package org.apache.helix.manager.zk;
   
   /*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.
   */
  
  import java.util.concurrent.BlockingQueue;
  import java.util.concurrent.LinkedBlockingQueue;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import org.I0Itec.zkclient.exception.ZkInterruptedException;
  import org.apache.log4j.Logger;
  
  // copy from ZkEventThread
  public class ZkCacheEventThread extends Thread
  {
  
    private static final Logger          LOG      =
                                                      Logger.getLogger(ZkCacheEventThread.class);
    private final BlockingQueue<ZkCacheEvent> _events  = new LinkedBlockingQueue<ZkCacheEvent>();
    private static AtomicInteger         _eventId = new AtomicInteger(0);
  
    static abstract class ZkCacheEvent
    {
  
      private final String _description;
  
      public ZkCacheEvent(String description)
      {
        _description = description;
      }
  
      public abstract void run() throws Exception;
  
      @Override
      public String toString()
      {
        return "ZkCacheEvent[" + _description + "]";
      }
    }
  
    ZkCacheEventThread(String name)
    {
      setDaemon(true);
      setName("ZkCache-EventThread-" + getId() + "-" + name);
    }
  
    @Override
    public void run()
    {
      LOG.info("Starting ZkCache event thread.");
      try
      {
        while (!isInterrupted())
        {
          ZkCacheEvent zkEvent = _events.take();
          int eventId = _eventId.incrementAndGet();
          LOG.debug("Delivering event #" + eventId + " " + zkEvent);
          try
          {
            zkEvent.run();
          }
          catch (InterruptedException e)
          {
            interrupt();
          }
          catch (ZkInterruptedException e)
          {
            interrupt();
          }
          catch (Throwable e)
          {
            LOG.error("Error handling event " + zkEvent, e);
          }
          LOG.debug("Delivering event #" + eventId + " done");
        }
      }
      catch (InterruptedException e)
      {
        LOG.info("Terminate ZkClient event thread.");
      }
    }
  
    public void send(ZkCacheEvent event)
   {
     if (!isInterrupted())
     {
       LOG.debug("New event: " + event);
       _events.add(event);
     }
   }
 }