RocketMQ——NameServer 路由规则

RocketMQ路由注册是通过Broker与NameServer的心跳功能实现。Broker启动时向集群中所有的NameServer发送心跳包,每隔30秒向集群中的所有NameServer发送心跳,NamerServer收到心跳包会更新brokerLiveTable缓存中的BrokerLiveInfo的lastUpdateTimestamp,然后NameServer每隔十秒扫描brokerLiveTable,如果连续120秒没有收到心跳包,NameServer将移除该broker的路由信息,同时关闭Socket连接。
这里也是为什么不建议线上开启autoCreateTopic的原因,因为默认缓存在broker中,所以开启后,多个broker同时默认创建topic,将会导致重复创建broker,最终同步到NameServer后的数据重复。

Broker发送心跳包

org.apache.rocketmq.broker.BrokerController#start

        this.scheduledExecutorService.scheduleAtFixedRate(() -> {
            try {
                BrokerController.this.registerBrokerAll(true, false, brokerConfig.isForceRegister());
            } catch (Throwable e) {
                log.error("registerBrokerAll Exception", e);
            }
        }, 1000 * 10, Math.max(10000, Math.min(brokerConfig.getRegisterNameServerPeriod(), 60000)), TimeUnit.MILLISECONDS);

跟踪代码,真正执行注册

this.brokerOuterAPI.registerBrokerAll

org.apache.rocketmq.broker.out.BrokerOuterAPI#registerBrokerAll

    public List<RegisterBrokerResult> registerBrokerAll(
        final String clusterName,
        final String brokerAddr,
        final String brokerName,
        final long brokerId,
        final String haServerAddr,
        final TopicConfigSerializeWrapper topicConfigWrapper,
        final List<String> filterServerList,
        final boolean oneway,
        final int timeoutMills,
        final boolean compressed) {

        final List<RegisterBrokerResult> registerBrokerResultList = Lists.newArrayList();
        //获取 NameServer 地址列表
        List<String> nameServerAddressList = this.remotingClient.getNameServerAddressList();
        if (nameServerAddressList != null && nameServerAddressList.size() > 0) {

            final RegisterBrokerRequestHeader requestHeader = new RegisterBrokerRequestHeader();
            //填充requestHeader属性

            RegisterBrokerBody requestBody = new RegisterBrokerBody();
            //填充body属性
            
            final CountDownLatch countDownLatch = new CountDownLatch(nameServerAddressList.size());
            for (final String namesrvAddr : nameServerAddressList) {
                brokerOuterExecutor.execute(new Runnable() {
                    @Override
                    public void run() {
                      //真正注册
                      RegisterBrokerResult result = registerBroker(namesrvAddr,oneway, timeoutMills,requestHeader,body);
                    }
                });
            }
        }

        return registerBrokerResultList;
    }

注册逻辑在registerBroker中执行,逻辑较为简单,发送http请求处理返回数据即可。

private RegisterBrokerResult registerBroker(
        final String namesrvAddr,
        final boolean oneway,
        final int timeoutMills,
        final RegisterBrokerRequestHeader requestHeader,
        final byte[] body
    ) throws RemotingCommandException, MQBrokerException, RemotingConnectException, RemotingSendRequestException, RemotingTimeoutException,
        InterruptedException {
        RemotingCommand request = RemotingCommand.createRequestCommand(RequestCode.REGISTER_BROKER, requestHeader);
        request.setBody(body);

        if (oneway) {
            try {
                this.remotingClient.invokeOneway(namesrvAddr, request, timeoutMills);
            } catch (RemotingTooMuchRequestException e) {
                // Ignore
            }
            return null;
        }

        RemotingCommand response = this.remotingClient.invokeSync(namesrvAddr, request, timeoutMills);
        assert response != null;
        switch (response.getCode()) {
            case ResponseCode.SUCCESS: {
                RegisterBrokerResponseHeader responseHeader =
                    (RegisterBrokerResponseHeader) response.decodeCommandCustomHeader(RegisterBrokerResponseHeader.class);
                RegisterBrokerResult result = new RegisterBrokerResult();
                result.setMasterAddr(responseHeader.getMasterAddr());
                result.setHaServerAddr(responseHeader.getHaServerAddr());
                if (response.getBody() != null) {
                    result.setKvTable(KVTable.decode(response.getBody(), KVTable.class));
                }
                return result;
            }
            default:
                break;
        }

