04、源码解析 Eureka 服务注册源码解析
Eureka服务注册源码解析
客户端注册逻辑源码解析
1.1 看一下 debug 后服务端的堆栈调用
register:183, AbstractInstanceRegistry (com.netflix.eureka.registry)
register:419, PeerAwareInstanceRegistryImpl (com.netflix.eureka.registry)
register:92, InstanceRegistry (org.springframework.cloud.netflix.eureka.server)
addInstance:185, ApplicationResource (com.netflix.eureka.resources)
因为之前已经分析过，jersey 请求最终都会到 Resource 下去做具体的操作
1、看堆栈调用可以知道是调用到 ApplicationResource 的 addInstance 方法
2、最终就是PeerAwareInstanceRegistryImpl(内部会调用父类的 register)
3、集群节点同步(如果有多个 eureka 节点就会把这个节点的数据同步过去)
1.2 服务调用流程图
1.3 register(服务注册方法)
看一个最终调用的 register 方法，就是 com.netflix.eureka.registry.AbstractInstanceRegistry#register
public void register(InstanceInfo registrant, int leaseDuration, boolean isReplication) {
try {
read.lock();
// 从注册表中获取 Lease 信息
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());
// 这里就是判断一下 lease 是否存在，存在的话进入 if 中
if (existingLease != null && (existingLease.getHolder() != null)) {
// 这里就是对比一下时间戳，如果新的时间戳小于已存在的时间戳，说明并不是最新的，应该还是使用已存在的实例信息
Long existingLastDirtyTimestamp = existingLease.getHolder().getLastDirtyTimestamp();
Long registrationLastDirtyTimestamp = registrant.getLastDirtyTimestamp();
// 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) {
// 省略了 log 打印的信息
registrant = existingLease.getHolder();
}
} else {
// 这里说明 lease 不存在，说明是新的注册
// The lease does not exist and hence it is a new registration
// 这里使用 synchronized 控制多线程并发操作
synchronized (lock) {
if (this.expectedNumberOfRenewsPerMin > 0) {
// 新的节点注册，期望心跳数= 原来的期望心跳数 + 2
this.expectedNumberOfRenewsPerMin = this.expectedNumberOfRenewsPerMin + 2;
// 心跳数阈值 = 期望心跳数 * 0.85
this.numberOfRenewsPerMinThreshold =
(int) (this.expectedNumberOfRenewsPerMin * serverConfig.getRenewalPercentThreshold());
}
}
logger.debug("No previous lease information found; it is new registration");
}
Lease<InstanceInfo> lease = new Lease<InstanceInfo>(registrant, leaseDuration);
if (existingLease != null) {
// 实例启动的时间，是不变的，如果 existingLease 不为空，就把 serviceUpTimestamp 赋值为原来的
lease.setServiceUpTimestamp(existingLease.getServiceUpTimestamp());
}
gMap.put(registrant.getId(), lease);
// 最近注册的 queue 添加一下实例信息
synchronized (recentRegisteredQueue) {
recentRegisteredQueue.add(new Pair<Long, String>(
System.currentTimeMillis(),
registrant.getAppName() + "(" + registrant.getId() + ")"));
}
// 状态覆盖的一些操作
// 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);
}
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())) {
// 设置启动时间(第 1 次调用有效，后续的调用不会生效)
lease.serviceUp();
}
/**
* 1、设置事件类型(register 就是 ADDED，如果 cancel[下线] 就是 DELETED)
* 2、添加到最近更改的队列中去
* 3、更新最后一次更新的时间
*/
registrant.setActionType(ActionType.ADDED);
recentlyChangedQueue.add(new RecentlyChangedItem(lease));
registrant.setLastUpdatedTimestamp();
// 失效缓存(可能实例信息变更了，所以把原来的缓存失效掉)
invalidateCache(registrant.getAppName(), registrant.getVIPAddress(), registrant.getSecureVipAddress());
logger.info("Registered instance {}/{} with status {} (replication={})",
registrant.getAppName(), registrant.getId(), registrant.getStatus(), isReplication);
} finally {
read.unlock();
}
}
1.4 replicateToPeers(信息复制到其他 peer 中)
Replicates all eureka actions to peer eureka nodes except for replication traffic to this node.
