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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   * 
30   * // Wait until the message is completely written out to the O/S buffer.
31   * future.awaitUninterruptibly();
32   * 
33   * if( future.isWritten() )
34   * {
35   *     // The message has been written successfully.
36   * }
37   * else
38   * {
39   *     // The message couldn't be written out completely for some reason.
40   *     // (e.g. Connection is closed)
41   * }
42   * </pre>
43   *
44   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
45   */
46  public interface WriteFuture extends IoFuture {
47      /**
48       * @return <tt>true</tt> if the write operation is finished successfully.
49       */
50      boolean isWritten();
51  
52      /**
53       * @return the cause of the write failure if and only if the write
54       * operation has failed due to an {@link Exception}.  Otherwise,
55       * <tt>null</tt> is returned.
56       */
57      Throwable getException();
58  
59      /**
60       * Sets the message is written, and notifies all threads waiting for
61       * this future.  This method is invoked by MINA internally.  Please do
62       * not call this method directly.
63       */
64      void setWritten();
65  
66      /**
67       * Sets the cause of the write failure, and notifies all threads waiting
68       * for this future.  This method is invoked by MINA internally.  Please
69       * do not call this method directly.
70       * 
71       * @param cause The exception to store in the Future instance
72       */
73      void setException(Throwable cause);
74  
75      /**
76       * Wait for the asynchronous operation to complete.
77       * The attached listeners will be notified when the operation is 
78       * completed.
79       * 
80       * @return the created {@link WriteFuture}
81       * @throws InterruptedException
82       */
83      WriteFuture await() throws InterruptedException;
84  
85      /**
86       * {@inheritDoc}
87       */
88      WriteFuture awaitUninterruptibly();
89  
90      /**
91       * {@inheritDoc}
92       */
93      WriteFuture addListener(IoFutureListener<?> listener);
94  
95      /**
96       * {@inheritDoc}
97       */
98      WriteFuture removeListener(IoFutureListener<?> listener);
99  }