content: /*
   * Copyright 1999-2022 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.istio.misc.IstioConfig;
  import com.alibaba.nacos.istio.model.PushRequest;
  
  import java.util.Date;
  import java.util.Queue;
  import java.util.Timer;
  import java.util.TimerTask;
  import java.util.concurrent.Callable;
  
  /**.
   * @author RocketEngine26
   * @date 2022/8/20 9:05
   */
  public class Debounce implements Callable<PushRequest> {
      private Date startDebounce;
      
      private Date lastConfigUpdateTime;
      
      private final IstioConfig istioConfig;
      
      private final Queue<PushRequest> pushRequestQueue;
      
      private PushRequest pushRequest;
      
      private int debouncedEvents = 0;
      
      private boolean free = true;
      
      private boolean flag = false;
      
      public Debounce(Queue<PushRequest> pushRequestQueue, IstioConfig istioConfig) {
          this.pushRequestQueue = pushRequestQueue;
          this.istioConfig = istioConfig;
      }
      
      @Override
      public PushRequest call() throws Exception {
          while (true) {
              if (flag) {
                  return pushRequest;
              }
              
              PushRequest otherRequest = pushRequestQueue.poll();
              
              if (otherRequest != null) {
                  lastConfigUpdateTime = new Date();
                  if (debouncedEvents == 0) {
                      startDebounce = lastConfigUpdateTime;
                      pushRequest = otherRequest;
                      new Timer().schedule(new TimerTask() {
                          @Override
                          public void run() {
                              if (free) {
                                  try {
                                      pushWorker();
                                  } catch (Exception e) {
                                      throw new RuntimeException(e);
                                  }
                              }
                          }
                      }, istioConfig.getDebounceAfter());
                  } else {
                      merge(otherRequest);
                  }
                  debouncedEvents++;
              }
          }
      }
      
      private void pushWorker() {
          long eventDelay = System.currentTimeMillis() - startDebounce.getTime();
          long quietTime = System.currentTimeMillis() - lastConfigUpdateTime.getTime();
          
          if (eventDelay > istioConfig.getDebounceMax() || quietTime > istioConfig.getDebounceAfter()) {
              if (pushRequest != null) {
                  free = false;
                  flag = true;
                  debouncedEvents = 0;
              }
          } else {
              new Timer().schedule(new TimerTask() {
                  @Override
                  public void run() {
                      if (free) {
                          try {
                              pushWorker();
                          } catch (Exception e) {
                              throw new RuntimeException(e);
                          }
                      }
                  }
              }, istioConfig.getDebounceAfter() - quietTime);
          }
      }
      
      private void merge(PushRequest otherRequest) {
          pushRequest.getReason().addAll(otherRequest.getReason());
          pushRequest.setFull(pushRequest.isFull() || otherRequest.isFull());
      }
  }
  