HAOGRE's blog

eureka-server-source-code

基本概念

  • Register:服务注册
    当Eureka客户端向Eureka Server注册时,它提供自身的元数据,比如IP地址、端口,运行状况指示符URL,主页等。

  • Renew:服务续约
    Eureka客户会每隔30秒发送一次心跳来续约。 通过续约来告知Eureka Server该Eureka客户仍然存在,没有出现问题。 正常情况下,如果Eureka Server在90秒没有收到Eureka客户的续约,它会将实例从其注册表中删除。 建议不要更改续约间隔.

  • Fetch Registries:
    获取注册列表信息 Eureka客户端从服务器获取注册表信息,并将其缓存在本地。客户端会使用该信息查找其他服务,从而进行远程调用。该注册列表信息定期(每30秒钟)更新一次。每次返回注册列表信息可能与Eureka客户端的缓存信息不同, Eureka客户端自动处理。如果由于某种原因导致注册列表信息不能及时匹配,Eureka客户端则会重新获取整个注册表信息。 Eureka服务器缓存注册列表信息,整个注册表以及每个应用程序的信息进行了压缩,压缩内容和没有压缩的内容完全相同。Eureka客户端和Eureka 服务器可以使用JSON / XML格式进行通讯。在默认的情况下Eureka客户端使用压缩JSON格式来获取注册列表的信息。

  • Cancel:服务下线
    Eureka客户端在程序关闭时向Eureka服务器发送取消请求。 发送请求后,该客户端实例信息将从服务器的实例注册表中删除。该下线请求不会自动完成,它需要调用以下内容: DiscoveryManager.getInstance().shutdownComponent();

  • Eviction 服务剔除
    在默认的情况下,当Eureka客户端连续90秒没有向Eureka服务器发送服务续约,即心跳,Eureka服务器会将该服务实例从服务注册列表删除,即服务剔除。

版本eureka-core:1.9.13

服务注册基本模块

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/*
* Copyright 2012 Netflix, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

package com.netflix.eureka.registry;

import javax.annotation.Nullable;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Random;
import java.util.Set;
import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

import com.google.common.cache.CacheBuilder;
import com.netflix.appinfo.InstanceInfo;
import com.netflix.appinfo.InstanceInfo.ActionType;
import com.netflix.appinfo.InstanceInfo.InstanceStatus;
import com.netflix.appinfo.LeaseInfo;
import com.netflix.discovery.EurekaClientConfig;
import com.netflix.discovery.shared.Application;
import com.netflix.discovery.shared.Applications;
import com.netflix.discovery.shared.Pair;
import com.netflix.eureka.EurekaServerConfig;
import com.netflix.eureka.lease.Lease;
import com.netflix.eureka.registry.rule.InstanceStatusOverrideRule;
import com.netflix.eureka.resources.ServerCodecs;
import com.netflix.eureka.util.MeasuredRate;
import com.netflix.servo.annotations.DataSourceType;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import static com.netflix.eureka.util.EurekaMonitors.*;

/**
* Handles all registry requests from eureka clients.
*
* <p>
* Primary operations that are performed are the
* <em>Registers</em>, <em>Renewals</em>, <em>Cancels</em>, <em>Expirations</em>, and <em>Status Changes</em>. The
* registry also stores only the delta operations
* </p>
*
* @author Karthik Ranganathan
*
*/
public abstract class AbstractInstanceRegistry implements InstanceRegistry {
private static final Logger logger = LoggerFactory.getLogger(AbstractInstanceRegistry.class);

private static final String[] EMPTY_STR_ARRAY = new String[0];
private final ConcurrentHashMap<String, Map<String, Lease<InstanceInfo>>> registry
= new ConcurrentHashMap<String, Map<String, Lease<InstanceInfo>>>();
protected Map<String, RemoteRegionRegistry> regionNameVSRemoteRegistry = new HashMap<String, RemoteRegionRegistry>();
protected final ConcurrentMap<String, InstanceStatus> overriddenInstanceStatusMap = CacheBuilder
.newBuilder().initialCapacity(500)
.expireAfterAccess(1, TimeUnit.HOURS)
.<String, InstanceStatus>build().asMap();

// CircularQueues here for debugging/statistics purposes only
private final CircularQueue<Pair<Long, String>> recentRegisteredQueue;
private final CircularQueue<Pair<Long, String>> recentCanceledQueue;
private ConcurrentLinkedQueue<RecentlyChangedItem> recentlyChangedQueue = new ConcurrentLinkedQueue<RecentlyChangedItem>();

private final ReentrantReadWriteLock readWriteLock = new ReentrantReadWriteLock();
private final Lock read = readWriteLock.readLock();
private final Lock write = readWriteLock.writeLock();
protected final Object lock = new Object();

private Timer deltaRetentionTimer = new Timer("Eureka-DeltaRetentionTimer", true);
private Timer evictionTimer = new Timer("Eureka-EvictionTimer", true);
private final MeasuredRate renewsLastMin;

private final AtomicReference<EvictionTask> evictionTaskRef = new AtomicReference<EvictionTask>();

protected String[] allKnownRemoteRegions = EMPTY_STR_ARRAY;
protected volatile int numberOfRenewsPerMinThreshold;
protected volatile int expectedNumberOfClientsSendingRenews;

protected final EurekaServerConfig serverConfig;
protected final EurekaClientConfig clientConfig;
protected final ServerCodecs serverCodecs;
protected volatile ResponseCache responseCache;

/**
* Create a new, empty instance registry.
*/
protected AbstractInstanceRegistry(EurekaServerConfig serverConfig, EurekaClientConfig clientConfig, ServerCodecs serverCodecs) {
this.serverConfig = serverConfig;
this.clientConfig = clientConfig;
this.serverCodecs = serverCodecs;
this.recentCanceledQueue = new CircularQueue<Pair<Long, String>>(1000);
this.recentRegisteredQueue = new CircularQueue<Pair<Long, String>>(1000);

this.renewsLastMin = new MeasuredRate(1000 * 60 * 1);

this.deltaRetentionTimer.schedule(getDeltaRetentionTask(),
serverConfig.getDeltaRetentionTimerIntervalInMs(),
serverConfig.getDeltaRetentionTimerIntervalInMs());
}

@Override
public synchronized void initializedResponseCache() {
if (responseCache == null) {
responseCache = new ResponseCacheImpl(serverConfig, serverCodecs, this);
}
}

protected void initRemoteRegionRegistry() throws MalformedURLException {
Map<String, String> remoteRegionUrlsWithName = serverConfig.getRemoteRegionUrlsWithName();
if (!remoteRegionUrlsWithName.isEmpty()) {
allKnownRemoteRegions = new String[remoteRegionUrlsWithName.size()];
int remoteRegionArrayIndex = 0;
for (Map.Entry<String, String> remoteRegionUrlWithName : remoteRegionUrlsWithName.entrySet()) {
RemoteRegionRegistry remoteRegionRegistry = new RemoteRegionRegistry(
serverConfig,
clientConfig,
serverCodecs,
remoteRegionUrlWithName.getKey(),
new URL(remoteRegionUrlWithName.getValue()));
regionNameVSRemoteRegistry.put(remoteRegionUrlWithName.getKey(), remoteRegionRegistry);
allKnownRemoteRegions[remoteRegionArrayIndex++] = remoteRegionUrlWithName.getKey();
}
}
logger.info("Finished initializing remote region registries. All known remote regions: {}",
(Object) allKnownRemoteRegions);
}

@Override
public ResponseCache getResponseCache() {
return responseCache;
}

public long getLocalRegistrySize() {
long total = 0;
for (Map<String, Lease<InstanceInfo>> entry : registry.values()) {
total += entry.size();
}
return total;
}

/**
* Completely clear the registry.
*/
@Override
public void clearRegistry() {
overriddenInstanceStatusMap.clear();
recentCanceledQueue.clear();
recentRegisteredQueue.clear();
recentlyChangedQueue.clear();
registry.clear();
}

// for server info use
@Override
public Map<String, InstanceStatus> overriddenInstanceStatusesSnapshot() {
return new HashMap<>(overriddenInstanceStatusMap);
}

