Eureka 源码解析 —— 应用实例注册发现(一)之注册
总阅读量:次
摘要: 原创出处 http://www.iocoder.cn/Eureka/instance-registry-register/ 「芋道源码」欢迎转载,保留摘要,谢谢!
本文主要基于 Eureka 1.8.X 版本
������关注微信公众号:【芋道源码】有福利:
- RocketMQ / MyCAT / Sharding-JDBC 所有源码分析文章列表
- RocketMQ / MyCAT / Sharding-JDBC 中文注释源码 GitHub 地址
- 您对于源码的疑问每条留言都将得到认真回复。甚至不知道如何读源码也可以请教噢。
- 新的源码解析文章实时收到通知。每周更新一篇左右。
- 认真的源码交流微信群。
1. 概述
本文主要分享 Eureka-Client 向 Eureka-Server 注册应用实例的过程。
FROM 《深度剖析服务发现组件Netflix Eureka》 二次编辑
- 蓝框部分,为本文重点。
- 非蓝框部分,Eureka-Server 集群间复制注册的应用实例信息,不在本文内容范畴。
推荐 Spring Cloud 书籍:
- 请支持正版。下载盗版,等于主动编写低级 BUG 。
- 程序猿DD —— 《Spring Cloud微服务实战》
- 周立 —— 《Spring Cloud与Docker微服务架构实战》
- 两书齐买,京东包邮。
2. Eureka-Client 发起注册
Eureka-Client 向 Eureka-Server 发起注册应用实例需要符合如下条件:
- 配置
eureka.registration.enabled = true
,Eureka-Client 向 Eureka-Server 发起注册应用实例的开关。 - InstanceInfo 在 Eureka-Client 和 Eureka-Server 数据不一致。
每次 InstanceInfo 发生属性变化时,标记 isInstanceInfoDirty
属性为 true
,表示 InstanceInfo 在 Eureka-Client 和 Eureka-Server 数据不一致,需要注册。另外,InstanceInfo 刚被创建时,在 Eureka-Server 不存在,也会被注册。
当符合条件时,InstanceInfo 不会立即向 Eureka-Server 注册,而是后台线程定时注册。
当 InstanceInfo 的状态( status
) 属性发生变化时,并且配置 eureka.shouldOnDemandUpdateStatusChange = true
时,立即向 Eureka-Server 注册。因为状态属性非常重要,一般情况下建议开启,当然默认情况也是开启的。
Let’s Go。让我们看看代码的实现。
2.1 应用实例信息复制器
// DiscoveryClient.java
public class DiscoveryClient implements EurekaClient {
/**
* 应用实例状态变更监听器
*/
private ApplicationInfoManager.StatusChangeListener statusChangeListener;
/**
* 应用实例信息复制器
*/
private InstanceInfoReplicator instanceInfoReplicator;
private void initScheduledTasks() {
// ... 省略无关代码
if (clientConfig.shouldRegisterWithEureka()) {
// ... 省略无关代码
// 创建 应用实例信息复制器
// InstanceInfo replicator
instanceInfoReplicator = new InstanceInfoReplicator(
this,
instanceInfo,
clientConfig.getInstanceInfoReplicationIntervalSeconds(),
2); // burstSize
// 创建 应用实例状态变更监听器
statusChangeListener = new ApplicationInfoManager.StatusChangeListener() {
@Override
public String getId() {
return "statusChangeListener";
}
@Override
public void notify(StatusChangeEvent statusChangeEvent) {
if (InstanceStatus.DOWN == statusChangeEvent.getStatus() ||
InstanceStatus.DOWN == statusChangeEvent.getPreviousStatus()) {
// log at warn level if DOWN was involved
logger.warn( "Saw local status change event {}", statusChangeEvent);
} else {
logger.info( "Saw local status change event {}", statusChangeEvent);
}
instanceInfoReplicator.onDemandUpdate();
}
};
// 注册 应用实例状态变更监听器
if (clientConfig.shouldOnDemandUpdateStatusChange()) {
applicationInfoManager.registerStatusChangeListener(statusChangeListener);
}
// 开启 应用实例信息复制器
instanceInfoReplicator.start(clientConfig.getInitialInstanceInfoReplicationIntervalSeconds());
}
}
}
|
com.netflix.discovery.InstanceInfoReplicator
,应用实例信息复制器。调用
InstanceInfoReplicator#start(...)
