package us.codecraft.webmagic.samples.scheduler;
   
   import us.codecraft.webmagic.Request;
   import us.codecraft.webmagic.Task;
   import us.codecraft.webmagic.scheduler.PriorityScheduler;
   
   /**
    * @author code4crafter@gmail.com
    */
  public class LevelLimitScheduler extends PriorityScheduler {
  
      private int levelLimit = 3;
  
      public LevelLimitScheduler(int levelLimit) {
          this.levelLimit = levelLimit;
      }
  
      @Override
      public synchronized void push(Request request, Task task) {
          if (((Integer) request.getExtra("_level")) <= levelLimit) {
              super.push(request, task);
          }
      }
  }