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| 1 | /* | ||
| 2 | * Copyright (c) 1995, 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 | * A piped input stream should be connected | ||
| 30 | * to a piped output stream; the piped input | ||
| 31 | * stream then provides whatever data bytes | ||
| 32 | * are written to the piped output stream. | ||
| 33 | * Typically, data is read from a <code>PipedInputStream</code> | ||
| 34 | * object by one thread and data is written | ||
| 35 | * to the corresponding <code>PipedOutputStream</code> | ||
| 36 | * by some other thread. Attempting to use | ||
| 37 | * both objects from a single thread is not | ||
| 38 | * recommended, as it may deadlock the thread. | ||
| 39 | * The piped input stream contains a buffer, | ||
| 40 | * decoupling read operations from write operations, | ||
| 41 | * within limits. | ||
| 42 | * A pipe is said to be <a name=BROKEN> <i>broken</i> </a> if a | ||
| 43 | * thread that was providing data bytes to the connected | ||
| 44 | * piped output stream is no longer alive. | ||
| 45 | * | ||
| 46 | * @author James Gosling | ||
| 47 | * @see java.io.PipedOutputStream | ||
| 48 | * @since JDK1.0 | ||
| 49 | */ | ||
| 50 | public class PipedInputStream extends InputStream { | ||
| 51 | boolean closedByWriter = false; | ||
| 52 | volatile boolean closedByReader = false; | ||
| 53 | boolean connected = false; | ||
| 54 | |||
| 55 | /* REMIND: identification of the read and write sides needs to be | ||
| 56 | more sophisticated. Either using thread groups (but what about | ||
| 57 | pipes within a thread?) or using finalization (but it may be a | ||
| 58 | long time until the next GC). */ | ||
| 59 | Thread readSide; | ||
| 60 | Thread writeSide; | ||
| 61 | |||
| 62 | private static final int DEFAULT_PIPE_SIZE = 1024; | ||
| 63 | |||
| 64 | /** | ||
| 65 | * The default size of the pipe's circular input buffer. | ||
| 66 | * @since JDK1.1 | ||
| 67 | */ | ||
| 68 | // This used to be a constant before the pipe size was allowed | ||
| 69 | // to change. This field will continue to be maintained | ||
| 70 | // for backward compatibility. | ||
| 71 | protected static final int PIPE_SIZE = DEFAULT_PIPE_SIZE; | ||
| 72 | |||
| 73 | /** | ||
| 74 | * The circular buffer into which incoming data is placed. | ||
| 75 | * @since JDK1.1 | ||
| 76 | */ | ||
| 77 | protected byte buffer[]; | ||
| 78 | |||
| 79 | /** | ||
| 80 | * The index of the position in the circular buffer at which the | ||
| 81 | * next byte of data will be stored when received from the connected | ||
| 82 | * piped output stream. <code>in<0</code> implies the buffer is empty, | ||
| 83 | * <code>in==out</code> implies the buffer is full | ||
| 84 | * @since JDK1.1 | ||
| 85 | */ | ||
| 86 | protected int in = -1; | ||
| 87 | |||
| 88 | /** | ||
| 89 | * The index of the position in the circular buffer at which the next | ||
| 90 | * byte of data will be read by this piped input stream. | ||
| 91 | * @since JDK1.1 | ||
| 92 | */ | ||
| 93 | protected int out = 0; | ||
| 94 | |||
| 95 | /** | ||
| 96 | * Creates a <code>PipedInputStream</code> so | ||
| 97 | * that it is connected to the piped output | ||
| 98 | * stream <code>src</code>. Data bytes written | ||
| 99 | * to <code>src</code> will then be available | ||
| 100 | * as input from this stream. | ||
| 101 | * | ||
| 102 | * @param src the stream to connect to. | ||
| 103 | * @exception IOException if an I/O error occurs. | ||
