在分析了EurekaServer启动的流程后,我们来分析一下Eureka注册服务的流程。先来介绍一个类ApplicationInfoManager,这个类是用来管理应用实例信息的。在DiscoveryClient初始化的时候,会向EurekaServer注册服务,
调用refreshInstanceInfo()方法，刷新应用实例信息。
调用register() 方法，Eureka-Client 向 Eureka-Server 注册应用实例。
-
调用 ScheduledExecutorService的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。
而在ApplicationInfoManager有一个内部类,其实是一个接口StatusChangeListener,监听注册节点状态的变化,并发送通知。
业务里，调用 ApplicationInfoManager的setInstanceStatus方法，设置应用实例信息的状态，从而通知 InstanceInfoReplicator的onDemandUpdate方法的调用。看下具体的实现public 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); } } } }
InstanceInfoReplicator的onDemandUpdate方法
public boolean onDemandUpdate() {
if (rateLimiter.acquire(burstSize, allowedRatePerMinute)) { // 限流相关，跳过
scheduler.submit(new Runnable() {
@Override
public 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 DiscoveryClient的refreshInstanceInfo方法，刷新实例信息。看下具体的实现
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的refreshDataCenterInfoIfRequired方法，刷新数据中心相关信息，看下具体的实现
public void refreshDataCenterInfoIfRequired() {
// hostname
String existingAddress = instanceInfo.getHostName();
String newAddress;
if (config instanceof RefreshableInstanceConfig) {
// Refresh data center info, and return up to date address
newAddress = ((RefreshableInstanceConfig) config).resolveDefaultAddress(true);
} else {
newAddress = config.getHostName(true);
}
// ip
String 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()); // dataCenterInfo
instanceInfo.setIsDirty();
}
}
调用 ApplicationInfoManager的refreshLeaseInfoIfRequired方法，刷新租约相关信息，看下具体的实现
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();
}
}
调用 DiscoveryClient的register方法，Eureka-Client 向 Eureka-Server 注册应用实例，看下具体的实现
boolean register() throws Throwable {
logger.info(PREFIX + appPathIdentifier + ": registering service...");
EurekaHttpResponse 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;
}
调用AbstractJerseyEurekaHttpClient的register方法发送请求
public EurekaHttpResponse register(InstanceInfo info) {
// 设置 请求地址
String urlPath = "apps/" + info.getAppName();
ClientResponse response = null;
try {
Builder resourceBuilder = jerseyClient.resource(serviceUrl).path(urlPath).getRequestBuilder();
// 设置 请求头
addExtraHeaders(resourceBuilder);
// 请求 Eureka-Server
response = resourceBuilder
.header("Accept-Encoding", "gzip") // GZIP
.type(MediaType.APPLICATION_JSON_TYPE) // 请求参数格式 JSON
.accept(MediaType.APPLICATION_JSON) // 响应结果格式 JSON
.post(ClientResponse.class, info); // 请求参数
// 创建 EurekaHttpResponse
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();
}
}
}
EurekaServer通过ApplicationResource的addInstance方法注册实例信息的请求
@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
}
调用 PeerAwareInstanceRegistryImpl的register方法，注册应用实例信息，看下具体的实现
public 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);
}
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。先来看看Lease类都有哪些属性
/**
* 操作
*/
enum Action {
/**
* 注册
*/
Register,
/**
* 取消注册
*/
Cancel,
/**
* 续约
*/
Renew
};
/**
* 默认租约持续时长，单位：秒
*/
public static final int DEFAULT_DURATION_IN_SECS = 90;
/**
* 实体
*/
private T holder;
/**
* 取消注册时间戳
*/
private long evictionTimestamp;
/**
* 注册时间戳
*/
private long registrationTimestamp;
/**
* 开始服务时间戳
*/
private long serviceUpTimestamp;
/**
* 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;
调用 AbstractInstanceRegistry的register方法，注册应用实例信息
public void register(InstanceInfo registrant, int leaseDuration, boolean isReplication) {
try {
// 获取读锁
read.lock();
Map> 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> gNewMap = new ConcurrentHashMap>();
gMap = registry.putIfAbsent(registrant.getAppName(), gNewMap); // 添加 应用
if (gMap == null) { // 添加 应用 成功
gMap = gNewMap;
}
}
Lease 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 lease = new Lease(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(
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();
}
}
这里有几个队列，一个是最近注册的调试队列，一个是最近租约变更记录队列。设置租约的最近更新时间，以及响应缓存周期，EurekaServer的注册实例信息就完成了。
ApplicationInfoManager的分析就到这里了。