NameServer架构设计

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Broker消息服务器在启动时向所有NameServer注册,消息生产者(Producer)在发送消息之前先从NameServer获取Broker服务器地址列表,然后根据负载均衡算法从列表中选择一台服务器进行消息发送。NameServer与每台Broker保持长连接,并间隔10s检测Broker是否存活,如果检测到Broker宕机,则从路由注册表中将其移除。

但是路由变化不会马上通知消息生产者,为什么要这样设计呢?
这是为了降低NameServer实现的复杂性,在消息发送端提供容错机制来保证消息发送的高可用性。

NameServer本身的高可用可通过部署多台NameServer服务器来实现,但彼此之间互不通信,也就是NameServer服务器之间在某一时刻的数据并不会完全相同,但这对消息发送不会造成任何影响,这也是RocketMQ NameServer设计的一个亮点,RocketMQ NameServer设计追求简单高效。

NameServer启动流程

NameServer启动类: org.apache.rocketmq.namesrv.NamesrvStartup
Step1: 首先来解析配置文件,需要填充NamesrvConfig、NettyServerConfig属性值。

            final NamesrvConfig namesrvConfig = new NamesrvConfig();
            final NettyServerConfig nettyServerConfig = new NettyServerConfig();
            nettyServerConfig.setListenPort(9876);
            if (commandLine.hasOption('c')) {
                String file = commandLine.getOptionValue('c');
                if (file != null) {
                    InputStream in = new BufferedInputStream(new FileInputStream(file));
                    properties = new Properties();
                    properties.load(in);
                    MixAll.properties2Object(properties, namesrvConfig);
                    MixAll.properties2Object(properties, nettyServerConfig);

                    namesrvConfig.setConfigStorePath(file);

                    System.out.printf("load config properties file OK, " + file + "%n");
                    in.close();
                }
            }

            if (commandLine.hasOption('p')) {
                MixAll.printObjectProperties(null, namesrvConfig);
                MixAll.printObjectProperties(null, nettyServerConfig);
                System.exit(0);
            }

            MixAll.properties2Object(ServerUtil.commandLine2Properties(commandLine), namesrvConfig);

从代码我们可以知道先创建NamesrvConfig(NameServer业务参数)、NettyServerConfig(NameServer网络参数),然后在解析启动时把指定的配置文件或启动命令中的选项值,填充到namesrvConfig,nettyServerConfig对象。
参数来源有如下两种方式:
1、-c configFile通过-c命令指定配置文件的路径
2、使用"--属性名 属性值",例如--listenPort 9876

NameServerConfig属性

    private String rocketmqHome = System.getProperty(MixAll.ROCKETMQ_HOME_PROPERTY, System.getenv(MixAll.ROCKETMQ_HOME_ENV));
    private String kvConfigPath = System.getProperty("user.home") + File.separator + "namesrv" + File.separator + "kvConfig.json";
    private String configStorePath = System.getProperty("user.home") + File.separator + "namesrv" + File.separator + "namesrv.properties";
    private String productEnvName = "center";
    private boolean clusterTest = false;
    private boolean orderMessageEnable = false;

• rocketmqhome: rocketmq主目录,可以通过-Drocketmq.home.dir=path或通过设置环境变量ROCKETMQ_HOME来配置RocketMQ的主目录。
• kvConfigPath: NameServer存储KV配置属性的持久化路径。
• configStorePath: nameServer默认配置文件路径,不生效。nameServer启动时如果要通过配置文件配置NameServer启动属性的话,请使用-c选项。
• orderMessageEnable: 是否支持顺序消息,默认是不支持

NettyServerConfig属性

    private int listenPort = 8888;
    private int serverWorkerThreads = 8;
    private int serverCallbackExecutorThreads = 0;
    private int serverSelectorThreads = 3;
    private int serverOnewaySemaphoreValue = 256;
    private int serverAsyncSemaphoreValue = 64;
    private int serverChannelMaxIdleTimeSeconds = 120;
    private int serverSocketSndBufSize = NettySystemConfig.socketSndbufSize;
    private int serverSocketRcvBufSize = NettySystemConfig.socketRcvbufSize;
    private boolean serverPooledByteBufAllocatorEnable = true;
    private boolean useEpollNativeSelector = false;

