--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/io/PipedInputStream.java Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,450 @@
+/*
+ * Copyright 1995-2006 Sun Microsystems, Inc. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation. Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package java.io;
+
+/**
+ * A piped input stream should be connected
+ * to a piped output stream; the piped input
+ * stream then provides whatever data bytes
+ * are written to the piped output stream.
+ * Typically, data is read from a <code>PipedInputStream</code>
+ * object by one thread and data is written
+ * to the corresponding <code>PipedOutputStream</code>
+ * by some other thread. Attempting to use
+ * both objects from a single thread is not
+ * recommended, as it may deadlock the thread.
+ * The piped input stream contains a buffer,
+ * decoupling read operations from write operations,
+ * within limits.
+ * A pipe is said to be <a name=BROKEN> <i>broken</i> </a> if a
+ * thread that was providing data bytes to the connected
+ * piped output stream is no longer alive.
+ *
+ * @author James Gosling
+ * @see java.io.PipedOutputStream
+ * @since JDK1.0
+ */
+public class PipedInputStream extends InputStream {
+ boolean closedByWriter = false;
+ volatile boolean closedByReader = false;
+ boolean connected = false;
+
+ /* REMIND: identification of the read and write sides needs to be
+ more sophisticated. Either using thread groups (but what about
+ pipes within a thread?) or using finalization (but it may be a
+ long time until the next GC). */
+ Thread readSide;
+ Thread writeSide;
+
+ private static final int DEFAULT_PIPE_SIZE = 1024;
+
+ /**
+ * The default size of the pipe's circular input buffer.
+ * @since JDK1.1
+ */
+ // This used to be a constant before the pipe size was allowed
+ // to change. This field will continue to be maintained
+ // for backward compatibility.
+ protected static final int PIPE_SIZE = DEFAULT_PIPE_SIZE;
+
+ /**
+ * The circular buffer into which incoming data is placed.
+ * @since JDK1.1
+ */
+ protected byte buffer[];
+
+ /**
+ * The index of the position in the circular buffer at which the
+ * next byte of data will be stored when received from the connected
+ * piped output stream. <code>in<0</code> implies the buffer is empty,
+ * <code>in==out</code> implies the buffer is full
+ * @since JDK1.1
+ */
+ protected int in = -1;
+
+ /**
+ * The index of the position in the circular buffer at which the next
+ * byte of data will be read by this piped input stream.
+ * @since JDK1.1
+ */
+ protected int out = 0;
+
+ /**
+ * Creates a <code>PipedInputStream</code> so
+ * that it is connected to the piped output
+ * stream <code>src</code>. Data bytes written
+ * to <code>src</code> will then be available
+ * as input from this stream.
+ *
+ * @param src the stream to connect to.
+ * @exception IOException if an I/O error occurs.
+ */
+ public PipedInputStream(PipedOutputStream src) throws IOException {
+ this(src, DEFAULT_PIPE_SIZE);
+ }
+
+ /**
+ * Creates a <code>PipedInputStream</code> so that it is
+ * connected to the piped output stream
+ * <code>src</code> and uses the specified pipe size for
+ * the pipe's buffer.
+ * Data bytes written to <code>src</code> will then
+ * be available as input from this stream.
+ *
+ * @param src the stream to connect to.
+ * @param pipeSize the size of the pipe's buffer.
+ * @exception IOException if an I/O error occurs.
+ * @exception IllegalArgumentException if <code>pipeSize <= 0</code>.
+ * @since 1.6
+ */
+ public PipedInputStream(PipedOutputStream src, int pipeSize)
+ throws IOException {
+ initPipe(pipeSize);
+ connect(src);
+ }
+
+ /**
+ * Creates a <code>PipedInputStream</code> so
+ * that it is not yet {@linkplain #connect(java.io.PipedOutputStream)
+ * connected}.
+ * It must be {@linkplain java.io.PipedOutputStream#connect(
+ * java.io.PipedInputStream) connected} to a
+ * <code>PipedOutputStream</code> before being used.
+ */
+ public PipedInputStream() {
+ initPipe(DEFAULT_PIPE_SIZE);
+ }
+
+ /**
+ * Creates a <code>PipedInputStream</code> so that it is not yet
+ * {@linkplain #connect(java.io.PipedOutputStream) connected} and
+ * uses the specified pipe size for the pipe's buffer.
+ * It must be {@linkplain java.io.PipedOutputStream#connect(
+ * java.io.PipedInputStream)
+ * connected} to a <code>PipedOutputStream</code> before being used.
+ *
+ * @param pipeSize the size of the pipe's buffer.
+ * @exception IllegalArgumentException if <code>pipeSize <= 0</code>.
