//
   //  ========================================================================
   //  Copyright (c) 1995-2013 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.io;
  
  import java.nio.channels.CancelledKeyException;
  import java.nio.channels.SelectionKey;
  import java.nio.channels.SocketChannel;
  import java.util.concurrent.atomic.AtomicBoolean;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import org.eclipse.jetty.io.SelectorManager.ManagedSelector;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  import org.eclipse.jetty.util.thread.Scheduler;
  
  /**
   * An ChannelEndpoint that can be scheduled by {@link SelectorManager}.
   */
  public class SelectChannelEndPoint extends ChannelEndPoint implements SelectorManager.SelectableEndPoint
  {
      public static final Logger LOG = Log.getLogger(SelectChannelEndPoint.class);
  
      private final Runnable _updateTask = new Runnable()
      {
          @Override
          public void run()
          {
              try
              {
                  if (getChannel().isOpen())
                  {
                      int oldInterestOps = _key.interestOps();
                      int newInterestOps = _interestOps.get();
                      if (newInterestOps != oldInterestOps)
                          setKeyInterests(oldInterestOps, newInterestOps);
                  }
              }
              catch (CancelledKeyException x)
              {
                  LOG.debug("Ignoring key update for concurrently closed channel {}", this);
                  close();
              }
              catch (Exception x)
              {
                  LOG.warn("Ignoring key update for " + this, x);
                  close();
              }
          }
      };
  
      /**
       * true if {@link ManagedSelector#destroyEndPoint(EndPoint)} has not been called
       */
      private final AtomicBoolean _open = new AtomicBoolean();
      private final SelectorManager.ManagedSelector _selector;
      private final SelectionKey _key;
      /**
       * The desired value for {@link SelectionKey#interestOps()}
       */
      private final AtomicInteger _interestOps = new AtomicInteger();
  
      public SelectChannelEndPoint(SocketChannel channel, ManagedSelector selector, SelectionKey key, Scheduler scheduler, long idleTimeout)
      {
          super(scheduler,channel);
          _selector = selector;
          _key = key;
          setIdleTimeout(idleTimeout);
      }
  
      @Override
      protected boolean needsFill()
      {
          updateLocalInterests(SelectionKey.OP_READ, true);
          return false;
      }
  
      @Override
      protected void onIncompleteFlush()
      {
          updateLocalInterests(SelectionKey.OP_WRITE, true);
      }
  
      @Override
     public void onSelected()
     {
         assert _selector.isSelectorThread();
         int oldInterestOps = _key.interestOps();
         int readyOps = _key.readyOps();
         int newInterestOps = oldInterestOps & ~readyOps;
         setKeyInterests(oldInterestOps, newInterestOps);
         updateLocalInterests(readyOps, false);
         if (_key.isReadable())
             getFillInterest().fillable();
         if (_key.isWritable())
             getWriteFlusher().completeWrite();
     }
 
 
     private void updateLocalInterests(int operation, boolean add)
     {
         while (true)
         {
             int oldInterestOps = _interestOps.get();
             int newInterestOps;
             if (add)
                 newInterestOps = oldInterestOps | operation;
             else
                 newInterestOps = oldInterestOps & ~operation;
 
             if (isInputShutdown())
                 newInterestOps &= ~SelectionKey.OP_READ;
             if (isOutputShutdown())
                 newInterestOps &= ~SelectionKey.OP_WRITE;
 
             if (newInterestOps != oldInterestOps)
             {
                 if (_interestOps.compareAndSet(oldInterestOps, newInterestOps))
                 {
                     LOG.debug("Local interests updated {} -> {} for {}", oldInterestOps, newInterestOps, this);
                     _selector.submit(_updateTask);
                 }
                 else
                 {
                     LOG.debug("Local interests update conflict: now {}, was {}, attempted {} for {}", _interestOps.get(), oldInterestOps, newInterestOps, this);
                     continue;
                 }
             }
             else
             {
                 LOG.debug("Ignoring local interests update {} -> {} for {}", oldInterestOps, newInterestOps, this);
             }
             break;
         }
     }
 
 
     private void setKeyInterests(int oldInterestOps, int newInterestOps)
     {
         assert _selector.isSelectorThread();
         LOG.debug("Key interests updated {} -> {}", oldInterestOps, newInterestOps);
         _key.interestOps(newInterestOps);
     }
 
     @Override
     public void close()
     {
         if (_open.compareAndSet(true, false))
         {
             super.close();
             _selector.destroyEndPoint(this);
         }
     }
 
     @Override
     public boolean isOpen()
     {
         // We cannot rely on super.isOpen(), because there is a race between calls to close() and isOpen():
         // a thread may call close(), which flips the boolean but has not yet called super.close(), and
         // another thread calls isOpen() which would return true - wrong - if based on super.isOpen().
         return _open.get();
     }
 
     @Override
     public void onOpen()
     {
         if (_open.compareAndSet(false, true))
             super.onOpen();
     }
 
     @Override
     public String toString()
     {
         // Do NOT use synchronized (this)
         // because it's very easy to deadlock when debugging is enabled.
         // We do a best effort to print the right toString() and that's it.
         try
         {
             boolean valid = _key!=null && _key.isValid();
             int keyInterests = valid ? _key.interestOps() : -1;
             int keyReadiness = valid ? _key.readyOps() : -1;
             return String.format("%s{io=%d,kio=%d,kro=%d}",
                     super.toString(),
                     _interestOps.get(),
                     keyInterests,
                     keyReadiness);
         }
         catch (CancelledKeyException x)
         {
             return String.format("%s{io=%s,kio=-2,kro=-2}", super.toString(), _interestOps.get());
         }
     }
 }