/*

  * 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.

  */

 package org.apache.giraph.comm;

 import org.apache.hadoop.io.Writable;

 import org.apache.hadoop.io.WritableComparable;

 import org.apache.log4j.Logger;

 import org.jboss.netty.buffer.ChannelBuffer;

 import org.jboss.netty.buffer.ChannelBuffers;

 import org.jboss.netty.channel.ChannelHandlerContext;

 import org.jboss.netty.channel.ChannelStateEvent;

 import org.jboss.netty.channel.ExceptionEvent;

 import org.jboss.netty.channel.MessageEvent;

 import org.jboss.netty.channel.SimpleChannelUpstreamHandler;

 /**

  * Generic handler of requests.

  *

  * @param <I> Vertex id

  * @param <V> Vertex data

  * @param <E> Edge data

  * @param <M> Message data

  */

 @SuppressWarnings("rawtypes")

 public class RequestServerHandler<I extends WritableComparable,

     V extends Writable, E extends Writable,

     M extends Writable> extends SimpleChannelUpstreamHandler {

   /** Class logger */

   private static final Logger LOG =

       Logger.getLogger(RequestServerHandler.class);

   /** Data that can be accessed for handling requests */

   private final ServerData<I, V, E, M> serverData;

   /**

    * Constructor with external server data

    *

    * @param serverData Data held by the server

    */

   public RequestServerHandler(ServerData<I, V, E, M> serverData) {

     this.serverData = serverData;

   }

   @Override

   public void messageReceived(

       ChannelHandlerContext ctx, MessageEvent e) {

     if (LOG.isDebugEnabled()) {

       LOG.debug("messageReceived: Got " + e.getMessage().getClass());

     }

     @SuppressWarnings("unchecked")

     WritableRequest<I, V, E, M> writableRequest =

         (WritableRequest<I, V, E, M>) e.getMessage();

     writableRequest.doRequest(serverData);

     // Send the success response with the request id

     ChannelBuffer buffer = ChannelBuffers.directBuffer(9);

     buffer.writeLong(writableRequest.getRequestId());

     buffer.writeByte(0);

     e.getChannel().write(buffer);

   }

   @Override

   public void channelConnected(ChannelHandlerContext ctx,

                                ChannelStateEvent e) throws Exception {

     if (LOG.isDebugEnabled()) {

       LOG.debug("channelConnected: Connected the channel on " +

           ctx.getChannel().getRemoteAddress());

     }

   }

   @Override

   public void channelClosed(ChannelHandlerContext ctx,

                             ChannelStateEvent e) throws Exception {

     if (LOG.isDebugEnabled()) {

       LOG.debug("channelClosed: Closed the channel on " +

           ctx.getChannel().getRemoteAddress());

     }

   }

   @Override

   public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) {

     throw new IllegalStateException("exceptionCaught: Channel failed with " +

         "remote address " + ctx.getChannel().getRemoteAddress(), e.getCause());

   }

 }