方法,开启应用实例信息复制器。实现代码如下:// InstanceInfoReplicator.javaclass InstanceInfoReplicator implements Runnable {private static final Logger logger = LoggerFactory.getLogger(InstanceInfoReplicator.class);private final DiscoveryClient discoveryClient;/*** 应用实例信息*/private final InstanceInfo instanceInfo;/*** 定时执行频率,单位:秒*/private final int replicationIntervalSeconds;/*** 定时执行器*/private final ScheduledExecutorService scheduler;/*** 定时执行任务的 Future*/private final AtomicReference<Future> scheduledPeriodicRef;/*** 是否开启调度*/private final AtomicBoolean started;private final RateLimiter rateLimiter; // 限流相关,跳过private final int burstSize; // 限流相关,跳过private final int allowedRatePerMinute; // 限流相关,跳过InstanceInfoReplicator(DiscoveryClient discoveryClient, InstanceInfo instanceInfo, int replicationIntervalSeconds, int burstSize) {this.discoveryClient = discoveryClient;this.instanceInfo = instanceInfo;this.scheduler = Executors.newScheduledThreadPool( 1,new ThreadFactoryBuilder().setNameFormat( "DiscoveryClient-InstanceInfoReplicator-%d").setDaemon( true).build());this.scheduledPeriodicRef = new AtomicReference<Future>();this.started = new AtomicBoolean( false);this.rateLimiter = new RateLimiter(TimeUnit.MINUTES);this.replicationIntervalSeconds = replicationIntervalSeconds;this.burstSize = burstSize;this.allowedRatePerMinute = 60 * this.burstSize / this.replicationIntervalSeconds;logger.info( "InstanceInfoReplicator onDemand update allowed rate per min is {}", allowedRatePerMinute);}public void start(int initialDelayMs) {if (started.compareAndSet( false, true)) {// 设置 应用实例信息 数据不一致instanceInfo.setIsDirty(); // for initial register// 提交任务,并设置该任务的 FutureFuture next = scheduler.schedule( this, initialDelayMs, TimeUnit.SECONDS);scheduledPeriodicRef.set(next);}}// ... 省略无关方法}// InstanceInfo.javaprivate volatile boolean isInstanceInfoDirty = false;private volatile Long lastDirtyTimestamp;public synchronized void setIsDirty() {isInstanceInfoDirty = true;lastDirtyTimestamp = System.currentTimeMillis();}- 执行
instanceInfo.setIsDirty()
代码块,因为 InstanceInfo 刚被创建时,在 Eureka-Server 不存在,也会被注册。 - 调用
ScheduledExecutorService#schedule(...)
方法,延迟initialDelayMs
毫秒执行一次任务。为什么此处设置scheduledPeriodicRef
?在InstanceInfoReplicator#onDemandUpdate()
方法会看到具体用途。
- 执行
定时检查 InstanceInfo 的状态(
status
) 属性是否发生变化。若是,发起注册。实现代码如下:// InstanceInfoReplicator.java@Overridepublic void run() {try {// 刷新 应用实例信息discoveryClient.refreshInstanceInfo();// 判断 应用实例信息 是否数据不一致Long dirtyTimestamp = instanceInfo.isDirtyWithTime();if (dirtyTimestamp != null) {// 发起注册discoveryClient.register();// 设置 应用实例信息 数据一致instanceInfo.unsetIsDirty(dirtyTimestamp);}} catch (Throwable t) {logger.warn( "There was a problem with the instance info replicator", t);} finally {// 提交任务,并设置该任务的 FutureFuture next = scheduler.schedule( this, replicationIntervalSeconds, TimeUnit.SECONDS);scheduledPeriodicRef.set(next);}}// InstanceInfo.javapublic synchronized long setIsDirtyWithTime() {setIsDirty();return lastDirtyTimestamp;}public synchronized void unsetIsDirty(long unsetDirtyTimestamp) {if (lastDirtyTimestamp <= unsetDirtyTimestamp) {isInstanceInfoDirty = false;} else {}}- 调用
DiscoveryClient#refreshInstanceInfo()
方法,刷新应用实例信息。此处可能导致应用实例信息数据不一致,在「2.2」刷新应用实例信息 详细解析。 - 调用
DiscoveryClient#register()
方法,Eureka-Client 向 Eureka-Server 注册应用实例。 - 调用
ScheduledExecutorService#schedule(...)
