J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1996-2006 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any 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 | } |