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AbstractInstanceRegistry.java
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AbstractInstanceRegistry.java
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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 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 javax.annotation.Nullable;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.*;
import java.util.Map.Entry;
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 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];
/**
* 租约映射
* key1 ：应用名 {@link InstanceInfo#appName}
* key2 ：应用实例信息编号 {@link InstanceInfo#instanceId}
* value ：租约
*/
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>();
/**
* 应用实例覆盖状态映射
* key：应用实例编号
*/
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
/**
* 最近注册的调试队列
* key ：添加时的时间戳
* value ：字符串 = 应用名(应用实例信息编号)
*/
private final CircularQueue<Pair<Long, String>> recentRegisteredQueue;
/**
* 最近取消注册的调试队列
* key ：添加时的时间戳
* value ：字符串 = 应用名(应用实例信息编号)
*/
private final CircularQueue<Pair<Long, String>> recentCanceledQueue;
/**
* 最近租约变更记录队列
*/
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();
/**
* 自我保护机锁
*
* 当计算如下参数时使用：
* 1. {@link #numberOfRenewsPerMinThreshold}
* 2. {@link #expectedNumberOfRenewsPerMin}
*/
protected final Object lock = new Object();
private Timer deltaRetentionTimer = new Timer("Eureka-DeltaRetentionTimer", true);
private Timer evictionTimer = new Timer("Eureka-EvictionTimer", true);
/**
* 续租每分钟次数
*/
private final MeasuredRate renewsLastMin;
/**
* 清理租约过期任务
*/
private final AtomicReference<EvictionTask> evictionTaskRef = new AtomicReference<EvictionTask>();
protected String[] allKnownRemoteRegions = EMPTY_STR_ARRAY;
/**
* 期望最小每分钟续约次数
*/
protected volatile int numberOfRenewsPerMinThreshold;
/**
* 期望最大每分钟续约次数
*/
protected volatile int expectedNumberOfRenewsPerMin;
/**
* Eureka-Server 配置
*/
protected final EurekaServerConfig serverConfig;
/**
* Eureka-Client 配置
*/
protected final EurekaClientConfig clientConfig;
/**
* Eureka-Server 请求和响应编解码器
*/
protected final ServerCodecs serverCodecs;
/**
* 响应缓存
*/
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.size() > 0) {
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: {}",
Arrays.toString(allKnownRemoteRegions));
}
@Override
public ResponseCache getResponseCache() {
return responseCache;
}
/**
* 获得本地注册应用实例信息数量
*
* @return 数量
*/
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);
}
/**
* 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 {
// TODO 为什么是读锁
read.lock();
Map<String, Lease<InstanceInfo>> gMap = registry.get(registrant.getAppName());
// 增加 注册次数 到 监控
REGISTER.increment(isReplication);
// 获得 应用实例信息 对应的 租约
if (gMap == null) {
final ConcurrentHashMap<String, Lease<InstanceInfo>> gNewMap = new ConcurrentHashMap<String, Lease<InstanceInfo>>();
gMap = registry.putIfAbsent(registrant.getAppName(), gNewMap); // 添加 应用
if (gMap == null) { // 添加 应用 成功
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)) { // 已存在时，使用数据不一致的时间大的应用注册信息为有效的
Long existingLastDirtyTimestamp = existingLease.getHolder().getLastDirtyTimestamp(); // Server 注册的 InstanceInfo
Long registrationLastDirtyTimestamp = registrant.getLastDirtyTimestamp(); // Client 请求的 InstanceInfo
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
// 【自我保护机制】增加 `numberOfRenewsPerMinThreshold` 、`expectedNumberOfRenewsPerMin`
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());
}
}
logger.debug("No previous lease information found; it is new registration");
}
// 创建 租约
Lease<InstanceInfo> lease = new Lease<InstanceInfo>(registrant, leaseDuration);
if (existingLease != null) { // 若租约已存在，设置 租约的开始服务的时间戳
lease.setServiceUpTimestamp(existingLease.getServiceUpTimestamp());
}
// 添加到 租约映射
gMap.put(registrant.getId(), lease);
// 添加到 最近注册的调试队列
