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本文主要研究一下eureka client的shutdown
EurekaRegistration
spring-cloud-netflix-eureka-client-2.0.0.RC1-sources.jar!/org/springframework/cloud/netflix/eureka/EurekaClientAutoConfiguration.java
@Bean
@ConditionalOnBean(AutoServiceRegistrationProperties.class)
@ConditionalOnProperty(value = "spring.cloud.service-registry.auto-registration.enabled", matchIfMissing = true)
public EurekaRegistration eurekaRegistration(EurekaClient eurekaClient, CloudEurekaInstanceConfig instanceConfig, ApplicationInfoManager applicationInfoManager, ObjectProvider<HealthCheckHandler> healthCheckHandler) {
return EurekaRegistration.builder(instanceConfig)
.with(applicationInfoManager)
.with(eurekaClient)
.with(healthCheckHandler)
.build();
}
@Bean
@ConditionalOnBean(AutoServiceRegistrationProperties.class)
@ConditionalOnProperty(value = "spring.cloud.service-registry.auto-registration.enabled", matchIfMissing = true)
public EurekaAutoServiceRegistration eurekaAutoServiceRegistration(ApplicationContext context, EurekaServiceRegistry registry, EurekaRegistration registration) {
return new EurekaAutoServiceRegistration(context, registry, registration);
}
//...
@Bean(destroyMethod = "shutdown")
@ConditionalOnMissingBean(value = EurekaClient.class, search = SearchStrategy.CURRENT)
public EurekaClient eurekaClient(ApplicationInfoManager manager, EurekaClientConfig config) {
return new CloudEurekaClient(manager, config, this.optionalArgs,
this.context);
}
这里自动创建EurekaRegistration，以及EurekaAutoServiceRegistration，EurekaClient
EurekaClient
eureka-client-1.8.8-sources.jar!/com/netflix/discovery/EurekaClient.java
可以看到EurekaClient标注了@Bean(destroyMethod = "shutdown")，也就是在bean销毁的时候，会触发eurekaClient.shutdown方法
EurekaRegistration
spring-cloud-netflix-eureka-client-2.0.0.RC1-sources.jar!/org/springframework/cloud/netflix/eureka/serviceregistry/EurekaRegistration.java
public class EurekaRegistration implements Registration, Closeable {
//......
@Override
public void close() throws IOException {
this.eurekaClient.shutdown();
}
}
这里实现了Closeable接口的close方法，在spring容器关闭的时候触发，这里调用了eurekaClient.shutdown()
EurekaAutoServiceRegistration
spring-cloud-netflix-eureka-client-2.0.0.RC1-sources.jar!/org/springframework/cloud/netflix/eureka/serviceregistry/EurekaAutoServiceRegistration.java
@Override
public void start() {
// only set the port if the nonSecurePort or securePort is 0 and this.port != 0
if (this.port.get() != 0) {
if (this.registration.getNonSecurePort() == 0) {
this.registration.setNonSecurePort(this.port.get());
}
if (this.registration.getSecurePort() == 0 && this.registration.isSecure()) {
this.registration.setSecurePort(this.port.get());
}
}
// only initialize if nonSecurePort is greater than 0 and it isn't already running
// because of containerPortInitializer below
if (!this.running.get() && this.registration.getNonSecurePort() > 0) {
this.serviceRegistry.register(this.registration);
this.context.publishEvent(
new InstanceRegisteredEvent<>(this, this.registration.getInstanceConfig()));
this.running.set(true);
}
}
@Override
public void stop() {
this.serviceRegistry.deregister(this.registration);
this.running.set(false);
}
这里的start，stop实现的是Lifecycle的方法，也就在spring容器关闭的时候，会触发stop方法，然后调用的是serviceRegistry.deregister(this.registration)
RefreshScopeRefreshedEvent
spring-cloud-netflix-eureka-client-2.0.0.RC1-sources.jar!/org/springframework/cloud/netflix/eureka/EurekaDiscoveryClientConfiguration.java
@Configuration
@ConditionalOnClass(RefreshScopeRefreshedEvent.class)
protected static class EurekaClientConfigurationRefresher {
@Autowired(required = false)
private EurekaClient eurekaClient;
@Autowired(required = false)
private EurekaAutoServiceRegistration autoRegistration;
