1 //******************************************************************************
2 //
3 // File: ObjectItemBuf.java
4 // Package: edu.rit.mp.buf
5 // Unit: Class edu.rit.mp.buf.ObjectItemBuf
6 //
7 // This Java source file is copyright (C) 2009 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.buf;
41
42 import edu.rit.mp.Buf;
43 import edu.rit.mp.ObjectBuf;
44 import edu.rit.pj.reduction.ObjectOp;
45 import edu.rit.pj.reduction.Op;
46
47 /**
48 * Class ObjectItemBuf provides a buffer for a single object item sent or
49 * received using the Message Protocol (MP). While an instance of class
50 * ObjectItemBuf may be constructed directly, normally you will use a factory
51 * method in class {@linkplain edu.rit.mp.ObjectBuf ObjectBuf}. See that class
52 * for further information.
53 *
54 * @param <T> Data type of the objects in the buffer.
55 * @author Alan Kaminsky
56 * @version 23-Mar-2009
57 */
58 @SuppressWarnings("unchecked")
59 public class ObjectItemBuf<T>
60 extends ObjectBuf<T> {
61
62 // Exported data members.
63 /**
64 * Object item to be sent or received.
65 */
66 public T item;
67
68 // Exported constructors.
69 /**
70 * Construct a new object item buffer.
71 */
72 public ObjectItemBuf() {
73 super(1);
74 }
75
76 /**
77 * Construct a new object item buffer with the given initial value.
78 *
79 * @param item Initial value of the {@link #item} field.
80 */
81 public ObjectItemBuf(T item) {
82 super(1);
83 this.item = item;
84 }
85
86 // Exported operations.
87 /**
88 * {@inheritDoc}
89 *
90 * Obtain the given item from this buffer.
91 * <P>
92 * The <code>get()</code> method must not block the calling thread; if it does,
93 * all message I/O in MP will be blocked.
94 */
95 public T get(int i) {
96 return this.item;
97 }
98
99 /**
100 * Store the given item in this buffer.
101 * <P>
102 * The <code>put()</code> method must not block the calling thread; if it does,
103 * all message I/O in MP will be blocked.
104 *
105 * @param i Item index in the range 0 .. <code>length()</code>-1.
106 * @param item Item to be stored at index <code>i</code>.
107 */
108 public void put(int i, T item) {
109 this.item = item;
110 reset();
111 }
112
113 /**
114 * {@inheritDoc}
115 *
116 * Create a buffer for performing parallel reduction using the given binary
117 * operation. The results of the reduction are placed into this buffer.
118 * @exception ClassCastException (unchecked exception) Thrown if this
119 * buffer's element data type and the given binary operation's argument data
120 * type are not the same.
121 */
122 public Buf getReductionBuf(Op op) {
123 return new ObjectItemReductionBuf<T>(this, (ObjectOp) op);
124 }
125
126 }