1 //******************************************************************************
2 //
3 // File: BackendFileReader.java
4 // Package: edu.rit.pj.cluster
5 // Unit: Class edu.rit.pj.cluster.BackendFileReader
6 //
7 // This Java source file is copyright (C) 2006 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.pj.cluster;
41
42 import java.io.File;
43 import java.io.IOException;
44 import java.util.HashMap;
45 import java.util.Map;
46
47 /**
48 * Class BackendFileReader provides an object that reads sequential files in the
49 * job backend process.
50 * <P>
51 * <I>Note:</I> Class BackendFileReader is not multiple thread safe; it assumes
52 * it is being called by a synchronized method in the job backend.
53 *
54 * @author Alan Kaminsky
55 * @version 20-Nov-2006
56 */
57 public class BackendFileReader {
58
59 // Exported data members.
60 /**
61 * Input stream for reading from the job frontend's standard input.
62 */
63 public final BackendFileInputStream in;
64
65 // Hidden data members.
66 private JobFrontendRef myJobFrontend;
67 private JobBackendRef myJobBackend;
68
69 // Mapping from backend file descriptor to backend file input stream.
70 private Map<Integer, BackendFileInputStream> myInputStreamForBFD
71 = new HashMap<Integer, BackendFileInputStream>();
72
73 // Mapping from frontend file descriptor to backend file input stream.
74 private Map<Integer, BackendFileInputStream> myInputStreamForFFD
75 = new HashMap<Integer, BackendFileInputStream>();
76
77 // Next backend file descriptor.
78 private int myNextBFD = 1;
79
80 // Exported constructors.
81 /**
82 * Construct a new backend file reader.
83 *
84 * @param theJobFrontend Job Frontend.
85 * @param theJobBackend Job Backend.
86 */
87 public BackendFileReader(JobFrontendRef theJobFrontend,
88 JobBackendRef theJobBackend) {
89 myJobFrontend = theJobFrontend;
90 myJobBackend = theJobBackend;
91
92 // Set up input stream for stdin.
93 in = new BackendFileInputStream(myJobFrontend, myJobBackend, 1);
94 myInputStreamForFFD.put(1, in);
95 }
96
97 // Exported operations.
98 /**
99 * Open a backend file input stream on the given file.
100 *
101 * @param file File.
102 * @return Backend file input stream.
103 * @exception IOException Thrown if an I/O error occurred.
104 * @throws java.io.IOException if any.
105 */
106 public BackendFileInputStream open(File file)
107 throws IOException {
108 BackendFileInputStream stream = null;
109 int bfd = 0;
110 int ffd = 0;
111
112 synchronized (this) {
113 stream = new BackendFileInputStream(myJobFrontend, myJobBackend);
114 bfd = myNextBFD++;
115 myInputStreamForBFD.put(bfd, stream);
116 }
117
118 ffd = stream.open(bfd, file);
119
120 synchronized (this) {
121 myInputStreamForFFD.put(ffd, stream);
122 }
123 return stream;
124 }
125
126 /**
127 * Report the result of opening the given input file.
128 *
129 * @param theJobFrontend Job Frontend that is calling this method.
130 * @param bfd Backend file descriptor.
131 * @param ffd Frontend file descriptor if success.
132 * @param exc Null if success, exception if failure.
133 */
134 public void inputFileOpenResult(JobFrontendRef theJobFrontend,
135 int bfd,
136 int ffd,
137 IOException exc) {
138 BackendFileInputStream stream = null;
139 synchronized (this) {
140 stream = myInputStreamForBFD.remove(bfd);
141 }
142 if (stream != null) {
143 stream.putResult(ffd, 0, 0L, exc);
144 }
145 }
146
147 /**
148 * Report the result of reading the given input file.
149 *
150 * @param theJobFrontend Job Frontend that is calling this method.
151 * @param ffd Frontend file descriptor.
152 * @param len Number of bytes read, or -1 if EOF.
153 * @param exc Null if success, exception if failure.
154 */
155 public void inputFileReadResult(JobFrontendRef theJobFrontend,
156 int ffd,
157 int len,
158 IOException exc) {
159 BackendFileInputStream stream = null;
160 synchronized (this) {
161 stream = myInputStreamForFFD.get(ffd);
162 }
163 if (stream != null) {
164 stream.putResult(ffd, len, 0L, exc);
165 }
166 }
167
168 /**
169 * Report the result of skipping the given input file.
170 *
171 * @param theJobFrontend Job Frontend that is calling this method.
172 * @param ffd Frontend file descriptor.
173 * @param len Number of bytes skipped.
174 * @param exc Null if success, exception if failure.
175 */
176 public void inputFileSkipResult(JobFrontendRef theJobFrontend,
177 int ffd,
178 long len,
179 IOException exc) {
180 BackendFileInputStream stream = null;
181 synchronized (this) {
182 stream = myInputStreamForFFD.get(ffd);
183 }
184 if (stream != null) {
185 stream.putResult(ffd, 0, len, exc);
186 }
187 }
188
189 /**
190 * Report the result of closing the given input file.
191 *
192 * @param theJobFrontend Job Frontend that is calling this method.
193 * @param ffd Frontend file descriptor.
194 * @param exc Null if success, exception if failure.
195 */
196 public void inputFileCloseResult(JobFrontendRef theJobFrontend,
197 int ffd,
198 IOException exc) {
199 BackendFileInputStream stream = null;
200 synchronized (this) {
201 stream = myInputStreamForFFD.remove(ffd);
202 }
203 if (stream != null) {
204 stream.putResult(ffd, 0, 0L, exc);
205 }
206 }
207
208 }