Erueka注册源码分析
在com.netfix.discovery包下有一个DiscoveryClient类中包含注册方法，DiscoveryClient实现了EurekaClient接口，并且是一个单例模式，而EurekaClient继承了LookupService接口。
DiscoveryClient类中有一个服务注册的方法register()，该方法通过http请求向EurekaServer注册。代码如下：
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() == Status.NO_CONTENT.getStatusCode(); }
DiscoveryClient的register()方法是被InstanceInfoReplicator类的run()调用，其中InstanceInfoReplicator实现了Runnable接口，run代码如下：
public void run() { try { discoveryClient.refreshInstanceInfo(); Long dirtyTimestamp = instanceInfo.isDirtyWithTime(); if (dirtyTimestamp != null) { discoveryClient.register(); instanceInfo.unsetIsDirty(dirtyTimestamp); } } catch (Throwable t) { logger.warn("There was a problem with the instance info replicator", t); } finally { Future next = scheduler.schedule(this, replicationIntervalSeconds, TimeUnit.SECONDS); scheduledPeriodicRef.set(next); } }
而InstanceInfoReplicator类是在DiscoveryClient初始化过程中使用的，其中有一个initScheduledTasks()方法，该方法主要开启了获取服务注册列表的信息，如果需要想Eureka server注册，则开启注册，同时开启了定时任务向Eureka Server服务续约
/** * Initializes all scheduled tasks. */ private void initScheduledTasks() { if (clientConfig.shouldFetchRegistry()) { // registry cache refresh timer int registryFetchIntervalSeconds = clientConfig.getRegistryFetchIntervalSeconds(); int expBackOffBound = clientConfig.getCacheRefreshExecutorExponentialBackOffBound(); scheduler.schedule( new TimedSupervisorTask( "cacheRefresh", scheduler, cacheRefreshExecutor, registryFetchIntervalSeconds, TimeUnit.SECONDS, expBackOffBound, new CacheRefreshThread() ), registryFetchIntervalSeconds, TimeUnit.SECONDS); } if (clientConfig.shouldRegisterWithEureka()) { int renewalIntervalInSecs = instanceInfo.getLeaseInfo().getRenewalIntervalInSecs(); int expBackOffBound = clientConfig.getHeartbeatExecutorExponentialBackOffBound(); logger.info("Starting heartbeat executor: " + "renew interval is: {}", renewalIntervalInSecs); // Heartbeat timer scheduler.schedule( new TimedSupervisorTask( "heartbeat", scheduler, heartbeatExecutor, renewalIntervalInSecs, TimeUnit.SECONDS, expBackOffBound, new HeartbeatThread() ), renewalIntervalInSecs, TimeUnit.SECONDS); // InstanceInfo replicator instanceInfoReplicator = new InstanceInfoReplicator( this, instanceInfo, clientConfig.getInstanceInfoReplicationIntervalSeconds(), 2); // burstSize statusChangeListener = new ApplicationInfoManager.StatusChangeListener() { @Override public String getId() { return "statusChangeListener"; } @Override public void notify(StatusChangeEvent statusChangeEvent) { if (InstanceStatus.DOWN == statusChangeEvent.getStatus() || InstanceStatus.DOWN == statusChangeEvent.getPreviousStatus()) { // log at warn level if DOWN was involved logger.warn("Saw local status change event {}", statusChangeEvent); } else { logger.info("Saw local status change event {}", statusChangeEvent); } instanceInfoReplicator.onDemandUpdate(); } }; if (clientConfig.shouldOnDemandUpdateStatusChange()) { applicationInfoManager.registerStatusChangeListener(statusChangeListener); } instanceInfoReplicator.start(clientConfig.getInitialInstanceInfoReplicationIntervalSeconds()); } else { logger.info("Not registering with Eureka server per configuration"); } }
二、再来看Eureka Server的代码，有一个EurekaBootStrap类的initEurekaServerContext初始化，其中PeerAwareInstanceRegistryImpl和PeerEurekaNodes方法对应服务注册和高可用。