// step 1. 服务注册
/**
* 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();
}
}

/**
* 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);
}

//step 4. 服务下线
/**
* {@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();
}
}

// step 2. 接受服务心跳
/**
* Marks the given instance of the given app name as renewed, and also marks whether it originated from
* replication.
*
* @see com.netflix.eureka.lease.LeaseManager#renew(java.lang.String, java.lang.String, boolean)
*/
public boolean renew(String appName, String id, boolean isReplication) {
RENEW.increment(isReplication);
Map<String, Lease<InstanceInfo>> gMap = registry.get(appName);
Lease<InstanceInfo> leaseToRenew = null;
if (gMap != null) {
leaseToRenew = gMap.get(id);
}
if (leaseToRenew == null) {
RENEW_NOT_FOUND.increment(isReplication);
logger.warn("DS: Registry: lease doesn't exist, registering resource: {} - {}", appName, id);
return false;
} else {
InstanceInfo instanceInfo = leaseToRenew.getHolder();
if (instanceInfo != null) {
// touchASGCache(instanceInfo.getASGName());
InstanceStatus overriddenInstanceStatus = this.getOverriddenInstanceStatus(
instanceInfo, leaseToRenew, isReplication);
if (overriddenInstanceStatus == InstanceStatus.UNKNOWN) {
logger.info("Instance status UNKNOWN possibly due to deleted override for instance {}"
+ "; re-register required", instanceInfo.getId());
RENEW_NOT_FOUND.increment(isReplication);
return false;
}
if (!instanceInfo.getStatus().equals(overriddenInstanceStatus)) {
logger.info(
"The instance status {} is different from overridden instance status {} for instance {}. "
+ "Hence setting the status to overridden status", instanceInfo.getStatus().name(),
instanceInfo.getOverriddenStatus().name(),
instanceInfo.getId());
instanceInfo.setStatusWithoutDirty(overriddenInstanceStatus);

}
}
renewsLastMin.increment();
leaseToRenew.renew();
return true;
}
}

/**
* @deprecated this is expensive, try not to use. See if you can use
* {@link #storeOverriddenStatusIfRequired(String, String, InstanceStatus)} instead.
*
* Stores overridden status if it is not already there. This happens during
* a reconciliation process during renewal requests.
*
* @param id the unique identifier of the instance.
* @param overriddenStatus Overridden status if any.
*/
@Deprecated
@Override
public void storeOverriddenStatusIfRequired(String id, InstanceStatus overriddenStatus) {
InstanceStatus instanceStatus = overriddenInstanceStatusMap.get(id);
if ((instanceStatus == null)
|| (!overriddenStatus.equals(instanceStatus))) {
// We might not have the overridden status if the server got restarted -this will help us maintain
// the overridden state from the replica
logger.info(
"Adding overridden status for instance id {} and the value is {}",
id, overriddenStatus.name());
overriddenInstanceStatusMap.put(id, overriddenStatus);
List<InstanceInfo> instanceInfo = this.getInstancesById(id, false);
if ((instanceInfo != null) && (!instanceInfo.isEmpty())) {
instanceInfo.iterator().next().setOverriddenStatus(overriddenStatus);
logger.info(
"Setting the overridden status for instance id {} and the value is {} ",
id, overriddenStatus.name());

}
}
}

/**
* Stores overridden status if it is not already there. This happens during
* a reconciliation process during renewal requests.
*
* @param appName the application name of the instance.
* @param id the unique identifier of the instance.
* @param overriddenStatus overridden status if any.
*/
@Override
public void storeOverriddenStatusIfRequired(String appName, String id, InstanceStatus overriddenStatus) {
InstanceStatus instanceStatus = overriddenInstanceStatusMap.get(id);
if ((instanceStatus == null) || (!overriddenStatus.equals(instanceStatus))) {
// We might not have the overridden status if the server got
// restarted -this will help us maintain the overridden state
// from the replica
logger.info("Adding overridden status for instance id {} and the value is {}",
id, overriddenStatus.name());
overriddenInstanceStatusMap.put(id, overriddenStatus);
InstanceInfo instanceInfo = this.getInstanceByAppAndId(appName, id, false);
instanceInfo.setOverriddenStatus(overriddenStatus);
logger.info("Set the overridden status for instance (appname:{}, id:{}} and the value is {} ",
appName, id, overriddenStatus.name());
}
}

/**
* Updates the status of an instance. Normally happens to put an instance
* between {@link InstanceStatus#OUT_OF_SERVICE} and
* {@link InstanceStatus#UP} to put the instance in and out of traffic.
*
* @param appName the application name of the instance.
* @param id the unique identifier of the instance.
* @param newStatus the new {@link InstanceStatus}.
* @param lastDirtyTimestamp last timestamp when this instance information was updated.
* @param isReplication true if this is a replication event from other nodes, false
* otherwise.
* @return true if the status was successfully updated, false otherwise.
*/
@Override
public boolean statusUpdate(String appName, String id,
InstanceStatus newStatus, String lastDirtyTimestamp,
boolean isReplication) {
try {
read.lock();
STATUS_UPDATE.increment(isReplication);
Map<String, Lease<InstanceInfo>> gMap = registry.get(appName);
Lease<InstanceInfo> lease = null;
if (gMap != null) {
lease = gMap.get(id);
}
if (lease == null) {
return false;
} else {
lease.renew();
InstanceInfo info = lease.getHolder();
// Lease is always created with its instance info object.
// This log statement is provided as a safeguard, in case this invariant is violated.
if (info == null) {
logger.error("Found Lease without a holder for instance id {}", id);
}
if ((info != null) && !(info.getStatus().equals(newStatus))) {
// Mark service as UP if needed
if (InstanceStatus.UP.equals(newStatus)) {
lease.serviceUp();
}
// This is NAC overriden status
overriddenInstanceStatusMap.put(id, newStatus);
// Set it for transfer of overridden status to replica on
// replica start up
info.setOverriddenStatus(newStatus);
long replicaDirtyTimestamp = 0;
info.setStatusWithoutDirty(newStatus);
if (lastDirtyTimestamp != null) {
replicaDirtyTimestamp = Long.valueOf(lastDirtyTimestamp);
}
// If the replication's dirty timestamp is more than the existing one, just update
// it to the replica's.
if (replicaDirtyTimestamp > info.getLastDirtyTimestamp()) {
info.setLastDirtyTimestamp(replicaDirtyTimestamp);
}
info.setActionType(ActionType.MODIFIED);
recentlyChangedQueue.add(new RecentlyChangedItem(lease));
info.setLastUpdatedTimestamp();
invalidateCache(appName, info.getVIPAddress(), info.getSecureVipAddress());
}
return true;
}
} finally {
read.unlock();
}
}

/**
* Removes status override for a give instance.
*
* @param appName the application name of the instance.
* @param id the unique identifier of the instance.
* @param newStatus the new {@link InstanceStatus}.
* @param lastDirtyTimestamp last timestamp when this instance information was updated.
* @param isReplication true if this is a replication event from other nodes, false
* otherwise.
* @return true if the status was successfully updated, false otherwise.
*/
@Override
public boolean deleteStatusOverride(String appName, String id,
InstanceStatus newStatus,
String lastDirtyTimestamp,
boolean isReplication) {
try {
read.lock();
STATUS_OVERRIDE_DELETE.increment(isReplication);
Map<String, Lease<InstanceInfo>> gMap = registry.get(appName);
Lease<InstanceInfo> lease = null;
if (gMap != null) {
lease = gMap.get(id);
}
if (lease == null) {
return false;
} else {
lease.renew();
InstanceInfo info = lease.getHolder();

// Lease is always created with its instance info object.
// This log statement is provided as a safeguard, in case this invariant is violated.
if (info == null) {
logger.error("Found Lease without a holder for instance id {}", id);
}

