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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 | +} | |