路由注册之Broker发送心跳包

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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30s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Name Server每隔10s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

BrokerController的start方法：

public void start() throws Exception {
    if (this.messageStore != null) {
        this.messageStore.start();
    }

    if (this.remotingServer != null) {
        this.remotingServer.start();
    }

    if (this.fastRemotingServer != null) {
        this.fastRemotingServer.start();
    }

    if (this.fileWatchService != null) {
        this.fileWatchService.start();
    }

    if (this.brokerOuterAPI != null) {
        this.brokerOuterAPI.start();
    }

    if (this.pullRequestHoldService != null) {
        this.pullRequestHoldService.start();
    }

    if (this.clientHousekeepingService != null) {
        this.clientHousekeepingService.start();
    }

    if (this.filterServerManager != null) {
        this.filterServerManager.start();
    }

    if (!messageStoreConfig.isEnableDLegerCommitLog()) {
        startProcessorByHa(messageStoreConfig.getBrokerRole());
        handleSlaveSynchronize(messageStoreConfig.getBrokerRole());
    }



    //注册Broker信息
    this.registerBrokerAll(true, false, true);

    //每隔30s上报Broker信息到NameServer
    this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {

        @Override
        public void run() {
            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);

    if (this.brokerStatsManager != null) {
        this.brokerStatsManager.start();
    }

    if (this.brokerFastFailure != null) {
        this.brokerFastFailure.start();
    }


}

遍历NameServer列表，Broker消息服务器依次向NameServer发送心跳包。

然后调用BrokerOuterAPI的registerBroker方法：

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());
}

RocketMQ网络传输基于Netty，网络跟踪方法：每个请求，RocketMQ都会定义一个RequestCode，然后在服务端会对应相应的网络处理器，搜索RequestCode就能找到相应的处理逻辑。