InstanceStatus currentOverride = overriddenInstanceStatusMap.remove(id);
if (currentOverride != null && info != null) {
info.setOverriddenStatus(InstanceStatus.UNKNOWN);
info.setStatusWithoutDirty(newStatus);
long replicaDirtyTimestamp = 0;
if (lastDirtyTimestamp != null) {
replicaDirtyTimestamp = Long.valueOf(lastDirtyTimestamp);
}
// If the replication's dirty timestamp is more than the existing one, just update
// it to the replica's.
if (replicaDirtyTimestamp > info.getLastDirtyTimestamp()) {
info.setLastDirtyTimestamp(replicaDirtyTimestamp);
}
info.setActionType(ActionType.MODIFIED);
recentlyChangedQueue.add(new RecentlyChangedItem(lease));
info.setLastUpdatedTimestamp();
invalidateCache(appName, info.getVIPAddress(), info.getSecureVipAddress());
}
return true;
}
} finally {
read.unlock();
}
}

// step 3. 服务剔除
/**
* Evicts everything in the instance registry that has expired, if expiry is enabled.
*
* @see com.netflix.eureka.lease.LeaseManager#evict()
*/
@Override
public void evict() {
evict(0l);
}

public void evict(long additionalLeaseMs) {
logger.debug("Running the evict task");

if (!isLeaseExpirationEnabled()) {
logger.debug("DS: lease expiration is currently disabled.");
return;
}

// We collect first all expired items, to evict them in random order. For large eviction sets,
// if we do not that, we might wipe out whole apps before self preservation kicks in. By randomizing it,
// the impact should be evenly distributed across all applications.
List<Lease<InstanceInfo>> expiredLeases = new ArrayList<>();
for (Entry<String, Map<String, Lease<InstanceInfo>>> groupEntry : registry.entrySet()) {
Map<String, Lease<InstanceInfo>> leaseMap = groupEntry.getValue();
if (leaseMap != null) {
for (Entry<String, Lease<InstanceInfo>> leaseEntry : leaseMap.entrySet()) {
Lease<InstanceInfo> lease = leaseEntry.getValue();
if (lease.isExpired(additionalLeaseMs) && lease.getHolder() != null) {
expiredLeases.add(lease);
}
}
}
}

// To compensate for GC pauses or drifting local time, we need to use current registry size as a base for
// triggering self-preservation. Without that we would wipe out full registry.
int registrySize = (int) getLocalRegistrySize();
int registrySizeThreshold = (int) (registrySize * serverConfig.getRenewalPercentThreshold());
int evictionLimit = registrySize - registrySizeThreshold;

int toEvict = Math.min(expiredLeases.size(), evictionLimit);
if (toEvict > 0) {
logger.info("Evicting {} items (expired={}, evictionLimit={})", toEvict, expiredLeases.size(), evictionLimit);

Random random = new Random(System.currentTimeMillis());
for (int i = 0; i < toEvict; i++) {
// Pick a random item (Knuth shuffle algorithm)
int next = i + random.nextInt(expiredLeases.size() - i);
Collections.swap(expiredLeases, i, next);
Lease<InstanceInfo> lease = expiredLeases.get(i);

String appName = lease.getHolder().getAppName();
String id = lease.getHolder().getId();
EXPIRED.increment();
logger.warn("DS: Registry: expired lease for {}/{}", appName, id);
internalCancel(appName, id, false);
}
}
}


/**
* Returns the given app that is in this instance only, falling back to other regions transparently only
* if specified in this client configuration.
*
* @param appName the application name of the application
* @return the application
*
* @see com.netflix.discovery.shared.LookupService#getApplication(java.lang.String)
*/
@Override
public Application getApplication(String appName) {
boolean disableTransparentFallback = serverConfig.disableTransparentFallbackToOtherRegion();
return this.getApplication(appName, !disableTransparentFallback);
}

/**
* Get application information.
*
* @param appName The name of the application
* @param includeRemoteRegion true, if we need to include applications from remote regions
* as indicated by the region {@link URL} by this property
* {@link EurekaServerConfig#getRemoteRegionUrls()}, false otherwise
* @return the application
*/
@Override
public Application getApplication(String appName, boolean includeRemoteRegion) {
Application app = null;

Map<String, Lease<InstanceInfo>> leaseMap = registry.get(appName);

if (leaseMap != null && leaseMap.size() > 0) {
for (Entry<String, Lease<InstanceInfo>> entry : leaseMap.entrySet()) {
if (app == null) {
app = new Application(appName);
}
app.addInstance(decorateInstanceInfo(entry.getValue()));
}
} else if (includeRemoteRegion) {
for (RemoteRegionRegistry remoteRegistry : this.regionNameVSRemoteRegistry.values()) {
Application application = remoteRegistry.getApplication(appName);
if (application != null) {
return application;
}
}
}
return app;
}

/**
* Get all applications in this instance registry, falling back to other regions if allowed in the Eureka config.
*
* @return the list of all known applications
*
* @see com.netflix.discovery.shared.LookupService#getApplications()
*/
public Applications getApplications() {
boolean disableTransparentFallback = serverConfig.disableTransparentFallbackToOtherRegion();
if (disableTransparentFallback) {
return getApplicationsFromLocalRegionOnly();
} else {
return getApplicationsFromAllRemoteRegions(); // Behavior of falling back to remote region can be disabled.
}
}

/**
* Returns applications including instances from all remote regions. <br/>
* Same as calling {@link #getApplicationsFromMultipleRegions(String[])} with a <code>null</code> argument.
*/
public Applications getApplicationsFromAllRemoteRegions() {
return getApplicationsFromMultipleRegions(allKnownRemoteRegions);
}

/**
* Returns applications including instances from local region only. <br/>
* Same as calling {@link #getApplicationsFromMultipleRegions(String[])} with an empty array.
*/
@Override
public Applications getApplicationsFromLocalRegionOnly() {
return getApplicationsFromMultipleRegions(EMPTY_STR_ARRAY);
}

/**
* This method will return applications with instances from all passed remote regions as well as the current region.
* Thus, this gives a union view of instances from multiple regions. <br/>
* The application instances for which this union will be done can be restricted to the names returned by
* {@link EurekaServerConfig#getRemoteRegionAppWhitelist(String)} for every region. In case, there is no whitelist
* defined for a region, this method will also look for a global whitelist by passing <code>null</code> to the
* method {@link EurekaServerConfig#getRemoteRegionAppWhitelist(String)} <br/>
* If you are not selectively requesting for a remote region, use {@link #getApplicationsFromAllRemoteRegions()}
* or {@link #getApplicationsFromLocalRegionOnly()}
*
* @param remoteRegions The remote regions for which the instances are to be queried. The instances may be limited
* by a whitelist as explained above. If <code>null</code> or empty no remote regions are
* included.
*
* @return The applications with instances from the passed remote regions as well as local region. The instances
* from remote regions can be only for certain whitelisted apps as explained above.
*/
public Applications getApplicationsFromMultipleRegions(String[] remoteRegions) {

boolean includeRemoteRegion = null != remoteRegions && remoteRegions.length != 0;

logger.debug("Fetching applications registry with remote regions: {}, Regions argument {}",
includeRemoteRegion, remoteRegions);

if (includeRemoteRegion) {
GET_ALL_WITH_REMOTE_REGIONS_CACHE_MISS.increment();
} else {
GET_ALL_CACHE_MISS.increment();
}
Applications apps = new Applications();
apps.setVersion(1L);
for (Entry<String, Map<String, Lease<InstanceInfo>>> entry : registry.entrySet()) {
Application app = null;

if (entry.getValue() != null) {
for (Entry<String, Lease<InstanceInfo>> stringLeaseEntry : entry.getValue().entrySet()) {
Lease<InstanceInfo> lease = stringLeaseEntry.getValue();
if (app == null) {
app = new Application(lease.getHolder().getAppName());
}
app.addInstance(decorateInstanceInfo(lease));
}
}
if (app != null) {
apps.addApplication(app);
}
}
if (includeRemoteRegion) {
for (String remoteRegion : remoteRegions) {
RemoteRegionRegistry remoteRegistry = regionNameVSRemoteRegistry.get(remoteRegion);
if (null != remoteRegistry) {
Applications remoteApps = remoteRegistry.getApplications();
for (Application application : remoteApps.getRegisteredApplications()) {
if (shouldFetchFromRemoteRegistry(application.getName(), remoteRegion)) {
logger.info("Application {} fetched from the remote region {}",
application.getName(), remoteRegion);