• listenPort: NameServer监听端口,该值默认会被初始化9876。
• serverWorkerThreads: Netty业务线程池线程个数。
• serverCallbackExecutorThreads: Netty public 任务线程池线程个数,Netty网络设计,根据业务类型会常见不同的线程池,比如处理消息发送、消息消费、心跳检测等等。如果该业务类型(RequestCode)未注册线程池,则由public线程池执行。
• serverSelectorThreads:IO线程池线程个数,主要是NameServer、Broker端解析请求、返回相应的线程个数,这类线程主要是处理网络请求的,解析请求包,然后转发到各个业务线程池完成具体的业务操作,然后将结果返回调用方。
• serverOnewaySemaphoreValue: send oneway消息请求并发度(Broker端参数)。
• serverAsyncSemaphoreValue: 异步消息发送最大并发度(Broker端参数)。
• serverChannelMaxIdleTimeSeconds: 网络连接最大空闲时间,默认120s。如果连接空闲时间超过该参数设置的值,连接将被关闭。
• serverSocketSndBufSize: 网络socket发送缓存区大小,默认64k。
• serverSocketRecBufSize: 网络socket接收缓存区大小,默认64k。
• serverPooledByteBufAllocatorEnable: ByteBuffer是否开启缓存,建议开启。
• useEpollNativeSelector: 是否启用Epoll IO模型,Linux环境建议开启。

在启动NameServer时,可以先使用./mqnameserver -c configFile -p 打印当前加载的配置属性。

Step2: 根据启动属性创建NamesrvController实例,并初始化该实例,NamesrvController实例为NameServer核心控制器。

NamesrvController#initialize代码片段

    public boolean initialize() {

        this.kvConfigManager.load();

        this.remotingServer = new NettyRemotingServer(this.nettyServerConfig, this.brokerHousekeepingService);

        this.remotingExecutor =
            Executors.newFixedThreadPool(nettyServerConfig.getServerWorkerThreads(), new ThreadFactoryImpl("RemotingExecutorThread_"));

        this.registerProcessor();

        this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {

            @Override
            public void run() {
                NamesrvController.this.routeInfoManager.scanNotActiveBroker();
            }
        }, 5, 10, TimeUnit.SECONDS);

        this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {

            @Override
            public void run() {
                NamesrvController.this.kvConfigManager.printAllPeriodically();
            }
        }, 1, 10, TimeUnit.MINUTES);

        return true;
    }

加载KV配置,创建NettyServer网络处理对象,然后开启两个定时任务,在RocketMQ中此类定时任务统称为心跳检测。

• 定时任务1: NameServer每隔10s扫描一次Broker,移除处于不激活状态的Broker。
• 定时任务2: NameServer每隔十分钟打印一次KV配置。

Step3: 注册JVM钩子函数并启动服务器,以便监听Broker、消息生产者的网络请求。

            Runtime.getRuntime().addShutdownHook(new ShutdownHookThread(log, new Callable<Void>() {
                @Override
                public Void call() throws Exception {
                    controller.shutdown();
                    return null;
                }
            }));

            controller.start();

NameServer路由注册、故障剔除

NameServer主要作用是为消息生产者和消息消费者提供关于主题Topic的路由信息,那么NameServer需要存储路由的基础信息,还要能够管理Broker节点,包括路由注册、路由删除等功能。

路由元信息

NameServer路由实现类: org.apache.rocketmq.namesrv.routeinfo.RouteInfoManager,在了解路由注册之前,我们首先看一下NameServer到底存储哪些信息。

    private final HashMap<String/* topic */, List<QueueData>> topicQueueTable;
    private final HashMap<String/* brokerName */, BrokerData> brokerAddrTable;
    private final HashMap<String/* clusterName */, Set<String/* brokerName */>> clusterAddrTable;
    private final HashMap<String/* brokerAddr */, BrokerLiveInfo> brokerLiveTable;
    private final HashMap<String/* brokerAddr */, List<String>/* Filter Server */> filterServerTable;