/** * init hook for server context. Override for custom logic. */ protected void initEurekaServerContext() throws Exception { EurekaServerConfig eurekaServerConfig = new DefaultEurekaServerConfig(); // For backward compatibility JsonXStream.getInstance().registerConverter(new V1AwareInstanceInfoConverter(), XStream.PRIORITY_VERY_HIGH); XmlXStream.getInstance().registerConverter(new V1AwareInstanceInfoConverter(), XStream.PRIORITY_VERY_HIGH); logger.info("Initializing the eureka client..."); logger.info(eurekaServerConfig.getJsonCodecName()); ServerCodecs serverCodecs = new DefaultServerCodecs(eurekaServerConfig); ApplicationInfoManager applicationInfoManager = null; if (eurekaClient == null) { EurekaInstanceConfig instanceConfig = isCloud(ConfigurationManager.getDeploymentContext()) ? new CloudInstanceConfig() : new MyDataCenterInstanceConfig(); applicationInfoManager = new ApplicationInfoManager( instanceConfig, new EurekaConfigBasedInstanceInfoProvider(instanceConfig).get()); EurekaClientConfig eurekaClientConfig = new DefaultEurekaClientConfig(); eurekaClient = new DiscoveryClient(applicationInfoManager, eurekaClientConfig); } else { applicationInfoManager = eurekaClient.getApplicationInfoManager(); } PeerAwareInstanceRegistry registry; if (isAws(applicationInfoManager.getInfo())) { registry = new AwsInstanceRegistry( eurekaServerConfig, eurekaClient.getEurekaClientConfig(), serverCodecs, eurekaClient ); awsBinder = new AwsBinderDelegate(eurekaServerConfig, eurekaClient.getEurekaClientConfig(), registry, applicationInfoManager); awsBinder.start(); } else { registry = new PeerAwareInstanceRegistryImpl( eurekaServerConfig, eurekaClient.getEurekaClientConfig(), serverCodecs, eurekaClient ); } PeerEurekaNodes peerEurekaNodes = getPeerEurekaNodes( registry, eurekaServerConfig, eurekaClient.getEurekaClientConfig(), serverCodecs, applicationInfoManager ); serverContext = new DefaultEurekaServerContext( eurekaServerConfig, serverCodecs, registry, peerEurekaNodes, applicationInfoManager ); EurekaServerContextHolder.initialize(serverContext); serverContext.initialize(); logger.info("Initialized server context"); // Copy registry from neighboring eureka node int registryCount = registry.syncUp(); registry.openForTraffic(applicationInfoManager, registryCount); // Register all monitoring statistics. EurekaMonitors.registerAllStats(); }
PeerAwareInstanceRegistryImpl类中有一个register()方法，该方法提供了服务注册，并且将服务注册后的信息同步到其他的Eureka Server服务，其中的super.register(info, leaseDuration, isReplication);，进入其父类AbstractInstanceRegistry，
注册列表的信息被保存在一个map中
public void register(final InstanceInfo info, final boolean isReplication) { int leaseDuration = Lease.DEFAULT_DURATION_IN_SECS; if (info.getLeaseInfo() != null && info.getLeaseInfo().getDurationInSecs() > 0) { leaseDuration = info.getLeaseInfo().getDurationInSecs(); } super.register(info, leaseDuration, isReplication); replicateToPeers(Action.Register, info.getAppName(), info.getId(), info, null, isReplication); }
最终的注册方法
/** * Registers a new instance with a given duration. * * @see com.netflix.eureka.lease.LeaseManager#register(java.lang.Object, int, boolean) */ public void register(InstanceInfo registrant, int leaseDuration, boolean isReplication) { try { read.lock(); Map<String, Lease<InstanceInfo>> gMap = registry.get(registrant.getAppName()); REGISTER.increment(isReplication); if (gMap == null) { final ConcurrentHashMap<String, Lease<InstanceInfo>> gNewMap = new ConcurrentHashMap<String, Lease<InstanceInfo>>(); gMap = registry.putIfAbsent(registrant.getAppName(), gNewMap); if (gMap == null) { gMap = gNewMap; } } Lease<InstanceInfo> existingLease = gMap.get(registrant.getId()); // Retain the last dirty timestamp without overwriting it, if there is already a lease if (existingLease != null && (existingLease.getHolder() != null)) { Long existingLastDirtyTimestamp = existingLease.getHolder().getLastDirtyTimestamp(); Long registrationLastDirtyTimestamp = registrant.getLastDirtyTimestamp(); logger.debug("Existing lease found (existing={}, provided={}", existingLastDirtyTimestamp, registrationLastDirtyTimestamp); // this is a > instead of a >= because if the timestamps are equal, we still take the remote transmitted // InstanceInfo instead of the server local copy. if (existingLastDirtyTimestamp > registrationLastDirtyTimestamp) { logger.warn("There is an existing lease and the existing lease's dirty timestamp {} is greater" + " than the one that is being registered {}", existingLastDirtyTimestamp, registrationLastDirtyTimestamp); logger.warn("Using the existing instanceInfo instead of the new instanceInfo as the registrant"); registrant = existingLease.getHolder(); } } else { // The lease does not exist and hence it is a new registration synchronized (lock) { if (this.expectedNumberOfClientsSendingRenews > 0) { // Since the client wants to register it, increase the number of clients sending renews this.expectedNumberOfClientsSendingRenews = this.expectedNumberOfClientsSendingRenews + 1; updateRenewsPerMinThreshold(); } } logger.debug("No previous lease information found; it is new registration"); } Lease<InstanceInfo> lease = new Lease<InstanceInfo>(registrant, leaseDuration); if (existingLease != null) { lease.setServiceUpTimestamp(existingLease.getServiceUpTimestamp()); } gMap.put(registrant.getId(), lease); synchronized (recentRegisteredQueue) { recentRegisteredQueue.add(new Pair<Long, String>( System.currentTimeMillis(), registrant.getAppName() + "(" + registrant.getId() + ")")); } // This is where the initial state transfer of overridden status happens if (!InstanceStatus.UNKNOWN.equals(registrant.getOverriddenStatus())) { logger.debug("Found overridden status {} for instance {}. Checking to see if needs to be add to the " + "overrides", registrant.getOverriddenStatus(), registrant.getId()); if (!overriddenInstanceStatusMap.containsKey(registrant.getId())) { logger.info("Not found overridden id {} and hence adding it", registrant.getId()); overriddenInstanceStatusMap.put(registrant.getId(), registrant.getOverriddenStatus()); } } InstanceStatus overriddenStatusFromMap = overriddenInstanceStatusMap.get(registrant.getId()); if (overriddenStatusFromMap != null) { logger.info("Storing overridden status {} from map", overriddenStatusFromMap); registrant.setOverriddenStatus(overriddenStatusFromMap); } // Set the status based on the overridden status rules InstanceStatus overriddenInstanceStatus = getOverriddenInstanceStatus(registrant, existingLease, isReplication); registrant.setStatusWithoutDirty(overriddenInstanceStatus); // If the lease is registered with UP status, set lease service up timestamp if (InstanceStatus.UP.equals(registrant.getStatus())) { lease.serviceUp(); } registrant.setActionType(ActionType.ADDED); recentlyChangedQueue.add(new RecentlyChangedItem(lease)); registrant.setLastUpdatedTimestamp(); invalidateCache(registrant.getAppName(), registrant.getVIPAddress(), registrant.getSecureVipAddress()); logger.info("Registered instance {}/{} with status {} (replication={})", registrant.getAppName(), registrant.getId(), registrant.getStatus(), isReplication); } finally { read.unlock(); } }
其中的replicateToPeers()方法用于将注册列表信息同步到其他Peers节点，该方法会循环遍历所有的peers节点注册，最终执行类是PeerEurekaNodes的register方法，通过执行一个任务向其他节点同步注册信息
/** * Replicates all eureka actions to peer eureka nodes except for replication * traffic to this node. * */ private void replicateToPeers(Action action, String appName, String id, InstanceInfo info /* optional */, InstanceStatus newStatus /* optional */, boolean isReplication) { Stopwatch tracer = action.getTimer().start(); try { if (isReplication) { numberOfReplicationsLastMin.increment(); } // If it is a replication already, do not replicate again as this will create a poison replication if (peerEurekaNodes == Collections.EMPTY_LIST || isReplication) { return; } for (final PeerEurekaNode node : peerEurekaNodes.getPeerEurekaNodes()) { // If the url represents this host, do not replicate to yourself. if (peerEurekaNodes.isThisMyUrl(node.getServiceUrl())) { continue; } replicateInstanceActionsToPeers(action, appName, id, info, newStatus, node); } } finally { tracer.stop(); } }
