File: Buf.java

package info (click to toggle)
libpj-java 0.0~20150107%2Bdfsg-4
  • links: PTS, VCS
  • area: main
  • in suites: bookworm, bullseye
  • size: 13,396 kB
  • sloc: java: 99,543; ansic: 987; sh: 153; xml: 26; makefile: 10; sed: 4
file content (297 lines) | stat: -rw-r--r-- 9,632 bytes parent folder | download | duplicates (2)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
//******************************************************************************
//
// File:    Buf.java
// Package: edu.rit.mp
// Unit:    Class edu.rit.mp.Buf
//
// This Java source file is copyright (C) 2007 by Alan Kaminsky. All rights
// reserved. For further information, contact the author, Alan Kaminsky, at
// ark@cs.rit.edu.
//
// This Java source file is part of the Parallel Java Library ("PJ"). PJ is free
// software; you can redistribute it and/or modify it under the terms of the GNU
// General Public License as published by the Free Software Foundation; either
// version 3 of the License, or (at your option) any later version.
//
// PJ is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
// A PARTICULAR PURPOSE. See the GNU General Public License for more details.
//
// Linking this library statically or dynamically with other modules is making a
// combined work based on this library. Thus, the terms and conditions of the
// GNU General Public License cover the whole combination.
//
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent modules, and
// to copy and distribute the resulting executable under terms of your choice,
// provided that you also meet, for each linked independent module, the terms
// and conditions of the license of that module. An independent module is a
// module which is not derived from or based on this library. If you modify this
// library, you may extend this exception to your version of the library, but
// you are not obligated to do so. If you do not wish to do so, delete this
// exception statement from your version.
//
// A copy of the GNU General Public License is provided in the file gpl.txt. You
// may also obtain a copy of the GNU General Public License on the World Wide
// Web at http://www.gnu.org/licenses/gpl.html.
//
//******************************************************************************

package edu.rit.mp;

import edu.rit.pj.reduction.Op;

import java.io.IOException;

import java.nio.ByteBuffer;

/**
 * Class Buf is the abstract base class for a buffer of items sent or received
 * using the Message Protocol (MP).
 * <P>
 * A buffer may be used to send one or more messages at the same time in
 * multiple threads. If a buffer is being used to send a message or messages,
 * the buffer must not be used to receive a message at the same time.
 * <P>
 * A buffer may be used to receive one message at a time. If a buffer is being
 * used to receive a message, the buffer must not be used to receive another
 * message in a different thread, and the buffer must not be used to send a
 * message or messages.
 * <P>
 * A buffer is a conduit for retrieving and storing data in some underlying data
 * structure. If the underlying data structure is multiple thread safe, then one
 * thread can be retrieving or storing data via the buffer at the same time as
 * other threads are accessing the data structure. If the underlying data
 * structure is not multiple thread safe, then other threads must not access the
 * data structure while one thread is retrieving or storing data via the buffer.
 *
 * @author  Alan Kaminsky
 * @version 03-May-2008
 */
public abstract class Buf
	{

// Hidden data members.

	/**
	 * Number of items in this buffer.
	 */
	protected final int myLength;

	// Type and length sent or received in a message. 
	byte myMessageType;
	int myMessageLength;

// Hidden constructors.

	/**
	 * Construct a new buffer.
	 *
	 * @param  theType       Item type.
	 * @param  theLength     Number of items.
	 *
	 * @exception  IllegalArgumentException
	 *     (unchecked exception) Thrown if <TT>theLength</TT> &lt; 0.
	 */
	Buf
		(byte theType,
		 int theLength)
		{
		if (theLength < 0)
			{
			throw new IllegalArgumentException
				("edu.rit.mp.Buf(): theLength = " + theLength + " illegal");
			}
		myLength = theLength;
		myMessageType = theType;
		myMessageLength = theLength;
		}

// Exported operations.

	/**
	 * Obtain the number of items in this buffer.
	 *
	 * @return  Number of items.
	 */
	public final int length()
		{
		return myLength;
		}

	/**
	 * Copy items from the given buffer to this buffer. The number of items
	 * copied is this buffer's length or <TT>theSrc</TT>'s length, whichever is
	 * smaller. If <TT>theSrc</TT> is this buffer, the <TT>copy()</TT> method
	 * does nothing.
	 *
	 * @param  theSrc  Source of items to copy into this buffer.
	 *
	 * @exception  ClassCastException
	 *     (unchecked exception) Thrown if <TT>theSrc</TT>'s item data type is
	 *     not the same as this buffer's item data type.
	 */
	public abstract void copy
		(Buf theSrc);