将所有 eureka 操作复制到其他的 eureka 节点，复制到此节点的流量除外(排除自己)
private void replicateToPeers(Action action, String appName, String id,
InstanceInfo info /* optional */,
InstanceStatus newStatus /* optional */, boolean isReplication) {
Stopwatch tracer = action.getTimer().start();
try {
// 如果是 replication，则把上一分钟的 replication 操作+1(numberOfReplicationsLastMin是一个 MeasureRate，主要用于统计信息)
if (isReplication) {
numberOfReplicationsLastMin.increment();
}
// 如果已经复制过了，就不要再复制了
// If it is a replication already, do not replicate again as this will create a poison replication
if (peerEurekaNodes == Collections.EMPTY_LIST || isReplication) {
return;
}
// 这里就是执行同步操作到 eureka 其他节点
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();
}
}
1.4.1 replicateInstanceActionsToPeers(复制实例变化到其他的 eureka 节点)
private void replicateInstanceActionsToPeers(Action action, String appName,
String id, InstanceInfo info, InstanceStatus newStatus,
PeerEurekaNode node) {
try {
InstanceInfo infoFromRegistry = null;
CurrentRequestVersion.set(Version.V2);
// 根据 action 去做不同的操作
switch (action) {
// 取消
case Cancel:
node.cancel(appName, id);
break;
// 心跳
case Heartbeat:
InstanceStatus overriddenStatus = overriddenInstanceStatusMap.get(id);
infoFromRegistry = getInstanceByAppAndId(appName, id, false);
node.heartbeat(appName, id, infoFromRegistry, overriddenStatus, false);
break;
// 注册
case Register:
node.register(info);
break;
// 状态变更
case StatusUpdate:
infoFromRegistry = getInstanceByAppAndId(appName, id, false);
node.statusUpdate(appName, id, newStatus, infoFromRegistry);
break;
//删除状态覆盖
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);
}
}
1.4.1.1 node.register
public void register(final InstanceInfo info) throws Exception {
long expiryTime = System.currentTimeMillis() + getLeaseRenewalOf(info);
// 这里是一个很重要的点通过把任务给一个 batchingDispatcher 来处理任务。
batchingDispatcher.process(
taskId("register", info),
new InstanceReplicationTask(targetHost, Action.Register, info, null, true) {
public EurekaHttpResponse<Void> execute() {
return replicationClient.register(info);
}
},
expiryTime
);
}
我们先来简单了解一下 TaskDispatcher，后面集群同步的时候会重点去剖析一下内部的 3 层队列实现
/**
* 1、TaskDispatcher 从客户端获取任务
* 2、然后委派这些任务给多个 Worker(这些 worker 可以配置)
* 3、任务可以单个执行也可以批量执行
* 4、只有不过期的任务才会执行，如果新的任务 id 与之前的重复，则旧的被丢弃
* 5、按需延迟分配给 Worker，保证数据始终是最新的，并且不会发生旧的任务处理。
*/
/**
* Task dispatcher takes task from clients, and delegates their execution to a configurable number of workers.
* The task can be processed one at a time or in batches. Only non-expired tasks are executed, and if a newer
* task with the same id is scheduled for execution, the old one is deleted. Lazy dispatch of work (only on demand)
* to workers, guarantees that data are always up to date, and no stale task processing takes place.
* <h3>Task processor</h3>
* A client of this component must provide an implementation of {@LinkTaskProcessor} interface, which will do
* the actual work of task processing. This implementation must be thread safe, as it is called concurrently by
* multiple threads.
* <h3>Execution modes</h3>
* To create non batched executor call {@LinkTaskDispatchers#createNonBatchingTaskDispatcher(String, int, int, long, long, TaskProcessor)}
* method. Batched executor is created by {@LinkTaskDispatchers#createBatchingTaskDispatcher(String, int, int, int, long, long, TaskProcessor)}.
*
* @author Tomasz Bak
*/
public interface TaskDispatcher<ID, T> {
void process(ID id, T task, long expiryTime);
void shutdown();
}
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