/** * Replicates all instance changes to peer eureka nodes except for * replication traffic to this node. * */ private void replicateInstanceActionsToPeers(Action action, String appName, String id, InstanceInfo info, InstanceStatus newStatus, PeerEurekaNode node) { try { InstanceInfo infoFromRegistry = null; CurrentRequestVersion.set(Version.V2); switch (action) { case Cancel: node.cancel(appName, id); break; case Heartbeat: InstanceStatus overriddenStatus = overriddenInstanceStatusMap.get(id); infoFromRegistry = getInstanceByAppAndId(appName, id, false); node.heartbeat(appName, id, infoFromRegistry, overriddenStatus, false); break; case Register: node.register(info); break; case StatusUpdate: infoFromRegistry = getInstanceByAppAndId(appName, id, false); node.statusUpdate(appName, id, newStatus, infoFromRegistry); break; case DeleteStatusOverride: infoFromRegistry = getInstanceByAppAndId(appName, id, false); node.deleteStatusOverride(appName, id, infoFromRegistry); break; } } catch (Throwable t) { logger.error("Cannot replicate information to {} for action {}", node.getServiceUrl(), action.name(), t); } }
/** * Sends the registration information of {@link InstanceInfo} receiving by * this node to the peer node represented by this class. * * @param info * the instance information {@link InstanceInfo} of any instance * that is send to this instance. * @throws Exception */ public void register(final InstanceInfo info) throws Exception { long expiryTime = System.currentTimeMillis() + getLeaseRenewalOf(info); batchingDispatcher.process( taskId("register", info), new InstanceReplicationTask(targetHost, Action.Register, info, null, true) { public EurekaHttpResponse<Void> execute() { return replicationClient.register(info); } }, expiryTime ); }
client是通过http注册的，那么肯定有一个API接口。ApplicationResource类的addInstance()方法，就是服务注册的接口
@POST @Consumes({"application/json", "application/xml"}) public Response addInstance(InstanceInfo info, @HeaderParam(PeerEurekaNode.HEADER_REPLICATION) String isReplication) { logger.debug("Registering instance {} (replication={})", info.getId(), isReplication); // validate that the instanceinfo contains all the necessary required fields if (isBlank(info.getId())) { return Response.status(400).entity("Missing instanceId").build(); } else if (isBlank(info.getHostName())) { return Response.status(400).entity("Missing hostname").build(); } else if (isBlank(info.getIPAddr())) { return Response.status(400).entity("Missing ip address").build(); } else if (isBlank(info.getAppName())) { return Response.status(400).entity("Missing appName").build(); } else if (!appName.equals(info.getAppName())) { return Response.status(400).entity("Mismatched appName, expecting " + 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(); } // handle cases where clients may be registering with bad DataCenterInfo with missing data DataCenterInfo dataCenterInfo = info.getDataCenterInfo(); if (dataCenterInfo instanceof UniqueIdentifier) { String dataCenterInfoId = ((UniqueIdentifier) dataCenterInfo).getId(); if (isBlank(dataCenterInfoId)) { boolean experimental = "true".equalsIgnoreCase(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(); } else if (dataCenterInfo instanceof AmazonInfo) { AmazonInfo amazonInfo = (AmazonInfo) dataCenterInfo; String effectiveId = amazonInfo.get(AmazonInfo.MetaDataKey.instanceId); if (effectiveId == null) { amazonInfo.getMetadata().put(AmazonInfo.MetaDataKey.instanceId.getName(), info.getId()); } } else { logger.warn("Registering DataCenterInfo of type {} without an appropriate id", dataCenterInfo.getClass()); } } } registry.register(info, "true".equals(isReplication)); return Response.status(204).build(); // 204 to be backwards compatible }
相同，服务续约的接口就在InstanceResource的renewLease()方法
