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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
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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
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33  // statement from your version.
34  //
35  // A copy of the GNU General Public License is provided in the file gpl.txt. You
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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 }