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1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one
3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *
10   *    http://www.apache.org/licenses/LICENSE-2.0
11   *
12   *  Unless required by applicable law or agreed to in writing,
13   *  software distributed under the License is distributed on an
14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *  KIND, either express or implied.  See the License for the
16   *  specific language governing permissions and limitations
17   *  under the License.
18   *
19   */
20  package org.apache.mina.core.future;
21  
22  
23  /**
24   * An {@link IoFuture} for asynchronous write requests.
25   *
26   * <h3>Example</h3>
27   * <pre>
28   * IoSession session = ...;
29   * WriteFuture future = session.write(...);
30   * // Wait until the message is completely written out to the O/S buffer.
31   * future.join();
32   * if( future.isWritten() )
33   * {
34   *     // The message has been written successfully.
35   * }
36   * else
37   * {
38   *     // The messsage couldn't be written out completely for some reason.
39   *     // (e.g. Connection is closed)
40   * }
41   * </pre>
42   *
43   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
44   */
45  public interface WriteFuture extends IoFuture {
46      /**
47       * Returns <tt>true</tt> if the write operation is finished successfully.
48       */
49      boolean isWritten();
50      
51      /**
52       * Returns the cause of the write failure if and only if the write
53       * operation has failed due to an {@link Exception}.  Otherwise,
54       * <tt>null</tt> is returned.
55       */
56      Throwable getException();
57  
58      /**
59       * Sets the message is written, and notifies all threads waiting for
60       * this future.  This method is invoked by MINA internally.  Please do
61       * not call this method directly.
62       */
63      void setWritten();
64      
65      /**
66       * Sets the cause of the write failure, and notifies all threads waiting
67       * for this future.  This method is invoked by MINA internally.  Please
68       * do not call this method directly.
69       */
70      void setException(Throwable cause);
71  
72      /**
73       * Wait for the asynchronous operation to complete.
74       * The attached listeners will be notified when the operation is 
75       * completed.
76       * 
77       * @return the created {@link WriteFuture}
78       * @throws InterruptedException
79       */
80      WriteFuture await() throws InterruptedException;
81  
82      /**
83       * {@inheritDoc}
84       */
85      WriteFuture awaitUninterruptibly();
86  
87      /**
88       * {@inheritDoc}
89       */
90      WriteFuture addListener(IoFutureListener<?> listener);
91  
92      /**
93       * {@inheritDoc}
94       */
95      WriteFuture removeListener(IoFutureListener<?> listener);
96  }