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

以上完成后,返回BrokerController#doRegisterBrokerAll 方法中

//注册并获取结果
 List<RegisterBrokerResult> registerBrokerResultList = this.brokerOuterAPI.registerBrokerAll(xxxx);
 //更新心跳包返回数据
        if (registerBrokerResultList.size() > 0) {
            RegisterBrokerResult registerBrokerResult = registerBrokerResultList.get(0);
            if (registerBrokerResult != null) {
                if (this.updateMasterHAServerAddrPeriodically && registerBrokerResult.getHaServerAddr() != null) {
                    this.messageStore.updateHaMasterAddress(registerBrokerResult.getHaServerAddr());
                }

                this.slaveSynchronize.setMasterAddr(registerBrokerResult.getMasterAddr());
              
                if (checkOrderConfig) {
                    this.getTopicConfigManager().updateOrderTopicConfig(registerBrokerResult.getKvTable());
                }
            }
        }

获取返回的结果,更新对应的masterAddr 以及 topicConfigTable

NameServer处理心跳包

org.apache.rocketmq.namesrv.processor.DefaultRequestProcessor 负责RocketMQ中处理所有相关的网络请求,对应的心跳包请求解析器为RequestCode.REGISTER_BROKER

case RequestCode.REGISTER_BROKER:
    Version brokerVersion = MQVersion.value2Version(request.getVersion());
    if (brokerVersion.ordinal() >= MQVersion.Version.V3_0_11.ordinal()) {
        return this.registerBrokerWithFilterServer(ctx, request);
    } else {
        return this.registerBroker(ctx, request);
    }

跟踪对应的代码,我们可以看到请求的处理和返回代码如下:

 RegisterBrokerResult result = this.namesrvController.getRouteInfoManager().registerBroker(
            requestHeader.getClusterName(),
            requestHeader.getBrokerAddr(),
            requestHeader.getBrokerName(),
            requestHeader.getBrokerId(),
            requestHeader.getHaServerAddr(),
            registerBrokerBody.getTopicConfigSerializeWrapper(),
            registerBrokerBody.getFilterServerList(),
            ctx.channel());

        responseHeader.setHaServerAddr(result.getHaServerAddr());
        responseHeader.setMasterAddr(result.getMasterAddr());

        byte[] jsonValue = this.namesrvController.getKvConfigManager().getKVListByNamespace(NamesrvUtil.NAMESPACE_ORDER_TOPIC_CONFIG);
        response.setBody(jsonValue);

        response.setCode(ResponseCode.SUCCESS);
        response.setRemark(null);

namesrvController.getRouteInfoManager().registerBroker 负责处理注册请求,处理后 返回体包装对应的 ServerAddr以及路由信息返回。
RouteInfoManager#registerBroker

    public RegisterBrokerResult registerBroker(
        final String clusterName,
        final String brokerAddr,
        final String brokerName,
        final long brokerId,
        final String haServerAddr,
        final TopicConfigSerializeWrapper topicConfigWrapper,
        final List<String> filterServerList,
        final Channel channel) {
        RegisterBrokerResult result = new RegisterBrokerResult();
        try {
            try {
            //写加锁
                this.lock.writeLock().lockInterruptibly();
                
                Set<String> brokerNames = this.clusterAddrTable.get(clusterName);
                if (null == brokerNames) {
                    brokerNames = new HashSet<String>();
                    this.clusterAddrTable.put(clusterName, brokerNames);
                }
                brokerNames.add(brokerName);

                boolean registerFirst = false;
                //获取brokerName,如果为空,则注册
                BrokerData brokerData = this.brokerAddrTable.get(brokerName);
                if (null == brokerData) {
                    registerFirst = true;
                    brokerData = new BrokerData(clusterName, brokerName, new HashMap<Long, String>());
                    this.brokerAddrTable.put(brokerName, brokerData);
                }
                Map<Long, String> brokerAddrsMap = brokerData.getBrokerAddrs();
                //Switch slave to master: first remove <1, IP:PORT> in namesrv, then add <0, IP:PORT>
                //The same IP:PORT must only have one record in brokerAddrTable
                Iterator<Entry<Long, String>> it = brokerAddrsMap.entrySet().iterator();
                while (it.hasNext()) {
                    Entry<Long, String> item = it.next();
                    if (null != brokerAddr && brokerAddr.equals(item.getValue()) && brokerId != item.getKey()) {
                        it.remove();
                    }
                }

