Nacos源码—8.Nacos升级gRPC分析六

大纲

7.服务端对服务实例进行健康检查

8.服务下线如何注销注册表和客户端等信息

9.事件驱动架构源码分析

一.处理ClientChangedEvent事件

也就是同步数据到集群节点：

public class DistroClientDataProcessor extends SmartSubscriber implements DistroDataStorage, DistroDataProcessor {
    ...
    @Override
    public void onEvent(Event event) {
        ...
        if (event instanceof ClientEvent.ClientVerifyFailedEvent) {
            syncToVerifyFailedServer((ClientEvent.ClientVerifyFailedEvent) event);
        } else {
            syncToAllServer((ClientEvent) event);
        }
    }

    private void syncToAllServer(ClientEvent event) {
        Client client = event.getClient();
        //Only ephemeral data sync by Distro, persist client should sync by raft.
        //临时实例使用Distro协议，持久化实例使用Raft协议
        //ClientManager.isResponsibleClient()方法，判断只有该client的责任节点才能进行集群数据同步
        if (null == client || !client.isEphemeral() || !clientManager.isResponsibleClient(client)) {
            return;
        }
        if (event instanceof ClientEvent.ClientDisconnectEvent) {
            //如果event是客户端注销实例时需要进行集群节点同步的事件
            DistroKey distroKey = new DistroKey(client.getClientId(), TYPE);
            distroProtocol.sync(distroKey, DataOperation.DELETE);
        } else if (event instanceof ClientEvent.ClientChangedEvent) {
            //如果event是客户端注册实例时需要进行集群节点同步的事件
            DistroKey distroKey = new DistroKey(client.getClientId(), TYPE);
            distroProtocol.sync(distroKey, DataOperation.CHANGE);
        }
    }
    ...
}

@Component
public class DistroProtocol {
    private final ServerMemberManager memberManager;
    private final DistroTaskEngineHolder distroTaskEngineHolder;
    ...

    //Start to sync by configured delay.
    public void sync(DistroKey distroKey, DataOperation action) {
        sync(distroKey, action, DistroConfig.getInstance().getSyncDelayMillis());
    }

    //Start to sync data to all remote server.
    public void sync(DistroKey distroKey, DataOperation action, long delay) {
        //遍历集群中除自身节点外的其他节点
        for (Member each : memberManager.allMembersWithoutSelf()) {
            syncToTarget(distroKey, action, each.getAddress(), delay);
        }
    }

    //Start to sync to target server.
    public void syncToTarget(DistroKey distroKey, DataOperation action, String targetServer, long delay) {
        //先把要同步的集群节点targetServer包装成DistroKey对象
        DistroKey distroKeyWithTarget = new DistroKey(distroKey.getResourceKey(), distroKey.getResourceType(), targetServer);
        //然后根据DistroKey对象创建DistroDelayTask任务
        DistroDelayTask distroDelayTask = new DistroDelayTask(distroKeyWithTarget, action, delay);
        //接着调用NacosDelayTaskExecuteEngine.addTask()方法
        //往延迟任务执行引擎DistroDelayTaskExecuteEngine中添加延迟任务DistroDelayTask
        distroTaskEngineHolder.getDelayTaskExecuteEngine().addTask(distroKeyWithTarget, distroDelayTask);
        if (Loggers.DISTRO.isDebugEnabled()) {
            Loggers.DISTRO.debug("[DISTRO-SCHEDULE] {} to {}", distroKey, targetServer);
        }
    }
    ...
}

二.处理ClientDeregisterServiceEvent事件

也就是移除注册表 + 订阅表的服务实例：

@Component
public class ClientServiceIndexesManager extends SmartSubscriber {
    //注册表(服务提供者)，一个Service服务对象，对应多个服务实例的clientId
    private final ConcurrentMap<Service, Set<String>> publisherIndexes = new ConcurrentHashMap<>();

    //订阅者列表(服务消费者)，一个Service服务对象，对应多个订阅者的cl