Application appInstanceTillNow = apps.getRegisteredApplications(application.getName());
if (appInstanceTillNow == null) {
appInstanceTillNow = new Application(application.getName());
apps.addApplication(appInstanceTillNow);
}
for (InstanceInfo instanceInfo : application.getInstances()) {
appInstanceTillNow.addInstance(instanceInfo);
}
} else {
logger.debug("Application {} not fetched from the remote region {} as there exists a "
+ "whitelist and this app is not in the whitelist.",
application.getName(), remoteRegion);
}
}
} else {
logger.warn("No remote registry available for the remote region {}", remoteRegion);
}
}
}
apps.setAppsHashCode(apps.getReconcileHashCode());
return apps;
}

private boolean shouldFetchFromRemoteRegistry(String appName, String remoteRegion) {
Set<String> whiteList = serverConfig.getRemoteRegionAppWhitelist(remoteRegion);
if (null == whiteList) {
whiteList = serverConfig.getRemoteRegionAppWhitelist(null); // see global whitelist.
}
return null == whiteList || whiteList.contains(appName);
}

/**
* Get the registry information about all {@link Applications}.
*
* @param includeRemoteRegion true, if we need to include applications from remote regions
* as indicated by the region {@link URL} by this property
* {@link EurekaServerConfig#getRemoteRegionUrls()}, false otherwise
* @return applications
*
* @deprecated Use {@link #getApplicationsFromMultipleRegions(String[])} instead. This method has a flawed behavior
* of transparently falling back to a remote region if no instances for an app is available locally. The new
* behavior is to explicitly specify if you need a remote region.
*/
@Deprecated
public Applications getApplications(boolean includeRemoteRegion) {
GET_ALL_CACHE_MISS.increment();
Applications apps = new Applications();
apps.setVersion(1L);
for (Entry<String, Map<String, Lease<InstanceInfo>>> entry : registry.entrySet()) {
Application app = null;

if (entry.getValue() != null) {
for (Entry<String, Lease<InstanceInfo>> stringLeaseEntry : entry.getValue().entrySet()) {

Lease<InstanceInfo> lease = stringLeaseEntry.getValue();

if (app == null) {
app = new Application(lease.getHolder().getAppName());
}

app.addInstance(decorateInstanceInfo(lease));
}
}
if (app != null) {
apps.addApplication(app);
}
}
if (includeRemoteRegion) {
for (RemoteRegionRegistry remoteRegistry : this.regionNameVSRemoteRegistry.values()) {
Applications applications = remoteRegistry.getApplications();
for (Application application : applications
.getRegisteredApplications()) {
Application appInLocalRegistry = apps
.getRegisteredApplications(application.getName());
if (appInLocalRegistry == null) {
apps.addApplication(application);
}
}
}
}
apps.setAppsHashCode(apps.getReconcileHashCode());
return apps;
}

/**
* Get the registry information about the delta changes. The deltas are
* cached for a window specified by
* {@link EurekaServerConfig#getRetentionTimeInMSInDeltaQueue()}. Subsequent
* requests for delta information may return the same information and client
* must make sure this does not adversely affect them.
*
* @return all application deltas.
* @deprecated use {@link #getApplicationDeltasFromMultipleRegions(String[])} instead. This method has a
* flawed behavior of transparently falling back to a remote region if no instances for an app is available locally.
* The new behavior is to explicitly specify if you need a remote region.
*/
@Deprecated
public Applications getApplicationDeltas() {
GET_ALL_CACHE_MISS_DELTA.increment();
Applications apps = new Applications();
apps.setVersion(responseCache.getVersionDelta().get());
Map<String, Application> applicationInstancesMap = new HashMap<String, Application>();
try {
write.lock();
Iterator<RecentlyChangedItem> iter = this.recentlyChangedQueue.iterator();
logger.debug("The number of elements in the delta queue is : {}",
this.recentlyChangedQueue.size());
while (iter.hasNext()) {
Lease<InstanceInfo> lease = iter.next().getLeaseInfo();
InstanceInfo instanceInfo = lease.getHolder();
logger.debug(
"The instance id {} is found with status {} and actiontype {}",
instanceInfo.getId(), instanceInfo.getStatus().name(), instanceInfo.getActionType().name());
Application app = applicationInstancesMap.get(instanceInfo
.getAppName());
if (app == null) {
app = new Application(instanceInfo.getAppName());
applicationInstancesMap.put(instanceInfo.getAppName(), app);
apps.addApplication(app);
}
app.addInstance(new InstanceInfo(decorateInstanceInfo(lease)));
}

boolean disableTransparentFallback = serverConfig.disableTransparentFallbackToOtherRegion();

if (!disableTransparentFallback) {
Applications allAppsInLocalRegion = getApplications(false);

for (RemoteRegionRegistry remoteRegistry : this.regionNameVSRemoteRegistry.values()) {
Applications applications = remoteRegistry.getApplicationDeltas();
for (Application application : applications.getRegisteredApplications()) {
Application appInLocalRegistry =
allAppsInLocalRegion.getRegisteredApplications(application.getName());
if (appInLocalRegistry == null) {
apps.addApplication(application);
}
}
}
}

Applications allApps = getApplications(!disableTransparentFallback);
apps.setAppsHashCode(allApps.getReconcileHashCode());
return apps;
} finally {
write.unlock();
}
}

/**
* Gets the application delta also including instances from the passed remote regions, with the instances from the
* local region. <br/>
*
* The remote regions from where the instances will be chosen can further be restricted if this application does not
* appear in the whitelist specified for the region as returned by
* {@link EurekaServerConfig#getRemoteRegionAppWhitelist(String)} for a region. In case, there is no whitelist
* defined for a region, this method will also look for a global whitelist by passing <code>null</code> to the
* method {@link EurekaServerConfig#getRemoteRegionAppWhitelist(String)} <br/>
*
* @param remoteRegions The remote regions for which the instances are to be queried. The instances may be limited
* by a whitelist as explained above. If <code>null</code> all remote regions are included.
* If empty list then no remote region is included.
*
* @return The delta with instances from the passed remote regions as well as local region. The instances
* from remote regions can be further be restricted as explained above. <code>null</code> if the application does
* not exist locally or in remote regions.
*/
public Applications getApplicationDeltasFromMultipleRegions(String[] remoteRegions) {
if (null == remoteRegions) {
remoteRegions = allKnownRemoteRegions; // null means all remote regions.
}

boolean includeRemoteRegion = remoteRegions.length != 0;

if (includeRemoteRegion) {
GET_ALL_WITH_REMOTE_REGIONS_CACHE_MISS_DELTA.increment();
} else {
GET_ALL_CACHE_MISS_DELTA.increment();
}

Applications apps = new Applications();
apps.setVersion(responseCache.getVersionDeltaWithRegions().get());
Map<String, Application> applicationInstancesMap = new HashMap<String, Application>();
try {
write.lock();
Iterator<RecentlyChangedItem> iter = this.recentlyChangedQueue.iterator();
logger.debug("The number of elements in the delta queue is :{}", this.recentlyChangedQueue.size());
while (iter.hasNext()) {
Lease<InstanceInfo> lease = iter.next().getLeaseInfo();
InstanceInfo instanceInfo = lease.getHolder();
logger.debug("The instance id {} is found with status {} and actiontype {}",
instanceInfo.getId(), instanceInfo.getStatus().name(), instanceInfo.getActionType().name());
Application app = applicationInstancesMap.get(instanceInfo.getAppName());
if (app == null) {
app = new Application(instanceInfo.getAppName());
applicationInstancesMap.put(instanceInfo.getAppName(), app);
apps.addApplication(app);
}
app.addInstance(new InstanceInfo(decorateInstanceInfo(lease)));
}

if (includeRemoteRegion) {
for (String remoteRegion : remoteRegions) {
RemoteRegionRegistry remoteRegistry = regionNameVSRemoteRegistry.get(remoteRegion);
if (null != remoteRegistry) {
Applications remoteAppsDelta = remoteRegistry.getApplicationDeltas();
if (null != remoteAppsDelta) {
for (Application application : remoteAppsDelta.getRegisteredApplications()) {
if (shouldFetchFromRemoteRegistry(application.getName(), remoteRegion)) {
Application appInstanceTillNow =
apps.getRegisteredApplications(application.getName());
if (appInstanceTillNow == null) {
appInstanceTillNow = new Application(application.getName());
apps.addApplication(appInstanceTillNow);
}
for (InstanceInfo instanceInfo : application.getInstances()) {
appInstanceTillNow.addInstance(new InstanceInfo(instanceInfo));
}
}
}
}
}
}
}