• topicQueueTable: Topic消息队列路由信息,消息发送时根据路由表进行负载均衡。
• brokerAddrTable: Broker基础信息,包含BrokerName、所属集群名称、主备Broker地址。
• clusterAddrTable: Broker集群信息,存储集群中所有Broker名称。
• brokerLiveTable: Broker状态信息。NameServer每次收到心跳包时会替换该信息。
• filterServerTable: Broker上的FilterServer列表,用于类模式消息过滤。

RocketMQ基于订阅发布机制,一个Topic拥有多个消息队列,一个Broker为每一主题默认创建4个读队列4个写队列。多个Broker组成一个集群,BrokerName由相同的多台Broker组成Master-Slave架构,brokerId为0表示Master,大于0表示Slave。BrokerLiveInfo中的lastUpdateTimestamp存储上次收到Broker心跳包的时间。

QueueData

    private String brokerName;
    private int readQueueNums;
    private int writeQueueNums;
    private int perm;
    private int topicSynFlag;

BrokerData

    private String cluster;
    private String brokerName;
    // brokerId为0表示Master,大于0表示Slave
    private HashMap<Long/* brokerId */, String/* broker address */> brokerAddrs;

BrokerLiveInfo

    private long lastUpdateTimestamp;
    private DataVersion dataVersion;
    private Channel channel;
    private String haServerAddr;

路由注册

RocketMQ路由注册是通过Broker与NameServer的心跳功能实现的。Broker启动时向集群中所有的NameServer发送心跳语句,每隔30秒向集群中所有NameServer发送心跳包,NameServer收到Broker心跳包时会更新brokerLiveTable缓存中BrokerLiveInfo的lastUpdateTimestamp,然后NameServer每隔10秒扫描brokerLiveTable,如果连续120s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。

Broker发送心跳包

Broker发送心跳包的核心代码如下所示。

Broker端心跳包发送(BrokerController#start)

        this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
            @Override
            public void run() {
                try {
                    BrokerController.this.registerBrokerAll(true, false);
                } catch (Throwable e) {
                    log.error("registerBrokerAll Exception", e);
                }
            }
        }, 1000 * 10, 1000 * 30, TimeUnit.MILLISECONDS);

BrokerOuterAPI#registerBrokerAll

        List<String> nameServerAddressList = this.remotingClient.getNameServerAddressList();
        if (nameServerAddressList != null) {
            for (String namesrvAddr : nameServerAddressList) {// 遍历所有NameServer列表
                try {
                    RegisterBrokerResult result = this.registerBroker(namesrvAddr, clusterName, brokerAddr, brokerName, brokerId,
                        haServerAddr, topicConfigWrapper, filterServerList, oneway, timeoutMills);// 分别向NameServer注册
                    if (result != null) {
                        registerBrokerResult = result;
                    }

                    log.info("register broker to name server {} OK", namesrvAddr);
                } catch (Exception e) {
                    log.warn("registerBroker Exception, {}", namesrvAddr, e);
                }
            }
        }

BrokerOuteAPI#registerBroker(网络发送代码)

        RegisterBrokerRequestHeader requestHeader = new RegisterBrokerRequestHeader();
        requestHeader.setBrokerAddr(brokerAddr);
        requestHeader.setBrokerId(brokerId);
        requestHeader.setBrokerName(brokerName);
        requestHeader.setClusterName(clusterName);
        requestHeader.setHaServerAddr(haServerAddr);
        RemotingCommand request = RemotingCommand.createRequestCommand(RequestCode.REGISTER_BROKER, requestHeader);

        RegisterBrokerBody requestBody = new RegisterBrokerBody();
        requestBody.setTopicConfigSerializeWrapper(topicConfigWrapper);
        requestBody.setFilterServerList(filterServerList);
        request.setBody(requestBody.encode());

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

        RemotingCommand response = this.remotingClient.invokeSync(namesrvAddr, request, timeoutMills);

