//
   //  ========================================================================
   //  Copyright (c) 1995-2016 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.io.IOException;
  import java.net.InetSocketAddress;
  import java.net.Socket;
  import java.net.SocketAddress;
  import java.nio.channels.SelectionKey;
  import java.nio.channels.ServerSocketChannel;
  import java.nio.channels.SocketChannel;
  import java.util.concurrent.Executor;
  
  import org.eclipse.jetty.util.TypeUtil;
  import org.eclipse.jetty.util.component.AbstractLifeCycle;
  import org.eclipse.jetty.util.component.ContainerLifeCycle;
  import org.eclipse.jetty.util.component.Dumpable;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  import org.eclipse.jetty.util.thread.Scheduler;
  
  /**
   * <p>{@link SelectorManager} manages a number of {@link ManagedSelector}s that
   * simplify the non-blocking primitives provided by the JVM via the {@code java.nio} package.</p>
   * <p>{@link SelectorManager} subclasses implement methods to return protocol-specific
   * {@link EndPoint}s and {@link Connection}s.</p>
   */
  public abstract class SelectorManager extends AbstractLifeCycle implements Dumpable
  {
      public static final int DEFAULT_CONNECT_TIMEOUT = 15000;
      protected static final Logger LOG = Log.getLogger(SelectorManager.class);
  
      private final Executor executor;
      private final Scheduler scheduler;
      private final ManagedSelector[] _selectors;
      private long _connectTimeout = DEFAULT_CONNECT_TIMEOUT;
      private long _selectorIndex;
  
      protected SelectorManager(Executor executor, Scheduler scheduler)
      {
          this(executor, scheduler, (Runtime.getRuntime().availableProcessors() + 1) / 2);
      }
  
      protected SelectorManager(Executor executor, Scheduler scheduler, int selectors)
      {
          if (selectors <= 0)
              throw new IllegalArgumentException("No selectors");
          this.executor = executor;
          this.scheduler = scheduler;
          _selectors = new ManagedSelector[selectors];
      }
  
      public Executor getExecutor()
      {
          return executor;
      }
  
      public Scheduler getScheduler()
      {
          return scheduler;
      }
  
      /**
       * Get the connect timeout
       *
       * @return the connect timeout (in milliseconds)
       */
      public long getConnectTimeout()
      {
          return _connectTimeout;
      }
  
      /**
       * Set the connect timeout (in milliseconds)
       *
       * @param milliseconds the number of milliseconds for the timeout
       */
      public void setConnectTimeout(long milliseconds)
      {
          _connectTimeout = milliseconds;
      }
  
      /**
      * @return the selector priority delta
      * @deprecated not implemented
      */
     @Deprecated
     public int getSelectorPriorityDelta()
     {
         return 0;
     }
 
     /**
      * @param selectorPriorityDelta the selector priority delta
      * @deprecated not implemented
      */
     @Deprecated
     public void setSelectorPriorityDelta(int selectorPriorityDelta)
     {
     }
 
     /**
      * Executes the given task in a different thread.
      *
      * @param task the task to execute
      */
     protected void execute(Runnable task)
     {
         executor.execute(task);
     }
 
     /**
      * @return the number of selectors in use
      */
     public int getSelectorCount()
     {
         return _selectors.length;
     }
 
     private ManagedSelector chooseSelector(SocketChannel channel)
     {
         // Ideally we would like to have all connections from the same client end
         // up on the same selector (to try to avoid smearing the data from a single 
         // client over all cores), but because of proxies, the remote address may not
         // really be the client - so we have to hedge our bets to ensure that all
         // channels don't end up on the one selector for a proxy.
         ManagedSelector candidate1 = null;
         if (channel != null)
         {
             try
             {
                 SocketAddress remote = channel.getRemoteAddress();
                 if (remote instanceof InetSocketAddress)
                 {
                     byte[] addr = ((InetSocketAddress)remote).getAddress().getAddress();
                     if (addr != null)
                     {
                         int s = addr[addr.length - 1] & 0xFF;
                         candidate1 = _selectors[s % getSelectorCount()];
                     }
                 }
             }
             catch (IOException x)
             {
                 LOG.ignore(x);
             }
         }
 
         // The ++ increment here is not atomic, but it does not matter,
         // so long as the value changes sometimes, then connections will
         // be distributed over the available selectors.
         long s = _selectorIndex++;
         int index = (int)(s % getSelectorCount());
         ManagedSelector candidate2 = _selectors[index];
 
         if (candidate1 == null || candidate1.size() >= candidate2.size() * 2)
             return candidate2;
         return candidate1;
     }
 
     /**
      * <p>Registers a channel to perform a non-blocking connect.</p>
      * <p>The channel must be set in non-blocking mode, {@link SocketChannel#connect(SocketAddress)}
      * must be called prior to calling this method, and the connect operation must not be completed
      * (the return value of {@link SocketChannel#connect(SocketAddress)} must be false).</p>
      *
      * @param channel    the channel to register
      * @param attachment the attachment object
      * @see #accept(SocketChannel, Object)
      */
     public void connect(SocketChannel channel, Object attachment)
     {
         ManagedSelector set = chooseSelector(channel);
         set.submit(set.new Connect(channel, attachment));
     }
 
     /**
      * @param channel the channel to accept
      * @see #accept(SocketChannel, Object)
      */
     public void accept(SocketChannel channel)
     {
         accept(channel, null);
     }
 
