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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   * An {@link IoFuture} for asynchronous write requests.
24   *
25   * <h3>Example</h3>
26   * <pre>
27   * IoSession session = ...;
28   * WriteFuture future = session.write(...);
29   * // Wait until the message is completely written out to the O/S buffer.
30   * future.join();
31   * if( future.isWritten() )
32   * {
33   *     // The message has been written successfully.
34   * }
35   * else
36   * {
37   *     // The messsage couldn't be written out completely for some reason.
38   *     // (e.g. Connection is closed)
39   * }
40   * </pre>
41   *
42   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
43   */
44  public interface WriteFuture extends IoFuture {
45      /**
46       * Returns <tt>true</tt> if the write operation is finished successfully.
47       */
48      boolean isWritten();
49  
50      /**
51       * Returns the cause of the write failure if and only if the write
52       * operation has failed due to an {@link Exception}.  Otherwise,
53       * <tt>null</tt> is returned.
54       */
55      Throwable getException();
56  
57      /**
58       * Sets the message is written, and notifies all threads waiting for
59       * this future.  This method is invoked by MINA internally.  Please do
60       * not call this method directly.
61       */
62      void setWritten();
63  
64      /**
65       * Sets the cause of the write failure, and notifies all threads waiting
66       * for this future.  This method is invoked by MINA internally.  Please
67       * do not call this method directly.
68       */
69      void setException(Throwable cause);
70  
71      /**
72       * Wait for the asynchronous operation to complete.
73       * The attached listeners will be notified when the operation is 
74       * completed.
75       * 
76       * @return the created {@link WriteFuture}
77       * @throws InterruptedException
78       */
79      WriteFuture await() throws InterruptedException;
80  
81      /**
82       * {@inheritDoc}
83       */
84      WriteFuture awaitUninterruptibly();
85  
86      /**
87       * {@inheritDoc}
88       */
89      WriteFuture addListener(IoFutureListener<?> listener);
90  
91      /**
92       * {@inheritDoc}
93       */
94      WriteFuture removeListener(IoFutureListener<?> listener);
95  }