发送心跳包具体逻辑,首先封装请求包头(Header)。

• brokerAddr: broker地址。
• brokerId: brokerId,0: Master ; 大于0: Slave。
• brokerName: broker名称。
• clusterName: 集群名称。
• haServerAddr: master地址,初次请求时该值为空,slave向Nameserver注册后返回。
• requestBody:
  • filterServerList: 消息过滤服务器列表。
  • topicConfigWapper: 主题配置,topicConfigWrapper内部封装的是TopicConfigManager中的topicConfigTable,内部存储的是Broker启动时默认的一些Topic,MixAll.SELF_TEST_TOPIC、MixAll.DEFAULT_TOPICC(AutoCreateTopicEnable=true)、MixAll.BENCHMARK_TOPIC、MixAll.OFFSET_MOVED_EVENT、BrokerConfig#brokerClusterName、BrokerConfig#brokerName。Broker中Topic默认存储在${Rocket_Home}/store/config/topics.json中。

NameServer处理心跳包

org.apache.rocketmq.namesrv.processor.DefaultRequestProcessor网络处理器解析请求类型,如果请求类型为RequestCode.REGISTER_BROKER,则请求最终转发到RouteInfoManager#registerBroker。

Step1: 路由注册需要加写锁,防止并发修改RouteInfoManager中的路由表。首先判断Broker所属集群是否存在,如果不存在,则创建,然后将broker名加入到集群Broker集合中。

RouteInfoManager#registerBroker clusterAddrTable维护

                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);

Step2: 维护BrokerData信息,首先从brokerAddrTable根据BrokerName尝试获取Broker信息,如果不存在,则新建BrokerData并放入brokerAddrTable,registerFirst设置为true;如果存在,直接替换原先的,registerFirst设置为false,表示非第一次注册

RouteInfoManager#registerBroker brokerAddrTable维护

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

Step3: 如果Broker为Master,并且Broker Topic配置信息发变化或者是初次注册,则需要创建或更新Topic路由元数据,填充topicQueueTable,其实就是为默认主题自动注册路由信息,其中包含MixAll.DEFAULT_TOPIC的路由信息。当消费生产者发送主题时,如果该主题未创建并且BrokerConfig的autoCreateTopicEnable为true时,则返回MixAll.DEFAULT_TOPIC的路由信息。

                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());
                            }
                        }
                    }
                }

根据TopicConfig创建QueueData数据结构,然后更新topicQueueTable
RouteInfoManager#createAndUpdateQueueData

    private void createAndUpdateQueueData(final String brokerName, final TopicConfig topicConfig) {
        QueueData queueData = new QueueData();
        queueData.setBrokerName(brokerName);
        queueData.setWriteQueueNums(topicConfig.getWriteQueueNums());
        queueData.setReadQueueNums(topicConfig.getReadQueueNums());
        queueData.setPerm(topicConfig.getPerm());
        queueData.setTopicSynFlag(topicConfig.getTopicSysFlag());

        List<QueueData> queueDataList = this.topicQueueTable.get(topicConfig.getTopicName());
        if (null == queueDataList) {
            queueDataList = new LinkedList<QueueData>();
            queueDataList.add(queueData);
            this.topicQueueTable.put(topicConfig.getTopicName(), queueDataList);
            log.info("new topic registered, {} {}", topicConfig.getTopicName(), queueData);
        } else {
            boolean addNewOne = true;

            Iterator<QueueData> it = queueDataList.iterator();
            while (it.hasNext()) {
                QueueData qd = it.next();
                if (qd.getBrokerName().equals(brokerName)) {
                    if (qd.equals(queueData)) {
                        addNewOne = false;
                    } else {
                        log.info("topic changed, {} OLD: {} NEW: {}", topicConfig.getTopicName(), qd,
                            queueData);
                        it.remove();
                    }
                }
            }

            if (addNewOne) {
                queueDataList.add(queueData);
            }
        }
    }

Step4: 更新BrokerLiveInfo,存活Broker信息表,BrokerLiveInfo是执行路由删除的重要依据

RouteInfoManager#registerBroker

                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);
                }

Step5: 注册Broker的过滤器Server地址列表,一个Broker上会关联多个FilterServer消息过滤服务器;如果此Broker为从节点,则需要查找该Broker的Master的节点信息,并更新对应的masterAddr属性。

                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);
                        }
                    }
                }

路由删除

NameServer会每隔10s扫描brokerLiveTable状态表,如果BrokerLive的lastUpdateTimestamp的时间戳距当前时间超过120s,则认为Broker失效,移除该Broker,关闭与Broker连接,并同时更新topicQueueTable、brokerAddrTable、brokerLiveTable、filterServerTable。

