// ========================================================================
   // Copyright (c) 2003-2009 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.server.nio;
  
  import java.io.IOException;
  import java.net.InetSocketAddress;
  import java.net.Socket;
  import java.nio.channels.SelectionKey;
  import java.nio.channels.ServerSocketChannel;
  import java.nio.channels.SocketChannel;
  
  import org.eclipse.jetty.continuation.Continuation;
  import org.eclipse.jetty.io.AsyncEndPoint;
  import org.eclipse.jetty.io.ConnectedEndPoint;
  import org.eclipse.jetty.io.Connection;
  import org.eclipse.jetty.io.EndPoint;
  import org.eclipse.jetty.io.nio.AsyncConnection;
  import org.eclipse.jetty.io.nio.SelectChannelEndPoint;
  import org.eclipse.jetty.io.nio.SelectorManager;
  import org.eclipse.jetty.io.nio.SelectorManager.SelectSet;
  import org.eclipse.jetty.server.AsyncHttpConnection;
  import org.eclipse.jetty.server.Request;
  import org.eclipse.jetty.util.thread.ThreadPool;
  
  /* ------------------------------------------------------------------------------- */
  /**
   * Selecting NIO connector.
   * <p>
   * This connector uses efficient NIO buffers with a non blocking threading model. Direct NIO buffers
   * are used and threads are only allocated to connections with requests. Synchronization is used to
   * simulate blocking for the servlet API, and any unflushed content at the end of request handling
   * is written asynchronously.
   * </p>
   * <p>
   * This connector is best used when there are a many connections that have idle periods.
   * </p>
   * <p>
   * When used with {@link org.eclipse.jetty.continuation.Continuation}, threadless waits are supported.
   * If a filter or servlet returns after calling {@link Continuation#suspend()} or when a
   * runtime exception is thrown from a call to {@link Continuation#undispatch()}, Jetty will
   * will not send a response to the client. Instead the thread is released and the Continuation is
   * placed on the timer queue. If the Continuation timeout expires, or it's
   * resume method is called, then the request is again allocated a thread and the request is retried.
   * The limitation of this approach is that request content is not available on the retried request,
   * thus if possible it should be read after the continuation or saved as a request attribute or as the
   * associated object of the Continuation instance.
   * </p>
   *
   * @org.apache.xbean.XBean element="nioConnector" description="Creates an NIO based socket connector"
   */
  public class SelectChannelConnector extends AbstractNIOConnector
  {
      protected ServerSocketChannel _acceptChannel;
      private int _lowResourcesConnections;
      private int _lowResourcesMaxIdleTime;
      private int _localPort=-1;
  
      private final SelectorManager _manager = new ConnectorSelectorManager();
  
      /* ------------------------------------------------------------------------------- */
      /**
       * Constructor.
       *
       */
      public SelectChannelConnector()
      {
          _manager.setMaxIdleTime(getMaxIdleTime());
          addBean(_manager,true);
          setAcceptors(Math.max(1,(Runtime.getRuntime().availableProcessors()+3)/4));
      }
  
      /* ------------------------------------------------------------ */
      @Override
      public void accept(int acceptorID) throws IOException
      {
          ServerSocketChannel server;
          synchronized(this)
          {
              server = _acceptChannel;
          }
  
          if (server!=null && server.isOpen() && _manager.isStarted())
          {
              SocketChannel channel = server.accept();
              channel.configureBlocking(false);
              Socket socket = channel.socket();
              configure(socket);
              _manager.register(channel);
         }
     }
 
     /* ------------------------------------------------------------ */
     public void close() throws IOException
     {
         synchronized(this)
         {
             if (_acceptChannel != null)
             {
                 removeBean(_acceptChannel);
                 if (_acceptChannel.isOpen())
                     _acceptChannel.close();
             }
             _acceptChannel = null;
             _localPort=-2;
         }
     }
 
     /* ------------------------------------------------------------------------------- */
     @Override
     public void customize(EndPoint endpoint, Request request) throws IOException
     {
         request.setTimeStamp(System.currentTimeMillis());
         endpoint.setMaxIdleTime(_maxIdleTime);
         super.customize(endpoint, request);
     }
 
     /* ------------------------------------------------------------------------------- */
     @Override
     public void persist(EndPoint endpoint) throws IOException
     {
         AsyncEndPoint aEndp = ((AsyncEndPoint)endpoint);
         aEndp.setCheckForIdle(true);
         super.persist(endpoint);
     }
 
     /* ------------------------------------------------------------ */
     public SelectorManager getSelectorManager()
     {
         return _manager;
     }
 
     /* ------------------------------------------------------------ */
     public synchronized Object getConnection()
     {
         return _acceptChannel;
     }
 
     /* ------------------------------------------------------------------------------- */
     public int getLocalPort()
     {
         synchronized(this)
         {
             return _localPort;
         }
     }
 
     /* ------------------------------------------------------------ */
     public void open() throws IOException
     {
         synchronized(this)
         {
             if (_acceptChannel == null)
             {
                 // Create a new server socket
                 _acceptChannel = ServerSocketChannel.open();
                 // Set to blocking mode
                 _acceptChannel.configureBlocking(true);
 