| 104 | */ | ||
| 105 | public PipedInputStream(PipedOutputStream src) throws IOException { | ||
| 106 | this(src, DEFAULT_PIPE_SIZE); | ||
| 107 | } | ||
| 108 | |||
| 109 | /** | ||
| 110 | * Creates a <code>PipedInputStream</code> so that it is | ||
| 111 | * connected to the piped output stream | ||
| 112 | * <code>src</code> and uses the specified pipe size for | ||
| 113 | * the pipe's buffer. | ||
| 114 | * Data bytes written to <code>src</code> will then | ||
| 115 | * be available as input from this stream. | ||
| 116 | * | ||
| 117 | * @param src the stream to connect to. | ||
| 118 | * @param pipeSize the size of the pipe's buffer. | ||
| 119 | * @exception IOException if an I/O error occurs. | ||
| 120 | * @exception IllegalArgumentException if <code>pipeSize <= 0</code>. | ||
| 121 | * @since 1.6 | ||
| 122 | */ | ||
| 123 | public PipedInputStream(PipedOutputStream src, int pipeSize) | ||
| 124 | throws IOException { | ||
| 125 | initPipe(pipeSize); | ||
| 126 | connect(src); | ||
| 127 | } | ||
| 128 | |||
| 129 | /** | ||
| 130 | * Creates a <code>PipedInputStream</code> so | ||
| 131 | * that it is not yet {@linkplain #connect(java.io.PipedOutputStream) | ||
| 132 | * connected}. | ||
| 133 | * It must be {@linkplain java.io.PipedOutputStream#connect( | ||
| 134 | * java.io.PipedInputStream) connected} to a | ||
| 135 | * <code>PipedOutputStream</code> before being used. | ||
| 136 | */ | ||
| 137 | public PipedInputStream() { | ||
| 138 | initPipe(DEFAULT_PIPE_SIZE); | ||
| 139 | } | ||
| 140 | |||
| 141 | /** | ||
| 142 | * Creates a <code>PipedInputStream</code> so that it is not yet | ||
| 143 | * {@linkplain #connect(java.io.PipedOutputStream) connected} and | ||
| 144 | * uses the specified pipe size for the pipe's buffer. | ||
| 145 | * It must be {@linkplain java.io.PipedOutputStream#connect( | ||
| 146 | * java.io.PipedInputStream) | ||
| 147 | * connected} to a <code>PipedOutputStream</code> before being used. | ||
| 148 | * | ||
| 149 | * @param pipeSize the size of the pipe's buffer. | ||
| 150 | * @exception IllegalArgumentException if <code>pipeSize <= 0</code>. | ||
| 151 | * @since 1.6 | ||
| 152 | */ | ||
| 153 | public PipedInputStream(int pipeSize) { | ||
| 154 | initPipe(pipeSize); | ||
| 155 | } | ||
| 156 | |||
| 157 | private void initPipe(int pipeSize) { | ||
| 158 | if (pipeSize <= 0) { | ||
| 159 | throw new IllegalArgumentException("Pipe Size <= 0"); | ||
| 160 | } | ||
| 161 | buffer = new byte[pipeSize]; | ||
| 162 | } | ||
| 163 | |||
| 164 | /** | ||
| 165 | * Causes this piped input stream to be connected | ||
| 166 | * to the piped output stream <code>src</code>. | ||
| 167 | * If this object is already connected to some | ||
| 168 | * other piped output stream, an <code>IOException</code> | ||
| 169 | * is thrown. | ||
| 170 | * <p> | ||
| 171 | * If <code>src</code> is an | ||
| 172 | * unconnected piped output stream and <code>snk</code> | ||
| 173 | * is an unconnected piped input stream, they | ||
| 174 | * may be connected by either the call: | ||
| 175 | * <p> | ||
| 176 | * <pre><code>snk.connect(src)</code> </pre> | ||
| 177 | * <p> | ||
| 178 | * or the call: | ||
| 179 | * <p> | ||
| 180 | * <pre><code>src.connect(snk)</code> </pre> | ||
| 181 | * <p> | ||
| 182 | * The two | ||
| 183 | * calls have the same effect. | ||
| 184 | * | ||
| 185 | * @param src The piped output stream to connect to. | ||