方法,再次延迟执行任务,并设置scheduledPeriodicRef
。通过这样的方式,不断循环定时执行任务。
- 调用
com.netflix.appinfo.ApplicationInfoManager.StatusChangeListener
内部类,监听应用实例信息状态的变更。调用
ApplicationInfoManager#registerStatusChangeListener(...)
方法,注册应用实例状态变更监听器。实现代码如下:public class ApplicationInfoManager {/*** 状态变更监听器*/protected final Map<String, StatusChangeListener> listeners;public void registerStatusChangeListener(StatusChangeListener listener) {listeners.put(listener.getId(), listener);}}业务里,调用
ApplicationInfoManager#setInstanceStatus(...)
方法,设置应用实例信息的状态,从而通知InstanceInfoReplicator#onDemandUpdate()
方法的调用。实现代码如下:// ApplicationInfoManager.javapublic synchronized void setInstanceStatus(InstanceStatus status) {InstanceStatus next = instanceStatusMapper.map(status);if (next == null) {return;}InstanceStatus prev = instanceInfo.setStatus(next);if (prev != null) {for (StatusChangeListener listener : listeners.values()) {try {listener.notify( new StatusChangeEvent(prev, next));} catch (Exception e) {logger.warn( "failed to notify listener: {}", listener.getId(), e);}}}}// InstanceInfo.javapublic synchronized InstanceStatus setStatus(InstanceStatus status) {if ( this.status != status) {InstanceStatus prev = this.status;this.status = status;// 设置 应用实例信息 数据一致setIsDirty();return prev;}return null;}InstanceInfoReplicator#onDemandUpdate()
,实现代码如下:// InstanceInfoReplicator.javapublic boolean onDemandUpdate() {if (rateLimiter.acquire(burstSize, allowedRatePerMinute)) { // 限流相关,跳过scheduler.submit( new Runnable() {@Overridepublic void run() {logger.debug( "Executing on-demand update of local InstanceInfo");// 取消任务Future latestPeriodic = scheduledPeriodicRef.get();if (latestPeriodic != null && !latestPeriodic.isDone()) {logger.debug( "Canceling the latest scheduled update, it will be rescheduled at the end of on demand update");latestPeriodic.cancel( false);}// 再次调用InstanceInfoReplicator. this.run();}});return true;} else {logger.warn( "Ignoring onDemand update due to rate limiter");return false;}}- 调用
Future#cancel(false)
方法,取消定时任务,避免无用的注册。 - 调用
InstanceInfoReplicator#run()
方法,发起注册。
- 调用
2.2 刷新应用实例信息
调用 DiscoveryClient#refreshInstanceInfo()
方法,刷新应用实例信息。此处可能导致应用实例信息数据不一致,实现代码如下:
void refreshInstanceInfo() {
// 刷新 数据中心信息
applicationInfoManager.refreshDataCenterInfoIfRequired();
// 刷新 租约信息
applicationInfoManager.refreshLeaseInfoIfRequired();
// 健康检查
InstanceStatus status;
try {
status = getHealthCheckHandler().getStatus(instanceInfo.getStatus());
} catch (Exception e) {
logger.warn( "Exception from healthcheckHandler.getStatus, setting status to DOWN", e);
status = InstanceStatus.DOWN;
}
if ( null != status) {
applicationInfoManager.setInstanceStatus(status);
}
}
|
调用
ApplicationInfoManager#refreshDataCenterInfoIfRequired()
方法,刷新数据中心相关信息,实现代码如下:// ApplicationInfoManager.javapublic void refreshDataCenterInfoIfRequired() {// hostnameString existingAddress = instanceInfo.getHostName();String newAddress;if (config instanceof RefreshableInstanceConfig) {// Refresh data center info, and return up to date addressnewAddress = ((RefreshableInstanceConfig) config).resolveDefaultAddress( true);} else {newAddress = config.getHostName( true);}// ipString newIp = config.getIpAddress();if (newAddress != null && !newAddress.equals(existingAddress)) {logger.warn( "The address changed from : {} => {}", existingAddress, newAddress);// :( in the legacy code here the builder is acting as a mutator.// This is hard to fix as this same instanceInfo instance is referenced elsewhere.