	/**
	 * Fill this buffer with the given item. The <TT>item</TT> is assigned to
	 * each element in this buffer.
	 * <P>
	 * If this buffer's item data type is a primitive type, the <TT>item</TT>
	 * must be an instance of the corresponding primitive wrapper class -- class
	 * Integer for type <TT>int</TT>, class Double for type <TT>double</TT>, and
	 * so on. If the <TT>item</TT> is null, the item data type's default initial
	 * value is assigned to each element in this buffer.
	 * <P>
	 * If this buffer's item data type is a nonprimitive type, the <TT>item</TT>
	 * must be an instance of the item class or a subclass thereof. The
	 * <TT>item</TT> may be null. Note that since <TT>item</TT> is
	 * <I>assigned</I> to every buffer element, every buffer element ends up
	 * referring to the same <TT>item</TT>.
	 *
	 * @param  item  Item.
	 *
	 * @exception  ClassCastException
	 *     (unchecked exception) Thrown if the <TT>item</TT>'s data type is not
	 *     the same as this buffer's item data type.
	 */
	public abstract void fill
		(Object item);

	/**
	 * Create a buffer for performing parallel reduction using the given binary
	 * operation. The results of the reduction are placed into this buffer.
	 * <P>
	 * Operations performed on the returned reduction buffer have the same
	 * effect as operations performed on this buffer, except whenever a source
	 * item <I>S</I> is put into a destination item <I>D</I> in this buffer,
	 * <I>D</I> is set to <I>D op S</I>, that is, the reduction of <I>D</I> and
	 * <I>S</I> using the given binary operation (rather than just setting
	 * <I>D</I> to <I>S</I>).
	 *
	 * @param  op  Binary operation.
	 *
	 * @exception  ClassCastException
	 *     (unchecked exception) Thrown if this buffer's element data type and
	 *     the given binary operation's argument data type are not the same.
	 */
	public abstract Buf getReductionBuf
		(Op op);

	/**
	 * Create a temporary buffer with the same type of items and the same length
	 * as this buffer. The new buffer items are stored in a newly created array,
	 * separate from the storage for this buffer's items.
	 */
	public abstract Buf getTemporaryBuf();

// Hidden operations.

	/**
	 * Called by the I/O thread before sending message items using this buffer.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	void preSend()
		throws IOException
		{
		}

	/**
	 * Send as many items as possible from this buffer to the given byte
	 * buffer.
	 * <P>
	 * The <TT>sendItems()</TT> method must not block the calling thread; if it
	 * does, all message I/O in MP will be blocked.
	 *
	 * @param  i       Index of first item to send, in the range 0 ..
	 *                 <TT>length</TT>-1.
	 * @param  buffer  Byte buffer.
	 *
	 * @return  Number of items sent.
	 */
	protected abstract int sendItems
		(int i,
		 ByteBuffer buffer);

	/**
	 * Called by the I/O thread after sending message items using this buffer.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	void postSend()
		throws IOException
		{
		}

	/**
	 * Called by the I/O thread before receiving message items using this
	 * buffer.
	 *
	 * @param  theReadLength  Actual number of items in message.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	void preReceive
		(int theReadLength)
		throws IOException
		{
		}

	/**
	 * Receive as many items as possible from the given byte buffer to this
	 * buffer.
	 * <P>
	 * The <TT>receiveItems()</TT> method must not block the calling thread; if
	 * it does, all message I/O in MP will be blocked.
	 *
	 * @param  i       Index of first item to receive, in the range 0 ..
	 *                 <TT>length</TT>-1.
	 * @param  num     Maximum number of items to receive.
	 * @param  buffer  Byte buffer.
	 *
	 * @return  Number of items received.
	 */
	protected abstract int receiveItems
		(int i,
		 int num,
		 ByteBuffer buffer);

	/**
	 * Skip as many items as possible from the given byte buffer.
	 *
	 * @param  num     Number of items to skip.
	 * @param  buffer  Buffer.
	 *
	 * @return  Number of items actually skipped.
	 */
	abstract int skipItems
		(int num,
		 ByteBuffer buffer);

	/**
	 * Called by the I/O thread after receiving message items using this
	 * buffer.
	 *
	 * @param  theStatus       Status object that will be returned for the
	 *                         message; its contents may be altered if
	 *                         necessary.
	 * @param  theClassLoader  Alternate class loader to be used when receiving
	 *                         objects, or null.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	void postReceive
		(Status theStatus,
		 ClassLoader theClassLoader)
		throws IOException
		{
		}

	}