RocketMQ有两个触发点来出发路由删除。
1、NameServer定时扫描brokerLiveTable检测上次心跳包与当前系统时间的时间差,如果时间戳大于120s,则需要移除该Broker信息。
2、Broker在正常被关闭的情况下,会执行unregisterBroker指令。
由于不管是何种方式出发的路由删除,路由删除的方法都是一样的,就是从topicQueueTable、brokerAddrTable、brokerLiveTable、filterServerTable删除与该Broker相关的信息。

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());
            }
        }
    }

遍历brokerLiveInfo路由表(HashMap),检测BrokerLiveInfo的lastUpdateTimestamp上次收到心跳包的时间如果超过当前时间120s,NameServer则认为该Broker已不可用,故需要将它移除,关闭Channel,然后删除与该Broker相关的路由信息,路由表维护过程,需要申请写锁。

Step1: 申请写锁,根据brokerAddress从brokerLiveTable、filterServerTable移除

RouteInfoManager#onChannelDestroy

                    this.lock.writeLock().lockInterruptibly();
                    this.brokerLiveTable.remove(brokerAddrFound);
                    this.filterServerTable.remove(brokerAddrFound);

Step2: 维护brokerAddrTable。遍历从HashMap<String/* brokerName * /, BrokerData> brokerAddrTable,从BrokerData的HashMap<Long/* brokerId * /, String/* broker address * /> brokerAddrs中,找到具体的Broker,从BrokerData中移除,如果移除后在BrokerData中不再包含其他Broker,则在brokerAddrTable中移除该brokerName对应的条目。

RouteInfoManager#onChannelDestroy

                    String brokerNameFound = null;
                    boolean removeBrokerName = false;
                    Iterator<Entry<String, BrokerData>> itBrokerAddrTable =
                        this.brokerAddrTable.entrySet().iterator();
                    while (itBrokerAddrTable.hasNext() && (null == brokerNameFound)) {
                        BrokerData brokerData = itBrokerAddrTable.next().getValue();

                        Iterator<Entry<Long, String>> it = brokerData.getBrokerAddrs().entrySet().iterator();
                        while (it.hasNext()) {
                            Entry<Long, String> entry = it.next();
                            Long brokerId = entry.getKey();
                            String brokerAddr = entry.getValue();
                            if (brokerAddr.equals(brokerAddrFound)) {
                                brokerNameFound = brokerData.getBrokerName();
                                it.remove();
                                log.info("remove brokerAddr[{}, {}] from brokerAddrTable, because channel destroyed",
                                    brokerId, brokerAddr);
                                break;
                            }
                        }

                        if (brokerData.getBrokerAddrs().isEmpty()) {
                            removeBrokerName = true;
                            itBrokerAddrTable.remove();
                            log.info("remove brokerName[{}] from brokerAddrTable, because channel destroyed",
                                brokerData.getBrokerName());
                        }

Step3: 根据BrokerName,从clusterAddrTable中找到Broker并从集群中移除。如果移除后,集群中不包含任何Broker,则将该集群从clusterAddrTable中移除。

RouteInfoManager#onChannelDestroy

                    if (brokerNameFound != null && removeBrokerName) {
                        Iterator<Entry<String, Set<String>>> it = this.clusterAddrTable.entrySet().iterator();
                        while (it.hasNext()) {
                            Entry<String, Set<String>> entry = it.next();
                            String clusterName = entry.getKey();
                            Set<String> brokerNames = entry.getValue();
                            boolean removed = brokerNames.remove(brokerNameFound);
                            if (removed) {
                                log.info("remove brokerName[{}], clusterName[{}] from clusterAddrTable, because channel destroyed",
                                        brokerNameFound, clusterName);

                                if (brokerNames.isEmpty()) {
                                    log.info("remove the clusterName[{}] from clusterAddrTable, because channel destroyed and no broker in this cluster",
                                            clusterName);
                                    it.remove();
                                }

                                break;
                            }
                        }
                    }

Step4: 根据brokerName,遍历所有主题的队列,如果队列中包含了当前Broker的队列,则移除,如果topic只包含待移除Broker的队列的话,从路由表中删除该topic。

