SpringCloud学习笔记（3）----Spring Cloud Netflix之深入理解Eureka
1. Eureka服务端的启动过程
1.1 入口类EurekaServerInitializerConfiguration类，
public void start() { (new Thread(new Runnable() { public void run() { try { EurekaServerInitializerConfiguration.this.eurekaServerBootstrap.contextInitialized(EurekaServerInitializerConfiguration.this.servletContext); EurekaServerInitializerConfiguration.log.info("Started Eureka Server"); EurekaServerInitializerConfiguration.this.publish(new EurekaRegistryAvailableEvent(EurekaServerInitializerConfiguration.this.getEurekaServerConfig())); EurekaServerInitializerConfiguration.this.running = true; EurekaServerInitializerConfiguration.this.publish(new EurekaServerStartedEvent(EurekaServerInitializerConfiguration.this.getEurekaServerConfig())); } catch (Exception var2) { EurekaServerInitializerConfiguration.log.error("Could not initialize Eureka servlet context", var2); } } })).start(); }
通过start()方法来加载上下文和相关的Server端的配置信息，该类上面使用了@Configuration注解，会被spring bean容器感知到。
2. Eureka的初始化
EurekaServerBootstrap类的contextInitialized方法
public void contextInitialized(ServletContext context) { try { this.initEurekaEnvironment(); //环境初始化 this.initEurekaServerContext(); //服务初始化 context.setAttribute(EurekaServerContext.class.getName(), this.serverContext); } catch (Throwable var3) { log.error("Cannot bootstrap eureka server :", var3); throw new RuntimeException("Cannot bootstrap eureka server :", var3); } }
查找服务初始化中的Evicetion
protected void initEurekaServerContext() throws Exception { JsonXStream.getInstance().registerConverter(new V1AwareInstanceInfoConverter(), 10000); XmlXStream.getInstance().registerConverter(new V1AwareInstanceInfoConverter(), 10000); if (this.isAws(this.applicationInfoManager.getInfo())) { this.awsBinder = new AwsBinderDelegate(this.eurekaServerConfig, this.eurekaClientConfig, this.registry, this.applicationInfoManager); this.awsBinder.start(); } EurekaServerContextHolder.initialize(this.serverContext); log.info("Initialized server context"); int registryCount = this.registry.syncUp(); this.registry.openForTraffic(this.applicationInfoManager, registryCount); EurekaMonitors.registerAllStats(); }
openForTraffic()
public void openForTraffic(ApplicationInfoManager applicationInfoManager, int count) { this.expectedNumberOfRenewsPerMin = count * 2; this.numberOfRenewsPerMinThreshold = (int)((double)this.expectedNumberOfRenewsPerMin * this.serverConfig.getRenewalPercentThreshold()); logger.info("Got {} instances from neighboring DS node", count); logger.info("Renew threshold is: {}", this.numberOfRenewsPerMinThreshold); this.startupTime = System.currentTimeMillis(); if (count > 0) { this.peerInstancesTransferEmptyOnStartup = false; } Name selfName = applicationInfoManager.getInfo().getDataCenterInfo().getName(); boolean isAws = Name.Amazon == selfName; if (isAws && this.serverConfig.shouldPrimeAwsReplicaConnections()) { logger.info("Priming AWS connections for all replicas.."); this.primeAwsReplicas(applicationInfoManager); } logger.info("Changing status to UP"); applicationInfoManager.setInstanceStatus(InstanceStatus.UP); super.postInit(); }
protected void postInit() { this.renewsLastMin.start(); if (this.evictionTaskRef.get() != null) { ((AbstractInstanceRegistry.EvictionTask)this.evictionTaskRef.get()).cancel(); } this.evictionTaskRef.set(new AbstractInstanceRegistry.EvictionTask()); this.evictionTimer.schedule((TimerTask)this.evictionTaskRef.get(), this.serverConfig.getEvictionIntervalTimerInMs(), this.serverConfig.getEvictionIntervalTimerInMs()); }
2. 客户端注册过程
客户端流程
1.入口：DiscoveryClient功能描述
1） 向Eureka Server注册服务实例
2）向Eureka Server续约
3） 当服务关闭的时候向Eureka Server取消租约
4） 查询注册到Eureka Server中的服务实例
2 实例化，调用构造方法
