Spring中Eureka的服务下线详解
作者：dalianpai
这篇文章主要介绍了Spring中Eureka的服务下线详解,根据默认的策略,如果在一定的时间内,客户端没有向注册中心发送续约请求,那么注册中心就会将该实例从注册中心移除,需要的朋友可以参考下
Eureka 下线
// DiscoveryClient.java
@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());
}
cancelScheduledTasks();
// If APPINFO was registered
if (applicationInfoManager != null
&& clientConfig.shouldRegisterWithEureka()
&& clientConfig.shouldUnregisterOnShutdown()) {
//讲服务实例的状态设置为DOWN
applicationInfoManager.setInstanceStatus(InstanceStatus.DOWN);
//取消注册
unregister();
}
//关闭网络通信组件
if (eurekaTransport != null) {
eurekaTransport.shutdown();
}
//关闭监听器
heartbeatStalenessMonitor.shutdown();
registryStalenessMonitor.shutdown();
Monitors.unregisterObject(this);
logger.info("Completed shut down of DiscoveryClient");
}
}- 调用 ApplicationInfoManager#setInstanceStatus(...) 方法，设置应用实例为关闭( DOWN )。
- 调用 #unregister() 方法，实现代码如下：
// DiscoveryClient.java
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 + appPathIdentifier + " - deregister status: " + httpResponse.getStatusCode());
} catch (Exception e) {
logger.error(PREFIX + appPathIdentifier + " - de-registration failed" + e.getMessage(), e);
}
}
}
// AbstractJerseyEurekaHttpClient.java
@Override
public EurekaHttpResponse<Void> cancel(String appName, String id) {
String urlPath = "apps/" + appName + '/' + id;
ClientResponse response = null;
try {
Builder resourceBuilder = jerseyClient.resource(serviceUrl).path(urlPath).getRequestBuilder();
addExtraHeaders(resourceBuilder);
response = resourceBuilder.delete(ClientResponse.class);
return anEurekaHttpResponse(response.getStatus()).headers(headersOf(response)).build();
} finally {
if (logger.isDebugEnabled()) {
logger.debug("Jersey HTTP DELETE {}/{}; statusCode={}", serviceUrl, urlPath, response == null ? "N/A" : response.getStatus());
}
if (response != null) {
response.close();
}
}
}- 调用 AbstractJerseyEurekaHttpClient#cancel(...) 方法，DELETE 请求 Eureka-Server 的 apps/${APP_NAME}/${INSTANCE_INFO_ID} 接口，实现应用实例信息的下线。
com.netflix.eureka.resources.InstanceResource，处理单个应用实例信息的请求操作的 Resource ( Controller )。
下线应用实例信息的请求，映射 InstanceResource#cancelLease() 方法，实现代码如下：
@DELETE
public Response cancelLease(
@HeaderParam(PeerEurekaNode.HEADER_REPLICATION) String isReplication) {
// 下线
boolean isSuccess = registry.cancel(app.getName(), id, "true".equals(isReplication));
if (isSuccess) { // 下线成功
logger.debug("Found (Cancel): " + app.getName() + " - " + id);
return Response.ok().build();
} else { // 下线成功
logger.info("Not Found (Cancel): " + app.getName() + " - " + id);
return Response.status(Status.NOT_FOUND).build();
}
}调用 AbstractInstanceRegistry#cancel(...) 方法，下线应用实例信息，实现代码如下：
@Override
public boolean cancel(String appName, String id, boolean isReplication) {
return internalCancel(appName, id, isReplication);
}
/**
* {@link #cancel(String, String, boolean)} method is overridden by {@link PeerAwareInstanceRegistry}, so each
* cancel request is replicated to the peers. This is however not desired for expires which would be counted
* in the remote peers as valid cancellations, so self preservation mode would not kick-in.
*/
protected boolean internalCancel(String appName, String id, boolean isReplication) {
read.lock();
try {
CANCEL.increment(isReplication);
Map<String, Lease<InstanceInfo>> gMap = registry.get(appName);
Lease<InstanceInfo> leaseToCancel = null;
if (gMap != null) {
leaseToCancel = gMap.remove(id);
}
//将服务实例加入最近下线的queue中
recentCanceledQueue.add(new Pair<Long, String>(System.currentTimeMillis(), appName + "(" + id + ")"));
InstanceStatus instanceStatus = overriddenInstanceStatusMap.remove(id);
if (instanceStatus != null) {
logger.debug("Removed instance id {} from the overridden map which has value {}", id, instanceStatus.name());
}
if (leaseToCancel == null) {
CANCEL_NOT_FOUND.increment(isReplication);
logger.warn("DS: Registry: cancel failed because Lease is not registered for: {}/{}", appName, id);
return false;
} else {
//调用cancel，保存一个时间戳
leaseToCancel.cancel();
InstanceInfo instanceInfo = leaseToCancel.getHolder();
String vip = null;
String svip = null;
if (instanceInfo != null) {
instanceInfo.setActionType(ActionType.DELETED);
//丢到最近改变的队列中
recentlyChangedQueue.add(new RecentlyChangedItem(leaseToCancel));
//设置了最近一次变更的时间戳
instanceInfo.setLastUpdatedTimestamp();
vip = instanceInfo.getVIPAddress();
svip = instanceInfo.getSecureVipAddress();
//服务的注册，下线，过期，都会代表这个服务实例变化了，都会将自己放入最近改变的队列中
//这个最近改变的队列，只会保留最近3分钟的实例
//所以说eureka client拉取增量注册表的时候，其实就是拉取最近3分钟有变化的服务实例。
}
invalidateCache(appName, vip, svip);
logger.info("Cancelled instance {}/{} (replication={})", appName, id, isReplication);
}
} finally {
read.unlock();
}
synchronized (lock) {
if (this.expectedNumberOfClientsSendingRenews > 0) {
// Since the client wants to cancel it, reduce the number of clients to send renews.
//修改期望值
this.expectedNumberOfClientsSendingRenews = this.expectedNumberOfClientsSendingRenews - 1;
updateRenewsPerMinThreshold();
}
}
return true;
}到此这篇关于Spring中Eureka的服务下线详解的文章就介绍到这了,更多相关Eureka的服务下线内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家！