| 186 | * @exception IOException if an I/O error occurs. | ||
| 187 | */ | ||
| 188 | public void connect(PipedOutputStream src) throws IOException { | ||
| 189 | src.connect(this); | ||
| 190 | } | ||
| 191 | |||
| 192 | /** | ||
| 193 | * Receives a byte of data. This method will block if no input is | ||
| 194 | * available. | ||
| 195 | * @param b the byte being received | ||
| 196 | * @exception IOException If the pipe is <a href=#BROKEN> <code>broken</code></a>, | ||
| 197 | * {@link #connect(java.io.PipedOutputStream) unconnected}, | ||
| 198 | * closed, or if an I/O error occurs. | ||
| 199 | * @since JDK1.1 | ||
| 200 | */ | ||
| 201 | protected synchronized void receive(int b) throws IOException { | ||
| 202 | checkStateForReceive(); | ||
| 203 | writeSide = Thread.currentThread(); | ||
| 204 | if (in == out) | ||
| 205 | awaitSpace(); | ||
| 206 | if (in < 0) { | ||
| 207 | in = 0; | ||
| 208 | out = 0; | ||
| 209 | } | ||
| 210 | buffer[in++] = (byte)(b & 0xFF); | ||
| 211 | if (in >= buffer.length) { | ||
| 212 | in = 0; | ||
| 213 | } | ||
| 214 | } | ||
| 215 | |||
| 216 | /** | ||
| 217 | * Receives data into an array of bytes. This method will | ||
| 218 | * block until some input is available. | ||
| 219 | * @param b the buffer into which the data is received | ||
| 220 | * @param off the start offset of the data | ||
| 221 | * @param len the maximum number of bytes received | ||
| 222 | * @exception IOException If the pipe is <a href=#BROKEN> broken</a>, | ||
| 223 | * {@link #connect(java.io.PipedOutputStream) unconnected}, | ||
| 224 | * closed,or if an I/O error occurs. | ||
| 225 | */ | ||
| 226 | synchronized void receive(byte b[], int off, int len) throws IOException { | ||
| 227 | checkStateForReceive(); | ||
| 228 | writeSide = Thread.currentThread(); | ||
| 229 | int bytesToTransfer = len; | ||
| 230 | while (bytesToTransfer > 0) { | ||
| 231 | if (in == out) | ||
| 232 | awaitSpace(); | ||
| 233 | int nextTransferAmount = 0; | ||
| 234 | if (out < in) { | ||
| 235 | nextTransferAmount = buffer.length - in; | ||
| 236 | } else if (in < out) { | ||
| 237 | if (in == -1) { | ||
| 238 | in = out = 0; | ||
| 239 | nextTransferAmount = buffer.length - in; | ||
| 240 | } else { | ||
| 241 | nextTransferAmount = out - in; | ||
| 242 | } | ||
| 243 | } | ||
| 244 | if (nextTransferAmount > bytesToTransfer) | ||
| 245 | nextTransferAmount = bytesToTransfer; | ||
| 246 | assert(nextTransferAmount > 0); | ||
| 247 | System.arraycopy(b, off, buffer, in, nextTransferAmount); | ||
| 248 | bytesToTransfer -= nextTransferAmount; | ||
| 249 | off += nextTransferAmount; | ||
| 250 | in += nextTransferAmount; | ||
| 251 | if (in >= buffer.length) { | ||
| 252 | in = 0; | ||
| 253 | } | ||
| 254 | } | ||
| 255 | } | ||
| 256 | |||
| 257 | private void checkStateForReceive() throws IOException { | ||
| 258 | if (!connected) { | ||
| 259 | throw new IOException("Pipe not connected"); | ||
| 260 | } else if (closedByWriter || closedByReader) { | ||
| 261 | throw new IOException("Pipe closed"); | ||
| 262 | } else if (readSide != null && !readSide.isAlive()) { | ||
| 263 | throw new IOException("Read end dead"); | ||
| 264 | } | ||
| 265 | } | ||
| 266 | |||
| 267 | private void awaitSpace() throws IOException { | ||
| 268 | while (in == out) { | ||
| 269 | checkStateForReceive(); | ||
| 270 | |||
| 271 | /* full: kick any waiting readers */ | ||
| 272 | notifyAll(); | ||
| 273 | try { | ||
| 274 | wait(1000); | ||