@Inject DiscoveryClient(ApplicationInfoManager applicationInfoManager, EurekaClientConfig config, AbstractDiscoveryClientOptionalArgs args, Provider<BackupRegistry> backupRegistryProvider) { this.RECONCILE_HASH_CODES_MISMATCH = Monitors.newCounter("DiscoveryClient_ReconcileHashCodeMismatch"); this.FETCH_REGISTRY_TIMER = Monitors.newTimer("DiscoveryClient_FetchRegistry"); this.REREGISTER_COUNTER = Monitors.newCounter("DiscoveryClient_Reregister"); this.localRegionApps = new AtomicReference(); this.fetchRegistryUpdateLock = new ReentrantLock(); this.healthCheckHandlerRef = new AtomicReference(); this.remoteRegionVsApps = new ConcurrentHashMap(); this.lastRemoteInstanceStatus = InstanceStatus.UNKNOWN; this.eventListeners = new CopyOnWriteArraySet(); this.registrySize = 0; this.lastSuccessfulRegistryFetchTimestamp = -1L; this.lastSuccessfulHeartbeatTimestamp = -1L; this.isShutdown = new AtomicBoolean(false); if (args != null) { this.healthCheckHandlerProvider = args.healthCheckHandlerProvider; this.healthCheckCallbackProvider = args.healthCheckCallbackProvider; this.eventListeners.addAll(args.getEventListeners()); this.preRegistrationHandler = args.preRegistrationHandler; } else { this.healthCheckCallbackProvider = null; this.healthCheckHandlerProvider = null; this.preRegistrationHandler = null; } this.applicationInfoManager = applicationInfoManager; InstanceInfo myInfo = applicationInfoManager.getInfo(); this.clientConfig = config; staticClientConfig = this.clientConfig; this.transportConfig = config.getTransportConfig(); this.instanceInfo = myInfo; if (myInfo != null) { this.appPathIdentifier = this.instanceInfo.getAppName() + "/" + this.instanceInfo.getId(); } else { logger.warn("Setting instanceInfo to a passed in null value"); } this.backupRegistryProvider = backupRegistryProvider; this.urlRandomizer = new InstanceInfoBasedUrlRandomizer(this.instanceInfo); this.localRegionApps.set(new Applications()); this.fetchRegistryGeneration = new AtomicLong(0L); this.remoteRegionsToFetch = new AtomicReference(this.clientConfig.fetchRegistryForRemoteRegions()); this.remoteRegionsRef = new AtomicReference(this.remoteRegionsToFetch.get() == null ? null : ((String)this.remoteRegionsToFetch.get()).split(",")); if (config.shouldFetchRegistry()) { this.registryStalenessMonitor = new ThresholdLevelsMetric(this, "eurekaClient.registry.lastUpdateSec_", new long[]{15L, 30L, 60L, 120L, 240L, 480L}); } else { this.registryStalenessMonitor = ThresholdLevelsMetric.NO_OP_METRIC; } if (config.shouldRegisterWithEureka()) { this.heartbeatStalenessMonitor = new ThresholdLevelsMetric(this, "eurekaClient.registration.lastHeartbeatSec_", new long[]{15L, 30L, 60L, 120L, 240L, 480L}); } else { this.heartbeatStalenessMonitor = ThresholdLevelsMetric.NO_OP_METRIC; } logger.info("Initializing Eureka in region {}", this.clientConfig.getRegion()); if (!config.shouldRegisterWithEureka() && !config.shouldFetchRegistry()) { logger.info("Client configured to neither register nor query for data."); this.scheduler = null; this.heartbeatExecutor = null; this.cacheRefreshExecutor = null; this.eurekaTransport = null; this.instanceRegionChecker = new InstanceRegionChecker(new PropertyBasedAzToRegionMapper(config), this.clientConfig.getRegion()); DiscoveryManager.getInstance().setDiscoveryClient(this); DiscoveryManager.getInstance().setEurekaClientConfig(config); this.initTimestampMs = System.currentTimeMillis(); logger.info("Discovery Client initialized at timestamp {} with initial instances count: {}", this.initTimestampMs, this.getApplications().size()); } else { try { this.scheduler = Executors.newScheduledThreadPool(2, (new ThreadFactoryBuilder()).setNameFormat("DiscoveryClient-%d").setDaemon(true).build()); this.heartbeatExecutor = new ThreadPoolExecutor(1, this.clientConfig.getHeartbeatExecutorThreadPoolSize(), 0L, TimeUnit.SECONDS, new SynchronousQueue(), (new