上期我们大概得了解了Eurake向Spring上下文中注册EurekaServiceRegistry和EurekaRegistration的详细过程，其中总调度类EurekaAutoServiceRegistration还专门采用lifeCycle的方式实现。昨天的分析中我们指出EurekaServiceRegistry是分析的重点，因此今天我们就重点突破一下这块的具体逻辑。

public void register(EurekaRegistration reg) {this.maybeInitializeClient(reg);if (log.isInfoEnabled()) {//打印服务的状态，UP表示正常启动log.info("Registering application " + reg.getInstanceConfig().getAppname() + " with eureka with status " + reg.getInstanceConfig().getInitialStatus());}//设置启动状态reg.getApplicationInfoManager().setInstanceStatus(reg.getInstanceConfig().getInitialStatus());if (reg.getHealthCheckHandler() != null) {reg.getEurekaClient().registerHealthCheck(reg.getHealthCheckHandler());}
}

我们原来以为EurekaServiceRegistry有大量的动作，但是发现这个类中什么也没有。等于与一个壳子，重点全是EurekaRegistration既然如此我们就重新分析EurekaRegistration吧。

发现这里有两个Eurake的客户端，但是cloudEurekaClient并没有怎么用唉，好像这里的eurekaClient才是真的老大。现在这里注入进来了，我们看看它是如何初始化的。这块我们直接DiscoveryClient的实现。

在DiscoveryClient的构造方法中，有几个线程相关的，分别是定时任务处理器、心跳线程池、缓存线程池。我们做过SpringCloud的同志都知道服务注册是通过定时任务去拉取服务信息，通过心态检测是否有服务宕机的。除此之外如果注册中心宕机了也会采用缓存。

private void initScheduledTasks() {int renewalIntervalInSecs;int expBackOffBound;//判断是否拉取配置，默认为trueif (this.clientConfig.shouldFetchRegistry()) {//多久拿一次，默认为30秒renewalIntervalInSecs = this.clientConfig.getRegistryFetchIntervalSeconds();//超时容许时间的倍数，和获取心跳或者服务信息失败的时间差的扩容有关系 默认10秒expBackOffBound = this.clientConfig.getCacheRefreshExecutorExponentialBackOffBound();//这里采用了代理模式，都是runnable接口哦，比较绕//启动刷新缓存的线程，也就是获取服务信息，全部打偶放到了定时任务中。this.scheduler.schedule(new TimedSupervisorTask("cacheRefresh", this.scheduler, this.cacheRefreshExecutor, renewalIntervalInSecs, TimeUnit.SECONDS, expBackOffBound, new DiscoveryClient.CacheRefreshThread()), (long)renewalIntervalInSecs, TimeUnit.SECONDS);}
//判断是否向eureka注册 默认为trueif (this.clientConfig.shouldRegisterWithEureka()) {//多久获取一次服务信息 默认30秒renewalIntervalInSecs = this.instanceInfo.getLeaseInfo().getRenewalIntervalInSecs();//超时容许时间的倍数，和获取心跳或者服务信息失败的时间差的扩容有关系 默认10秒expBackOffBound = this.clientConfig.getHeartbeatExecutorExponentialBackOffBound();logger.info("Starting heartbeat executor: renew interval is: " + renewalIntervalInSecs);//启动心跳线程this.scheduler.schedule(new TimedSupervisorTask("heartbeat", this.scheduler, this.heartbeatExecutor, renewalIntervalInSecs, TimeUnit.SECONDS, expBackOffBound, new DiscoveryClient.HeartbeatThread()), (long)renewalIntervalInSecs, TimeUnit.SECONDS);this.instanceInfoReplicator = new InstanceInfoReplicator(this, this.instanceInfo, this.clientConfig.getInstanceInfoReplicationIntervalSeconds(), 2);//定义一个监听器，用来看获取定时任务还在吗this.statusChangeListener = new StatusChangeListener() {public String getId() {return "statusChangeListener";}public void notify(StatusChangeEvent statusChangeEvent) {if (InstanceStatus.DOWN != statusChangeEvent.getStatus() && InstanceStatus.DOWN != statusChangeEvent.getPreviousStatus()) {DiscoveryClient.logger.info("Saw local status change event {}", statusChangeEvent);} else {DiscoveryClient.logger.warn("Saw local status change event {}", statusChangeEvent);}DiscoveryClient.this.instanceInfoReplicator.onDemandUpdate();}};if (this.clientConfig.shouldOnDemandUpdateStatusChange()) {this.applicationInfoManager.registerStatusChangeListener(this.statusChangeListener);}//启动监听this.instanceInfoReplicator.start(this.clientConfig.getInitialInstanceInfoReplicationIntervalSeconds());} else {logger.info("Not registering with Eureka server per configuration");}}