| 275 | } catch (InterruptedException ex) { | ||
| 276 | throw new java.io.InterruptedIOException(); | ||
| 277 | } | ||
| 278 | } | ||
| 279 | } | ||
| 280 | |||
| 281 | /** | ||
| 282 | * Notifies all waiting threads that the last byte of data has been | ||
| 283 | * received. | ||
| 284 | */ | ||
| 285 | synchronized void receivedLast() { | ||
| 286 | closedByWriter = true; | ||
| 287 | notifyAll(); | ||
| 288 | } | ||
| 289 | |||
| 290 | /** | ||
| 291 | * Reads the next byte of data from this piped input stream. The | ||
| 292 | * value byte is returned as an <code>int</code> in the range | ||
| 293 | * <code>0</code> to <code>255</code>. | ||
| 294 | * This method blocks until input data is available, the end of the | ||
| 295 | * stream is detected, or an exception is thrown. | ||
| 296 | * | ||
| 297 | * @return the next byte of data, or <code>-1</code> if the end of the | ||
| 298 | * stream is reached. | ||
| 299 | * @exception IOException if the pipe is | ||
| 300 | * {@link #connect(java.io.PipedOutputStream) unconnected}, | ||
| 301 | * <a href=#BROKEN> <code>broken</code></a>, closed, | ||
| 302 | * or if an I/O error occurs. | ||
| 303 | */ | ||
| 304 | public synchronized int read() throws IOException { | ||
| 305 | if (!connected) { | ||
| 306 | throw new IOException("Pipe not connected"); | ||
| 307 | } else if (closedByReader) { | ||
| 308 | throw new IOException("Pipe closed"); | ||
| 309 | } else if (writeSide != null && !writeSide.isAlive() | ||
| 310 | && !closedByWriter && (in < 0)) { | ||
| 311 | throw new IOException("Write end dead"); | ||
| 312 | } | ||
| 313 | |||
| 314 | readSide = Thread.currentThread(); | ||
| 315 | int trials = 2; | ||
| 316 | while (in < 0) { | ||
| 317 | if (closedByWriter) { | ||
| 318 | /* closed by writer, return EOF */ | ||
| 319 | return -1; | ||
| 320 | } | ||
| 321 | if ((writeSide != null) && (!writeSide.isAlive()) && (--trials < 0)) { | ||
| 322 | throw new IOException("Pipe broken"); | ||
| 323 | } | ||
| 324 | /* might be a writer waiting */ | ||
| 325 | notifyAll(); | ||
| 326 | try { | ||
| 327 | wait(1000); | ||
| 328 | } catch (InterruptedException ex) { | ||
| 329 | throw new java.io.InterruptedIOException(); | ||
| 330 | } | ||
| 331 | } | ||
| 332 | int ret = buffer[out++] & 0xFF; | ||
| 333 | if (out >= buffer.length) { | ||
| 334 | out = 0; | ||
| 335 | } | ||
| 336 | if (in == out) { | ||
| 337 | /* now empty */ | ||
| 338 | in = -1; | ||
| 339 | } | ||
| 340 | |||
| 341 | return ret; | ||
| 342 | } | ||
| 343 | |||
| 344 | /** | ||
| 345 | * Reads up to <code>len</code> bytes of data from this piped input | ||
| 346 | * stream into an array of bytes. Less than <code>len</code> bytes | ||
| 347 | * will be read if the end of the data stream is reached or if | ||
| 348 | * <code>len</code> exceeds the pipe's buffer size. | ||
| 349 | * If <code>len </code> is zero, then no bytes are read and 0 is returned; | ||
| 350 | * otherwise, the method blocks until at least 1 byte of input is | ||
| 351 | * available, end of the stream has been detected, or an exception is | ||
| 352 | * thrown. | ||
| 353 | * | ||
| 354 | * @param b the buffer into which the data is read. | ||
| 355 | * @param off the start offset in the destination array <code>b</code> | ||
| 356 | * @param len the maximum number of bytes read. | ||
| 357 | * @return the total number of bytes read into the buffer, or | ||
| 358 | * <code>-1</code> if there is no more data because the end of | ||