ThreadFactoryBuilder()).setNameFormat("DiscoveryClient-HeartbeatExecutor-%d").setDaemon(true).build()); this.cacheRefreshExecutor = new ThreadPoolExecutor(1, this.clientConfig.getCacheRefreshExecutorThreadPoolSize(), 0L, TimeUnit.SECONDS, new SynchronousQueue(), (new ThreadFactoryBuilder()).setNameFormat("DiscoveryClient-CacheRefreshExecutor-%d").setDaemon(true).build()); this.eurekaTransport = new DiscoveryClient.EurekaTransport(); this.scheduleServerEndpointTask(this.eurekaTransport, args); Object azToRegionMapper; if (this.clientConfig.shouldUseDnsForFetchingServiceUrls()) { azToRegionMapper = new DNSBasedAzToRegionMapper(this.clientConfig); } else { azToRegionMapper = new PropertyBasedAzToRegionMapper(this.clientConfig); } if (null != this.remoteRegionsToFetch.get()) { ((AzToRegionMapper)azToRegionMapper).setRegionsToFetch(((String)this.remoteRegionsToFetch.get()).split(",")); } this.instanceRegionChecker = new InstanceRegionChecker((AzToRegionMapper)azToRegionMapper, this.clientConfig.getRegion()); } catch (Throwable var9) { throw new RuntimeException("Failed to initialize DiscoveryClient!", var9); } if (this.clientConfig.shouldFetchRegistry() && !this.fetchRegistry(false)) { this.fetchRegistryFromBackup(); } if (this.preRegistrationHandler != null) { this.preRegistrationHandler.beforeRegistration(); } if (this.clientConfig.shouldRegisterWithEureka() && this.clientConfig.shouldEnforceRegistrationAtInit()) { try { if (!this.register()) { throw new IllegalStateException("Registration error at startup. Invalid server response."); } } catch (Throwable var8) { logger.error("Registration error at startup: {}", var8.getMessage()); throw new IllegalStateException(var8); } } this.initScheduledTasks(); //注册任务主要是在这个定时任务里面实现 try { Monitors.registerObject(this); } catch (Throwable var7) { logger.warn("Cannot register timers", var7); } DiscoveryManager.getInstance().setDiscoveryClient(this); DiscoveryManager.getInstance().setEurekaClientConfig(config); this.initTimestampMs = System.currentTimeMillis(); logger.info("Discovery Client initialized at timestamp {} with initial instances count: {}", this.initTimestampMs, this.getApplications().size()); } }
public boolean onDemandUpdate() { if (this.rateLimiter.acquire(this.burstSize, (long)this.allowedRatePerMinute)) { if (!this.scheduler.isShutdown()) { this.scheduler.submit(new Runnable() { public void run() { InstanceInfoReplicator.logger.debug("Executing on-demand update of local InstanceInfo"); Future latestPeriodic = (Future)InstanceInfoReplicator.this.scheduledPeriodicRef.get(); if (latestPeriodic != null && !latestPeriodic.isDone()) { InstanceInfoReplicator.logger.debug("Canceling the latest scheduled update, it will be rescheduled at the end of on demand update"); latestPeriodic.cancel(false); } InstanceInfoReplicator.this.run(); } }); return true; } else { logger.warn("Ignoring onDemand update due to stopped scheduler"); return false; } } else { logger.warn("Ignoring onDemand update due to rate limiter"); return false; } } public void run() { boolean var6 = false; ScheduledFuture next; label53: { try { var6 = true; this.discoveryClient.refreshInstanceInfo(); Long dirtyTimestamp = this.instanceInfo.isDirtyWithTime(); if (dirtyTimestamp != null) { this.discoveryClient.register(); this.instanceInfo.unsetIsDirty(dirtyTimestamp); var6 = false; } else { var6 = false; } break label53; } catch (Throwable var7) { logger.warn("There was a problem with the instance info replicator", var7); var6 = false; } finally { if (var6) { ScheduledFuture next = this.scheduler.schedule(this, (long)this.replicationIntervalSeconds, TimeUnit.SECONDS); this.scheduledPeriodicRef.set(next); } } next = this.scheduler.schedule(this, (long)this.replicationIntervalSeconds, TimeUnit.SECONDS); this.scheduledPeriodicRef.set(next); return; } next = this.scheduler.schedule(this, (long)this.replicationIntervalSeconds, TimeUnit.SECONDS); this.scheduledPeriodicRef.set(next); }