+ * @since 1.6
+ */
+ public PipedInputStream(int pipeSize) {
+ initPipe(pipeSize);
+ }
+
+ private void initPipe(int pipeSize) {
+ if (pipeSize <= 0) {
+ throw new IllegalArgumentException("Pipe Size <= 0");
+ }
+ buffer = new byte[pipeSize];
+ }
+
+ /**
+ * Causes this piped input stream to be connected
+ * to the piped output stream <code>src</code>.
+ * If this object is already connected to some
+ * other piped output stream, an <code>IOException</code>
+ * is thrown.
+ * <p>
+ * If <code>src</code> is an
+ * unconnected piped output stream and <code>snk</code>
+ * is an unconnected piped input stream, they
+ * may be connected by either the call:
+ * <p>
+ * <pre><code>snk.connect(src)</code> </pre>
+ * <p>
+ * or the call:
+ * <p>
+ * <pre><code>src.connect(snk)</code> </pre>
+ * <p>
+ * The two
+ * calls have the same effect.
+ *
+ * @param src The piped output stream to connect to.
+ * @exception IOException if an I/O error occurs.
+ */
+ public void connect(PipedOutputStream src) throws IOException {
+ src.connect(this);
+ }
+
+ /**
+ * Receives a byte of data. This method will block if no input is
+ * available.
+ * @param b the byte being received
+ * @exception IOException If the pipe is <a href=#BROKEN> <code>broken</code></a>,
+ * {@link #connect(java.io.PipedOutputStream) unconnected},
+ * closed, or if an I/O error occurs.
+ * @since JDK1.1
+ */
+ protected synchronized void receive(int b) throws IOException {
+ checkStateForReceive();
+ writeSide = Thread.currentThread();
+ if (in == out)
+ awaitSpace();
+ if (in < 0) {
+ in = 0;
+ out = 0;
+ }
+ buffer[in++] = (byte)(b & 0xFF);
+ if (in >= buffer.length) {
+ in = 0;
+ }
+ }
+
+ /**
+ * Receives data into an array of bytes. This method will
+ * block until some input is available.
+ * @param b the buffer into which the data is received
+ * @param off the start offset of the data
+ * @param len the maximum number of bytes received
+ * @exception IOException If the pipe is <a href=#BROKEN> broken</a>,
+ * {@link #connect(java.io.PipedOutputStream) unconnected},
+ * closed,or if an I/O error occurs.
+ */
+ synchronized void receive(byte b[], int off, int len) throws IOException {
+ checkStateForReceive();
+ writeSide = Thread.currentThread();
+ int bytesToTransfer = len;
+ while (bytesToTransfer > 0) {
+ if (in == out)
+ awaitSpace();
+ int nextTransferAmount = 0;
+ if (out < in) {
+ nextTransferAmount = buffer.length - in;
+ } else if (in < out) {
+ if (in == -1) {
+ in = out = 0;
+ nextTransferAmount = buffer.length - in;
+ } else {
+ nextTransferAmount = out - in;
+ }
+ }
+ if (nextTransferAmount > bytesToTransfer)
+ nextTransferAmount = bytesToTransfer;
+ assert(nextTransferAmount > 0);
+ System.arraycopy(b, off, buffer, in, nextTransferAmount);
+ bytesToTransfer -= nextTransferAmount;
+ off += nextTransferAmount;
+ in += nextTransferAmount;
+ if (in >= buffer.length) {
+ in = 0;
+ }
+ }
+ }
+
+ private void checkStateForReceive() throws IOException {
+ if (!connected) {
+ throw new IOException("Pipe not connected");
+ } else if (closedByWriter || closedByReader) {
+ throw new IOException("Pipe closed");
+ } else if (readSide != null && !readSide.isAlive()) {
+ throw new IOException("Read end dead");
+ }
+ }
+
+ private void awaitSpace() throws IOException {
+ while (in == out) {
+ checkStateForReceive();
+
+ /* full: kick any waiting readers */
+ notifyAll();
+ try {
+ wait(1000);
+ } catch (InterruptedException ex) {
+ throw new java.io.InterruptedIOException();
+ }
+ }
+ }
+
+ /**
+ * Notifies all waiting threads that the last byte of data has been
+ * received.
+ */
+ synchronized void receivedLast() {
+ closedByWriter = true;
+ notifyAll();
+ }
+
+ /**
+ * Reads the next byte of data from this piped input stream. The
+ * value byte is returned as an <code>int</code> in the range
+ * <code>0</code> to <code>255</code>.
+ * This method blocks until input data is available, the end of the
+ * stream is detected, or an exception is thrown.
+ *
+ * @return the next byte of data, or <code>-1</code> if the end of the
+ * stream is reached.