// We will most likely re-write the client at sometime so not fixing for now.InstanceInfo.Builder builder = new InstanceInfo.Builder(instanceInfo);builder.setHostName(newAddress) // hostname.setIPAddr(newIp) // ip.setDataCenterInfo(config.getDataCenterInfo()); // dataCenterInfoinstanceInfo.setIsDirty();}}public abstract class AbstractInstanceConfig implements EurekaInstanceConfig {private static final Pair<String, String> hostInfo = getHostInfo();@Overridepublic String getHostName(boolean refresh) {return hostInfo.second();}@Overridepublic String getIpAddress() {return hostInfo.first();}private static Pair<String, String> getHostInfo() {Pair<String, String> pair;try {InetAddress localHost = InetAddress.getLocalHost();pair = new Pair<String, String>(localHost.getHostAddress(), localHost.getHostName());} catch (UnknownHostException e) {logger.error( "Cannot get host info", e);pair = new Pair<String, String>( "", "");}return pair;}}- 关注应用实例信息的
hostName
、ipAddr
、dataCenterInfo
属性的变化。 - 一般情况下,我们使用的是非 RefreshableInstanceConfig 实现的配置类( 一般是 MyDataCenterInstanceConfig ),因为
AbstractInstanceConfig.hostInfo
是静态属性,即使本机修改了 IP 等信息,Eureka-Client 进程也不会感知到。TODO[0022]:看下springcloud 的实现
- 关注应用实例信息的
调用
ApplicationInfoManager#refreshLeaseInfoIfRequired()
方法,刷新租约相关信息,实现代码如下:public void refreshLeaseInfoIfRequired() {LeaseInfo leaseInfo = instanceInfo.getLeaseInfo();if (leaseInfo == null) {return;}int currentLeaseDuration = config.getLeaseExpirationDurationInSeconds();int currentLeaseRenewal = config.getLeaseRenewalIntervalInSeconds();if (leaseInfo.getDurationInSecs() != currentLeaseDuration // 租约过期时间 改变|| leaseInfo.getRenewalIntervalInSecs() != currentLeaseRenewal) { // 租约续约频率 改变LeaseInfo newLeaseInfo = LeaseInfo.Builder.newBuilder().setRenewalIntervalInSecs(currentLeaseRenewal).setDurationInSecs(currentLeaseDuration).build();instanceInfo.setLeaseInfo(newLeaseInfo);instanceInfo.setIsDirty();}}- 关注应用实例信息的
renewalIntervalInSecs
、durationInSecs
属性的变化。
- 关注应用实例信息的
调用
HealthCheckHandler#getStatus()
方法,健康检查。这里先暂时跳过,我们在TODO[0004]:健康检查 详细解析。
2.3 发起注册应用实例
调用 DiscoveryClient#register()
方法,Eureka-Client 向 Eureka-Server 注册应用实例,实现代码如下:
// DiscoveryClient.java
boolean register() throws Throwable {
logger.info(PREFIX + appPathIdentifier + ": registering service...");
EurekaHttpResponse<Void> httpResponse;
try {
httpResponse = eurekaTransport.registrationClient.register(instanceInfo);
} catch (Exception e) {
logger.warn( "{} - registration failed {}", PREFIX + appPathIdentifier, e.getMessage(), e);
throw e;
}
if (logger.isInfoEnabled()) {
logger.info( "{} - registration status: {}", PREFIX + appPathIdentifier, httpResponse.getStatusCode());
}
return httpResponse.getStatusCode() == 204;
}
// AbstractJerseyEurekaHttpClient.java
@Override
public EurekaHttpResponse<Void> register(InstanceInfo info) {
String urlPath = "apps/" + info.getAppName();
ClientResponse response = null;
try {
Builder resourceBuilder = jerseyClient.resource(serviceUrl).path(urlPath).getRequestBuilder();
addExtraHeaders(resourceBuilder);
response = resourceBuilder
.header( "Accept-Encoding", "gzip")
.type(MediaType.APPLICATION_JSON_TYPE)
.accept(MediaType.APPLICATION_JSON)
.post(ClientResponse.class, info);
return anEurekaHttpResponse(response.getStatus()).headers(headersOf(response)).build();
} finally {
if (logger.isDebugEnabled()) {
logger.debug( "Jersey HTTP POST {}/{} with instance {}; statusCode={}", serviceUrl, urlPath, info.getId(),
response == null ? "N/A" : response.getStatus());
}
if (response != null) {
response.close();
}
}
}
|
- 调用
AbstractJerseyEurekaHttpClient#register(...)