Applications allApps = getApplicationsFromMultipleRegions(remoteRegions);
apps.setAppsHashCode(allApps.getReconcileHashCode());
return apps;
} finally {
write.unlock();
}
}

/**
* Gets the {@link InstanceInfo} information.
*
* @param appName the application name for which the information is requested.
* @param id the unique identifier of the instance.
* @return the information about the instance.
*/
@Override
public InstanceInfo getInstanceByAppAndId(String appName, String id) {
return this.getInstanceByAppAndId(appName, id, true);
}

/**
* Gets the {@link InstanceInfo} information.
*
* @param appName the application name for which the information is requested.
* @param id the unique identifier of the instance.
* @param includeRemoteRegions true, if we need to include applications from remote regions
* as indicated by the region {@link URL} by this property
* {@link EurekaServerConfig#getRemoteRegionUrls()}, false otherwise
* @return the information about the instance.
*/
@Override
public InstanceInfo getInstanceByAppAndId(String appName, String id, boolean includeRemoteRegions) {
Map<String, Lease<InstanceInfo>> leaseMap = registry.get(appName);
Lease<InstanceInfo> lease = null;
if (leaseMap != null) {
lease = leaseMap.get(id);
}
if (lease != null
&& (!isLeaseExpirationEnabled() || !lease.isExpired())) {
return decorateInstanceInfo(lease);
} else if (includeRemoteRegions) {
for (RemoteRegionRegistry remoteRegistry : this.regionNameVSRemoteRegistry.values()) {
Application application = remoteRegistry.getApplication(appName);
if (application != null) {
return application.getByInstanceId(id);
}
}
}
return null;
}

/**
* @deprecated Try {@link #getInstanceByAppAndId(String, String)} instead.
*
* Get all instances by ID, including automatically asking other regions if the ID is unknown.
*
* @see com.netflix.discovery.shared.LookupService#getInstancesById(String)
*/
@Deprecated
public List<InstanceInfo> getInstancesById(String id) {
return this.getInstancesById(id, true);
}

/**
* @deprecated Try {@link #getInstanceByAppAndId(String, String, boolean)} instead.
*
* Get the list of instances by its unique id.
*
* @param id the unique id of the instance
* @param includeRemoteRegions true, if we need to include applications from remote regions
* as indicated by the region {@link URL} by this property
* {@link EurekaServerConfig#getRemoteRegionUrls()}, false otherwise
* @return list of InstanceInfo objects.
*/
@Deprecated
public List<InstanceInfo> getInstancesById(String id, boolean includeRemoteRegions) {
List<InstanceInfo> list = new ArrayList<InstanceInfo>();

for (Iterator<Entry<String, Map<String, Lease<InstanceInfo>>>> iter =
registry.entrySet().iterator(); iter.hasNext(); ) {

Map<String, Lease<InstanceInfo>> leaseMap = iter.next().getValue();
if (leaseMap != null) {
Lease<InstanceInfo> lease = leaseMap.get(id);

if (lease == null || (isLeaseExpirationEnabled() && lease.isExpired())) {
continue;
}

if (list == Collections.EMPTY_LIST) {
list = new ArrayList<InstanceInfo>();
}
list.add(decorateInstanceInfo(lease));
}
}
if (list.isEmpty() && includeRemoteRegions) {
for (RemoteRegionRegistry remoteRegistry : this.regionNameVSRemoteRegistry.values()) {
for (Application application : remoteRegistry.getApplications()
.getRegisteredApplications()) {
InstanceInfo instanceInfo = application.getByInstanceId(id);
if (instanceInfo != null) {
list.add(instanceInfo);
return list;
}
}
}
}
return list;
}

private InstanceInfo decorateInstanceInfo(Lease<InstanceInfo> lease) {
InstanceInfo info = lease.getHolder();

// client app settings
int renewalInterval = LeaseInfo.DEFAULT_LEASE_RENEWAL_INTERVAL;
int leaseDuration = LeaseInfo.DEFAULT_LEASE_DURATION;

// TODO: clean this up
if (info.getLeaseInfo() != null) {
renewalInterval = info.getLeaseInfo().getRenewalIntervalInSecs();
leaseDuration = info.getLeaseInfo().getDurationInSecs();
}

info.setLeaseInfo(LeaseInfo.Builder.newBuilder()
.setRegistrationTimestamp(lease.getRegistrationTimestamp())
.setRenewalTimestamp(lease.getLastRenewalTimestamp())
.setServiceUpTimestamp(lease.getServiceUpTimestamp())
.setRenewalIntervalInSecs(renewalInterval)
.setDurationInSecs(leaseDuration)
.setEvictionTimestamp(lease.getEvictionTimestamp()).build());

info.setIsCoordinatingDiscoveryServer();
return info;
}

/**
* Servo route; do not call.
*
* @return servo data
*/
@com.netflix.servo.annotations.Monitor(name = "numOfRenewsInLastMin",
description = "Number of total heartbeats received in the last minute", type = DataSourceType.GAUGE)
@Override
public long getNumOfRenewsInLastMin() {
return renewsLastMin.getCount();
}


/**
* Gets the threshold for the renewals per minute.
*
* @return the integer representing the threshold for the renewals per
* minute.
*/
@com.netflix.servo.annotations.Monitor(name = "numOfRenewsPerMinThreshold", type = DataSourceType.GAUGE)
@Override
public int getNumOfRenewsPerMinThreshold() {
return numberOfRenewsPerMinThreshold;
}

/**
* Get the N instances that are most recently registered.
*
* @return
*/
@Override
public List<Pair<Long, String>> getLastNRegisteredInstances() {
List<Pair<Long, String>> list = new ArrayList<Pair<Long, String>>();

synchronized (recentRegisteredQueue) {
for (Pair<Long, String> aRecentRegisteredQueue : recentRegisteredQueue) {
list.add(aRecentRegisteredQueue);
}
}
Collections.reverse(list);
return list;
}

/**
* Get the N instances that have most recently canceled.
*
* @return
*/
@Override
public List<Pair<Long, String>> getLastNCanceledInstances() {
List<Pair<Long, String>> list = new ArrayList<Pair<Long, String>>();
synchronized (recentCanceledQueue) {
for (Pair<Long, String> aRecentCanceledQueue : recentCanceledQueue) {
list.add(aRecentCanceledQueue);
}
}
Collections.reverse(list);
return list;
}

private void invalidateCache(String appName, @Nullable String vipAddress, @Nullable String secureVipAddress) {
// invalidate cache
responseCache.invalidate(appName, vipAddress, secureVipAddress);
}

protected void updateRenewsPerMinThreshold() {
this.numberOfRenewsPerMinThreshold = (int) (this.expectedNumberOfClientsSendingRenews
* (60.0 / serverConfig.getExpectedClientRenewalIntervalSeconds())
* serverConfig.getRenewalPercentThreshold());
}

private static final class RecentlyChangedItem {
private long lastUpdateTime;
private Lease<InstanceInfo> leaseInfo;

public RecentlyChangedItem(Lease<InstanceInfo> lease) {
this.leaseInfo = lease;
lastUpdateTime = System.currentTimeMillis();
}

public long getLastUpdateTime() {
return this.lastUpdateTime;
}

public Lease<InstanceInfo> getLeaseInfo() {
return this.leaseInfo;
}
}

protected void postInit() {
renewsLastMin.start();
if (evictionTaskRef.get() != null) {
evictionTaskRef.get().cancel();
}
evictionTaskRef.set(new EvictionTask());
evictionTimer.schedule(evictionTaskRef.get(),
serverConfig.getEvictionIntervalTimerInMs(),
serverConfig.getEvictionIntervalTimerInMs());
}

