rightOffset = -1;
            long leftIndexValue = -1L, rightIndexValue = -1L;

            // 获取commitLog的最小物理偏移量
            long minPhysicOffset = this.defaultMessageStore.getMinPhyOffset();
            SelectMappedBufferResult sbr = mappedFile.selectMappedBuffer(0);
            if (null != sbr) {
                ByteBuffer byteBuffer = sbr.getByteBuffer();
                high = byteBuffer.limit() - CQ_STORE_UNIT_SIZE;
                try {
                    // 二分查找确定时间戳对应的位移
                    while (high >= low) {
                        // 二分查找的midOffset及对应的commitLog的phyOffset
                        midOffset = (low + high) / (2 * CQ_STORE_UNIT_SIZE) * CQ_STORE_UNIT_SIZE;
                        byteBuffer.position(midOffset);
                        long phyOffset = byteBuffer.getLong();
                        int size = byteBuffer.getInt();
                        // 比较二分查找中间值的位移和minPhysicOffset进行比较
                        // 如果中间值偏小那么就从中间值往右进行查找
                        if (phyOffset < minPhysicOffset) {
                            low = midOffset + CQ_STORE_UNIT_SIZE;
                            leftOffset = midOffset;
                            continue;
                        }
                        // 根据consumeQueue的记录的commitLog的消息位移和文件大小查找对应的消息存储时间
                        long storeTime =
                            this.defaultMessageStore.getCommitLog().pickupStoreTimestamp(phyOffset, size);
                        // 判断storeTime的时间和timestamp进行下比较
                        if (storeTime < 0) {
                            return 0;
                        } else if (storeTime == timestamp) {
                            // 查找到目的commitLog的位移
                            targetOffset = midOffset;
                            break;
                        } else if (storeTime > timestamp) {
                            // 查找到消息的存储时间比当前查找的timestamp大
                            high = midOffset - CQ_STORE_UNIT_SIZE;
                            rightOffset = midOffset;
                            rightIndexValue = storeTime;
                        } else {
                            // 查找到消息的存储时间比当前查找的timestamp小
                            low = midOffset + CQ_STORE_UNIT_SIZE;
                            leftOffset = midOffset;
                            leftIndexValue = storeTime;
                        }
                    }

                    if (targetOffset != -1) {
                        offset = targetOffset;
                    } else {
                        if (leftIndexValue == -1) {
                            offset = rightOffset;
                        } else if (rightIndexValue == -1) {
                            offset = leftOffset;
                        } else {
                            offset =
                                Math.abs(timestamp - leftIndexValue) > Math.abs(timestamp
                                    - rightIndexValue) ? rightOffset : leftOffset;
                        }
                    }

                    return (mappedFile.getFileFromOffset() + offset) / CQ_STORE_UNIT_SIZE;
                } finally {
                    sbr.release();
                }
            }
        }
        return 0;
    }
}

• 通过二分查找方法来定位重置时间戳对应的consumeQueue的位移。

consumer

public class ClientRemotingProcessor extends AsyncNettyRequestProcessor implements NettyRequestProcessor {

    public RemotingCommand resetOffset(ChannelHandlerContext ctx,
        RemotingCommand request) throws RemotingCommandException {
        // 1、解析ResetOffsetRequestHeader对象
        final ResetOffsetRequestHeader requestHeader =
            (ResetOffsetRequestHeader) request.decodeCommandCustomHeader(ResetOffsetRequestHeader.class);
        // 2、解析重置的offsetTable
        Map<MessageQueue, Long> offsetTable = new HashMap<MessageQueue, Long>();
        if (request.getBody() != null) {
            ResetOffsetBody body = ResetOffsetBody.decode(request.getBody(), ResetOffsetBody.class);
            offsetTable = body.getOffsetTable();
        }

        // 3、通过offsetTable来重置client的消费位移
        this.mqClientFactory.resetOffset(requestHeader.getTopic(), requestHeader.getGroup(), offsetTable);
        return null;
    }
}

• ClientRemotingProcessor#resetOffset负责执行broker通知client的重置位移命令。

public class MQClientInstance {

    public void resetOffset(String topic, String group, Map<MessageQueue, Long> offsetTable) {
        DefaultMQPushConsumerImpl consumer = null;
        try {
            MQConsumerInner impl = this.consumerTable.get(group);
            if (impl != null && impl instanceof DefaultMQPushConsumerImpl) {
                consumer = (DefaultMQPushConsumerImpl) impl;
            } else {
                log.info("[reset-offset] consumer dose not exist. group={}", group);
                return;
            }
            consumer.suspend();

            ConcurrentMap<MessageQueue, ProcessQueue> processQueueTable = consumer.getRebalanceImpl().getProcessQueueTable();
            for (Map.Entry<MessageQueue, ProcessQueue> entry : processQueueTable.entrySet()) {
                MessageQueue mq = entry.getKey();
                // 重置所有的ProcessQueue标记为dropped
                if (topic.equals(mq.getTopic()) && offsetTable.containsKey(mq)) {
                    ProcessQueue pq = entry.getValue();
                    pq.setDropped(true);
                    pq.clear();
                }
            }

            try {
                TimeUnit.SECONDS.sleep(10);
            } catch (InterruptedException e) {
            }

            Iterator<MessageQueue> iterator = processQueueTable.keySet().iterator();
            while (iterator.hasNext()) {
                MessageQueue mq = iterator.next();
                Long offset = offsetTable.get(mq);
                if (topic.equals(mq.getTopic()) && offset != null) {
                    try {
                        consumer.updateConsumeOffset(mq, offset);
                        consumer.getRebalanceImpl().removeUnnecessaryMessageQueue(mq, processQueueTable.get(mq));
                        iterator.remove();
                    } catch (Exception e) {
                        log.warn("reset offset failed. group={}, {}", group, mq, e);
                    }
                }
            }
        } finally {
            if (consumer != null) {
                consumer.resume();
            }
        }
    }
}

• consumer会匹配所有重置位移的MessageQueue，然后设置对应的ProcessQueue的状态为Dropped。
• consumer会针对所有的MessageQueue持久化对应的重置消费位移。
• consumer会移除processQueueTable所有相关的MessageQueue对象。
• ConsumeRequest在ProcessQueue的状态为Dropped会停止拉取消息。
• consumer在定时rebalance过程中会重新生成ConsumeRequest并重新开始拉取消息。