上述代码只要用来获取服务的注册和发现。也对上述功能的线程进行了监听。上边的代理模式，我们打开看看TimedSupervisorTask

public void run() {Future future = null;try {//这里task是注册刷新的任务 future = this.executor.submit(this.task);//获取活动线程的个数this.threadPoolLevelGauge.set((long)this.executor.getActiveCount());//使用future任务类型，这里获取拿到的服务信息future.get(this.timeoutMillis, TimeUnit.MILLISECONDS);this.delay.set(this.timeoutMillis);this.threadPoolLevelGauge.set((long)this.executor.getActiveCount());} catch (TimeoutException var12) {//如果超时了，这里还会将当前的时间间隔扩大一倍logger.error("task supervisor timed out", var12);this.timeoutCounter.increment();long currentDelay = this.delay.get();long newDelay = Math.min(this.maxDelay, currentDelay * 2L);this.delay.compareAndSet(currentDelay, newDelay);} catch (RejectedExecutionException var13) {if (!this.executor.isShutdown() && !this.scheduler.isShutdown()) {logger.error("task supervisor rejected the task", var13);} else {logger.warn("task supervisor shutting down, reject the task", var13);}this.rejectedCounter.increment();} catch (Throwable var14) {//如果异常服务处理，就直接中断了if (!this.executor.isShutdown() && !this.scheduler.isShutdown()) {logger.error("task supervisor threw an exception", var14);} else {logger.warn("task supervisor shutting down, can't accept the task");}this.throwableCounter.increment();} finally {if (future != null) {future.cancel(true);}if (!this.scheduler.isShutdown()) {//如果没有启动的话就重新创建一个this.scheduler.schedule(this, this.delay.get(), TimeUnit.MILLISECONDS);}}
}

    //刷新的任务    @VisibleForTestingvoid refreshRegistry() {try {boolean isFetchingRemoteRegionRegistries = this.isFetchingRemoteRegionRegistries();boolean remoteRegionsModified = false;//先会判断这个值是否为空，如果为空话就从这里获取配置String latestRemoteRegions = this.clientConfig.fetchRegistryForRemoteRegions();if (null != latestRemoteRegions) {String currentRemoteRegions = (String)this.remoteRegionsToFetch.get();if (!latestRemoteRegions.equals(currentRemoteRegions)) {synchronized(this.instanceRegionChecker.getAzToRegionMapper()) {if (this.remoteRegionsToFetch.compareAndSet(currentRemoteRegions, latestRemoteRegions)) {//设置最新的服务地址，用来获取服务配置String[] remoteRegions = latestRemoteRegions.split(",");this.remoteRegionsRef.set(remoteRegions);this.instanceRegionChecker.getAzToRegionMapper().setRegionsToFetch(remoteRegions);remoteRegionsModified = true;} else {logger.info("Remote regions to fetch modified concurrently, ignoring change from {} to {}", currentRemoteRegions, latestRemoteRegions);}}} else {this.instanceRegionChecker.getAzToRegionMapper().refreshMapping();}}//查看从eureka服务上获取配置是否成功， 真正的获取服务信息boolean success = this.fetchRegistry(remoteRegionsModified);if (success) {this.registrySize = ((Applications)this.localRegionApps.get()).size();this.lastSuccessfulRegistryFetchTimestamp = System.currentTimeMillis();}if (logger.isDebugEnabled()) {StringBuilder allAppsHashCodes = new StringBuilder();allAppsHashCodes.append("Local region apps hashcode: ");allAppsHashCodes.append(((Applications)this.localRegionApps.get()).getAppsHashCode());allAppsHashCodes.append(", is fetching remote regions? ");allAppsHashCodes.append(isFetchingRemoteRegionRegistries);Iterator var11 = this.remoteRegionVsApps.entrySet().iterator();while(var11.hasNext()) {Entry<String, Applications> entry = (Entry)var11.next();allAppsHashCodes.append(", Remote region: ");allAppsHashCodes.append((String)entry.getKey());allAppsHashCodes.append(" , apps hashcode: ");allAppsHashCodes.append(((Applications)entry.getValue()).getAppsHashCode());}logger.debug("Completed cache refresh task for discovery. All Apps hash code is {} ", allAppsHashCodes.toString());}} catch (Throwable var9) {logger.error("Cannot fetch registry from server", var9);}}

在从Eureka服务器上获取服务所有信息的时候代码是这样写的

    private void getAndStoreFullRegistry() throws Throwable {long currentUpdateGeneration = this.fetchRegistryGeneration.get();logger.info("Getting all instance registry info from the eureka server");Applications apps = null;//这块就是从拉取服务所有信息的EurekaHttpResponse<Applications> httpResponse = this.clientConfig.getRegistryRefreshSingleVipAddress() == null ?this.eurekaTransport.queryClient.getApplications((String[])this.remoteRegionsRef.get()) : this.eurekaTransport.queryClient.getVip(this.clientConfig.getRegistryRefreshSingleVipAddress(), (String[])this.remoteRegionsRef.get());if (httpResponse.getStatusCode() == Status.OK.getStatusCode()) {//处理成实体类型apps = (Applications)httpResponse.getEntity();}logger.info("The response status is {}", httpResponse.getStatusCode());if (apps == null) {logger.error("The application is null for some reason. Not storing this information");} else if (this.fetchRegistryGeneration.compareAndSet(currentUpdateGeneration, currentUpdateGeneration + 1L)) {this.localRegionApps.set(this.filterAndShuffle(apps));logger.debug("Got full registry with apps hashcode {}", apps.getAppsHashCode());} else {logger.warn("Not updating applications as another thread is updating it already");}}

看到这里，我也蒙了。本来一串也走下来了，但是让我疑惑的是我的serviceurl在哪里设置进去的？找了一圈remoteRegionsRef也没找到。fetch-remote-regions-registry这个配置是找到了，当我把这两个都配置上的时候就报错了。但是用Idea看的时候确实没有serviceUrl的踪迹。所以我是觉得是反编译的问题？有知道的朋友可以给我留言哦！谢谢