/**
* Perform all cleanup and shutdown operations.
*/
@Override
public void shutdown() {
deltaRetentionTimer.cancel();
evictionTimer.cancel();
renewsLastMin.stop();
}

@com.netflix.servo.annotations.Monitor(name = "numOfElementsinInstanceCache", description = "Number of overrides in the instance Cache", type = DataSourceType.GAUGE)
public long getNumberofElementsininstanceCache() {
return overriddenInstanceStatusMap.size();
}

/* visible for testing */ class EvictionTask extends TimerTask {

private final AtomicLong lastExecutionNanosRef = new AtomicLong(0l);

@Override
public void run() {
try {
long compensationTimeMs = getCompensationTimeMs();
logger.info("Running the evict task with compensationTime {}ms", compensationTimeMs);
evict(compensationTimeMs);
} catch (Throwable e) {
logger.error("Could not run the evict task", e);
}
}

/**
* compute a compensation time defined as the actual time this task was executed since the prev iteration,
* vs the configured amount of time for execution. This is useful for cases where changes in time (due to
* clock skew or gc for example) causes the actual eviction task to execute later than the desired time
* according to the configured cycle.
*/
long getCompensationTimeMs() {
long currNanos = getCurrentTimeNano();
long lastNanos = lastExecutionNanosRef.getAndSet(currNanos);
if (lastNanos == 0l) {
return 0l;
}

long elapsedMs = TimeUnit.NANOSECONDS.toMillis(currNanos - lastNanos);
long compensationTime = elapsedMs - serverConfig.getEvictionIntervalTimerInMs();
return compensationTime <= 0l ? 0l : compensationTime;
}

long getCurrentTimeNano() { // for testing
return System.nanoTime();
}

}

private class CircularQueue<E> extends ConcurrentLinkedQueue<E> {
private int size = 0;

public CircularQueue(int size) {
this.size = size;
}

@Override
public boolean add(E e) {
this.makeSpaceIfNotAvailable();
return super.add(e);

}

private void makeSpaceIfNotAvailable() {
if (this.size() == size) {
this.remove();
}
}

public boolean offer(E e) {
this.makeSpaceIfNotAvailable();
return super.offer(e);
}
}

/**
* @return The rule that will process the instance status override.
*/
protected abstract InstanceStatusOverrideRule getInstanceInfoOverrideRule();

protected InstanceInfo.InstanceStatus getOverriddenInstanceStatus(InstanceInfo r,
Lease<InstanceInfo> existingLease,
boolean isReplication) {
InstanceStatusOverrideRule rule = getInstanceInfoOverrideRule();
logger.debug("Processing override status using rule: {}", rule);
return rule.apply(r, existingLease, isReplication).status();
}

private TimerTask getDeltaRetentionTask() {
return new TimerTask() {

@Override
public void run() {
Iterator<RecentlyChangedItem> it = recentlyChangedQueue.iterator();
while (it.hasNext()) {
if (it.next().getLastUpdateTime() <
System.currentTimeMillis() - serverConfig.getRetentionTimeInMSInDeltaQueue()) {
it.remove();
} else {
break;
}
}
}

};
}
}

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/*
* Copyright 2012 Netflix, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

package com.netflix.eureka.registry;

import java.net.URI;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;

import com.netflix.appinfo.AmazonInfo;
import com.netflix.appinfo.AmazonInfo.MetaDataKey;
import com.netflix.appinfo.ApplicationInfoManager;
import com.netflix.appinfo.DataCenterInfo;
import com.netflix.appinfo.DataCenterInfo.Name;
import com.netflix.appinfo.InstanceInfo;
import com.netflix.appinfo.InstanceInfo.InstanceStatus;
import com.netflix.appinfo.LeaseInfo;
import com.netflix.discovery.EurekaClient;
import com.netflix.discovery.EurekaClientConfig;
import com.netflix.discovery.shared.Application;
import com.netflix.discovery.shared.Applications;
import com.netflix.eureka.registry.rule.DownOrStartingRule;
import com.netflix.eureka.registry.rule.FirstMatchWinsCompositeRule;
import com.netflix.eureka.registry.rule.InstanceStatusOverrideRule;
import com.netflix.eureka.registry.rule.LeaseExistsRule;
import com.netflix.eureka.registry.rule.OverrideExistsRule;
import com.netflix.eureka.resources.CurrentRequestVersion;
import com.netflix.eureka.EurekaServerConfig;
import com.netflix.eureka.Version;
import com.netflix.eureka.cluster.PeerEurekaNode;
import com.netflix.eureka.cluster.PeerEurekaNodes;
import com.netflix.eureka.lease.Lease;
import com.netflix.eureka.resources.ASGResource.ASGStatus;
import com.netflix.eureka.resources.ServerCodecs;
import com.netflix.eureka.util.MeasuredRate;
import com.netflix.servo.DefaultMonitorRegistry;
import com.netflix.servo.annotations.DataSourceType;
import com.netflix.servo.monitor.Monitors;
import com.netflix.servo.monitor.Stopwatch;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.inject.Inject;
import javax.inject.Singleton;

/**
* Handles replication of all operations to {@link AbstractInstanceRegistry} to peer
* <em>Eureka</em> nodes to keep them all in sync.
*
* <p>
* Primary operations that are replicated are the
* <em>Registers,Renewals,Cancels,Expirations and Status Changes</em>
* </p>
*
* <p>
* When the eureka server starts up it tries to fetch all the registry
* information from the peer eureka nodes.If for some reason this operation
* fails, the server does not allow the user to get the registry information for
* a period specified in
* {@link com.netflix.eureka.EurekaServerConfig#getWaitTimeInMsWhenSyncEmpty()}.
* </p>
*
* <p>
* One important thing to note about <em>renewals</em>.If the renewal drops more
* than the specified threshold as specified in
* {@link com.netflix.eureka.EurekaServerConfig#getRenewalPercentThreshold()} within a period of
* {@link com.netflix.eureka.EurekaServerConfig#getRenewalThresholdUpdateIntervalMs()}, eureka
* perceives this as a danger and stops expiring instances.
* </p>
*
* @author Karthik Ranganathan, Greg Kim
*
*/
@Singleton
public class PeerAwareInstanceRegistryImpl extends AbstractInstanceRegistry implements PeerAwareInstanceRegistry {
private static final Logger logger = LoggerFactory.getLogger(PeerAwareInstanceRegistryImpl.class);

private static final String US_EAST_1 = "us-east-1";
private static final int PRIME_PEER_NODES_RETRY_MS = 30000;

private long startupTime = 0;
private boolean peerInstancesTransferEmptyOnStartup = true;

public enum Action {
Heartbeat, Register, Cancel, StatusUpdate, DeleteStatusOverride;

private com.netflix.servo.monitor.Timer timer = Monitors.newTimer(this.name());

public com.netflix.servo.monitor.Timer getTimer() {
return this.timer;
}
}

private static final Comparator<Application> APP_COMPARATOR = new Comparator<Application>() {
public int compare(Application l, Application r) {
return l.getName().compareTo(r.getName());
}
};

private final MeasuredRate numberOfReplicationsLastMin;

protected final EurekaClient eurekaClient;
protected volatile PeerEurekaNodes peerEurekaNodes;

private final InstanceStatusOverrideRule instanceStatusOverrideRule;

private Timer timer = new Timer(
"ReplicaAwareInstanceRegistry - RenewalThresholdUpdater", true);

@Inject
public PeerAwareInstanceRegistryImpl(
EurekaServerConfig serverConfig,
EurekaClientConfig clientConfig,
ServerCodecs serverCodecs,
EurekaClient eurekaClient
) {
super(serverConfig, clientConfig, serverCodecs);
this.eurekaClient = eurekaClient;
this.numberOfReplicationsLastMin = new MeasuredRate(1000 * 60 * 1);
// We first check if the instance is STARTING or DOWN, then we check explicit overrides,
// then we check the status of a potentially existing lease.
this.instanceStatusOverrideRule = new FirstMatchWinsCompositeRule(new DownOrStartingRule(),
new OverrideExistsRule(overriddenInstanceStatusMap), new LeaseExistsRule());
}