+ * @exception IOException if the pipe is
+ * {@link #connect(java.io.PipedOutputStream) unconnected},
+ * <a href=#BROKEN> <code>broken</code></a>, closed,
+ * or if an I/O error occurs.
+ */
+ public synchronized int read() throws IOException {
+ if (!connected) {
+ throw new IOException("Pipe not connected");
+ } else if (closedByReader) {
+ throw new IOException("Pipe closed");
+ } else if (writeSide != null && !writeSide.isAlive()
+ && !closedByWriter && (in < 0)) {
+ throw new IOException("Write end dead");
+ }
+
+ readSide = Thread.currentThread();
+ int trials = 2;
+ while (in < 0) {
+ if (closedByWriter) {
+ /* closed by writer, return EOF */
+ return -1;
+ }
+ if ((writeSide != null) && (!writeSide.isAlive()) && (--trials < 0)) {
+ throw new IOException("Pipe broken");
+ }
+ /* might be a writer waiting */
+ notifyAll();
+ try {
+ wait(1000);
+ } catch (InterruptedException ex) {
+ throw new java.io.InterruptedIOException();
+ }
+ }
+ int ret = buffer[out++] & 0xFF;
+ if (out >= buffer.length) {
+ out = 0;
+ }
+ if (in == out) {
+ /* now empty */
+ in = -1;
+ }
+
+ return ret;
+ }
+
+ /**
+ * Reads up to <code>len</code> bytes of data from this piped input
+ * stream into an array of bytes. Less than <code>len</code> bytes
+ * will be read if the end of the data stream is reached or if
+ * <code>len</code> exceeds the pipe's buffer size.
+ * If <code>len </code> is zero, then no bytes are read and 0 is returned;
+ * otherwise, the method blocks until at least 1 byte of input is
+ * available, end of the stream has been detected, or an exception is
+ * thrown.
+ *
+ * @param b the buffer into which the data is read.
+ * @param off the start offset in the destination array <code>b</code>
+ * @param len the maximum number of bytes read.
+ * @return the total number of bytes read into the buffer, or
+ * <code>-1</code> if there is no more data because the end of
+ * the stream has been reached.
+ * @exception NullPointerException If <code>b</code> is <code>null</code>.
+ * @exception IndexOutOfBoundsException If <code>off</code> is negative,
+ * <code>len</code> is negative, or <code>len</code> is greater than
+ * <code>b.length - off</code>
+ * @exception IOException if the pipe is <a href=#BROKEN> <code>broken</code></a>,
+ * {@link #connect(java.io.PipedOutputStream) unconnected},
+ * closed, or if an I/O error occurs.
+ */
+ public synchronized int read(byte b[], int off, int len) throws IOException {
+ if (b == null) {
+ throw new NullPointerException();
+ } else if (off < 0 || len < 0 || len > b.length - off) {
+ throw new IndexOutOfBoundsException();
+ } else if (len == 0) {
+ return 0;
+ }
+
+ /* possibly wait on the first character */
+ int c = read();
+ if (c < 0) {
+ return -1;
+ }
+ b[off] = (byte) c;
+ int rlen = 1;
+ while ((in >= 0) && (len > 1)) {
+
+ int available;
+
+ if (in > out) {
+ available = Math.min((buffer.length - out), (in - out));
+ } else {
+ available = buffer.length - out;
+ }
+
+ // A byte is read beforehand outside the loop
+ if (available > (len - 1)) {
+ available = len - 1;
+ }
+ System.arraycopy(buffer, out, b, off + rlen, available);
+ out += available;
+ rlen += available;
+ len -= available;
+
+ if (out >= buffer.length) {
+ out = 0;
+ }
+ if (in == out) {
+ /* now empty */
+ in = -1;
+ }
+ }
+ return rlen;
+ }
+
+ /**
+ * Returns the number of bytes that can be read from this input
+ * stream without blocking.
+ *
+ * @return the number of bytes that can be read from this input stream
+ * without blocking, or {@code 0} if this input stream has been
+ * closed by invoking its {@link #close()} method, or if the pipe
+ * is {@link #connect(java.io.PipedOutputStream) unconnected}, or
+ * <a href=#BROKEN> <code>broken</code></a>.
+ *
+ * @exception IOException if an I/O error occurs.
+ * @since JDK1.0.2
+ */
+ public synchronized int available() throws IOException {
+ if(in < 0)
+ return 0;
+ else if(in == out)
+ return buffer.length;
+ else if (in > out)
+ return in - out;
+ else
+ return in + buffer.length - out;
+ }
+
+ /**
+ * Closes this piped input stream and releases any system resources
+ * associated with the stream.
+ *
+ * @exception IOException if an I/O error occurs.
+ */
+ public void close() throws IOException {
+ closedByReader = true;
+ synchronized (this) {
+ in = -1;
+ }
+ }
+}