RouteInfoManager#onChannelDestroy

                    if (removeBrokerName) {
                        Iterator<Entry<String, List<QueueData>>> itTopicQueueTable =
                                this.topicQueueTable.entrySet().iterator();
                        while (itTopicQueueTable.hasNext()) {
                            Entry<String, List<QueueData>> entry = itTopicQueueTable.next();
                            String topic = entry.getKey();
                            List<QueueData> queueDataList = entry.getValue();

                            Iterator<QueueData> itQueueData = queueDataList.iterator();
                            while (itQueueData.hasNext()) {
                                QueueData queueData = itQueueData.next();
                                if (queueData.getBrokerName().equals(brokerNameFound)) {
                                    itQueueData.remove();
                                    log.info("remove topic[{} {}], from topicQueueTable, because channel destroyed",
                                            topic, queueData);
                                }
                            }

                            if (queueDataList.isEmpty()) {
                                itTopicQueueTable.remove();
                                log.info("remove topic[{}] all queue, from topicQueueTable, because channel destroyed",
                                        topic);
                            }
                        }
                    }

Step5: 释放锁,完成路由删除。

RouteInfoManager#onChannelDestroy

                finally {
                    this.lock.writeLock().unlock();
                }

路由发现

RocketMQ路由发现是非实时的,当Topic路由出现变化后,NameServer不主动推送给客户端,而是由客户端定时拉取主题最新的路由。根据主题名称拉取路由信息的命令编码为: GET_ROUTEINFO_BY_TOPIC。

private String orderTopicConf;
private List<QueueData> queueDatas;
private List<BrokerData> brokerDatas;
private HashMap<String/* brokerAddr */, List<String>/* Filter Server */> filterServerTable;

• orderTopicConf: 顺序消息配置内容,来自于kvConfig。
• List<QueueData> queueDatas: topic队列元数据
• List<BrokerData> brokerDatas: topic分布的broker元数据
• HashMap<String/* brokerAddr /, List<String>/ Filter Server */> filterServerTable: broker上过滤服务器地址列表。

NameServer路由发现实现类: DefaultRequestProcessor#getRouteInfoByTopic

DefaultRequestProcessor#getRouteInfoByTopic

    public RemotingCommand getRouteInfoByTopic(ChannelHandlerContext ctx,
        RemotingCommand request) throws RemotingCommandException {
        final RemotingCommand response = RemotingCommand.createResponseCommand(null);
        final GetRouteInfoRequestHeader requestHeader =
            (GetRouteInfoRequestHeader) request.decodeCommandCustomHeader(GetRouteInfoRequestHeader.class);

        TopicRouteData topicRouteData = this.namesrvController.getRouteInfoManager().pickupTopicRouteData(requestHeader.getTopic());

        if (topicRouteData != null) {
            if (this.namesrvController.getNamesrvConfig().isOrderMessageEnable()) {
                String orderTopicConf =
                    this.namesrvController.getKvConfigManager().getKVConfig(NamesrvUtil.NAMESPACE_ORDER_TOPIC_CONFIG,
                        requestHeader.getTopic());
                topicRouteData.setOrderTopicConf(orderTopicConf);
            }

            byte[] content = topicRouteData.encode();
            response.setBody(content);
            response.setCode(ResponseCode.SUCCESS);
            response.setRemark(null);
            return response;
        }

        response.setCode(ResponseCode.TOPIC_NOT_EXIST);
        response.setRemark("No topic route info in name server for the topic: " + requestHeader.getTopic()
            + FAQUrl.suggestTodo(FAQUrl.APPLY_TOPIC_URL));
        return response;
    }

Step1: 调用RouterInfoManager的方法,从路由表topicQueueTable、brokerAddrTable、filterServerTable中分别填充TopicRouteData中的List<QueueData>、List<BrokerData>和filterServer地址表。
Step2: 如果找到主题对应的路由信息并且该主题为顺序消息,则从NameServer KVconfig中获取关于顺序消息相关的配置填充路由信息。如果找不到路由信息CODE则使用TOPIC_NOT_EXISTS,表示没有找到对应的路由。

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