@Override
protected InstanceStatusOverrideRule getInstanceInfoOverrideRule() {
return this.instanceStatusOverrideRule;
}

@Override
public void init(PeerEurekaNodes peerEurekaNodes) throws Exception {
this.numberOfReplicationsLastMin.start();
this.peerEurekaNodes = peerEurekaNodes;
initializedResponseCache();
scheduleRenewalThresholdUpdateTask();
initRemoteRegionRegistry();

try {
Monitors.registerObject(this);
} catch (Throwable e) {
logger.warn("Cannot register the JMX monitor for the InstanceRegistry :", e);
}
}

/**
* Perform all cleanup and shutdown operations.
*/
@Override
public void shutdown() {
try {
DefaultMonitorRegistry.getInstance().unregister(Monitors.newObjectMonitor(this));
} catch (Throwable t) {
logger.error("Cannot shutdown monitor registry", t);
}
try {
peerEurekaNodes.shutdown();
} catch (Throwable t) {
logger.error("Cannot shutdown ReplicaAwareInstanceRegistry", t);
}
numberOfReplicationsLastMin.stop();

super.shutdown();
}

/**
* Schedule the task that updates <em>renewal threshold</em> periodically.
* The renewal threshold would be used to determine if the renewals drop
* dramatically because of network partition and to protect expiring too
* many instances at a time.
*
*/
private void scheduleRenewalThresholdUpdateTask() {
timer.schedule(new TimerTask() {
@Override
public void run() {
updateRenewalThreshold();
}
}, serverConfig.getRenewalThresholdUpdateIntervalMs(),
serverConfig.getRenewalThresholdUpdateIntervalMs());
}

/**
* Populates the registry information from a peer eureka node. This
* operation fails over to other nodes until the list is exhausted if the
* communication fails.
*/
@Override
public int syncUp() {
// Copy entire entry from neighboring DS node
int count = 0;

for (int i = 0; ((i < serverConfig.getRegistrySyncRetries()) && (count == 0)); i++) {
if (i > 0) {
try {
Thread.sleep(serverConfig.getRegistrySyncRetryWaitMs());
} catch (InterruptedException e) {
logger.warn("Interrupted during registry transfer..");
break;
}
}
Applications apps = eurekaClient.getApplications();
for (Application app : apps.getRegisteredApplications()) {
for (InstanceInfo instance : app.getInstances()) {
try {
if (isRegisterable(instance)) {
register(instance, instance.getLeaseInfo().getDurationInSecs(), true);
count++;
}
} catch (Throwable t) {
logger.error("During DS init copy", t);
}
}
}
}
return count;
}

@Override
public void openForTraffic(ApplicationInfoManager applicationInfoManager, int count) {
// Renewals happen every 30 seconds and for a minute it should be a factor of 2.
this.expectedNumberOfClientsSendingRenews = count;
updateRenewsPerMinThreshold();
logger.info("Got {} instances from neighboring DS node", count);
logger.info("Renew threshold is: {}", numberOfRenewsPerMinThreshold);
this.startupTime = System.currentTimeMillis();
if (count > 0) {
this.peerInstancesTransferEmptyOnStartup = false;
}
DataCenterInfo.Name selfName = applicationInfoManager.getInfo().getDataCenterInfo().getName();
boolean isAws = Name.Amazon == selfName;
if (isAws && serverConfig.shouldPrimeAwsReplicaConnections()) {
logger.info("Priming AWS connections for all replicas..");
primeAwsReplicas(applicationInfoManager);
}
logger.info("Changing status to UP");
applicationInfoManager.setInstanceStatus(InstanceStatus.UP);
super.postInit();
}

/**
* Prime connections for Aws replicas.
* <p>
* Sometimes when the eureka servers comes up, AWS firewall may not allow
* the network connections immediately. This will cause the outbound
* connections to fail, but the inbound connections continue to work. What
* this means is the clients would have switched to this node (after EIP
* binding) and so the other eureka nodes will expire all instances that
* have been switched because of the lack of outgoing heartbeats from this
* instance.
* </p>
* <p>
* The best protection in this scenario is to block and wait until we are
* able to ping all eureka nodes successfully atleast once. Until then we
* won't open up the traffic.
* </p>
*/
private void primeAwsReplicas(ApplicationInfoManager applicationInfoManager) {
boolean areAllPeerNodesPrimed = false;
while (!areAllPeerNodesPrimed) {
String peerHostName = null;
try {
Application eurekaApps = this.getApplication(applicationInfoManager.getInfo().getAppName(), false);
if (eurekaApps == null) {
areAllPeerNodesPrimed = true;
logger.info("No peers needed to prime.");
return;
}
for (PeerEurekaNode node : peerEurekaNodes.getPeerEurekaNodes()) {
for (InstanceInfo peerInstanceInfo : eurekaApps.getInstances()) {
LeaseInfo leaseInfo = peerInstanceInfo.getLeaseInfo();
// If the lease is expired - do not worry about priming
if (System.currentTimeMillis() > (leaseInfo
.getRenewalTimestamp() + (leaseInfo
.getDurationInSecs() * 1000))
+ (2 * 60 * 1000)) {
continue;
}
peerHostName = peerInstanceInfo.getHostName();
logger.info("Trying to send heartbeat for the eureka server at {} to make sure the " +
"network channels are open", peerHostName);
// Only try to contact the eureka nodes that are in this instance's registry - because
// the other instances may be legitimately down
if (peerHostName.equalsIgnoreCase(new URI(node.getServiceUrl()).getHost())) {
node.heartbeat(
peerInstanceInfo.getAppName(),
peerInstanceInfo.getId(),
peerInstanceInfo,
null,
true);
}
}
}
areAllPeerNodesPrimed = true;
} catch (Throwable e) {
logger.error("Could not contact {}", peerHostName, e);
try {
Thread.sleep(PRIME_PEER_NODES_RETRY_MS);
} catch (InterruptedException e1) {
logger.warn("Interrupted while priming : ", e1);
areAllPeerNodesPrimed = true;
}
}
}
}

/**
* Checks to see if the registry access is allowed or the server is in a
* situation where it does not all getting registry information. The server
* does not return registry information for a period specified in
* {@link EurekaServerConfig#getWaitTimeInMsWhenSyncEmpty()}, if it cannot
* get the registry information from the peer eureka nodes at start up.
*
* @return false - if the instances count from a replica transfer returned
* zero and if the wait time has not elapsed, otherwise returns true
*/
@Override
public boolean shouldAllowAccess(boolean remoteRegionRequired) {
if (this.peerInstancesTransferEmptyOnStartup) {
if (!(System.currentTimeMillis() > this.startupTime + serverConfig.getWaitTimeInMsWhenSyncEmpty())) {
return false;
}
}
if (remoteRegionRequired) {
for (RemoteRegionRegistry remoteRegionRegistry : this.regionNameVSRemoteRegistry.values()) {
if (!remoteRegionRegistry.isReadyForServingData()) {
return false;
}
}
}
return true;
}

public boolean shouldAllowAccess() {
return shouldAllowAccess(true);
}

/**
* @deprecated use {@link com.netflix.eureka.cluster.PeerEurekaNodes#getPeerEurekaNodes()} directly.
*
* Gets the list of peer eureka nodes which is the list to replicate
* information to.
*
* @return the list of replica nodes.
*/
@Deprecated
public List<PeerEurekaNode> getReplicaNodes() {
return Collections.unmodifiableList(peerEurekaNodes.getPeerEurekaNodes());
}

/*
* (non-Javadoc)
*
* @see com.netflix.eureka.registry.InstanceRegistry#cancel(java.lang.String,
* java.lang.String, long, boolean)
*/
@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.expectedNumberOfClientsSendingRenews > 0) {
// Since the client wants to cancel it, reduce the number of clients to send renews
this.expectedNumberOfClientsSendingRenews = this.expectedNumberOfClientsSendingRenews - 1;
updateRenewsPerMinThreshold();
}
}
return true;
}
return false;
}

