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!!!
