Showing the changes to java/pkg/java/io/PipedReader.java (1 of 18352 files). Show all
Unified · Split
| @@ -0,0 +1,363 @@ | |||
| 1 | /* | ||
| 2 | * Copyright (c) 1996, 2006, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | package java.io; | ||
| 27 | |||
| 28 | |||
| 29 | /** | ||
| 30 | * Piped character-input streams. | ||
| 31 | * | ||
| 32 | * @author Mark Reinhold | ||
| 33 | * @since JDK1.1 | ||
| 34 | */ | ||
| 35 | |||
| 36 | public class PipedReader extends Reader { | ||
| 37 | boolean closedByWriter = false; | ||
| 38 | boolean closedByReader = false; | ||
| 39 | boolean connected = false; | ||
| 40 | |||
| 41 | /* REMIND: identification of the read and write sides needs to be | ||
| 42 | more sophisticated. Either using thread groups (but what about | ||
| 43 | pipes within a thread?) or using finalization (but it may be a | ||
| 44 | long time until the next GC). */ | ||
| 45 | Thread readSide; | ||
| 46 | Thread writeSide; | ||
| 47 | |||
| 48 | /** | ||
| 49 | * The size of the pipe's circular input buffer. | ||
| 50 | */ | ||
| 51 | private static final int DEFAULT_PIPE_SIZE = 1024; | ||
| 52 | |||
| 53 | /** | ||
| 54 | * The circular buffer into which incoming data is placed. | ||
| 55 | */ | ||
| 56 | char buffer[]; | ||
| 57 | |||
| 58 | /** | ||
| 59 | * The index of the position in the circular buffer at which the | ||
| 60 | * next character of data will be stored when received from the connected | ||
| 61 | * piped writer. <code>in<0</code> implies the buffer is empty, | ||
| 62 | * <code>in==out</code> implies the buffer is full | ||
| 63 | */ | ||
| 64 | int in = -1; | ||
| 65 | |||
| 66 | /** | ||
| 67 | * The index of the position in the circular buffer at which the next | ||
| 68 | * character of data will be read by this piped reader. | ||
| 69 | */ | ||
| 70 | int out = 0; | ||
| 71 | |||
| 72 | /** | ||
| 73 | * Creates a <code>PipedReader</code> so | ||
| 74 | * that it is connected to the piped writer | ||
| 75 | * <code>src</code>. Data written to <code>src</code> | ||
| 76 | * will then be available as input from this stream. | ||
| 77 | * | ||
| 78 | * @param src the stream to connect to. | ||
| 79 | * @exception IOException if an I/O error occurs. | ||
| 80 | */ | ||
| 81 | public PipedReader(PipedWriter src) throws IOException { | ||
| 82 | this(src, DEFAULT_PIPE_SIZE); | ||
| 83 | } | ||
| 84 | |||
| 85 | /** | ||
| 86 | * Creates a <code>PipedReader</code> so that it is connected | ||
| 87 | * to the piped writer <code>src</code> and uses the specified | ||
| 88 | * pipe size for the pipe's buffer. Data written to <code>src</code> | ||
| 89 | * will then be available as input from this stream. | ||
| 90 | |||
| 91 | * @param src the stream to connect to. | ||
| 92 | * @param pipeSize the size of the pipe's buffer. | ||
| 93 | * @exception IOException if an I/O error occurs. | ||
| 94 | * @exception IllegalArgumentException if <code>pipeSize <= 0</code>. | ||
| 95 | * @since 1.6 | ||
| 96 | */ | ||
| 97 | public PipedReader(PipedWriter src, int pipeSize) throws IOException { | ||
| 98 | initPipe(pipeSize); | ||
| 99 | connect(src); | ||
| 100 | } | ||
| 101 | |||
| 102 | |||
| 103 | /** | ||
| 104 | * Creates a <code>PipedReader</code> so | ||
| 105 | * that it is not yet {@linkplain #connect(java.io.PipedWriter) | ||
