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    1   /*
    2    * Copyright 2009 Red Hat, Inc.
    3    *
    4    * Red Hat licenses this file to you under the Apache License, version 2.0
    5    * (the "License"); you may not use this file except in compliance with the
    6    * License.  You may obtain a copy of the License at:
    7    *
    8    *    http://www.apache.org/licenses/LICENSE-2.0
    9    *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
    12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
    13   * License for the specific language governing permissions and limitations
    14   * under the License.
    15   */
    16  package org.jboss.netty.example.factorial;
    17
    18  import java.math.BigInteger;
    19  import java.util.concurrent.BlockingQueue;
    20  import java.util.concurrent.LinkedBlockingQueue;
    21  import java.util.logging.Level;
    22  import java.util.logging.Logger;
    23
    24  import org.jboss.netty.channel.Channel;
    25  import org.jboss.netty.channel.ChannelEvent;
    26  import org.jboss.netty.channel.ChannelFuture;
    27  import org.jboss.netty.channel.ChannelFutureListener;
    28  import org.jboss.netty.channel.ChannelHandlerContext;
    29  import org.jboss.netty.channel.ChannelStateEvent;
    30  import org.jboss.netty.channel.ExceptionEvent;
    31  import org.jboss.netty.channel.MessageEvent;
    32  import org.jboss.netty.channel.SimpleChannelUpstreamHandler;
    33
    34  /**
    35   * Handler for a client-side channel.  This handler maintains stateful
    36   * information which is specific to a certain channel using member variables.
    37   * Therefore, an instance of this handler can cover only one channel.  You have
    38   * to create a new handler instance whenever you create a new channel and insert
    39   * this handler to avoid a race condition.
    40   *
    41   * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
    42   * @author <a href="http://gleamynode.net/">Trustin Lee</a>
    43   *
    44   * @version $Rev: 2121 $, $Date: 2010-02-02 09:38:07 +0900 (Tue, 02 Feb 2010) $
    45   */
    46  public class FactorialClientHandler extends SimpleChannelUpstreamHandler {
    47
    48      private static final Logger logger = Logger.getLogger(
    49              FactorialClientHandler.class.getName());
    50
    51      // Stateful properties
    52      private int i = 1;
    53      private int receivedMessages = 0;
    54      private final int count;
    55      final BlockingQueue<BigInteger> answer = new LinkedBlockingQueue<BigInteger>();
    56
    57      public FactorialClientHandler(int count) {
    58          this.count = count;
    59      }
    60
    61      public BigInteger getFactorial() {
    62          boolean interrupted = false;
    63          for (;;) {
    64              try {
    65                  BigInteger factorial = answer.take();
    66                  if (interrupted) {
    67                      Thread.currentThread().interrupt();
    68                  }
    69                  return factorial;
    70              } catch (InterruptedException e) {
    71                  interrupted = true;
    72              }
    73          }
    74      }
    75
    76      @Override
    77      public void handleUpstream(
    78              ChannelHandlerContext ctx, ChannelEvent e) throws Exception {
    79          if (e instanceof ChannelStateEvent) {
    80              logger.info(e.toString());
    81          }
    82          super.handleUpstream(ctx, e);
    83      }
    84
    85      @Override
    86      public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) {
    87          sendNumbers(e);
    88      }
    89
    90      @Override
    91      public void channelInterestChanged(ChannelHandlerContext ctx, ChannelStateEvent e) {
    92          sendNumbers(e);
    93      }
    94
    95      @Override
    96      public void messageReceived(
    97              ChannelHandlerContext ctx, final MessageEvent e) {
    98          receivedMessages ++;
    99          if (receivedMessages == count) {
    100             // Offer the answer after closing the connection.
    101             e.getChannel().close().addListener(new ChannelFutureListener() {
    102                 public void operationComplete(ChannelFuture future) {
    103                     boolean offered = answer.offer((BigInteger) e.getMessage());
    104                     assert offered;
    105                 }
    106             });
    107         }
    108     }
    109
    110     @Override
    111     public void exceptionCaught(
    112             ChannelHandlerContext ctx, ExceptionEvent e) {
    113         logger.log(
    114                 Level.WARNING,
    115                 "Unexpected exception from downstream.",
    116                 e.getCause());
    117         e.getChannel().close();
    118     }
    119
    120     private void sendNumbers(ChannelStateEvent e) {
    121         Channel channel = e.getChannel();
    122         while (channel.isWritable()) {
    123             if (i <= count) {
    124                 channel.write(Integer.valueOf(i));
    125                 i ++;
    126             } else {
    127                 break;
    128             }
    129         }
    130     }
    131 }