RocketMQ源碼閱讀（4）-Broker啓動向NameServer註冊、發送心跳

1、Broker啓動向NameServer註冊

在BrokerStartup類的main方法運行的時候，創建了BrokerController，然後調用了BrokerController的start方法，在該方法中有如下代碼

// 啓動的時候向每個NameServer發起註冊
this.registerBrokerAll(true, false, true);


this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
            @Override
            public void run() {
                try {
                    // Broker會每隔30s向NameSrv註冊並更新自身topic信息,完成心跳功能
                    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);

首先在Broker啓動的時候就會向每個NameServer進行註冊。

// true false true
    public synchronized void registerBrokerAll(final boolean checkOrderConfig, boolean oneway, boolean forceRegister) {
        // ConcurrentMap<String, TopicConfig> topicConfigTable
        // 將topicConfigTable封裝到TopicConfigSerializeWrapper中
        TopicConfigSerializeWrapper topicConfigWrapper = this.getTopicConfigManager().buildTopicConfigSerializeWrapper();

        // 判斷權限如果爲不可讀或不可寫那麼久在拼裝一下topicConfigTable到TopicConfigSerializeWrapper中
        if (!PermName.isWriteable(this.getBrokerConfig().getBrokerPermission())
            || !PermName.isReadable(this.getBrokerConfig().getBrokerPermission())) {
            ConcurrentHashMap<String, TopicConfig> topicConfigTable = new ConcurrentHashMap<String, TopicConfig>();
            for (TopicConfig topicConfig : topicConfigWrapper.getTopicConfigTable().values()) {
                TopicConfig tmp =
                    new TopicConfig(topicConfig.getTopicName(), topicConfig.getReadQueueNums(), topicConfig.getWriteQueueNums(),
                        this.brokerConfig.getBrokerPermission());
                topicConfigTable.put(topicConfig.getTopicName(), tmp);
            }
            topicConfigWrapper.setTopicConfigTable(topicConfigTable);
        }

        // forceRegister是否強制註冊
        // needRegister方法是與配置的每個NameServer進行通信，判斷topicConfigTable是否改變了，只要其中一個改變了那麼久需要發起註冊
        // QUERY_DATA_VERSION = 322;
        if (forceRegister || needRegister(this.brokerConfig.getBrokerClusterName(),
                this.getBrokerAddr(),
                this.brokerConfig.getBrokerName(),
                this.brokerConfig.getBrokerId(),
                this.brokerConfig.getRegisterBrokerTimeoutMills())) {
            // REGISTER_BROKER = 103;
            doRegisterBrokerAll(checkOrderConfig, oneway, topicConfigWrapper);
        }
    }




private void doRegisterBrokerAll(boolean checkOrderConfig, boolean oneway,
        TopicConfigSerializeWrapper topicConfigWrapper) {
        List<RegisterBrokerResult> registerBrokerResultList = this.brokerOuterAPI.registerBrokerAll(
            this.brokerConfig.getBrokerClusterName(),
            this.getBrokerAddr(),
            this.brokerConfig.getBrokerName(),
            this.brokerConfig.getBrokerId(),
            this.getHAServerAddr(),
            topicConfigWrapper,
            this.filterServerManager.buildNewFilterServerList(),
            oneway,
            this.brokerConfig.getRegisterBrokerTimeoutMills(),
            this.brokerConfig.isCompressedRegister());

        if (registerBrokerResultList.size() > 0) {
            RegisterBrokerResult registerBrokerResult = registerBrokerResultList.get(0);
            if (registerBrokerResult != null) {
                // 根據updateMasterHAServerAddrPeriodically標註位（在初始化時若Broker的配置文件中沒有haMasterAddress參數配置，則標記爲true，表示註冊之後需要更新主用Broker地址）
                // 以及NameServer返回的HaServerAddr地址是否爲空，若標記位是true且返回的HaServerAddr不爲空，則用HaServerAddr地址更新HAService.HAClient.masterAddress的值；
                // 該HAClient.masterAddress值用於主備Broker之間的commitlog數據同步之用
                if (this.updateMasterHAServerAddrPeriodically && registerBrokerResult.getHaServerAddr() != null) {
                    this.messageStore.updateHaMasterAddress(registerBrokerResult.getHaServerAddr());
                }

                // 用NameServer返回的MasterAddr值更新SlaveSynchronize.masterAddr值，用於主備Broker同步Config文件使用；
                this.slaveSynchronize.setMasterAddr(registerBrokerResult.getMasterAddr());

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

在NameServer中DefaultRequestProcessor類負責處理請求，在processRequest中根據不同的請求code調用不同的方法。

// 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 {
                // 加鎖，防止併發修改RouteInfoManager中的路由表
                this.lock.writeLock().lockInterruptibly();

                // 判斷broker所屬集羣是否存在，如果不存在則創建，然後將改broker加入到集羣中去
                Set<String> brokerNames = this.clusterAddrTable.get(clusterName);
                if (null == brokerNames) {
                    brokerNames = new HashSet<String>();
                    this.clusterAddrTable.put(clusterName, brokerNames);
                }
                brokerNames.add(brokerName);

                // 是否首次註冊標記
                boolean registerFirst = false;

                // 維護brokerData信息；如果不存在則創建並放入到brokerAddrTable集合中
                // HashMap<String/* brokerName */, BrokerData> brokerAddrTable
                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);

                // 如果broker爲master，並且broker topic配置信息發生變化或者初次註冊則需要創建或者更新Topic路由元數據，填充topicQueueTable
                // 就是爲默認主題自動註冊路由信息，其中包含MixAll.DEFAULT_TOPIC的路由信息。當消息生產者發送主題時，
                // 如果該主題未創建並且BrokerConfig的autoCreateTopicEnable爲true時，將返回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());
                            }
                        }
                    }
                }

                // 更新prevBrokerLiveInfo
                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;
    }