不懂Ribbon原理的可以进来看看哦，分析RibbonClientConfiguration完成了哪些核心初始操作

Posted 2021-09-06 波波烤鸭

  本文在前一篇文章的基础上来继续分析Ribbon的核心内容。
不懂Ribbon原理的可以进来看看哦，分析SpringBoot自动装配完成了Ribbon哪些核心操作

RibbonClientConfiguration

  RibbonClientConfiguration是一个非常中的Ribbon配置类，在第一个发起Ribbon请求的时候会完成对应的初始化操作。会完成多个相关的默认设置。

接口	默认实现	描述
IClientConfig	DefaultClientConfigImpl	管理配置接口
IRule	ZoneAvoidanceRule	均衡策略接口
IPing	DummyPing	检查服务可用性接口
ServerList<Server>	ConfigurationBasedServerList	获取服务列表接口
ILoadBalancer	ZoneAwareLoadBalancer	负载均衡接口
ServerListUpdater	PollingServerListUpdater	定时更新服务列表接口
ServerIntrospector	DefaultServerIntrospector	安全端口接口

@Bean
    @ConditionalOnMissingBean
    public IClientConfig ribbonClientConfig() {
        DefaultClientConfigImpl config = new DefaultClientConfigImpl();
        config.loadProperties(this.name);
        config.set(CommonClientConfigKey.ConnectTimeout, 1000);
        config.set(CommonClientConfigKey.ReadTimeout, 1000);
        config.set(CommonClientConfigKey.GZipPayload, true);
        return config;
    }

    @Bean
    @ConditionalOnMissingBean
    public IRule ribbonRule(IClientConfig config) {
        if (this.propertiesFactory.isSet(IRule.class, this.name)) {
            return (IRule)this.propertiesFactory.get(IRule.class, config, this.name);
        } else {
            ZoneAvoidanceRule rule = new ZoneAvoidanceRule();
            rule.initWithNiwsConfig(config);
            return rule;
        }
    }

    @Bean
    @ConditionalOnMissingBean
    public IPing ribbonPing(IClientConfig config) {
        return (IPing)(this.propertiesFactory.isSet(IPing.class, this.name) ? (IPing)this.propertiesFactory.get(IPing.class, config, this.name) : new DummyPing());
    }

    @Bean
    @ConditionalOnMissingBean
    public ServerList<Server> ribbonServerList(IClientConfig config) {
        if (this.propertiesFactory.isSet(ServerList.class, this.name)) {
            return (ServerList)this.propertiesFactory.get(ServerList.class, config, this.name);
        } else {
            ConfigurationBasedServerList serverList = new ConfigurationBasedServerList();
            serverList.initWithNiwsConfig(config);
            return serverList;
        }
    }

    @Bean
    @ConditionalOnMissingBean
    public ServerListUpdater ribbonServerListUpdater(IClientConfig config) {
        return new PollingServerListUpdater(config);
    }

    @Bean
    @ConditionalOnMissingBean
    public ILoadBalancer ribbonLoadBalancer(IClientConfig config, ServerList<Server> serverList, ServerListFilter<Server> serverListFilter, IRule rule, IPing ping, ServerListUpdater serverListUpdater) {
        return (ILoadBalancer)(this.propertiesFactory.isSet(ILoadBalancer.class, this.name) ? (ILoadBalancer)this.propertiesFactory.get(ILoadBalancer.class, config, this.name) : new ZoneAwareLoadBalancer(config, rule, ping, serverList, serverListFilter, serverListUpdater));

  在众多的默认实现中比较重要的是【ILoadBalancer】对象的实现。即【ZoneAwareLoadBalancer】的实现。实现的原理图为：

在【ZoneAwareLoadBalancer】里面完成了服务地址动态获取和服务地址更新定时任务的配置。首先会进入【ZoneAwareLoadBalancer】的构造方法中

public ZoneAwareLoadBalancer(IClientConfig clientConfig, IRule rule,
                                 IPing ping, ServerList<T> serverList, ServerListFilter<T> filter,
                                 ServerListUpdater serverListUpdater) {
        super(clientConfig, rule, ping, serverList, filter, serverListUpdater);
    }

  通过源码能够发现会调用父类中的构造方法。

    public DynamicServerListLoadBalancer(IClientConfig clientConfig, IRule rule, IPing ping,
                                         ServerList<T> serverList, ServerListFilter<T> filter,
                                         ServerListUpdater serverListUpdater) {
        // 继续调用父类中的方法
        super(clientConfig, rule, ping);
        this.serverListImpl = serverList;
        this.filter = filter;
        this.serverListUpdater = serverListUpdater;
        if (filter instanceof AbstractServerListFilter) {
            ((AbstractServerListFilter) filter).setLoadBalancerStats(getLoadBalancerStats());
        }
        // 完成相关的初始操作  服务地址获取和更新
        restOfInit(clientConfig);
    }

  在上面的源码中我们先继续跟踪父类中的方法。

    void initWithConfig(IClientConfig clientConfig, IRule rule, IPing ping, LoadBalancerStats stats) {
        this.config = clientConfig;
        String clientName = clientConfig.getClientName();
        this.name = clientName;
        // 设置了定时任务的间隔时间为30秒。
        int pingIntervalTime = Integer.parseInt(""
                + clientConfig.getProperty(
                        CommonClientConfigKey.NFLoadBalancerPingInterval,
                        Integer.parseInt("30")));
        int maxTotalPingTime = Integer.parseInt(""
                + clientConfig.getProperty(
                        CommonClientConfigKey.NFLoadBalancerMaxTotalPingTime,
                        Integer.parseInt("2")));

        setPingInterval(pingIntervalTime);
        setMaxTotalPingTime(maxTotalPingTime);

