SpringCloud源码分析 (Eureka-Client-服务下架与服务下线) (四)

put请求, 有请求体的为服务下线, 称为服务的平滑下线。请求体为status和value
delete请求没有请求体为服务下架。

1.服务下架

1.1 shutdown

    /**
     * Shuts down Eureka Client. Also sends a deregistration request to the
     * eureka server.
     */
    @PreDestroy
    @Override
    public synchronized void shutdown() {
        if (isShutdown.compareAndSet(false, true)) {
            logger.info("Shutting down DiscoveryClient ...");

            if (statusChangeListener != null && applicationInfoManager != null) {
                applicationInfoManager.unregisterStatusChangeListener(statusChangeListener.getId());
            }
            
			// 取消定时任务
            cancelScheduledTasks();

            // 未注册情况
            if (applicationInfoManager != null
                    && clientConfig.shouldRegisterWithEureka()
                    && clientConfig.shouldUnregisterOnShutdown()) {
                applicationInfoManager.setInstanceStatus(InstanceStatus.DOWN);
                // 未注册情况
                unregister();
            }

            if (eurekaTransport != null) {
                eurekaTransport.shutdown();
            }

            heartbeatStalenessMonitor.shutdown();
            registryStalenessMonitor.shutdown();

            logger.info("Completed shut down of DiscoveryClient");
        }
    }
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首先把定时器去掉了, 然后 cancelScheduledTasks, 然后

1.2 cancelScheduledTasks

取消定时任务

    private void cancelScheduledTasks() {
    	// 定时更新Client信息给Server
        if (instanceInfoReplicator != null) {
            instanceInfoReplicator.stop();
        }
        // 定时续约, 更新心跳
        if (heartbeatExecutor != null) {
            heartbeatExecutor.shutdownNow();
        }
        // 定时更新客户端注册表
        if (cacheRefreshExecutor != null) {
            cacheRefreshExecutor.shutdownNow();
        }
        if (scheduler != null) {
            scheduler.shutdownNow();
        }
    }
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这里有定时更新Client信息给Server, 定时续约, 定时更新客户端注册表, 定时器, 和两个任务都取消了

1.3 unregister

未注册的情况

    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);
            }
        }
    }
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1.4 发送delete请求

cancal() -> delete()

2.服务下线

服务下线是调用的是spring-cloud-commons包中的ServiceRegistryAutoConfiguration

Status 为 UP或OUT_OF_SERVICE

2.1 入口

spring.factories:

2.2 ServiceRegistryAutoConfiguration

2.3 ServiceRegistryEndPoint

有设置状态和得到状态的到注册中心。

	@Override
	public void setStatus(EurekaRegistration registration, String status) {
		InstanceInfo info = registration.getApplicationInfoManager().getInfo();

		// TODO: howto deal with delete properly?
		if ("CANCEL_OVERRIDE".equalsIgnoreCase(status)) {
			registration.getEurekaClient().cancelOverrideStatus(info);
			return;
		}

		// TODO: howto deal with status types across discovery systems?
		InstanceInfo.InstanceStatus newStatus = InstanceInfo.InstanceStatus
				.toEnum(status);
		registration.getEurekaClient().setStatus(newStatus, info);
	}
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2.4 方向一

CANCEL_OVERRIDE

Client会通过jersey向server提交delete请求, 用于在Server将InstanceInfo的overrideStatus
修改为UNKNOWN, 此时Client发送的心跳server不接受, 返回为404。

2.5 方向二

setStatus() -> statusUpdate() -> put()

携带Value 和 lastDirtyTimestamp

服务下架的话, 如果没有服务发现的功能的话会500