方法,POST
请求 Eureka-Server 的apps/${APP_NAME}
接口,参数为 InstanceInfo ,实现注册实例信息的注册。
3. Eureka-Server 接收注册
3.1 接收注册请求
com.netflix.eureka.resources.ApplicationResource
,处理单个应用的请求操作的 Resource ( Controller )。
注册应用实例信息的请求,映射 ApplicationResource#addInstance()
方法,实现代码如下:
@Produces({ "application/xml", "application/json"})
public class ApplicationResource {
@POST
@Consumes({ "application/json", "application/xml"})
public Response addInstance(InstanceInfo info,
@HeaderParam(PeerEurekaNode.HEADER_REPLICATION) String isReplication) {
// 校验参数是否合法
logger.debug( "Registering instance {} (replication={})", info.getId(), isReplication);
// validate that the instanceinfo contains all the necessary required fields
if (isBlank(info.getId())) {
return Response.status( 400).entity( "Missing instanceId").build();
} else if (isBlank(info.getHostName())) {
return Response.status( 400).entity( "Missing hostname").build();
} else if (isBlank(info.getIPAddr())) {
return Response.status( 400).entity( "Missing ip address").build();
} else if (isBlank(info.getAppName())) {
return Response.status( 400).entity( "Missing appName").build();
} else if (!appName.equals(info.getAppName())) {
return Response.status( 400).entity( "Mismatched appName, expecting " + appName + " but was " + info.getAppName()).build();
} else if (info.getDataCenterInfo() == null) {
return Response.status( 400).entity( "Missing dataCenterInfo").build();
} else if (info.getDataCenterInfo().getName() == null) {
return Response.status( 400).entity( "Missing dataCenterInfo Name").build();
}
// AWS 相关,跳过
// handle cases where clients may be registering with bad DataCenterInfo with missing data
DataCenterInfo dataCenterInfo = info.getDataCenterInfo();
if (dataCenterInfo instanceof UniqueIdentifier) {
String dataCenterInfoId = ((UniqueIdentifier) dataCenterInfo).getId();
if (isBlank(dataCenterInfoId)) {
boolean experimental = "true".equalsIgnoreCase(serverConfig.getExperimental( "registration.validation.dataCenterInfoId"));
if (experimental) {
String entity = "DataCenterInfo of type " + dataCenterInfo.getClass() + " must contain a valid id";
return Response.status( 400).entity(entity).build();
} else if (dataCenterInfo instanceof AmazonInfo) {
AmazonInfo amazonInfo = (AmazonInfo) dataCenterInfo;
String effectiveId = amazonInfo.get(AmazonInfo.MetaDataKey.instanceId);
if (effectiveId == null) {
amazonInfo.getMetadata().put(AmazonInfo.MetaDataKey.instanceId.getName(), info.getId());
}
} else {
logger.warn( "Registering DataCenterInfo of type {} without an appropriate id", dataCenterInfo.getClass());
}
}
}
// 注册应用实例信息
registry.register(info, "true".equals(isReplication));
// 返回 204 成功
return Response.status( 204).build(); // 204 to be backwards compatible
}
}
|
- 请求头
isReplication
参数,和 Eureka-Server 集群复制相关,暂时跳过。 调用
PeerAwareInstanceRegistryImpl#register(...)
