1 //******************************************************************************
2 //
3 // File: StreamFile.java
4 // Package: edu.rit.pj.io
5 // Unit: Class edu.rit.pj.io.StreamFile
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.io;
41
42 import java.io.File;
43 import java.io.FileInputStream;
44 import java.io.FileOutputStream;
45 import java.io.IOException;
46 import java.io.InputStream;
47 import java.io.OutputStream;
48
49 import edu.rit.pj.cluster.JobBackend;
50
51 /**
52 * Class StreamFile represents a file that resides in the user's account in the
53 * job frontend process of a PJ cluster parallel program. Operations are
54 * provided to open an input stream or an output stream to read or write the
55 * file in the frontend processor.
56 *
57 * @author Alan Kaminsky
58 * @version 06-Nov-2006
59 */
60 public class StreamFile {
61
62 // Hidden data members.
63 private File myFile;
64
65 // Exported constructors.
66 /**
67 * Construct a new stream file that refers to the given file in the frontend
68 * processor.
69 *
70 * @param theFile File.
71 * @exception NullPointerException (unchecked exception) Thrown if
72 * <code>theFile</code> is null.
73 */
74 public StreamFile(File theFile) {
75 if (theFile == null) {
76 throw new NullPointerException("StreamFile(): theFile is null");
77 }
78 myFile = theFile;
79 }
80
81 // Exported operations.
82 /**
83 * Obtain the file in the frontend processor to which this stream file
84 * refers.
85 *
86 * @return File.
87 */
88 public File getFile() {
89 return myFile;
90 }
91
92 /**
93 * Open an output stream for writing this stream file. If the file does not
94 * exist, it is created; if the file exists, it is overwritten.
95 * <P>
96 * When called from a job backend process in a cluster parallel program, the
97 * returned output stream communicates with the job frontend process to
98 * write the file in the frontend processor. Otherwise, the returned output
99 * stream is a normal file output stream to write the file directly.
100 * <P>
101 * <I>Note:</I> The returned output stream does not do any buffering. Each
102 * method call sends a message to and receives a message from the job
103 * frontend. Consider layering a BufferedOutputStream on top of the returned
104 * output stream.
105 *
106 * @return Output stream.
107 * @exception IOException Thrown if an I/O error occurred.
108 * @throws java.io.IOException if any.
109 */
110 public OutputStream getOutputStream()
111 throws IOException {
112 return getOutputStream(false);
113 }
114
115 /**
116 * Open an output stream for writing this stream file. If the file does not
117 * exist, it is created; if the file exists and the <code>append</code> flag is
118 * false, the file is overwritten; if the file exists and the
119 * <code>append</code> flag is true, data is written after the end of the file.
120 * <P>
121 * When called from a job backend process in a cluster parallel program, the
122 * returned output stream communicates with the job frontend process to
123 * write the file in the frontend processor. Otherwise, the returned output
124 * stream is a normal file output stream to write the file directly.
125 * <P>
126 * <I>Note:</I> The returned output stream does not do any buffering. Each
127 * method call sends a message to and receives a message from the job
128 * frontend. Consider layering a BufferedOutputStream on top of the returned
129 * output stream.
130 *
131 * @param append True to append, false to overwrite.
132 * @return Output stream.
133 * @exception IOException Thrown if an I/O error occurred.
134 * @throws java.io.IOException if any.
135 */
136 public OutputStream getOutputStream(boolean append)
137 throws IOException {
138 JobBackend backend = JobBackend.getJobBackend();
139 if (backend == null) {
140 return new FileOutputStream(myFile, append);
141 } else {
142 return backend.getFileWriter().open(myFile, append);
143 }
144 }
145
146 /**
147 * Open an input stream for reading this stream file.
148 * <P>
149 * When called from a job backend process in a cluster parallel program, the
150 * returned input stream communicates with the job frontend process to read
151 * the file in the frontend processor. Otherwise, the returned input stream
152 * is a normal file input stream to read the file directly.
153 * <P>
154 * <I>Note:</I> The returned input stream does not do any buffering. Each
155 * method call sends a message to and receives a message from the job
156 * frontend. Consider layering a BufferedInputStream on top of the returned
157 * input stream.
158 *
159 * @return Input stream.
160 * @exception IOException Thrown if an I/O error occurred.
161 * @throws java.io.IOException if any.
162 */
163 public InputStream getInputStream()
164 throws IOException {
165 JobBackend backend = JobBackend.getJobBackend();
166 if (backend == null) {
167 return new FileInputStream(myFile);
168 } else {
169 return backend.getFileReader().open(myFile);
170 }
171 }
172
173 /**
174 * {@inheritDoc}
175 *
176 * Determine if this stream file is equal to the given object.
177 */
178 public boolean equals(Object obj) {
179 return (obj instanceof StreamFile)
180 && (this.myFile.equals(((StreamFile) obj).myFile));
181 }
182
183 /**
184 * Returns a hash code for this stream file.
185 *
186 * @return Hash code.
187 */
188 public int hashCode() {
189 return myFile.hashCode();
190 }
191
192 /**
193 * Returns a string version of this stream file.
194 *
195 * @return String version.
196 */
197 public String toString() {
198 return myFile.toString();
199 }
200
201 }