1 //******************************************************************************
2 //
3 // File: ObjectItemReductionBuf.java
4 // Package: edu.rit.mp.buf
5 // Unit: Class edu.rit.mp.buf.ObjectItemReductionBuf
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 ObjectItemReductionBuf provides a reduction buffer for class
49 * {@linkplain ObjectItemBuf}.
50 *
51 * @param <T> Data type of the objects in the buffer.
52 *
53 * @author Alan Kaminsky
54 * @version 23-Mar-2009
55 */
56 class ObjectItemReductionBuf<T>
57 extends ObjectBuf<T> {
58
59 // Hidden data members.
60 ObjectItemBuf<T> myBuf;
61 ObjectOp<T> myOp;
62
63 // Exported constructors.
64 /**
65 * Construct a new object item reduction buffer.
66 *
67 * @param buf Buffer containing the item.
68 * @param op Binary operation.
69 * @exception NullPointerException (unchecked exception) Thrown if
70 * <code>op</code> is null.
71 */
72 public ObjectItemReductionBuf(ObjectItemBuf<T> buf,
73 ObjectOp<T> op) {
74 super(1);
75 if (op == null) {
76 throw new NullPointerException("ObjectItemReductionBuf(): op is null");
77 }
78 myBuf = buf;
79 myOp = op;
80 }
81
82 // Exported operations.
83 /**
84 * {@inheritDoc}
85 *
86 * Obtain the given item from this buffer.
87 * <P>
88 * The <code>get()</code> method must not block the calling thread; if it does,
89 * all message I/O in MP will be blocked.
90 */
91 public T get(int i) {
92 return myBuf.item;
93 }
94
95 /**
96 * Store the given item in this buffer. The item at index <code>i</code> in this
97 * buffer is combined with the given <code>item</code> using the binary
98 * operation.
99 * <P>
100 * The <code>put()</code> method must not block the calling thread; if it does,
101 * all message I/O in MP will be blocked.
102 *
103 * @param i Item index in the range 0 .. <code>length()</code>-1.
104 * @param item Item to be stored at index <code>i</code>.
105 */
106 public void put(int i, T item) {
107 myBuf.item = myOp.op(myBuf.item, item);
108 reset();
109 myBuf.reset();
110 }
111
112 /**
113 * {@inheritDoc}
114 *
115 * Create a buffer for performing parallel reduction using the given binary
116 * operation. The results of the reduction are placed into this buffer.
117 * @exception ClassCastException (unchecked exception) Thrown if this
118 * buffer's element data type and the given binary operation's argument data
119 * type are not the same.
120 */
121 public Buf getReductionBuf(Op op) {
122 throw new UnsupportedOperationException();
123 }
124
125 }