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1   //******************************************************************************
2   //
3   // File:    SharedByteArrayBuf_1.java
4   // Package: edu.rit.mp.buf
5   // Unit:    Class edu.rit.mp.buf.SharedByteArrayBuf_1
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
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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.ByteOp;
46  import edu.rit.pj.reduction.Op;
47  import edu.rit.pj.reduction.SharedByteArray;
48  import edu.rit.util.Range;
49  
50  /**
51   * Class SharedByteArrayBuf_1 provides a buffer for a multiple thread safe array
52   * of byte items sent or received using the Message Protocol (MP). The array
53   * element stride must be 1. While an instance of class SharedByteArrayBuf_1 may
54   * be constructed directly, normally you will use a factory method in class
55   * {@linkplain edu.rit.mp.ByteBuf ByteBuf}. See that class for further
56   * information.
57   *
58   * @author Alan Kaminsky
59   * @version 26-Oct-2007
60   */
61  public class SharedByteArrayBuf_1
62          extends SharedByteArrayBuf {
63  
64  // Exported constructors.
65      /**
66       * Construct a new shared byte array buffer.
67       *
68       * @param theArray Shared array.
69       * @param theRange Range of array elements to include in the buffer. The
70       * stride is assumed to be 1.
71       */
72      public SharedByteArrayBuf_1(SharedByteArray theArray,
73              Range theRange) {
74          super(theArray, theRange);
75      }
76  
77  // Exported operations.
78      /**
79       * {@inheritDoc}
80       *
81       * Obtain the given item from this buffer.
82       * <P>
83       * The <code>get()</code> method must not block the calling thread; if it does,
84       * all message I/O in MP will be blocked.
85       */
86      public byte get(int i) {
87          return myArray.get(myArrayOffset + i);
88      }
89  
90      /**
91       * {@inheritDoc}
92       *
93       * Store the given item in this buffer.
94       * <P>
95       * The <code>put()</code> method must not block the calling thread; if it does,
96       * all message I/O in MP will be blocked.
97       */
98      public void put(int i,
99              byte item) {
100         myArray.set(myArrayOffset + i, item);
101     }
102 
103     /**
104      * {@inheritDoc}
105      *
106      * Create a buffer for performing parallel reduction using the given binary
107      * operation. The results of the reduction are placed into this buffer.
108      * @exception ClassCastException (unchecked exception) Thrown if this
109      * buffer's element data type and the given binary operation's argument data
110      * type are not the same.
111      */
112     public Buf getReductionBuf(Op op) {
113         return new SharedByteArrayReductionBuf_1(myArray, myRange, (ByteOp) op);
114     }
115 
116 // Hidden operations.
117     /**
118      * {@inheritDoc}
119      *
120      * Send as many items as possible from this buffer to the given byte buffer.
121      * <P>
122      * The <code>sendItems()</code> method must not block the calling thread; if it
123      * does, all message I/O in MP will be blocked.
124      */
125     protected int sendItems(int i,
126             ByteBuffer buffer) {
127         int index = i;
128         int off = myArrayOffset + i;
129         while (index < myLength && buffer.remaining() >= 1) {
130             buffer.put(myArray.get(off));
131             ++index;
132             ++off;
133         }
134         return index - i;
135     }
136 
137     /**
138      * {@inheritDoc}
139      *
140      * Receive as many items as possible from the given byte buffer to this
141      * buffer.
142      * <P>
143      * The <code>receiveItems()</code> method must not block the calling thread; if
144      * it does, all message I/O in MP will be blocked.
145      */
146     protected int receiveItems(int i,
147             int num,
148             ByteBuffer buffer) {
149         int index = i;
150         int off = myArrayOffset + i;
151         int max = Math.min(i + num, myLength);
152         while (index < max && buffer.remaining() >= 1) {
153             myArray.set(off, buffer.get());
154             ++index;
155             ++off;
156         }
157         return index - i;
158     }
159 
160 }