RocketMQ 源码解读二 NameSrv启动篇

 NameSrv启动的main方法，核心就2个，createNamesrvController和start方法

    public static NamesrvController main0(String[] args) {

        try {
            NamesrvController controller = createNamesrvController(args);
            start(controller);
            String tip = "The Name Server boot success. serializeType=" + RemotingCommand.getSerializeTypeConfigInThisServer();
            log.info(tip);
            System.out.printf("%s%n", tip);
            return controller;
        } catch (Throwable e) {
            e.printStackTrace();
            System.exit(-1);
        }

        return null;
    }

createNamesrvController方法源码如下。比较简单，主要就是将配置信息写入到对象中

    public static NamesrvController createNamesrvController(String[] args) throws IOException, JoranException {

        // 设置RocketMQ版本号
        System.setProperty(RemotingCommand.REMOTING_VERSION_KEY, Integer.toString(MQVersion.CURRENT_VERSION));

        // 解析命令行中的参数
        Options options = ServerUtil.buildCommandlineOptions(new Options());
        commandLine = ServerUtil.parseCmdLine("mqnamesrv", args, buildCommandlineOptions(options), new PosixParser());
        if (null == commandLine) {
            System.exit(-1);
            return null;
        }

        // 从环境变量中获取rocketmqHome、kvConfig.json、namesrv.properties的路径
        final NamesrvConfig namesrvConfig = new NamesrvConfig();

        // 设置netty服务端信息，如端口是9876
        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, %s%n", file);
                in.close();
            }
        }

        if (commandLine.hasOption('p')) {
            InternalLogger console = InternalLoggerFactory.getLogger(LoggerName.NAMESRV_CONSOLE_NAME);
            MixAll.printObjectProperties(console, namesrvConfig);
            MixAll.printObjectProperties(console, nettyServerConfig);
            System.exit(0);
        }

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

        if (null == namesrvConfig.getRocketmqHome()) {
            System.out.printf("Please set the %s variable in your environment to match the location of the RocketMQ installation%n", MixAll.ROCKETMQ_HOME_ENV);
            System.exit(-2);
        }

        LoggerContext lc = (LoggerContext) LoggerFactory.getILoggerFactory();
        JoranConfigurator configurator = new JoranConfigurator();
        configurator.setContext(lc);
        lc.reset();

        // 读取logback_namesrv.xml文件中的内容
        configurator.doConfigure(namesrvConfig.getRocketmqHome() + "/conf/logback_namesrv.xml");

        log = InternalLoggerFactory.getLogger(LoggerName.NAMESRV_LOGGER_NAME);

        MixAll.printObjectProperties(log, namesrvConfig);
        MixAll.printObjectProperties(log, nettyServerConfig);

        // 创建NamesrvController
        final NamesrvController controller = new NamesrvController(namesrvConfig, nettyServerConfig);

        // 将命令行中设置的参数添加到对象中
        controller.getConfiguration().registerConfig(properties);

        return controller;
    }

start方法中主要包含2段，initialize和start方法。initialize源码如下

    public boolean initialize() {

        // 读取kvConfig.json文件的内容，并赋值到KVConfigManager对象中
        this.kvConfigManager.load();

        // 创建Netty服务端对象，并会在start方法中启动
        this.remotingServer = new NettyRemotingServer(this.nettyServerConfig, this.brokerHousekeepingService);

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

        // 往Netty服务端注册Processor，后续服务端处理收到的数据就会用这个Processor
        // 默认是使用DefaultRequestProcessor，如果NamesrvConfig的ClusterTest属性是true，就使用ClusterTestRequestProcessor
        this.registerProcessor();

        // 如果Broker有2分钟没有收到心跳，就关闭这个Broker的连接
        this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {

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

        // 就打印KVConfigManager中的成员变量中的内容，不知道作用是什么
        this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {

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

        if (TlsSystemConfig.tlsMode != TlsMode.DISABLED) {
            // Register a listener to reload SslContext
            try {
                fileWatchService = new FileWatchService(
                    new String[] {
                        TlsSystemConfig.tlsServerCertPath,
                        TlsSystemConfig.tlsServerKeyPath,
                        TlsSystemConfig.tlsServerTrustCertPath
                    },
                    new FileWatchService.Listener() {
                        boolean certChanged, keyChanged = false;
                        @Override
                        public void onChanged(String path) {
                            if (path.equals(TlsSystemConfig.tlsServerTrustCertPath)) {
                                log.info("The trust certificate changed, reload the ssl context");
                                reloadServerSslContext();
                            }
                            if (path.equals(TlsSystemConfig.tlsServerCertPath)) {
                                certChanged = true;
                            }
                            if (path.equals(TlsSystemConfig.tlsServerKeyPath)) {
                                keyChanged = true;
                            }
                            if (certChanged && keyChanged) {
                                log.info("The certificate and private key changed, reload the ssl context");
                                certChanged = keyChanged = false;
                                reloadServerSslContext();
                            }
                        }
                        private void reloadServerSslContext() {
                            ((NettyRemotingServer) remotingServer).loadSslContext();
                        }
                    });
            } catch (Exception e) {
                log.warn("FileWatchService created error, can't load the certificate dynamically");
            }
        }

        return true;
    }

start源码如下

    public void start() throws Exception {

        // 启动NettyRemotingServer类，这就是一个Netty服务端
        this.remotingServer.start();

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

总结，NameSrv的启动类比较简单，主要注意KVConfigManager、DefaultRequestProcessor、ClusterTestRequestProcessor这3个类。KVConfigManager类暂不清楚作用，后2个类是用于处理接收到的TCP数据的