boolean register() throws Throwable { logger.info("DiscoveryClient_{}: registering service...", this.appPathIdentifier); EurekaHttpResponse httpResponse; try { httpResponse = this.eurekaTransport.registrationClient.register(this.instanceInfo); } catch (Exception var3) { logger.warn("DiscoveryClient_{} - registration failed {}", new Object[]{this.appPathIdentifier, var3.getMessage(), var3}); throw var3; } if (logger.isInfoEnabled()) { logger.info("DiscoveryClient_{} - registration status: {}", this.appPathIdentifier, httpResponse.getStatusCode()); } return httpResponse.getStatusCode() == 204; }
最后调用register方法对服务进行注册
3. 服务端接收注册的流程
接受注册的流程
1.入口：ApplicationResource的addInstance()方法
@POST @Consumes({"application/json", "application/xml"}) public Response addInstance(InstanceInfo info, @HeaderParam("x-netflix-discovery-replication") String isReplication) { logger.debug("Registering instance {} (replication={})", info.getId(), isReplication); if (this.isBlank(info.getId())) { return Response.status(400).entity("Missing instanceId").build(); } else if (this.isBlank(info.getHostName())) { return Response.status(400).entity("Missing hostname").build(); } else if (this.isBlank(info.getIPAddr())) { return Response.status(400).entity("Missing ip address").build(); } else if (this.isBlank(info.getAppName())) { return Response.status(400).entity("Missing appName").build(); } else if (!this.appName.equals(info.getAppName())) { return Response.status(400).entity("Mismatched appName, expecting " + this.appName + " but was " + info.getAppName()).build(); } else if (info.getDataCenterInfo() == null) { return Response.status(400).entity("Missing dataCenterInfo").build(); } else if (info.getDataCenterInfo().getName() == null) { return Response.status(400).entity("Missing dataCenterInfo Name").build(); } else { DataCenterInfo dataCenterInfo = info.getDataCenterInfo(); if (dataCenterInfo instanceof UniqueIdentifier) { String dataCenterInfoId = ((UniqueIdentifier)dataCenterInfo).getId(); if (this.isBlank(dataCenterInfoId)) { boolean experimental = "true".equalsIgnoreCase(this.serverConfig.getExperimental("registration.validation.dataCenterInfoId")); if (experimental) { String entity = "DataCenterInfo of type " + dataCenterInfo.getClass() + " must contain a valid id"; return Response.status(400).entity(entity).build(); } if (dataCenterInfo instanceof AmazonInfo) { AmazonInfo amazonInfo = (AmazonInfo)dataCenterInfo; String effectiveId = amazonInfo.get(MetaDataKey.instanceId); if (effectiveId == null) { amazonInfo.getMetadata().put(MetaDataKey.instanceId.getName(), info.getId()); } } else { logger.warn("Registering DataCenterInfo of type {} without an appropriate id", dataCenterInfo.getClass()); } } } this.registry.register(info, "true".equals(isReplication)); return Response.status(204).build(); } }
register()方法
public void register(final InstanceInfo info, final boolean isReplication) { this.handleRegistration(info, this.resolveInstanceLeaseDuration(info), isReplication); super.register(info, isReplication); }
·super.register()方法
public void register(InstanceInfo info, boolean isReplication) { int leaseDuration = 90; if (info.getLeaseInfo() != null && info.getLeaseInfo().getDurationInSecs() > 0) { leaseDuration = info.getLeaseInfo().getDurationInSecs(); } super.register(info, leaseDuration, isReplication); this.replicateToPeers(PeerAwareInstanceRegistryImpl.Action.Register, info.getAppName(), info.getId(), info, (InstanceStatus)null, isReplication); }
说明：
1、 调用PeerAwareInstanceRegistryImpl的register方法
2、 完成服务注册后，调用replicateToPeers向其它Eureka Server节点（Peer）做状态同步
