1 //******************************************************************************
2 //
3 // File: LoopbackChannel.java
4 // Package: edu.rit.mp
5 // Unit: Class edu.rit.mp.LoopbackChannel
6 //
7 // This Java source file is copyright (C) 2008 by Alan Kaminsky. All rights
8 // reserved. For further information, contact the author, Alan Kaminsky, at
9 // ark@cs.rit.edu.
10 //
11 // This Java source file is part of the Parallel Java Library ("PJ"). PJ is free
12 // software; you can redistribute it and/or modify it under the terms of the GNU
13 // General Public License as published by the Free Software Foundation; either
14 // version 3 of the License, or (at your option) any later version.
15 //
16 // PJ is distributed in the hope that it will be useful, but WITHOUT ANY
17 // WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
18 // A PARTICULAR PURPOSE. See the GNU General Public License for more details.
19 //
20 // Linking this library statically or dynamically with other modules is making a
21 // combined work based on this library. Thus, the terms and conditions of the GNU
22 // General Public License cover the whole combination.
23 //
24 // As a special exception, the copyright holders of this library give you
25 // permission to link this library with independent modules to produce an
26 // executable, regardless of the license terms of these independent modules, and
27 // to copy and distribute the resulting executable under terms of your choice,
28 // provided that you also meet, for each linked independent module, the terms
29 // and conditions of the license of that module. An independent module is a module
30 // which is not derived from or based on this library. If you modify this library,
31 // you may extend this exception to your version of the library, but you are not
32 // obligated to do so. If you do not wish to do so, delete this exception
33 // statement from your version.
34 //
35 // A copy of the GNU General Public License is provided in the file gpl.txt. You
36 // may also obtain a copy of the GNU General Public License on the World Wide
37 // Web at http://www.gnu.org/licenses/gpl.html.
38 //
39 //******************************************************************************
40 package edu.rit.mp;
41
42 import java.io.IOException;
43 import java.io.InterruptedIOException;
44 import java.net.InetSocketAddress;
45
46 /**
47 * Class LoopbackChannel provides a channel for sending and receiving messages
48 * within the same process in the Message Protocol (MP).
49 *
50 * @author Alan Kaminsky
51 * @version 13-May-2008
52 */
53 class LoopbackChannel
54 extends Channel {
55
56 // Hidden constructors.
57 /**
58 * Construct a new loopback channel.
59 *
60 * @param theChannelGroup Enclosing channel group.
61 */
62 LoopbackChannel(ChannelGroup theChannelGroup) {
63 super(theChannelGroup);
64 }
65
66 // Exported operations.
67 /**
68 * Obtain the channel group ID of this channel's near end channel group.
69 *
70 * @return Near end channel group ID.
71 */
72 public int nearEndChannelGroupId() {
73 return myChannelGroup.myChannelGroupId;
74 }
75
76 /**
77 * Obtain the channel group ID of this channel's far end channel group.
78 *
79 * @return Far end channel group ID.
80 */
81 public int farEndChannelGroupId() {
82 return myChannelGroup.myChannelGroupId;
83 }
84
85 /**
86 * Obtain this channel's near end address. This is the host and port of the
87 * near end of this channel's connection.
88 *
89 * @return Near end address.
90 */
91 public InetSocketAddress nearEndAddress() {
92 return new InetSocketAddress(0);
93 }
94
95 /**
96 * Obtain this channel's far end address. This is the host and port of the
97 * far end of this channel's connection.
98 *
99 * @return Far end address.
100 */
101 public InetSocketAddress farEndAddress() {
102 return new InetSocketAddress(0);
103 }
104
105 // Hidden operations.
106 /**
107 * Send a message via this channel. The I/O request object must be newly
108 * constructed with the message tag and source buffer fields filled in. This
109 * method is allowed to return immediately and let the message be sent in a
110 * separate thread. The calling thread should use the I/O request object to
111 * wait for the message send to complete.
112 *
113 * @param theIORequest I/O request object.
114 *
115 * @exception IOException Thrown if an I/O error occurred.
116 */
117 void send(IORequest theIORequest)
118 throws IOException {
119 synchronized (this) {
120 // Check whether channel is closed.
121 if (myWriteState == WRITE_CLOSED) {
122 throw new IOException("edu.rit.mp.LoopbackChannel: Channel closed");
123 }
124 }
125
126 // Wait until there is a matching receive request.
127 IORequest recvRequest;
128 try {
129 recvRequest = myIORequestList.waitForMatch(theIORequest);
130 } catch (InterruptedException exc) {
131 IOException exc2
132 = new InterruptedIOException("edu.rit.mp.LoopbackChannel: Send interrupted");
133 exc2.initCause(exc);
134 throw exc2;
135 }
136
137 // Copy source buffer to destination buffer.
138 recvRequest.myBuf.copy(theIORequest.myBuf);
139
140 // Set up status object.
141 recvRequest.myStatus
142 = new Status(this,
143 theIORequest.myTagLb,
144 theIORequest.myBuf.myLength);
145
146 // Report success.
147 theIORequest.reportSuccess();
148 recvRequest.reportSuccess();
149 }
150
151 }