@EventListener(RefreshScopeRefreshedEvent.class)
public void onApplicationEvent(RefreshScopeRefreshedEvent event) {
//This will force the creation of the EurkaClient bean if not already created
//to make sure the client will be reregistered after a refresh event
if(eurekaClient != null) {
eurekaClient.getApplications();
}
if (autoRegistration != null) {
// register in case meta data changed
this.autoRegistration.stop();
this.autoRegistration.start();
}
}
}
接收到RefreshScopeRefreshedEvent的时候，会先stop，再start
DiscoveryClient.shutdown
eureka-client-1.8.8-sources.jar!/com/netflix/discovery/DiscoveryClient.java
public synchronized void shutdown() {
if (isShutdown.compareAndSet(false, true)) {
logger.info("Shutting down DiscoveryClient ...");
if (statusChangeListener != null && applicationInfoManager != null) {
applicationInfoManager.unregisterStatusChangeListener(statusChangeListener.getId());
}
cancelScheduledTasks();
// If APPINFO was registered
if (applicationInfoManager != null
&& clientConfig.shouldRegisterWithEureka()
&& clientConfig.shouldUnregisterOnShutdown()) {
applicationInfoManager.setInstanceStatus(InstanceStatus.DOWN);
unregister();
}
if (eurekaTransport != null) {
eurekaTransport.shutdown();
}
heartbeatStalenessMonitor.shutdown();
registryStalenessMonitor.shutdown();
logger.info("Completed shut down of DiscoveryClient");
}
}
/**
* unregister w/ the eureka service.
*/
void unregister() {
// It can be null if shouldRegisterWithEureka == false
if(eurekaTransport != null && eurekaTransport.registrationClient != null) {
try {
logger.info("Unregistering ...");
EurekaHttpResponse<Void> httpResponse = eurekaTransport.registrationClient.cancel(instanceInfo.getAppName(), instanceInfo.getId());
logger.info(PREFIX + "{} - deregister status: {}", appPathIdentifier, httpResponse.getStatusCode());
} catch (Exception e) {
logger.error(PREFIX + "{} - de-registration failed{}", appPathIdentifier, e.getMessage(), e);
}
}
}
这里可以看到，先设置状态为DOWN，然后调用cancel方法
RestTemplateEurekaHttpClient
spring-cloud-netflix-eureka-client-2.0.0.RC1-sources.jar!/org/springframework/cloud/netflix/eureka/http/RestTemplateEurekaHttpClient.java
public EurekaHttpResponse<Void> cancel(String appName, String id) {
String urlPath = serviceUrl + "apps/" + appName + '/' + id;
ResponseEntity<Void> response = restTemplate.exchange(urlPath, HttpMethod.DELETE,
null, Void.class);
return anEurekaHttpResponse(response.getStatusCodeValue())
.headers(headersOf(response)).build();
}
@Override
public EurekaHttpResponse<Void> register(InstanceInfo info) {
String urlPath = serviceUrl + "apps/" + info.getAppName();
HttpHeaders headers = new HttpHeaders();
headers.add(HttpHeaders.ACCEPT_ENCODING, "gzip");
headers.add(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE);
ResponseEntity<Void> response = restTemplate.exchange(urlPath, HttpMethod.POST,
new HttpEntity<>(info, headers), Void.class);
return anEurekaHttpResponse(response.getStatusCodeValue())
.headers(headersOf(response)).build();
}
cancel方法就是调用REST的DELETE操作，注销掉服务
小结
springcloud封装的eureka自动注册，关闭的时候主要分两大类：
- 依赖生命周期在销毁时调用shutdown、close
EurekaRegistration是在close的时候，会触发eurekaClient.shutdown方法
EurekaAutoServiceRegistration则在stop的时候，标记状态为DOWN，发布StatusChangeEvent事件
EurekaClient则标注了@Bean(destroyMethod = "shutdown")，也就是在bean销毁的时候，会触发eurekaClient.shutdown方法
- 期间状态变更发布StatusChangeEvent事件
com/netflix/discovery/DiscoveryClient.java有个StatusChangeListener，状态变更在需要的时候，会触发InstanceInfoReplicator的onDemandUpdate方法，该方法会调用discoveryClient.register()去与eureka server更新自身实例的状态。
这里相当于变相通过register接口更改status状态。
这里要区分一下cancel与StatusChangeEvent的区别，cancel是从eureka server删掉这条instanceInfo，而StatusChangeEvent变更状态，不会删除这条instanceInfo，只是更新status状态(status状态一共有UP,DOWN,STARTING,OUT_OF_SERVICE,UNKNOWN几类)。
