View Javadoc
1   //******************************************************************************
2   //
3   // File:    SharedUnsigned16BitIntegerArrayReductionBuf.java
4   // Package: edu.rit.mp.buf
5   // Unit:    Class edu.rit.mp.buf.SharedUnsigned16BitIntegerArrayReductionBuf
6   //
7   // This Java source file is copyright (C) 2007 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 java.nio.ByteBuffer;
43  
44  import edu.rit.mp.Buf;
45  import edu.rit.pj.reduction.IntegerOp;
46  import edu.rit.pj.reduction.Op;
47  import edu.rit.pj.reduction.SharedIntegerArray;
48  import edu.rit.util.Range;
49  
50  /**
51   * Class SharedUnsigned16BitIntegerArrayReductionBuf provides a reduction buffer
52   * for class {@linkplain SharedUnsigned16BitIntegerArrayBuf}.
53   *
54   * @author Alan Kaminsky
55   * @version 26-Oct-2007
56   */
57  class SharedUnsigned16BitIntegerArrayReductionBuf
58          extends SharedUnsigned16BitIntegerArrayBuf {
59  
60  // Hidden data members.
61      IntegerOp myOp;
62  
63  // Exported constructors.
64      /**
65       * Construct a new shared unsigned 16-bit integer array reduction buffer.
66       *
67       * @param theArray Shared array.
68       * @param theRange Range of array elements to include in the buffer.
69       * @param op Binary operation.
70       * @exception NullPointerException (unchecked exception) Thrown if
71       * <code>op</code> is null.
72       */
73      public SharedUnsigned16BitIntegerArrayReductionBuf(SharedIntegerArray theArray,
74              Range theRange,
75              IntegerOp op) {
76          super(theArray, theRange);
77          if (op == null) {
78              throw new NullPointerException("SharedUnsigned16BitIntegerArrayReductionBuf(): op is null");
79          }
80          myOp = op;
81      }
82  
83  // Exported operations.
84      /**
85       * {@inheritDoc}
86       *
87       * Store the given item in this buffer.
88       * <P>
89       * The <code>put()</code> method must not block the calling thread; if it does,
90       * all message I/O in MP will be blocked.
91       */
92      public void put(int i,
93              int item) {
94          myArray.reduce(myArrayOffset + i * myStride, item, myOp);
95      }
96  
97      /**
98       * {@inheritDoc}
99       *
100      * Create a buffer for performing parallel reduction using the given binary
101      * operation. The results of the reduction are placed into this buffer.
102      * @exception ClassCastException (unchecked exception) Thrown if this
103      * buffer's element data type and the given binary operation's argument data
104      * type are not the same.
105      */
106     public Buf getReductionBuf(Op op) {
107         throw new UnsupportedOperationException();
108     }
109 
110 // Hidden operations.
111     /**
112      * {@inheritDoc}
113      *
114      * Receive as many items as possible from the given byte buffer to this
115      * buffer.
116      * <P>
117      * The <code>receiveItems()</code> method must not block the calling thread; if
118      * it does, all message I/O in MP will be blocked.
119      */
120     protected int receiveItems(int i,
121             int num,
122             ByteBuffer buffer) {
123         int index = i;
124         int off = myArrayOffset + i * myStride;
125         int max = Math.min(i + num, myLength);
126         while (index < max && buffer.remaining() >= 2) {
127             myArray.reduce(off, buffer.getShort() & 0xFFFF, myOp);
128             ++index;
129             off += myStride;
130         }
131         return index - i;
132     }
133 
134 }