方法,注册应用实例信息。实现代码如下:@Overridepublic void register(final InstanceInfo info, final boolean isReplication) {// 租约过期时间int leaseDuration = Lease.DEFAULT_DURATION_IN_SECS;if (info.getLeaseInfo() != null && info.getLeaseInfo().getDurationInSecs() > 0) {leaseDuration = info.getLeaseInfo().getDurationInSecs();}// 注册应用实例信息super.register(info, leaseDuration, isReplication);// Eureka-Server 复制replicateToPeers(Action.Register, info.getAppName(), info.getId(), info, null, isReplication);}- 调用父类
AbstractInstanceRegistry#register(...)
方法,注册应用实例信息。
- 调用父类
3.2 Lease
在看具体的注册应用实例信息的逻辑之前,我们先来看下 com.netflix.eureka.lease.Lease
,租约。实现代码如下:
public class Lease<T> {
/**
* 实体
*/
private T holder;
/**
* 注册时间戳
*/
private long registrationTimestamp;
/**
* 开始服务时间戳
*/
private long serviceUpTimestamp;
/**
* 取消注册时间戳
*/
private long evictionTimestamp;
/**
* 最后更新时间戳
*/
// Make it volatile so that the expiration task would see this quicker
private volatile long lastUpdateTimestamp;
/**
* 租约持续时长,单位:毫秒
*/
private long duration;
public Lease(T r, int durationInSecs) {
holder = r;
registrationTimestamp = System.currentTimeMillis();
lastUpdateTimestamp = registrationTimestamp;
duration = (durationInSecs * 1000);
}
}
|
holder
属性,租约的持有者。在 Eureka-Server 里,暂时只有 InstanceInfo 使用。registrationTimestamp
属性,注册( 创建 )租约时间戳。在构造方法里可以看租约对象的创建时间戳即为注册租约时间戳。serviceUpTimestamp
属性,开始服务时间戳。注册应用实例信息会使用到它如下两个方法,实现代码如下:public void serviceUp() {if (serviceUpTimestamp == 0) { // 第一次有效serviceUpTimestamp = System.currentTimeMillis();}}public void setServiceUpTimestamp(long serviceUpTimestamp) {this.serviceUpTimestamp = serviceUpTimestamp;}lastUpdatedTimestamp
属性,最后更新租约时间戳。每次续租时,更新该时间戳。注册应用实例信息会使用到它如下方法,实现代码如下:public void setLastUpdatedTimestamp() {this.lastUpdatedTimestamp = System.currentTimeMillis();}duration
属性,租约持续时间,单位:毫秒。当租约过久未续租,即当前时间 -lastUpdatedTimestamp
>duration
时,租约过期。evictionTimestamp
属性,租约过期时间戳。
3.3 注册应用实例信息
调用 AbstractInstanceRegistry#register(...)
方法,注册应用实例信息,实现代码如下:
1: public void register(InstanceInfo registrant, int leaseDuration, boolean isReplication) {
2: try {
3: // 获取读锁
4: read.lock();
5: Map<String, Lease<InstanceInfo>> gMap = registry.get(registrant.getAppName());
6: // 增加 注册次数 到 监控
7: REGISTER.increment(isReplication);
8: // 获得 应用实例信息 对应的 租约
9: if (gMap == null) {
10: final ConcurrentHashMap<String, Lease<InstanceInfo>> gNewMap = new ConcurrentHashMap<String, Lease<InstanceInfo>>();
11: gMap = registry.putIfAbsent(registrant.getAppName(), gNewMap); // 添加 应用
12: if (gMap == null) { // 添加 应用 成功
13: gMap = gNewMap;
14: }
15: }
16: Lease<InstanceInfo> existingLease = gMap.get(registrant.getId());
17: // Retain the last dirty timestamp without overwriting it, if there is already a lease
18: 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
19: Long existingLastDirtyTimestamp = existingLease.getHolder().getLastDirtyTimestamp(); // Server 注册的 InstanceInfo
20: Long registrationLastDirtyTimestamp = registrant.getLastDirtyTimestamp(); // Client 请求的 InstanceInfo
21: logger.debug( "Existing lease found (existing={}, provided={}", existingLastDirtyTimestamp, registrationLastDirtyTimestamp);
22:
23: // this is a > instead of a >= because if the timestamps are equal, we still take the remote transmitted
24: // InstanceInfo instead of the server local copy.