| 359 | * the stream has been reached. | ||
| 360 | * @exception NullPointerException If <code>b</code> is <code>null</code>. | ||
| 361 | * @exception IndexOutOfBoundsException If <code>off</code> is negative, | ||
| 362 | * <code>len</code> is negative, or <code>len</code> is greater than | ||
| 363 | * <code>b.length - off</code> | ||
| 364 | * @exception IOException if the pipe is <a href=#BROKEN> <code>broken</code></a>, | ||
| 365 | * {@link #connect(java.io.PipedOutputStream) unconnected}, | ||
| 366 | * closed, or if an I/O error occurs. | ||
| 367 | */ | ||
| 368 | public synchronized int read(byte b[], int off, int len) throws IOException { | ||
| 369 | if (b == null) { | ||
| 370 | throw new NullPointerException(); | ||
| 371 | } else if (off < 0 || len < 0 || len > b.length - off) { | ||
| 372 | throw new IndexOutOfBoundsException(); | ||
| 373 | } else if (len == 0) { | ||
| 374 | return 0; | ||
| 375 | } | ||
| 376 | |||
| 377 | /* possibly wait on the first character */ | ||
| 378 | int c = read(); | ||
| 379 | if (c < 0) { | ||
| 380 | return -1; | ||
| 381 | } | ||
| 382 | b[off] = (byte) c; | ||
| 383 | int rlen = 1; | ||
| 384 | while ((in >= 0) && (len > 1)) { | ||
| 385 | |||
| 386 | int available; | ||
| 387 | |||
| 388 | if (in > out) { | ||
| 389 | available = Math.min((buffer.length - out), (in - out)); | ||
| 390 | } else { | ||
| 391 | available = buffer.length - out; | ||
| 392 | } | ||
| 393 | |||
| 394 | // A byte is read beforehand outside the loop | ||
| 395 | if (available > (len - 1)) { | ||
| 396 | available = len - 1; | ||
| 397 | } | ||
| 398 | System.arraycopy(buffer, out, b, off + rlen, available); | ||
| 399 | out += available; | ||
| 400 | rlen += available; | ||
| 401 | len -= available; | ||
| 402 | |||
| 403 | if (out >= buffer.length) { | ||
| 404 | out = 0; | ||
| 405 | } | ||
| 406 | if (in == out) { | ||
| 407 | /* now empty */ | ||
| 408 | in = -1; | ||
| 409 | } | ||
| 410 | } | ||
| 411 | return rlen; | ||
| 412 | } | ||
| 413 | |||
| 414 | /** | ||
| 415 | * Returns the number of bytes that can be read from this input | ||
| 416 | * stream without blocking. | ||
| 417 | * | ||
| 418 | * @return the number of bytes that can be read from this input stream | ||
| 419 | * without blocking, or {@code 0} if this input stream has been | ||
| 420 | * closed by invoking its {@link #close()} method, or if the pipe | ||
| 421 | * is {@link #connect(java.io.PipedOutputStream) unconnected}, or | ||
| 422 | * <a href=#BROKEN> <code>broken</code></a>. | ||
| 423 | * | ||
| 424 | * @exception IOException if an I/O error occurs. | ||
| 425 | * @since JDK1.0.2 | ||
| 426 | */ | ||
| 427 | public synchronized int available() throws IOException { | ||
| 428 | if(in < 0) | ||
| 429 | return 0; | ||
| 430 | else if(in == out) | ||
| 431 | return buffer.length; | ||
| 432 | else if (in > out) | ||
| 433 | return in - out; | ||
| 434 | else | ||
| 435 | return in + buffer.length - out; | ||
| 436 | } | ||
| 437 | |||
| 438 | /** | ||
| 439 | * Closes this piped input stream and releases any system resources | ||
| 440 | * associated with the stream. | ||
| 441 | * | ||
| 442 | * @exception IOException if an I/O error occurs. | ||
| 443 | */ | ||
| 444 | public void close() throws IOException { | ||
| 445 | closedByReader = true; | ||
| 446 | synchronized (this) { | ||
| 447 | in = -1; | ||
| 448 | } | ||
| 449 | } | ||
| 450 | } | ||