Nacos - NacosNamingService初始化

Nacos - 启动提到了NacosWatch#start会获取NamingService，他托管NacosServiceManager来完成这件事。

NacosServiceManager#getNamingService

为空的时候，去建立一个NamingService

public NamingService getNamingService(Properties properties) {
    // 为空的时候，去建立一个NamingService
    if (Objects.isNull(this.namingService)) {
        buildNamingService(properties);
    }
    // 返回namingService
    return namingService;
}

NacosServiceManager#buildNamingService

加锁保证只能有一个namingService

private NamingService buildNamingService(Properties properties) {
    if (Objects.isNull(namingService)) {
        // 加锁保证只能有一个namingService
        synchronized (NacosServiceManager.class) {
            if (Objects.isNull(namingService)) {
                namingService = createNewNamingService(properties);
            }
        }
    }
    return namingService;
}

最终调用NamingFactory#createNamingService来建立NamingService对象。

private NamingService createNewNamingService(Properties properties) {
    try {
        return createNamingService(properties);
    }
    catch (NacosException e) {
        throw new RuntimeException(e);
    }
}
// NacosFactory中的方法
public static NamingService createNamingService(Properties properties) throws NacosException {
    return NamingFactory.createNamingService(properties);
}

NamingFactory#createNamingService

经过反射的方式建立了com.alibaba.nacos.client.naming.NacosNamingService对象。

public static NamingService createNamingService(String serverList) throws NacosException {
    try {
        Class<?> driverImplClass = Class.forName("com.alibaba.nacos.client.naming.NacosNamingService");
        Constructor constructor = driverImplClass.getConstructor(String.class);
        NamingService vendorImpl = (NamingService) constructor.newInstance(serverList);
        return vendorImpl;
    } catch (Throwable e) {
        throw new NacosException(NacosException.CLIENT_INVALID_PARAM, e);
    }
}

NacosNamingService#init

主要是初始化namespace、序列化、注册中心服务地址、WebRootContext上下文、缓存路径、日志名称、EventDispatcher、NamingProxy、BeatReactor、HostReactor。
EventDispatcher负责处理服务监听相关。
NamingProxy负责和Nacos服务的通讯，好比服务注册、服务取消注册、心跳等。
BeatReactor负责检测心跳。
HostReactor负责获取、更新并保存服务信息。

private void init(Properties properties) throws NacosException {
    ValidatorUtils.checkInitParam(properties);
    // namespace默认public
    this.namespace = InitUtils.initNamespaceForNaming(properties);
    // 序列化初始化
    InitUtils.initSerialization();
    // 注册中心服务地址初始化，这个从配置文件取
    initServerAddr(properties);
    //初始化WebRootContext上下文
    InitUtils.initWebRootContext();
    // 初始化缓存路径 System.getProperty("user.home") + "/nacos/naming/" + namespace
    initCacheDir();
    // 初始化日志名称naming.log
    initLogName(properties);
    // 初始化EventDispatcher
    this.eventDispatcher = new EventDispatcher();
    // 初始化NamingProxy
    this.serverProxy = new NamingProxy(this.namespace, this.endpoint, this.serverList, properties);
    // 初始化BeatReactor
    this.beatReactor = new BeatReactor(this.serverProxy, initClientBeatThreadCount(properties));
    // 初始化HostReactor
    this.hostReactor = new HostReactor(this.eventDispatcher, this.serverProxy, beatReactor, this.cacheDir,
            isLoadCacheAtStart(properties), initPollingThreadCount(properties));
}