synchronized (recentRegisteredQueue) {
recentRegisteredQueue.add(new Pair<Long, String>(
System.currentTimeMillis(),
registrant.getAppName() + "(" + registrant.getId() + ")"));
}
// 添加到 应用实例覆盖状态映射（Eureka-Server 初始化使用）
// 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());
}
}
// 设置 应用实例覆盖状态
InstanceStatus overriddenStatusFromMap = overriddenInstanceStatusMap.get(registrant.getId());
if (overriddenStatusFromMap != null) {
logger.info("Storing overridden status {} from map", overriddenStatusFromMap);
registrant.setOverriddenStatus(overriddenStatusFromMap);
}
// 获得 应用实例状态
// Set the status based on the overridden status rules
InstanceStatus overriddenInstanceStatus = getOverriddenInstanceStatus(registrant, existingLease, isReplication);
// 设置 应用实例状态
registrant.setStatusWithoutDirty(overriddenInstanceStatus);
// 设置 租约的开始服务的时间戳（只有第一次有效）
// If the lease is registered with UP status, set lease service up timestamp
if (InstanceStatus.UP.equals(registrant.getStatus())) {
lease.serviceUp();
}
// 设置 应用实例信息的操作类型 为 添加
registrant.setActionType(ActionType.ADDED);
// 添加到 最近租约变更记录队列
recentlyChangedQueue.add(new RecentlyChangedItem(lease));
// 设置 租约的最后更新时间戳
registrant.setLastUpdatedTimestamp();
// 设置 响应缓存 过期
invalidateCache(registrant.getAppName(), registrant.getVIPAddress(), registrant.getSecureVipAddress());
logger.info("Registered instance {}/{} with status {} (replication={})",
registrant.getAppName(), registrant.getId(), registrant.getStatus(), isReplication);
} finally {
// 释放锁
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);
}
/**
* {@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 {
// 获得锁 TODO 芋艿：疑问
read.lock();
// 增加 取消注册次数 到 监控
CANCEL.increment(isReplication);
// 移除 租约映射
Map<String, Lease<InstanceInfo>> gMap = registry.get(appName);
Lease<InstanceInfo> leaseToCancel = null;
if (gMap != null) {
leaseToCancel = gMap.remove(id);
}
// 添加到 最近取消注册的调试队列
synchronized (recentCanceledQueue) {
recentCanceledQueue.add(new Pair<Long, String>(System.currentTimeMillis(), appName + "(" + id + ")"));
}
// 移除 应用实例覆盖状态映射
InstanceStatus instanceStatus = overriddenInstanceStatusMap.remove(id);
if (instanceStatus != null) {
logger.debug("Removed instance id {} from the overridden map which has value {}", id, instanceStatus.name());
}
// 租约不存在
if (leaseToCancel == null) {
CANCEL_NOT_FOUND.increment(isReplication); // 添加 取消注册不存在 到 监控
logger.warn("DS: Registry: cancel failed because Lease is not registered for: {}/{}", appName, id);
return false; // 失败
} else {
// 设置 租约的取消注册时间戳
leaseToCancel.cancel();
// 添加到 最近租约变更记录队列
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();
}
// 设置 响应缓存 过期
invalidateCache(appName, vip, svip);
logger.info("Cancelled instance {}/{} (replication={})", appName, id, isReplication);
return true; // 成功
}
} finally {
// 释放锁
read.unlock();
}
}
/**
* 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) {
// 增加 续租次数 到 监控
RENEW.increment(isReplication);
// 获得 租约
Map<String, Lease<InstanceInfo>> gMap = registry.get(appName);
Lease<InstanceInfo> leaseToRenew = null;
if (gMap != null) {
leaseToRenew = gMap.get(id);
}
// 租约不存在
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());
// 获得 应用实例状态
InstanceStatus overriddenInstanceStatus = this.getOverriddenInstanceStatus(
instanceInfo, leaseToRenew, isReplication);
// 应用实例状态未知，无法续约
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;
}
// 设置 应用实例状态
if (!instanceInfo.getStatus().equals(overriddenInstanceStatus)) {
Object[] args = {
instanceInfo.getStatus().name(),
instanceInfo.getOverriddenStatus().name(),
instanceInfo.getId()
};
logger.info(
"The instance status {} is different from overridden instance status {} for instance {}. "
+ "Hence setting the status to overridden status", args);
instanceInfo.setStatusWithoutDirty(overriddenInstanceStatus);
}
}
// 新增 续租每分钟次数
