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    1   /*
    2    * Copyright 2012 The Netty Project
    3    *
    4    * The Netty Project licenses this file to you under the Apache License,
    5    * version 2.0 (the "License"); you may not use this file except in compliance
    6    * with the 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  public class FactorialClientHandler extends SimpleChannelUpstreamHandler {
    42
    43      private static final Logger logger = Logger.getLogger(
    44              FactorialClientHandler.class.getName());
    45
    46      // Stateful properties
    47      private int i = 1;
    48      private int receivedMessages;
    49      private final int count;
    50      final BlockingQueue<BigInteger> answer = new LinkedBlockingQueue<BigInteger>();
    51
    52      public FactorialClientHandler(int count) {
    53          this.count = count;
    54      }
    55
    56      public BigInteger getFactorial() {
    57          boolean interrupted = false;
    58          for (;;) {
    59              try {
    60                  BigInteger factorial = answer.take();
    61                  if (interrupted) {
    62                      Thread.currentThread().interrupt();
    63                  }
    64                  return factorial;
    65              } catch (InterruptedException e) {
    66                  interrupted = true;
    67              }
    68          }
    69      }
    70
    71      @Override
    72      public void handleUpstream(
    73              ChannelHandlerContext ctx, ChannelEvent e) throws Exception {
    74          if (e instanceof ChannelStateEvent) {
    75              logger.info(e.toString());
    76          }
    77          super.handleUpstream(ctx, e);
    78      }
    79
    80      @Override
    81      public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) {
    82          sendNumbers(e);
    83      }
    84
    85      @Override
    86      public void channelInterestChanged(ChannelHandlerContext ctx, ChannelStateEvent e) {
    87          sendNumbers(e);
    88      }
    89
    90      @Override
    91      public void messageReceived(
    92              ChannelHandlerContext ctx, final MessageEvent e) {
    93          receivedMessages ++;
    94          if (receivedMessages == count) {
    95              // Offer the answer after closing the connection.
    96              e.getChannel().close().addListener(new ChannelFutureListener() {
    97                  public void operationComplete(ChannelFuture future) {
    98                      boolean offered = answer.offer((BigInteger) e.getMessage());
    99                      assert offered;
    100                 }
    101             });
    102         }
    103     }
    104
    105     @Override
    106     public void exceptionCaught(
    107             ChannelHandlerContext ctx, ExceptionEvent e) {
    108         logger.log(
    109                 Level.WARNING,
    110                 "Unexpected exception from downstream.",
    111                 e.getCause());
    112         e.getChannel().close();
    113     }
    114
    115     private void sendNumbers(ChannelStateEvent e) {
    116         Channel channel = e.getChannel();
    117         while (channel.isWritable()) {
    118             if (i <= count) {
    119                 channel.write(i);
    120                 i ++;
    121             } else {
    122                 break;
    123             }
    124         }
    125     }
    126 }