content: /*
   * Copyright 1999-2018 Alibaba Group Holding Ltd.
   *
   * 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.alibaba.nacos.istio.common;
  
  import com.alibaba.nacos.api.naming.pojo.ServiceInfo;
  import com.alibaba.nacos.common.notify.NotifyCenter;
  import com.alibaba.nacos.common.notify.listener.SmartSubscriber;
  import com.alibaba.nacos.istio.misc.IstioConfig;
  import com.alibaba.nacos.istio.model.IstioService;
  import com.alibaba.nacos.istio.model.PushRequest;
  import com.alibaba.nacos.istio.util.IstioCrdUtil;
  import com.alibaba.nacos.naming.core.v2.ServiceManager;
  import com.alibaba.nacos.naming.core.v2.event.client.ClientOperationEvent;
  import com.alibaba.nacos.naming.core.v2.event.metadata.InfoChangeEvent;
  import com.alibaba.nacos.naming.core.v2.event.publisher.NamingEventPublisherFactory;
  import com.alibaba.nacos.naming.core.v2.index.ServiceStorage;
  import com.alibaba.nacos.naming.core.v2.pojo.Service;
  import org.springframework.beans.factory.annotation.Autowired;
  
  import java.util.HashMap;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Map;
  import java.util.Queue;
  import java.util.Set;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentLinkedQueue;
  import java.util.concurrent.ExecutionException;
  import java.util.concurrent.Future;
  
  import static com.alibaba.nacos.istio.util.IstioExecutor.cycleDebounce;
  import static com.alibaba.nacos.istio.util.IstioExecutor.debouncePushChange;
  
  /**
   * @author special.fy
   */
  @org.springframework.stereotype.Service
  public class NacosServiceInfoResourceWatcher extends SmartSubscriber {
  
      private final Map<String, IstioService> serviceInfoMap = new ConcurrentHashMap<>(16);
      
      private final Queue<PushRequest> pushRequestQueue = new ConcurrentLinkedQueue<>();
      
      private boolean isInitial = true;
      
      @Autowired
      private IstioConfig istioConfig;
      
      @Autowired
      private ServiceStorage serviceStorage;
  
      @Autowired
      private EventProcessor eventProcessor;
      
      public NacosServiceInfoResourceWatcher() {
          NotifyCenter.registerSubscriber(this, NamingEventPublisherFactory.getInstance());
      }
      
      public Map<String, IstioService> snapshot() {
          return new HashMap<>(serviceInfoMap);
      }
      
      @Override
      public List<Class<? extends com.alibaba.nacos.common.notify.Event>> subscribeTypes() {
          List<Class<? extends com.alibaba.nacos.common.notify.Event>> result = new LinkedList<>();
          result.add(ClientOperationEvent.ClientRegisterServiceEvent.class);
          result.add(ClientOperationEvent.ClientDeregisterServiceEvent.class);
          result.add(InfoChangeEvent.ServiceInfoChangeEvent.class);
          result.add(InfoChangeEvent.InstanceInfoChangeEvent.class);
          return result;
      }
      
      public void onEvent(com.alibaba.nacos.common.notify.Event event) {
          if (isInitial) {
              init();
              isInitial = false;
              cycleDebounce(new ToNotify());
          }
          
          if (event instanceof ClientOperationEvent.ClientRegisterServiceEvent) {
              // If service changed, push to all subscribers.
              ClientOperationEvent.ClientRegisterServiceEvent clientRegisterServiceEvent = (ClientOperationEvent.ClientRegisterServiceEvent) event;
              Service service = clientRegisterServiceEvent.getService();
              String serviceName = IstioCrdUtil.buildServiceName(service);
              
              IstioService old = serviceInfoMap.get(serviceName);
              PushRequest pushRequest;
              
              boolean full = update(serviceName, service);
              if (old != null) {
                  pushRequest = new PushRequest(serviceName, full);
              } else {
                  pushRequest = new PushRequest(serviceName, true);
              }
              pushRequestQueue.add(pushRequest);
          } else if (event instanceof ClientOperationEvent.ClientDeregisterServiceEvent) {
              ClientOperationEvent.ClientDeregisterServiceEvent clientDeregisterServiceEvent = (ClientOperationEvent
                      .ClientDeregisterServiceEvent) event;
              Service service = clientDeregisterServiceEvent.getService();
              String serviceName = IstioCrdUtil.buildServiceName(service);
              PushRequest pushRequest;
      
              boolean full = update(serviceName, service);
              if (serviceStorage.getPushData(service).ipCount() <= 0) {
                  pushRequest = new PushRequest(serviceName, true);
                  serviceInfoMap.remove(serviceName);
              } else {
                  pushRequest = new PushRequest(serviceName, full);
              }
              pushRequestQueue.add(pushRequest);
          } else if (event instanceof InfoChangeEvent.ServiceInfoChangeEvent) {
              InfoChangeEvent.ServiceInfoChangeEvent serviceInfoChangeEvent = (InfoChangeEvent.ServiceInfoChangeEvent) event;
              Service service = serviceInfoChangeEvent.getService();
              String serviceName = IstioCrdUtil.buildServiceName(service);
              PushRequest pushRequest = new PushRequest(serviceName, true);
              
              update(serviceName, service);
              pushRequestQueue.add(pushRequest);
              
          } else if (event instanceof InfoChangeEvent.InstanceInfoChangeEvent) {
              InfoChangeEvent.InstanceInfoChangeEvent instanceInfoChangeEvent = (InfoChangeEvent.InstanceInfoChangeEvent) event;
              Service service = instanceInfoChangeEvent.getService();
              String serviceName = IstioCrdUtil.buildServiceName(service);
      
              boolean full = update(serviceName, service);
              PushRequest pushRequest = new PushRequest(serviceName, full);
              pushRequestQueue.add(pushRequest);
          }
      }
      
      private void init() {
          Set<String> namespaces =  ServiceManager.getInstance().getAllNamespaces();
          for (String namespace : namespaces) {
              Set<Service> services = ServiceManager.getInstance().getSingletons(namespace);
              if (services.isEmpty()) {
                  continue;
              }
          
              for (Service service : services) {
                  String serviceName = IstioCrdUtil.buildServiceName(service);
                  ServiceInfo serviceInfo = serviceStorage.getPushData(service);
                  if (!serviceInfo.isValid()) {
                      continue;
                  }
                  serviceInfoMap.put(serviceName, new IstioService(service, serviceInfo));
                  pushRequestQueue.add(new PushRequest(serviceName, true));
              }
          }
      }
      
      private boolean update(String serviceName, Service service) {
          ServiceInfo serviceInfo = serviceStorage.getPushData(service);
          if (!serviceInfo.isValid()) {
              serviceInfoMap.remove(serviceName);
              return true;
          }
          
          IstioService old = serviceInfoMap.get(serviceName);
          if (old != null) {
              serviceInfoMap.put(serviceName, new IstioService(service, serviceInfo, old));
          } else {
              serviceInfoMap.put(serviceName, new IstioService(service, serviceInfo));
          }
          return false;
      }
      
      private class ToNotify implements Runnable {
          @Override
          public void run() {
              while (true) {
                  if (pushRequestQueue.size() > 0) {
                      PushRequest updatePush;
                      Future<PushRequest> futureUpdate = debouncePushChange(new Debounce(pushRequestQueue, istioConfig));
      
                      try {
                          updatePush = futureUpdate.get();
                          if (updatePush != null) {
                              eventProcessor.notify(updatePush);
                          }
                      } catch (InterruptedException | ExecutionException e) {
                          throw new RuntimeException(e);
                      }
                  }
              }
          }
      }
  }