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 import org.apache.mina.core.session.IoSession;
23
24 /**
25 * An {@link IoFuture} for {@link IoSession#read() asynchronous read requests}.
26 *
27 * <h3>Example</h3>
28 * <pre>
29 * IoSession session = ...;
30 *
31 * // useReadOperation must be enabled to use read operation.
32 * session.getConfig().setUseReadOperation(true);
33 *
34 * ReadFuture future = session.read();
35 *
36 * // Wait until a message is received.
37 * future.awaitUninterruptibly();
38 *
39 * try {
40 * Object message = future.getMessage();
41 * } catch (Exception e) {
42 * ...
43 * }
44 * </pre>
45 *
46 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
47 */
48 public interface ReadFuture extends IoFuture {
49
50 /**
51 * Get the read message.
52 *
53 * @return the received message. It returns <tt>null</tt> if this
54 * future is not ready or the associated {@link IoSession} has been closed.
55 */
56 Object getMessage();
57
58 /**
59 * @return <tt>true</tt> if a message was received successfully.
60 */
61 boolean isRead();
62
63 /**
64 * @return <tt>true</tt> if the {@link IoSession} associated with this
65 * future has been closed.
66 */
67 boolean isClosed();
68
69 /**
70 * @return the cause of the read failure if and only if the read
71 * operation has failed due to an {@link Exception}. Otherwise,
72 * <tt>null</tt> is returned.
73 */
74 Throwable getException();
75
76 /**
77 * Sets the message is written, and notifies all threads waiting for
78 * this future. This method is invoked by MINA internally. Please do
79 * not call this method directly.
80 *
81 * @param message The received message to store in this future
82 */
83 void setRead(Object message);
84
85 /**
86 * Sets the associated {@link IoSession} is closed. This method is invoked
87 * by MINA internally. Please do not call this method directly.
88 */
89 void setClosed();
90
91 /**
92 * Sets the cause of the read failure, and notifies all threads waiting
93 * for this future. This method is invoked by MINA internally. Please
94 * do not call this method directly.
95 *
96 * @param cause The exception to store in the Future instance
97 */
98 void setException(Throwable cause);
99
100 /**
101 * {@inheritDoc}
102 */
103 ReadFuture await() throws InterruptedException;
104
105 /**
106 * {@inheritDoc}
107 */
108 ReadFuture awaitUninterruptibly();
109
110 /**
111 * {@inheritDoc}
112 */
113 ReadFuture addListener(IoFutureListener<?> listener);
114
115 /**
116 * {@inheritDoc}
117 */
118 ReadFuture removeListener(IoFutureListener<?> listener);
119 }
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