        // cross associate with each other
        // i.e. Rule,Ping meet your container LB
        // LB, these are your Ping and Rule guys ...
        setRule(rule);
        setPing(ping);

        setLoadBalancerStats(stats);
        rule.setLoadBalancer(this);
        if (ping instanceof AbstractLoadBalancerPing) {
            ((AbstractLoadBalancerPing) ping).setLoadBalancer(this);
        }
        logger.info("Client: {} instantiated a LoadBalancer: {}", name, this);
        boolean enablePrimeConnections = clientConfig.get(
                CommonClientConfigKey.EnablePrimeConnections, DefaultClientConfigImpl.DEFAULT_ENABLE_PRIME_CONNECTIONS);

        if (enablePrimeConnections) {
            this.setEnablePrimingConnections(true);
            PrimeConnections primeConnections = new PrimeConnections(
                    this.getName(), clientConfig);
            this.setPrimeConnections(primeConnections);
        }
        init();

    }

  在initWithConfig方法中比较中的就是设置了定时任务的间隔时间。然后我们再回到restOfInit方法中。

    void restOfInit(IClientConfig clientConfig) {
        boolean primeConnection = this.isEnablePrimingConnections();
        // turn this off to avoid duplicated asynchronous priming done in BaseLoadBalancer.setServerList()
        this.setEnablePrimingConnections(false);
        // 设置定时任务
        enableAndInitLearnNewServersFeature();
		// 获取并更新服务地址
        updateListOfServers();
        if (primeConnection && this.getPrimeConnections() != null) {
            this.getPrimeConnections()
                    .primeConnections(getReachableServers());
        }
        this.setEnablePrimingConnections(primeConnection);
        LOGGER.info("DynamicServerListLoadBalancer for client {} initialized: {}", clientConfig.getClientName(), this.toString());
    }

  先看enableAndInitLearnNewServersFeature方法

    public void enableAndInitLearnNewServersFeature() {
        LOGGER.info("Using serverListUpdater {}", serverListUpdater.getClass().getSimpleName());
        serverListUpdater.start(updateAction);
    }

  start方法的实现有多种，根据我们的服务选择对应的选择即可。比如本地就使用PollingServerListUpdater,如果是Eureka注册中心就选择EurekaNotificationServerListUpdater.

以本地为例：

@Override
    public synchronized void start(final UpdateAction updateAction) {
        if (isActive.compareAndSet(false, true)) {
            // 定时任务的  任务体
            final Runnable wrapperRunnable = new Runnable() {
                @Override
                public void run() {
                    if (!isActive.get()) {
                        if (scheduledFuture != null) {
                            scheduledFuture.cancel(true);
                        }
                        return;
                    }
                    try {
                        // doUpdate()的方法体要注意
                        updateAction.doUpdate();
                        lastUpdated = System.currentTimeMillis();
                    } catch (Exception e) {
                        logger.warn("Failed one update cycle", e);
                    }
                }
            };
			// 设置定时任务 10秒开始第一次检查，间隔时间是30秒
            scheduledFuture = getRefreshExecutor().scheduleWithFixedDelay(
                    wrapperRunnable,
                    initialDelayMs,
                    refreshIntervalMs,
                    TimeUnit.MILLISECONDS
            );
        } else {
            logger.info("Already active, no-op");
        }
    }

  此处要注意定时任务的具体内容，以本地为例。

 所以定时任务执行的方法也就是【updateListOfServers】方法，也就是：

emsp; 所以我们继续来看看【updateListOfServers】方法中的逻辑

    @VisibleForTesting
    public void updateListOfServers() {
        List<T> servers = new ArrayList<T>();
        if (serverListImpl != null) {
            // 从本地或者Eureka或者Nacos等各个配置中心中获取对应的服务地址信息
            servers = serverListImpl.getUpdatedListOfServers();
            LOGGER.debug("List of Servers for {} obtained from Discovery client: {}",
                    getIdentifier(), servers);

            if (filter != null) {
                servers = filter.getFilteredListOfServers(servers);
                LOGGER.debug("Filtered List of Servers for {} obtained from Discovery client: {}",
                        getIdentifier(), servers);
            }
        }
        // 更新服务地址信息
        updateAllServerList(servers);
    }

  上面代码中重要的方法是【getUpdatedListOfServers】和【updateAllServerList】，先来看【getUpdatedListOfServers】方法

  查看本地的逻辑，Eureka的自行查看

	@Override
	public List<Server> getUpdatedListOfServers() {
        // 从本地配置中获取
        String listOfServers = clientConfig.get(CommonClientConfigKey.ListOfServers);
        return derive(listOfServers);
	}

  然后就是【updateAllServerList】方法

    protected void updateAllServerList(List<T> ls) {
        // other threads might be doing this - in which case, we pass
        // 通过CAS保证操作的原子性
        if (serverListUpdateInProgress.compareAndSet(false, true)) {
            try {
                for (T s : ls) {
                    s.setAlive(true); // set so that clients can start using these
                                      // servers right away instead
                                      // of having to wait out the ping cycle.
                }
                // 更新服务地址信息
                setServersList(ls);
                // 强制ping服务地址
                super.forceQuickPing();
            } finally {
                serverListUpdateInProgress.set(false);
            }
        }
    }

以上的操作流程图为：

好了~【RibbonClientConfiguration】这个配置类的内容就给大家介绍到这里，欢迎大家一键三连!!!