     /**
      * <p>Registers a channel to perform non-blocking read/write operations.</p>
      * <p>This method is called just after a channel has been accepted by {@link ServerSocketChannel#accept()},
      * or just after having performed a blocking connect via {@link Socket#connect(SocketAddress, int)}, or
      * just after a non-blocking connect via {@link SocketChannel#connect(SocketAddress)} that completed
      * successfully.</p>
      *
      * @param channel    the channel to register
      * @param attachment the attachment object
      */
     public void accept(SocketChannel channel, Object attachment)
     {
         final ManagedSelector selector = chooseSelector(channel);
         selector.submit(selector.new Accept(channel, attachment));
     }
 
     /**
      * <p>Registers a server channel for accept operations.
      * When a {@link SocketChannel} is accepted from the given {@link ServerSocketChannel}
      * then the {@link #accepted(SocketChannel)} method is called, which must be
      * overridden by a derivation of this class to handle the accepted channel
      *
      * @param server the server channel to register
      */
     public void acceptor(ServerSocketChannel server)
     {
         final ManagedSelector selector = chooseSelector(null);
         selector.submit(selector.new Acceptor(server));
     }
 
     /**
      * Callback method when a channel is accepted from the {@link ServerSocketChannel}
      * passed to {@link #acceptor(ServerSocketChannel)}.
      * The default impl throws an {@link UnsupportedOperationException}, so it must
      * be overridden by subclasses if a server channel is provided.
      *
      * @param channel the
      * @throws IOException if unable to accept channel
      */
     protected void accepted(SocketChannel channel) throws IOException
     {
         throw new UnsupportedOperationException();
     }
 
     @Override
     protected void doStart() throws Exception
     {
         super.doStart();
         for (int i = 0; i < _selectors.length; i++)
         {
             ManagedSelector selector = newSelector(i);
             _selectors[i] = selector;
             selector.start();
             execute(selector);
         }
     }
 
     /**
      * <p>Factory method for {@link ManagedSelector}.</p>
      *
      * @param id an identifier for the {@link ManagedSelector to create}
      * @return a new {@link ManagedSelector}
      */
     protected ManagedSelector newSelector(int id)
     {
         return new ManagedSelector(this, id);
     }
 
     @Override
     protected void doStop() throws Exception
     {
         for (ManagedSelector selector : _selectors)
             selector.stop();
         super.doStop();
     }
 
     /**
      * <p>Callback method invoked when an endpoint is opened.</p>
      *
      * @param endpoint the endpoint being opened
      */
     protected void endPointOpened(EndPoint endpoint)
     {
         endpoint.onOpen();
     }
 
     /**
      * <p>Callback method invoked when an endpoint is closed.</p>
      *
      * @param endpoint the endpoint being closed
      */
     protected void endPointClosed(EndPoint endpoint)
     {
         endpoint.onClose();
     }
 
     /**
      * <p>Callback method invoked when a connection is opened.</p>
      *
      * @param connection the connection just opened
      */
     public void connectionOpened(Connection connection)
     {
         try
         {
             connection.onOpen();
         }
         catch (Throwable x)
         {
             if (isRunning())
                 LOG.warn("Exception while notifying connection " + connection, x);
             else
                 LOG.debug("Exception while notifying connection " + connection, x);
         }
     }
 
     /**
      * <p>Callback method invoked when a connection is closed.</p>
      *
      * @param connection the connection just closed
      */
     public void connectionClosed(Connection connection)
     {
         try
         {
             connection.onClose();
         }
         catch (Throwable x)
         {
             LOG.debug("Exception while notifying connection " + connection, x);
         }
     }
 
     protected boolean finishConnect(SocketChannel channel) throws IOException
     {
         return channel.finishConnect();
     }
 
     /**
      * <p>Callback method invoked when a non-blocking connect cannot be completed.</p>
      * <p>By default it just logs with level warning.</p>
      *
      * @param channel    the channel that attempted the connect
      * @param ex         the exception that caused the connect to fail
      * @param attachment the attachment object associated at registration
      */
     protected void connectionFailed(SocketChannel channel, Throwable ex, Object attachment)
     {
         LOG.warn(String.format("%s - %s", channel, attachment), ex);
     }
 
     /**
      * <p>Factory method to create {@link EndPoint}.</p>
      * <p>This method is invoked as a result of the registration of a channel via {@link #connect(SocketChannel, Object)}
      * or {@link #accept(SocketChannel)}.</p>
      *
      * @param channel      the channel associated to the endpoint
      * @param selector     the selector the channel is registered to
      * @param selectionKey the selection key
      * @return a new endpoint
      * @throws IOException if the endPoint cannot be created
      * @see #newConnection(SocketChannel, EndPoint, Object)
      */
     protected abstract EndPoint newEndPoint(SocketChannel channel, ManagedSelector selector, SelectionKey selectionKey) throws IOException;
 
     /**
      * <p>Factory method to create {@link Connection}.</p>
      *
      * @param channel    the channel associated to the connection
      * @param endpoint   the endpoint
      * @param attachment the attachment
      * @return a new connection
      * @throws IOException if unable to create new connection
      * @see #newEndPoint(SocketChannel, ManagedSelector, SelectionKey)
      */
     public abstract Connection newConnection(SocketChannel channel, EndPoint endpoint, Object attachment) throws IOException;
 
     @Override
     public String dump()
     {
         return ContainerLifeCycle.dump(this);
     }
 
     @Override
     public void dump(Appendable out, String indent) throws IOException
     {
         ContainerLifeCycle.dumpObject(out, this);
         ContainerLifeCycle.dump(out, indent, TypeUtil.asList(_selectors));
     }
 }