25: if (existingLastDirtyTimestamp > registrationLastDirtyTimestamp) {
26: logger.warn( "There is an existing lease and the existing lease's dirty timestamp {} is greater" +
27: " than the one that is being registered {}", existingLastDirtyTimestamp, registrationLastDirtyTimestamp);
28: logger.warn( "Using the existing instanceInfo instead of the new instanceInfo as the registrant");
29: registrant = existingLease.getHolder();
30: }
31: } else {
32: // The lease does not exist and hence it is a new registration
33: // 【自我保护机制】增加 `numberOfRenewsPerMinThreshold` 、`expectedNumberOfRenewsPerMin`
34: synchronized (lock) {
35: if ( this.expectedNumberOfRenewsPerMin > 0) {
36: // Since the client wants to cancel it, reduce the threshold
37: // (1
38: // for 30 seconds, 2 for a minute)
39: this.expectedNumberOfRenewsPerMin = this.expectedNumberOfRenewsPerMin + 2;
40: this.numberOfRenewsPerMinThreshold =
41: ( int) ( this.expectedNumberOfRenewsPerMin * serverConfig.getRenewalPercentThreshold());
42: }
43: }
44: logger.debug( "No previous lease information found; it is new registration");
45: }
46: // 创建 租约
47: Lease<InstanceInfo> lease = new Lease<InstanceInfo>(registrant, leaseDuration);
48: if (existingLease != null) { // 若租约已存在,设置 租约的开始服务的时间戳
49: lease.setServiceUpTimestamp(existingLease.getServiceUpTimestamp());
50: }
51: // 添加到 租约映射
52: gMap.put(registrant.getId(), lease);
53: // 添加到 最近注册的调试队列
54: synchronized (recentRegisteredQueue) {
55: recentRegisteredQueue.add( new Pair<Long, String>(
56: System.currentTimeMillis(),
57: registrant.getAppName() + "(" + registrant.getId() + ")"));
58: }
59: // 添加到 应用实例覆盖状态映射(Eureka-Server 初始化使用)
60: // This is where the initial state transfer of overridden status happens
61: if (!InstanceStatus.UNKNOWN.equals(registrant.getOverriddenStatus())) {
62: logger.debug( "Found overridden status {} for instance {}. Checking to see if needs to be add to the "
63: + "overrides", registrant.getOverriddenStatus(), registrant.getId());
64: if (!overriddenInstanceStatusMap.containsKey(registrant.getId())) {
65: logger.info( "Not found overridden id {} and hence adding it", registrant.getId());
66: overriddenInstanceStatusMap.put(registrant.getId(), registrant.getOverriddenStatus());
67: }
68: }
69: InstanceStatus overriddenStatusFromMap = overriddenInstanceStatusMap.get(registrant.getId());
70: if (overriddenStatusFromMap != null) {
71: logger.info( "Storing overridden status {} from map", overriddenStatusFromMap);
72: registrant.setOverriddenStatus(overriddenStatusFromMap);
73: }
74:
75: // 获得应用实例最终状态,并设置应用实例的状态
76: // Set the status based on the overridden status rules
77: InstanceStatus overriddenInstanceStatus = getOverriddenInstanceStatus(registrant, existingLease, isReplication);
