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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 io.netty.handler.timeout;
17  
18  import io.netty.bootstrap.ServerBootstrap;
19  import io.netty.channel.Channel;
20  import io.netty.channel.ChannelDuplexHandler;
21  import io.netty.channel.ChannelHandlerContext;
22  import io.netty.channel.ChannelInitializer;
23  
24  import java.util.concurrent.TimeUnit;
25  
26  /**
27   * Raises a {@link ReadTimeoutException} when no data was read within a certain
28   * period of time.
29   *
30   * <pre>
31   * // The connection is closed when there is no inbound traffic
32   * // for 30 seconds.
33   *
34   * public class MyChannelInitializer extends {@link ChannelInitializer}&lt;{@link Channel}&gt; {
35   *     public void initChannel({@link Channel} channel) {
36   *         channel.pipeline().addLast("readTimeoutHandler", new {@link ReadTimeoutHandler}(30);
37   *         channel.pipeline().addLast("myHandler", new MyHandler());
38   *     }
39   * }
40   *
41   * // Handler should handle the {@link ReadTimeoutException}.
42   * public class MyHandler extends {@link ChannelDuplexHandler} {
43   *     {@code @Override}
44   *     public void exceptionCaught({@link ChannelHandlerContext} ctx, {@link Throwable} cause)
45   *             throws {@link Exception} {
46   *         if (cause instanceof {@link ReadTimeoutException}) {
47   *             // do something
48   *         } else {
49   *             super.exceptionCaught(ctx, cause);
50   *         }
51   *     }
52   * }
53   *
54   * {@link ServerBootstrap} bootstrap = ...;
55   * ...
56   * bootstrap.childHandler(new MyChannelInitializer());
57   * ...
58   * </pre>
59   * @see WriteTimeoutHandler
60   * @see IdleStateHandler
61   */
62  public class ReadTimeoutHandler extends IdleStateHandler {
63      private boolean closed;
64  
65      /**
66       * Creates a new instance.
67       *
68       * @param timeoutSeconds
69       *        read timeout in seconds
70       */
71      public ReadTimeoutHandler(int timeoutSeconds) {
72          this(timeoutSeconds, TimeUnit.SECONDS);
73      }
74  
75      /**
76       * Creates a new instance.
77       *
78       * @param timeout
79       *        read timeout
80       * @param unit
81       *        the {@link TimeUnit} of {@code timeout}
82       */
83      public ReadTimeoutHandler(long timeout, TimeUnit unit) {
84          super(timeout, 0, 0, unit);
85      }
86  
87      @Override
88      protected final void channelIdle(ChannelHandlerContext ctx, IdleStateEvent evt) throws Exception {
89          assert evt.state() == IdleState.READER_IDLE;
90          readTimedOut(ctx);
91      }
92  
93      /**
94       * Is called when a read timeout was detected.
95       */
96      protected void readTimedOut(ChannelHandlerContext ctx) throws Exception {
97          if (!closed) {
98              ctx.fireExceptionCaught(ReadTimeoutException.INSTANCE);
99              ctx.close();
100             closed = true;
101         }
102     }
103 }