                String oldAddr = brokerData.getBrokerAddrs().put(brokerId, brokerAddr);
                registerFirst = registerFirst || (null == oldAddr);

                if (null != topicConfigWrapper
                    && MixAll.MASTER_ID == brokerId) {
                    if (this.isBrokerTopicConfigChanged(brokerAddr, topicConfigWrapper.getDataVersion())
                        || registerFirst) {
                        ConcurrentMap<String, TopicConfig> tcTable =
                            topicConfigWrapper.getTopicConfigTable();
                        if (tcTable != null) {
                            for (Map.Entry<String, TopicConfig> entry : tcTable.entrySet()) {
                                this.createAndUpdateQueueData(brokerName, entry.getValue());
                            }
                        }
                    }
                }

                BrokerLiveInfo prevBrokerLiveInfo = this.brokerLiveTable.put(brokerAddr,
                    new BrokerLiveInfo(
                        System.currentTimeMillis(),
                        topicConfigWrapper.getDataVersion(),
                        channel,
                        haServerAddr));
                if (null == prevBrokerLiveInfo) {
                    log.info("new broker registered, {} HAServer: {}", brokerAddr, haServerAddr);
                }

                if (filterServerList != null) {
                    if (filterServerList.isEmpty()) {
                        this.filterServerTable.remove(brokerAddr);
                    } else {
                        this.filterServerTable.put(brokerAddr, filterServerList);
                    }
                }

                if (MixAll.MASTER_ID != brokerId) {
                    String masterAddr = brokerData.getBrokerAddrs().get(MixAll.MASTER_ID);
                    if (masterAddr != null) {
                        BrokerLiveInfo brokerLiveInfo = this.brokerLiveTable.get(masterAddr);
                        if (brokerLiveInfo != null) {
                            result.setHaServerAddr(brokerLiveInfo.getHaServerAddr());
                            result.setMasterAddr(masterAddr);
                        }
                    }
                }
            } finally {
                this.lock.writeLock().unlock();
            }
        } catch (Exception e) {
            log.error("registerBroker Exception", e);
        }

        return result;
    }

路由删除

如上所示,broker每隔30秒向NameServer注册路由信息,那么如果一个broker宕机后,NameServer如何剔除Broker呢?同样的NameServer每隔10秒扫描broker列表,管理broker存活信息。
RocketMQ有两个出发点来完成路由删除:

  1. NameServer定时扫描brokerLiveTable检测上次心跳包与当前系统的时间差,如果时间差大于120s,则需要剔除该broker信息
  2. Broker正常关闭的情况下,执行unregisterBroker命令
    RouteInfoManager#scanNotActiveBroker
    public void scanNotActiveBroker() {
        Iterator<Entry<String, BrokerLiveInfo>> it = this.brokerLiveTable.entrySet().iterator();
        while (it.hasNext()) {
            Entry<String, BrokerLiveInfo> next = it.next();
            long last = next.getValue().getLastUpdateTimestamp();
            if ((last + BROKER_CHANNEL_EXPIRED_TIME) < System.currentTimeMillis()) {
                RemotingUtil.closeChannel(next.getValue().getChannel());
                it.remove();
                log.warn("The broker channel expired, {} {}ms", next.getKey(), BROKER_CHANNEL_EXPIRED_TIME);
                this.onChannelDestroy(next.getKey(), next.getValue().getChannel());
            }
        }
    }

onChannelDestroy 中申请写锁,然后遍历移除。

路由发现

RocketMQ的路由发现不是实时的,当topic路由发生变化时,NameServer不主动推送给客户端,而是客户端定时拉取最新的主题信息。根据主题名拉取路由信息的命令编码命名为RequestCode.GET_ROUTEINTO_BY_TOPIC。
请求依然由DefaultRequestProcessor处理。

case RequestCode.GET_ROUTEINTO_BY_TOPIC:
     return this.getRouteInfoByTopic(ctx, request);

核心实现

TopicRouteData topicRouteData = this.namesrvController.getRouteInfoManager().pickupTopicRouteData(requestHeader.getTopic());
public class TopicRouteData extends RemotingSerializable {
    private String orderTopicConf;//顺序消息配置
    private List<QueueData> queueDatas;//队列元数据
    private List<BrokerData> brokerDatas;//topic分布的broker原数据
    private HashMap<String/* brokerAddr */, List<String>/* Filter Server */> filterServerTable;//broker上过滤服务器列表

核心实现则由 namesrvController.getRouteInfoManager().pickupTopicRouteData

总结

AF8AFD9D88EEEF147E552C3FACBC4979.jpg
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