Spring Cloud Eureka (八) 服务下线

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概述

服务下线,通常在服务关闭的时候触发,在注册中心剔除下线的服务

服务下线(cancel)

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/**
* 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 ...");
// 移除监听
if (statusChangeListener != null && applicationInfoManager != null) {
applicationInfoManager.unregisterStatusChangeListener(statusChangeListener.getId());
}
// 取消定时任务(心跳等)
cancelScheduledTasks();

// If APPINFO was registered
// 服务下线
if (applicationInfoManager != null && clientConfig.shouldRegisterWithEureka()) {
applicationInfoManager.setInstanceStatus(InstanceStatus.DOWN);
unregister();
}

if (eurekaTransport != null) {
eurekaTransport.shutdown();
}
//停止监控
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 + appPathIdentifier + " - deregister status: " + httpResponse.getStatusCode());
} catch (Exception e) {
logger.error(PREFIX + appPathIdentifier + " - de-registration failed" + e.getMessage(), e);
}
}
}

eureka-client-cancel

服务下线(Server端)

InstanceResource.java

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/**
* Handles cancellation of leases for this particular instance.
*
* @param isReplication
* a header parameter containing information whether this is
* replicated from other nodes.
* @return response indicating whether the operation was a success or
* failure.
*/
@DELETE
public Response cancelLease(
@HeaderParam(PeerEurekaNode.HEADER_REPLICATION) String isReplication) {
boolean isSuccess = registry.cancel(app.getName(), id,
"true".equals(isReplication));

if (isSuccess) {
logger.debug("Found (Cancel): " + app.getName() + " - " + id);
return Response.ok().build();
} else {
logger.info("Not Found (Cancel): " + app.getName() + " - " + id);
return Response.status(Status.NOT_FOUND).build();
}
}

PeerAwareInstanceRegistryImpl.java

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@Override
public boolean cancel(final String appName, final String id,
final boolean isReplication) {
if (super.cancel(appName, id, isReplication)) {
replicateToPeers(Action.Cancel, appName, id, null, null, isReplication);
synchronized (lock) {
if (this.expectedNumberOfRenewsPerMin > 0) {
// Since the client wants to cancel it, reduce the threshold (1 for 30 seconds, 2 for a minute)
this.expectedNumberOfRenewsPerMin = this.expectedNumberOfRenewsPerMin - 2;
this.numberOfRenewsPerMinThreshold =
(int) (this.expectedNumberOfRenewsPerMin * serverConfig.getRenewalPercentThreshold());
}
}
return true;
}
return false;
}

AbstractInstanceRegistry.java

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/**
* Cancels the registration of an instance.
*
* <p>
* This is normally invoked by a client when it shuts down informing the
* server to remove the instance from traffic.
* </p>
*
* @param appName the application name of the application.
* @param id the unique identifier of the instance.
* @param isReplication true if this is a replication event from other nodes, false
* otherwise.
* @return true if the instance was removed from the {@link AbstractInstanceRegistry} successfully, false otherwise.
*/
@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) {
try {
read.lock();
CANCEL.increment(isReplication);
Map<String, Lease<InstanceInfo>> gMap = registry.get(appName);
Lease<InstanceInfo> leaseToCancel = null;
if (gMap != null) {
leaseToCancel = gMap.remove(id);
}
synchronized (recentCanceledQueue) {
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 {
leaseToCancel.cancel();
InstanceInfo instanceInfo = leaseToCancel.getHolder();
String vip = null;
String svip = null;
if (instanceInfo != null) {
instanceInfo.setActionType(ActionType.DELETED);
recentlyChangedQueue.add(new RecentlyChangedItem(leaseToCancel));
instanceInfo.setLastUpdatedTimestamp();
vip = instanceInfo.getVIPAddress();
svip = instanceInfo.getSecureVipAddress();
}
invalidateCache(appName, vip, svip);
logger.info("Cancelled instance {}/{} (replication={})", appName, id, isReplication);
return true;
}
} finally {
read.unlock();
}
}

eureka-server-cancel

您的支持就是我的动力