| 106 | * connected}. It must be {@linkplain java.io.PipedWriter#connect( | ||
| 107 | * java.io.PipedReader) connected} to a <code>PipedWriter</code> | ||
| 108 | * before being used. | ||
| 109 | */ | ||
| 110 | public PipedReader() { | ||
| 111 | initPipe(DEFAULT_PIPE_SIZE); | ||
| 112 | } | ||
| 113 | |||
| 114 | /** | ||
| 115 | * Creates a <code>PipedReader</code> so that it is not yet | ||
| 116 | * {@link #connect(java.io.PipedWriter) connected} and uses | ||
| 117 | * the specified pipe size for the pipe's buffer. | ||
| 118 | * It must be {@linkplain java.io.PipedWriter#connect( | ||
| 119 | * java.io.PipedReader) connected} to a <code>PipedWriter</code> | ||
| 120 | * before being used. | ||
| 121 | * | ||
| 122 | * @param pipeSize the size of the pipe's buffer. | ||
| 123 | * @exception IllegalArgumentException if <code>pipeSize <= 0</code>. | ||
| 124 | * @since 1.6 | ||
| 125 | */ | ||
| 126 | public PipedReader(int pipeSize) { | ||
| 127 | initPipe(pipeSize); | ||
| 128 | } | ||
| 129 | |||
| 130 | private void initPipe(int pipeSize) { | ||
| 131 | if (pipeSize <= 0) { | ||
| 132 | throw new IllegalArgumentException("Pipe size <= 0"); | ||
| 133 | } | ||
| 134 | buffer = new char[pipeSize]; | ||
| 135 | } | ||
| 136 | |||
| 137 | /** | ||
| 138 | * Causes this piped reader to be connected | ||
| 139 | * to the piped writer <code>src</code>. | ||
| 140 | * If this object is already connected to some | ||
| 141 | * other piped writer, an <code>IOException</code> | ||
| 142 | * is thrown. | ||
| 143 | * <p> | ||
| 144 | * If <code>src</code> is an | ||
| 145 | * unconnected piped writer and <code>snk</code> | ||
| 146 | * is an unconnected piped reader, they | ||
| 147 | * may be connected by either the call: | ||
| 148 | * <p> | ||
| 149 | * <pre><code>snk.connect(src)</code> </pre> | ||
| 150 | * <p> | ||
| 151 | * or the call: | ||
| 152 | * <p> | ||
| 153 | * <pre><code>src.connect(snk)</code> </pre> | ||
| 154 | * <p> | ||
| 155 | * The two | ||
| 156 | * calls have the same effect. | ||
| 157 | * | ||
| 158 | * @param src The piped writer to connect to. | ||
| 159 | * @exception IOException if an I/O error occurs. | ||
| 160 | */ | ||
| 161 | public void connect(PipedWriter src) throws IOException { | ||
| 162 | src.connect(this); | ||
| 163 | } | ||
| 164 | |||
| 165 | /** | ||
| 166 | * Receives a char of data. This method will block if no input is | ||
| 167 | * available. | ||
| 168 | */ | ||
| 169 | synchronized void receive(int c) throws IOException { | ||
| 170 | if (!connected) { | ||
| 171 | throw new IOException("Pipe not connected"); | ||
| 172 | } else if (closedByWriter || closedByReader) { | ||
| 173 | throw new IOException("Pipe closed"); | ||
| 174 | } else if (readSide != null && !readSide.isAlive()) { | ||
| 175 | throw new IOException("Read end dead"); | ||
| 176 | } | ||
| 177 | |||
| 178 | writeSide = Thread.currentThread(); | ||
| 179 | while (in == out) { | ||
| 180 | if ((readSide != null) && !readSide.isAlive()) { | ||
| 181 | throw new IOException("Pipe broken"); | ||
| 182 | } | ||
| 183 | /* full: kick any waiting readers */ | ||
| 184 | notifyAll(); | ||
| 185 | try { | ||
| 186 | wait(1000); | ||
| 187 | } catch (InterruptedException ex) { | ||
| 188 | throw new java.io.InterruptedIOException(); | ||
| 189 | } | ||
| 190 | } | ||
| 191 | if (in < 0) { | ||