                 // Bind the server socket to the local host and port
                 _acceptChannel.socket().setReuseAddress(getReuseAddress());
                 InetSocketAddress addr = getHost()==null?new InetSocketAddress(getPort()):new InetSocketAddress(getHost(),getPort());
                 _acceptChannel.socket().bind(addr,getAcceptQueueSize());
 
                 _localPort=_acceptChannel.socket().getLocalPort();
                 if (_localPort<=0)
                     throw new IOException("Server channel not bound");
 
                 addBean(_acceptChannel);
             }
         }
     }
 
     /* ------------------------------------------------------------ */
     @Override
     public void setMaxIdleTime(int maxIdleTime)
     {
         _manager.setMaxIdleTime(maxIdleTime);
         super.setMaxIdleTime(maxIdleTime);
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @return the lowResourcesConnections
      */
     public int getLowResourcesConnections()
     {
         return _lowResourcesConnections;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * Set the number of connections, which if exceeded places this manager in low resources state.
      * This is not an exact measure as the connection count is averaged over the select sets.
      * @param lowResourcesConnections the number of connections
      * @see #setLowResourcesMaxIdleTime(int)
      */
     public void setLowResourcesConnections(int lowResourcesConnections)
     {
         _lowResourcesConnections=lowResourcesConnections;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @return the lowResourcesMaxIdleTime
      */
     @Override
     public int getLowResourcesMaxIdleTime()
     {
         return _lowResourcesMaxIdleTime;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * Set the period in ms that a connection is allowed to be idle when this there are more
      * than {@link #getLowResourcesConnections()} connections.  This allows the server to rapidly close idle connections
      * in order to gracefully handle high load situations.
      * @param lowResourcesMaxIdleTime the period in ms that a connection is allowed to be idle when resources are low.
      * @see #setMaxIdleTime(int)
      */
     @Override
     public void setLowResourcesMaxIdleTime(int lowResourcesMaxIdleTime)
     {
         _lowResourcesMaxIdleTime=lowResourcesMaxIdleTime;
         super.setLowResourcesMaxIdleTime(lowResourcesMaxIdleTime);
     }
 
 
     /* ------------------------------------------------------------ */
     /*
      * @see org.eclipse.jetty.server.server.AbstractConnector#doStart()
      */
     @Override
     protected void doStart() throws Exception
     {
         _manager.setSelectSets(getAcceptors());
         _manager.setMaxIdleTime(getMaxIdleTime());
         _manager.setLowResourcesConnections(getLowResourcesConnections());
         _manager.setLowResourcesMaxIdleTime(getLowResourcesMaxIdleTime());
 
         super.doStart();
     }
 
     /* ------------------------------------------------------------ */
     protected SelectChannelEndPoint newEndPoint(SocketChannel channel, SelectSet selectSet, SelectionKey key) throws IOException
     {
         SelectChannelEndPoint endp= new SelectChannelEndPoint(channel,selectSet,key, SelectChannelConnector.this._maxIdleTime);
         endp.setConnection(selectSet.getManager().newConnection(channel,endp, key.attachment()));
         return endp;
     }
 
     /* ------------------------------------------------------------------------------- */
     protected void endPointClosed(SelectChannelEndPoint endpoint)
     {
         connectionClosed(endpoint.getConnection());
     }
 
     /* ------------------------------------------------------------------------------- */
     protected AsyncConnection newConnection(SocketChannel channel,final AsyncEndPoint endpoint)
     {
         return new AsyncHttpConnection(SelectChannelConnector.this,endpoint,getServer());
     }
 
 
     /* ------------------------------------------------------------ */
     /* ------------------------------------------------------------ */
     /* ------------------------------------------------------------ */
     private final class ConnectorSelectorManager extends SelectorManager
     {
         @Override
         public boolean dispatch(Runnable task)
         {
             ThreadPool pool=getThreadPool();
             if (pool==null)
                 pool=getServer().getThreadPool();
             return pool.dispatch(task);
         }
 
         @Override
         protected void endPointClosed(final SelectChannelEndPoint endpoint)
         {
             SelectChannelConnector.this.endPointClosed(endpoint);
         }
 
         @Override
         protected void endPointOpened(SelectChannelEndPoint endpoint)
         {
             // TODO handle max connections and low resources
             connectionOpened(endpoint.getConnection());
         }
 
         @Override
         protected void endPointUpgraded(ConnectedEndPoint endpoint, Connection oldConnection)
         {
             connectionUpgraded(oldConnection,endpoint.getConnection());
         }
 
         @Override
         public AsyncConnection newConnection(SocketChannel channel,AsyncEndPoint endpoint, Object attachment)
         {
             return SelectChannelConnector.this.newConnection(channel,endpoint);
         }
 
         @Override
         protected SelectChannelEndPoint newEndPoint(SocketChannel channel, SelectSet selectSet, SelectionKey sKey) throws IOException
         {
             return SelectChannelConnector.this.newEndPoint(channel,selectSet,sKey);
         }
     }
 }