renewsLastMin.increment();
// 设置 租约最后更新时间（续租）
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 {
// TODO 为什么是读锁
read.lock();
// 添加 覆盖状态变更次数 到 监控
STATUS_UPDATE.increment(isReplication);
// 获得 租约
Map<String, Lease<InstanceInfo>> gMap = registry.get(appName);
Lease<InstanceInfo> lease = null;
if (gMap != null) {
lease = gMap.get(id);
}
// 租约不存在
if (lease == null) {
return false;
} else {
// 设置 租约最后更新时间（续租）
lease.renew();
// 应用实例信息不存在( 防御型编程 )
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))) {
// 设置 租约的开始服务的时间戳（只有第一次有效）
// Mark service as UP if needed
if (InstanceStatus.UP.equals(newStatus)) {
lease.serviceUp();
}
// 添加到 应用实例覆盖状态映射
// This is NAC overridden status
overriddenInstanceStatusMap.put(id, newStatus);
// 设置 应用实例覆盖状态
// Set it for transfer of overridden status to replica on
// replica start up
info.setOverriddenStatus(newStatus);
// 设置 应用实例信息 数据不一致时间
long replicaDirtyTimestamp = 0;
// 设置 应用实例状态
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);
}
// 添加到 最近租约变更记录队列
info.setActionType(ActionType.MODIFIED);
recentlyChangedQueue.add(new RecentlyChangedItem(lease));
// 设置 最后更新时间
info.setLastUpdatedTimestamp();
// 设置 响应缓存 过期
invalidateCache(appName, info.getVIPAddress(), info.getSecureVipAddress());
}
return true;
}
} finally {
// 释放锁
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 {
// TODO 为什么是读锁
read.lock();
// 添加 覆盖状态删除次数 到 监控
STATUS_OVERRIDE_DELETE.increment(isReplication);
// 获得 租约
Map<String, Lease<InstanceInfo>> gMap = registry.get(appName);
Lease<InstanceInfo> lease = null;
if (gMap != null) {
lease = gMap.get(id);
}
// 租约不存在
if (lease == null) {
return false;
} else {
// 设置 租约最后更新时间（续租）
lease.renew();
// 应用实例信息不存在( 防御型编程 )
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);
}
// 移除 应用实例覆盖状态
InstanceStatus currentOverride = overriddenInstanceStatusMap.remove(id);
if (currentOverride != null && info != null) {
// 设置 应用实例覆盖状态
info.setOverriddenStatus(InstanceStatus.UNKNOWN);
// 设置 应用实例状态
info.setStatusWithoutDirty(newStatus);
// 设置 应用实例信息 数据不一致时间
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);
}
// 添加到 最近租约变更记录队列
info.setActionType(ActionType.MODIFIED);
recentlyChangedQueue.add(new RecentlyChangedItem(lease));
// 设置 最后更新时间
info.setLastUpdatedTimestamp();
// 设置 响应缓存 过期
invalidateCache(appName, info.getVIPAddress(), info.getSecureVipAddress());
}
return true;
}
} finally {
// 释放锁
read.unlock();
}
}
/**
* 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;
}
// 获得 所有过期的租约
// 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) { // 过期
expiredLeases.add(lease);
}
}
}
}
// 计算 最大允许清理租约数量
// 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;
// 计算 清理租约数量
int toEvict = Math.min(expiredLeases.size(), evictionLimit);
if (toEvict > 0) {
logger.info("Evicting {} items (expired={}, evictionLimit={})", toEvict, expiredLeases.size(), evictionLimit);
// 逐个过期
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) { // TODO[0009]：RemoteRegionRegistry
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) {
// TODO[0009]：RemoteRegionRegistry
boolean includeRemoteRegion = null != remoteRegions && remoteRegions.length != 0;
logger.debug("Fetching applications registry with remote regions: {}, Regions argument {}",
includeRemoteRegion, Arrays.toString(remoteRegions));
if (includeRemoteRegion) {
GET_ALL_WITH_REMOTE_REGIONS_CACHE_MISS.increment();
} else {
GET_ALL_CACHE_MISS.increment();
}
// 获得获得注册的应用集合
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);
}
}
// TODO[0009]：RemoteRegionRegistry
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);
}
}
}
// 设置 应用集合 hashcode
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() {
// 添加 增量获取次数 到 监控
GET_ALL_CACHE_MISS_DELTA.increment();
// 初始化 变化的应用集合
Applications apps = new Applications();
apps.setVersion(responseCache.getVersionDelta().get());