| 192 | in = 0; | ||
| 193 | out = 0; | ||
| 194 | } | ||
| 195 | buffer[in++] = (char) c; | ||
| 196 | if (in >= buffer.length) { | ||
| 197 | in = 0; | ||
| 198 | } | ||
| 199 | } | ||
| 200 | |||
| 201 | /** | ||
| 202 | * Receives data into an array of characters. This method will | ||
| 203 | * block until some input is available. | ||
| 204 | */ | ||
| 205 | synchronized void receive(char c[], int off, int len) throws IOException { | ||
| 206 | while (--len >= 0) { | ||
| 207 | receive(c[off++]); | ||
| 208 | } | ||
| 209 | } | ||
| 210 | |||
| 211 | /** | ||
| 212 | * Notifies all waiting threads that the last character of data has been | ||
| 213 | * received. | ||
| 214 | */ | ||
| 215 | synchronized void receivedLast() { | ||
| 216 | closedByWriter = true; | ||
| 217 | notifyAll(); | ||
| 218 | } | ||
| 219 | |||
| 220 | /** | ||
| 221 | * Reads the next character of data from this piped stream. | ||
| 222 | * If no character is available because the end of the stream | ||
| 223 | * has been reached, the value <code>-1</code> is returned. | ||
| 224 | * This method blocks until input data is available, the end of | ||
| 225 | * the stream is detected, or an exception is thrown. | ||
| 226 | * | ||
| 227 | * @return the next character of data, or <code>-1</code> if the end of the | ||
| 228 | * stream is reached. | ||
| 229 | * @exception IOException if the pipe is | ||
| 230 | * <a href=PipedInputStream.html#BROKEN> <code>broken</code></a>, | ||
| 231 | * {@link #connect(java.io.PipedWriter) unconnected}, closed, | ||
| 232 | * or an I/O error occurs. | ||
| 233 | */ | ||
| 234 | public synchronized int read() throws IOException { | ||
| 235 | if (!connected) { | ||
| 236 | throw new IOException("Pipe not connected"); | ||
| 237 | } else if (closedByReader) { | ||
| 238 | throw new IOException("Pipe closed"); | ||
| 239 | } else if (writeSide != null && !writeSide.isAlive() | ||
| 240 | && !closedByWriter && (in < 0)) { | ||
| 241 | throw new IOException("Write end dead"); | ||
| 242 | } | ||
| 243 | |||
| 244 | readSide = Thread.currentThread(); | ||
| 245 | int trials = 2; | ||
| 246 | while (in < 0) { | ||
| 247 | if (closedByWriter) { | ||
| 248 | /* closed by writer, return EOF */ | ||
| 249 | return -1; | ||
| 250 | } | ||
| 251 | if ((writeSide != null) && (!writeSide.isAlive()) && (--trials < 0)) { | ||
| 252 | throw new IOException("Pipe broken"); | ||
| 253 | } | ||
| 254 | /* might be a writer waiting */ | ||
| 255 | notifyAll(); | ||
| 256 | try { | ||
| 257 | wait(1000); | ||
| 258 | } catch (InterruptedException ex) { | ||
| 259 | throw new java.io.InterruptedIOException(); | ||
| 260 | } | ||
| 261 | } | ||
| 262 | int ret = buffer[out++]; | ||
| 263 | if (out >= buffer.length) { | ||
| 264 | out = 0; | ||
| 265 | } | ||
| 266 | if (in == out) { | ||
| 267 | /* now empty */ | ||
| 268 | in = -1; | ||
| 269 | } | ||
| 270 | return ret; | ||
| 271 | } | ||
| 272 | |||
| 273 | /** | ||
| 274 | * Reads up to <code>len</code> characters of data from this piped | ||
| 275 | * stream into an array of characters. Less than <code>len</code> characters | ||
| 276 | * will be read if the end of the data stream is reached or if | ||
| 277 | * <code>len</code> exceeds the pipe's buffer size. This method | ||
| 278 | * blocks until at least one character of input is available. | ||
