1 //******************************************************************************
2 //
3 // File: ObjectArrayReductionBuf.java
4 // Package: edu.rit.mp.buf
5 // Unit: Class edu.rit.mp.buf.ObjectArrayReductionBuf
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 import edu.rit.pj.reduction.ReduceArrays;
47 import edu.rit.util.Range;
48
49 /**
50 * Class ObjectArrayReductionBuf provides a reduction buffer for class
51 * {@linkplain ObjectArrayBuf}.
52 *
53 * @param <T> Data type of the objects in the buffer.
54 *
55 * @author Alan Kaminsky
56 * @version 23-Mar-2009
57 */
58 @SuppressWarnings("unchecked")
59 class ObjectArrayReductionBuf<T>
60 extends ObjectArrayBuf<T> {
61
62 // Hidden data members.
63 ObjectOp<T> myOp;
64 ObjectArrayBuf<T> myBuf;
65
66 // Exported constructors.
67 /**
68 * Construct a new object array reduction buffer.
69 *
70 * @param theArray Array.
71 * @param theRange Range of array elements to include in the buffer.
72 * @param op Binary operation.
73 * @param theBuf Underlying object array buffer.
74 * @exception NullPointerException (unchecked exception) Thrown if
75 * <code>op</code> is null.
76 */
77 public ObjectArrayReductionBuf(T[] theArray,
78 Range theRange,
79 ObjectOp<T> op,
80 ObjectArrayBuf<T> theBuf) {
81 super(theArray, theRange);
82 if (op == null) {
83 throw new NullPointerException("ObjectArrayReductionBuf(): op is null");
84 }
85 myOp = op;
86 myBuf = theBuf;
87 }
88
89 // Exported operations.
90 /**
91 * Store the given item in this buffer.
92 * <P>
93 * The <code>put()</code> method must not block the calling thread; if it does,
94 * all message I/O in MP will be blocked.
95 *
96 * @param i Item index in the range 0 .. <code>length()</code>-1.
97 * @param item Item to be stored at index <code>i</code>.
98 */
99 public void put(int i, T item) {
100 int off = myArrayOffset + i * myStride;
101 myArray[off] = myOp.op(myArray[off], item);
102 reset();
103 myBuf.reset();
104 }
105
106 /**
107 * {@inheritDoc}
108 *
109 * Copy items from the given buffer to this buffer. The number of items
110 * copied is this buffer's length or <code>theSrc</code>'s length, whichever is
111 * smaller. If <code>theSrc</code> is this buffer, the <code>copy()</code> method
112 * does nothing.
113 * @exception ClassCastException (unchecked exception) Thrown if
114 * <code>theSrc</code>'s item data type is not the same as this buffer's item
115 * data type.
116 */
117 public void copy(Buf theSrc) {
118 if (theSrc == this) {
119 } else if (theSrc instanceof ObjectArrayBuf) {
120 ObjectArrayBuf<T> src = (ObjectArrayBuf<T>) theSrc;
121 ReduceArrays.reduce(src.myArray, src.myRange, this.myArray, this.myRange, myOp);
122 reset();
123 myBuf.reset();
124 } else {
125 ObjectBuf.defaultCopy((ObjectBuf<T>) theSrc, this);
126 reset();
127 myBuf.reset();
128 }
129 }
130
131 /**
132 * {@inheritDoc}
133 *
134 * Create a buffer for performing parallel reduction using the given binary
135 * operation. The results of the reduction are placed into this buffer.
136 * @exception ClassCastException (unchecked exception) Thrown if this
137 * buffer's element data type and the given binary operation's argument data
138 * type are not the same.
139 */
140 public Buf getReductionBuf(Op op) {
141 throw new UnsupportedOperationException();
142 }
143
144 }