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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.channel;
17  
18  import static org.jboss.netty.channel.Channels.*;
19  
20  /**
21   * A skeletal {@link ChannelSink} implementation.
22   */
23  public abstract class AbstractChannelSink implements ChannelSink {
24  
25      /**
26       * Creates a new instance.
27       */
28      protected AbstractChannelSink() {
29      }
30  
31      /**
32       * Sends an {@link ExceptionEvent} upstream with the specified
33       * {@code cause}.
34       *
35       * @param event the {@link ChannelEvent} which caused a
36       *              {@link ChannelHandler} to raise an exception
37       * @param cause the exception raised by a {@link ChannelHandler}
38       */
39      public void exceptionCaught(ChannelPipeline pipeline,
40              ChannelEvent event, ChannelPipelineException cause) throws Exception {
41          Throwable actualCause = cause.getCause();
42          if (actualCause == null) {
43              actualCause = cause;
44          }
45          if (isFireExceptionCaughtLater(event, actualCause)) {
46              fireExceptionCaughtLater(event.getChannel(), actualCause);
47          } else {
48              fireExceptionCaught(event.getChannel(), actualCause);
49          }
50      }
51  
52      /**
53       * Returns {@code true} if and only if the specified {@code actualCause}, which was raised while
54       * handling the specified {@code event}, must trigger an {@code exceptionCaught()} event in
55       * an I/O thread.
56       *
57       * @param event the event which raised exception
58       * @param actualCause the raised exception
59       */
60      protected boolean isFireExceptionCaughtLater(ChannelEvent event, Throwable actualCause) {
61          return false;
62      }
63  
64      /**
65       * This implementation just directly call {@link Runnable#run()}.
66       * Sub-classes should override this if they can handle it in a better way
67       */
68      public ChannelFuture execute(ChannelPipeline pipeline, Runnable task) {
69          try {
70              task.run();
71              return succeededFuture(pipeline.getChannel());
72          } catch (Throwable t) {
73              return failedFuture(pipeline.getChannel(), t);
74          }
75      }
76  }