/**
* Registers the information about the {@link InstanceInfo} and replicates
* this information to all peer eureka nodes. If this is replication event
* from other replica nodes then it is not replicated.
*
* @param info
* the {@link InstanceInfo} to be registered and replicated.
* @param isReplication
* true if this is a replication event from other replica nodes,
* false otherwise.
*/
@Override
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);
}

/*
* (non-Javadoc)
*
* @see com.netflix.eureka.registry.InstanceRegistry#renew(java.lang.String,
* java.lang.String, long, boolean)
*/
public boolean renew(final String appName, final String id, final boolean isReplication) {
if (super.renew(appName, id, isReplication)) {
replicateToPeers(Action.Heartbeat, appName, id, null, null, isReplication);
return true;
}
return false;
}

/*
* (non-Javadoc)
*
* @see com.netflix.eureka.registry.InstanceRegistry#statusUpdate(java.lang.String,
* java.lang.String, com.netflix.appinfo.InstanceInfo.InstanceStatus,
* java.lang.String, boolean)
*/
@Override
public boolean statusUpdate(final String appName, final String id,
final InstanceStatus newStatus, String lastDirtyTimestamp,
final boolean isReplication) {
if (super.statusUpdate(appName, id, newStatus, lastDirtyTimestamp, isReplication)) {
replicateToPeers(Action.StatusUpdate, appName, id, null, newStatus, isReplication);
return true;
}
return false;
}

@Override
public boolean deleteStatusOverride(String appName, String id,
InstanceStatus newStatus,
String lastDirtyTimestamp,
boolean isReplication) {
if (super.deleteStatusOverride(appName, id, newStatus, lastDirtyTimestamp, isReplication)) {
replicateToPeers(Action.DeleteStatusOverride, appName, id, null, null, isReplication);
return true;
}
return false;
}

/**
* Replicate the <em>ASG status</em> updates to peer eureka nodes. If this
* event is a replication from other nodes, then it is not replicated to
* other nodes.
*
* @param asgName the asg name for which the status needs to be replicated.
* @param newStatus the {@link ASGStatus} information that needs to be replicated.
* @param isReplication true if this is a replication event from other nodes, false otherwise.
*/
@Override
public void statusUpdate(final String asgName, final ASGStatus newStatus, final boolean isReplication) {
// If this is replicated from an other node, do not try to replicate again.
if (isReplication) {
return;
}
for (final PeerEurekaNode node : peerEurekaNodes.getPeerEurekaNodes()) {
replicateASGInfoToReplicaNodes(asgName, newStatus, node);

}
}

@Override
public boolean isLeaseExpirationEnabled() {
if (!isSelfPreservationModeEnabled()) {
// The self preservation mode is disabled, hence allowing the instances to expire.
return true;
}
return numberOfRenewsPerMinThreshold > 0 && getNumOfRenewsInLastMin() > numberOfRenewsPerMinThreshold;
}

/**
* Checks to see if the self-preservation mode is enabled.
*
* <p>
* The self-preservation mode is enabled if the expected number of renewals
* per minute {@link #getNumOfRenewsInLastMin()} is lesser than the expected
* threshold which is determined by {@link #getNumOfRenewsPerMinThreshold()}
* . Eureka perceives this as a danger and stops expiring instances as this
* is most likely because of a network event. The mode is disabled only when
* the renewals get back to above the threshold or if the flag
* {@link EurekaServerConfig#shouldEnableSelfPreservation()} is set to
* false.
* </p>
*
* @return true if the self-preservation mode is enabled, false otherwise.
*/
@Override
public boolean isSelfPreservationModeEnabled() {
return serverConfig.shouldEnableSelfPreservation();
}

@Override
public InstanceInfo getNextServerFromEureka(String virtualHostname, boolean secure) {
// TODO Auto-generated method stub
return null;
}

/**
* Updates the <em>renewal threshold</em> based on the current number of
* renewals. The threshold is a percentage as specified in
* {@link EurekaServerConfig#getRenewalPercentThreshold()} of renewals
* received per minute {@link #getNumOfRenewsInLastMin()}.
*/
private void updateRenewalThreshold() {
try {
Applications apps = eurekaClient.getApplications();
int count = 0;
for (Application app : apps.getRegisteredApplications()) {
for (InstanceInfo instance : app.getInstances()) {
if (this.isRegisterable(instance)) {
++count;
}
}
}
synchronized (lock) {
// Update threshold only if the threshold is greater than the
// current expected threshold or if self preservation is disabled.
if ((count) > (serverConfig.getRenewalPercentThreshold() * expectedNumberOfClientsSendingRenews)
|| (!this.isSelfPreservationModeEnabled())) {
this.expectedNumberOfClientsSendingRenews = count;
updateRenewsPerMinThreshold();
}
}
logger.info("Current renewal threshold is : {}", numberOfRenewsPerMinThreshold);
} catch (Throwable e) {
logger.error("Cannot update renewal threshold", e);
}
}

/**
* Gets the list of all {@link Applications} from the registry in sorted
* lexical order of {@link Application#getName()}.
*
* @return the list of {@link Applications} in lexical order.
*/
@Override
public List<Application> getSortedApplications() {
List<Application> apps = new ArrayList<Application>(getApplications().getRegisteredApplications());
Collections.sort(apps, APP_COMPARATOR);
return apps;
}

/**
* Gets the number of <em>renewals</em> in the last minute.
*
* @return a long value representing the number of <em>renewals</em> in the last minute.
*/
@com.netflix.servo.annotations.Monitor(name = "numOfReplicationsInLastMin",
description = "Number of total replications received in the last minute",
type = com.netflix.servo.annotations.DataSourceType.GAUGE)
public long getNumOfReplicationsInLastMin() {
return numberOfReplicationsLastMin.getCount();
}

/**
* Checks if the number of renewals is lesser than threshold.
*
* @return 0 if the renewals are greater than threshold, 1 otherwise.
*/
@com.netflix.servo.annotations.Monitor(name = "isBelowRenewThreshold", description = "0 = false, 1 = true",
type = com.netflix.servo.annotations.DataSourceType.GAUGE)
@Override
public int isBelowRenewThresold() {
if ((getNumOfRenewsInLastMin() <= numberOfRenewsPerMinThreshold)
&&
((this.startupTime > 0) && (System.currentTimeMillis() > this.startupTime + (serverConfig.getWaitTimeInMsWhenSyncEmpty())))) {
return 1;
} else {
return 0;
}
}

/**
* Checks if an instance is registerable in this region. Instances from other regions are rejected.
*
* @param instanceInfo th instance info information of the instance
* @return true, if it can be registered in this server, false otherwise.
*/
public boolean isRegisterable(InstanceInfo instanceInfo) {
DataCenterInfo datacenterInfo = instanceInfo.getDataCenterInfo();
String serverRegion = clientConfig.getRegion();
if (AmazonInfo.class.isInstance(datacenterInfo)) {
AmazonInfo info = AmazonInfo.class.cast(instanceInfo.getDataCenterInfo());
String availabilityZone = info.get(MetaDataKey.availabilityZone);
// Can be null for dev environments in non-AWS data center
if (availabilityZone == null && US_EAST_1.equalsIgnoreCase(serverRegion)) {
return true;
} else if ((availabilityZone != null) && (availabilityZone.contains(serverRegion))) {
// If in the same region as server, then consider it registerable
return true;
}
}
return true; // Everything non-amazon is registrable.
}

/**
* 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);
}
}

/**
* Replicates all ASG status changes to peer eureka nodes except for
* replication traffic to this node.
*/
private void replicateASGInfoToReplicaNodes(final String asgName,
final ASGStatus newStatus, final PeerEurekaNode node) {
CurrentRequestVersion.set(Version.V2);
try {
node.statusUpdate(asgName, newStatus);
} catch (Throwable e) {
logger.error("Cannot replicate ASG status information to {}", node.getServiceUrl(), e);
}
}

@Override
@com.netflix.servo.annotations.Monitor(name = "localRegistrySize",
description = "Current registry size", type = DataSourceType.GAUGE)
public long getLocalRegistrySize() {
return super.getLocalRegistrySize();
}
}