78: registrant.setStatusWithoutDirty(overriddenInstanceStatus);
79:
80: // 设置 租约的开始服务的时间戳(只有第一次有效)
81: // If the lease is registered with UP status, set lease service up timestamp
82: if (InstanceStatus.UP.equals(registrant.getStatus())) {
83: lease.serviceUp();
84: }
85: // 设置 应用实例信息的操作类型 为 添加
86: registrant.setActionType(ActionType.ADDED);
87: // 添加到 最近租约变更记录队列
88: recentlyChangedQueue.add( new RecentlyChangedItem(lease));
89: // 设置 租约的最后更新时间戳
90: registrant.setLastUpdatedTimestamp();
91: // 设置 响应缓存 过期
92: invalidateCache(registrant.getAppName(), registrant.getVIPAddress(), registrant.getSecureVipAddress());
93: logger.info( "Registered instance {}/{} with status {} (replication={})",
94: registrant.getAppName(), registrant.getId(), registrant.getStatus(), isReplication);
95: } finally {
96: // 释放锁
97: read.unlock();
98: }
99: }
|
- 第 3 行 :添加到应用实例覆盖状态映射,在 《Eureka 源码解析 —— Eureka-Server 集群同步》 详细解析。
- 第 6 至 7 行 :增加注册次数到监控。配合 Netflix Servo 实现监控信息采集。
第 5 至 16 行 :获得应用实例信息对应的租约。
registry
实现代码如下:/*** 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>>>();第 17 至 30 行 :当租约已存在,判断 Server 已存在的 InstanceInfo 的
lastDirtyTimestamp
是否大于( 不包括等于 ) Client 请求的 InstanceInfo ,若是,使用 Server 的 InstanceInfo 进行替代。- 第 31 至 44 行 :增加
numberOfRenewsPerMinThreshold
、expectedNumberOfRenewsPerMin
,自我保护机制相关,在 《Eureka 源码解析 —— 应用实例注册发现(四)之自我保护机制》 有详细解析。 - 第 45 至 52 行 :创建租约,并添加到租约映射(
registry
)。 第 53 至 58 行 :添加到最近注册的调试队列(
recentRegisteredQueue
),用于 Eureka-Server 运维界面的显示,无实际业务逻辑使用。实现代码如下:/*** 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;/*** 循环队列** @param <E> 泛型*/private class CircularQueue<E> extends ConcurrentLinkedQueue<E> {/*** 队列大小*/private int size = 0;public CircularQueue(int size) {this.size = size;}@Overridepublic boolean add(E e) {this.makeSpaceIfNotAvailable();return super.add(e);}/*** 保证空间足够** 当空间不够时,移除首元素*/private void makeSpaceIfNotAvailable() {if ( this.size() == size) {this.remove();}}public boolean offer(E e) {this.makeSpaceIfNotAvailable();return super.offer(e);}}第 59 至 68 行 :添加到应用实例覆盖状态映射,在 《Eureka 源码解析 —— Eureka-Server 集群同步》 详细解析。
- 第 69 至 73 行 :设置应用实例的覆盖状态(
overridestatus
),避免注册应用实例后,丢失覆盖状态。在《应用实例注册发现 (八)之覆盖状态》详细解析。 - 第 75 至 78 行 : 获得应用实例最终状态,并设置应用实例的状态。在《应用实例注册发现 (八)之覆盖状态》详细解析。
- 第 80 至 84 行 :设置租约的开始服务的时间戳( 只有第一次有效 )。
第 85 至 88 行 :设置应用实例信息的操作类型为添加,并添加到最近租约变更记录队列(
recentlyChangedQueue
)。recentlyChangedQueue
用于注册信息的增量获取,在《应用实例注册发现 (七)之增量获取》详细解析。实现代码如下:/*** 最近租约变更记录队列*/private ConcurrentLinkedQueue<RecentlyChangedItem> recentlyChangedQueue = new ConcurrentLinkedQueue<RecentlyChangedItem>();第 89 至 90 行 :设置租约的最后更新时间戳。
- 第 91 至 92 行 :设置响应缓存( ResponseCache )过期,在《Eureka 源码解析 —— 应用实例注册发现 (六)之全量获取》详细解析。
- 第 96 至 97 行 :释放锁。
666. 彩蛋
嘿嘿,蛮嗨的,比起前面几篇写配置相关的文章来说。
胖友,分享我的公众号( 芋道源码 ) 给你的胖友可好?