| 279 | * | ||
| 280 | * @param cbuf the buffer into which the data is read. | ||
| 281 | * @param off the start offset of the data. | ||
| 282 | * @param len the maximum number of characters read. | ||
| 283 | * @return the total number of characters read into the buffer, or | ||
| 284 | * <code>-1</code> if there is no more data because the end of | ||
| 285 | * the stream has been reached. | ||
| 286 | * @exception IOException if the pipe is | ||
| 287 | * <a href=PipedInputStream.html#BROKEN> <code>broken</code></a>, | ||
| 288 | * {@link #connect(java.io.PipedWriter) unconnected}, closed, | ||
| 289 | * or an I/O error occurs. | ||
| 290 | */ | ||
| 291 | public synchronized int read(char cbuf[], int off, int len) throws IOException { | ||
| 292 | if (!connected) { | ||
| 293 | throw new IOException("Pipe not connected"); | ||
| 294 | } else if (closedByReader) { | ||
| 295 | throw new IOException("Pipe closed"); | ||
| 296 | } else if (writeSide != null && !writeSide.isAlive() | ||
| 297 | && !closedByWriter && (in < 0)) { | ||
| 298 | throw new IOException("Write end dead"); | ||
| 299 | } | ||
| 300 | |||
| 301 | if ((off < 0) || (off > cbuf.length) || (len < 0) || | ||
| 302 | ((off + len) > cbuf.length) || ((off + len) < 0)) { | ||
| 303 | throw new IndexOutOfBoundsException(); | ||
| 304 | } else if (len == 0) { | ||
| 305 | return 0; | ||
| 306 | } | ||
| 307 | |||
| 308 | /* possibly wait on the first character */ | ||
| 309 | int c = read(); | ||
| 310 | if (c < 0) { | ||
| 311 | return -1; | ||
| 312 | } | ||
| 313 | cbuf[off] = (char)c; | ||
| 314 | int rlen = 1; | ||
| 315 | while ((in >= 0) && (--len > 0)) { | ||
| 316 | cbuf[off + rlen] = buffer[out++]; | ||
| 317 | rlen++; | ||
| 318 | if (out >= buffer.length) { | ||
| 319 | out = 0; | ||
| 320 | } | ||
| 321 | if (in == out) { | ||
| 322 | /* now empty */ | ||
| 323 | in = -1; | ||
| 324 | } | ||
| 325 | } | ||
| 326 | return rlen; | ||
| 327 | } | ||
| 328 | |||
| 329 | /** | ||
| 330 | * Tell whether this stream is ready to be read. A piped character | ||
| 331 | * stream is ready if the circular buffer is not empty. | ||
| 332 | * | ||
| 333 | * @exception IOException if the pipe is | ||
| 334 | * <a href=PipedInputStream.html#BROKEN> <code>broken</code></a>, | ||
| 335 | * {@link #connect(java.io.PipedWriter) unconnected}, or closed. | ||
| 336 | */ | ||
| 337 | public synchronized boolean ready() throws IOException { | ||
| 338 | if (!connected) { | ||
| 339 | throw new IOException("Pipe not connected"); | ||
| 340 | } else if (closedByReader) { | ||
| 341 | throw new IOException("Pipe closed"); | ||
| 342 | } else if (writeSide != null && !writeSide.isAlive() | ||
| 343 | && !closedByWriter && (in < 0)) { | ||
| 344 | throw new IOException("Write end dead"); | ||
| 345 | } | ||
| 346 | if (in < 0) { | ||
| 347 | return false; | ||
| 348 | } else { | ||
| 349 | return true; | ||
| 350 | } | ||
| 351 | } | ||
| 352 | |||
| 353 | /** | ||
| 354 | * Closes this piped stream and releases any system resources | ||
| 355 | * associated with the stream. | ||
| 356 | * | ||
| 357 | * @exception IOException if an I/O error occurs. | ||
| 358 | */ | ||
| 359 | public void close() throws IOException { | ||
| 360 | in = -1; | ||
| 361 | closedByReader = true; | ||
| 362 | } | ||
| 363 | } | ||