1 //******************************************************************************
2 //
3 // File: SharedObjectArrayBuf.java
4 // Package: edu.rit.mp.buf
5 // Unit: Class edu.rit.mp.buf.SharedObjectArrayBuf
6 //
7 // This Java source file is copyright (C) 2012 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.SharedObjectArray;
47 import edu.rit.util.Range;
48
49 /**
50 * Class SharedObjectArrayBuf provides a buffer for a multiple thread safe array
51 * of object items sent or received using the Message Protocol (MP). The array
52 * element stride may be 1 or greater than 1. While an instance of class
53 * SharedObjectArrayBuf may be constructed directly, normally you will use a
54 * factory method in class {@linkplain edu.rit.mp.ObjectBuf
55 * ObjectBuf}. See that class for further information.
56 *
57 * @param <T> Data type of the objects in the buffer.
58 * @author Alan Kaminsky
59 * @version 01-Apr-2012
60 */
61 @SuppressWarnings("unchecked")
62 public class SharedObjectArrayBuf<T>
63 extends ObjectBuf<T> {
64
65 // Hidden data members.
66 SharedObjectArray<T> myArray;
67 Range myRange;
68 int myArrayOffset;
69 int myStride;
70
71 // Exported constructors.
72 /**
73 * Construct a new shared object array buffer.
74 *
75 * @param theArray Shared array.
76 * @param theRange Range of array elements to include in the buffer.
77 */
78 public SharedObjectArrayBuf(SharedObjectArray<T> theArray,
79 Range theRange) {
80 super(theRange.length());
81 myArray = theArray;
82 myRange = theRange;
83 myArrayOffset = theRange.lb();
84 myStride = theRange.stride();
85 }
86
87 // Exported operations.
88 /**
89 * {@inheritDoc}
90 *
91 * Obtain the given item from this buffer.
92 * <P>
93 * The <code>get()</code> method must not block the calling thread; if it does,
94 * all message I/O in MP will be blocked.
95 */
96 public T get(int i) {
97 return myArray.get(myArrayOffset + i * myStride);
98 }
99
100 /**
101 * Store the given item in this buffer.
102 * <P>
103 * The <code>put()</code> method must not block the calling thread; if it does,
104 * all message I/O in MP will be blocked.
105 *
106 * @param i Item index in the range 0 .. <code>length()</code>-1.
107 * @param item Item to be stored at index <code>i</code>.
108 */
109 public void put(int i,
110 T item) {
111 myArray.set(myArrayOffset + i * myStride, item);
112 mySerializedItems = null;
113 }
114
115 /**
116 * {@inheritDoc}
117 *
118 * Create a buffer for performing parallel reduction using the given binary
119 * operation. The results of the reduction are placed into this buffer.
120 * @exception ClassCastException (unchecked exception) Thrown if this
121 * buffer's element data type and the given binary operation's argument data
122 * type are not the same.
123 */
124 public Buf getReductionBuf(Op op) {
125 return new SharedObjectArrayReductionBuf<T>(myArray, myRange, (ObjectOp<T>) op, this);
126 }
127
128 }