--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/io/PipedReader.java Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,363 @@
+/*
+ * Copyright 1996-2006 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;
+
+
+/**
+ * Piped character-input streams.
+ *
+ * @author Mark Reinhold
+ * @since JDK1.1
+ */
+
+public class PipedReader extends Reader {
+ boolean closedByWriter = false;
+ 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;
+
+ /**
+ * The size of the pipe's circular input buffer.
+ */
+ private static final int DEFAULT_PIPE_SIZE = 1024;
+
+ /**
+ * The circular buffer into which incoming data is placed.
+ */
+ char buffer[];
+
+ /**
+ * The index of the position in the circular buffer at which the
+ * next character of data will be stored when received from the connected
+ * piped writer. <code>in<0</code> implies the buffer is empty,
+ * <code>in==out</code> implies the buffer is full
+ */
+ int in = -1;
+
+ /**
+ * The index of the position in the circular buffer at which the next
+ * character of data will be read by this piped reader.
+ */
+ int out = 0;
+
+ /**
+ * Creates a <code>PipedReader</code> so
+ * that it is connected to the piped writer
+ * <code>src</code>. Data 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 PipedReader(PipedWriter src) throws IOException {
+ this(src, DEFAULT_PIPE_SIZE);
+ }
+
+ /**
+ * Creates a <code>PipedReader</code> so that it is connected
+ * to the piped writer <code>src</code> and uses the specified
+ * pipe size for the pipe's buffer. Data 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 PipedReader(PipedWriter src, int pipeSize) throws IOException {
+ initPipe(pipeSize);
+ connect(src);
+ }
+
+
+ /**
+ * Creates a <code>PipedReader</code> so
+ * that it is not yet {@linkplain #connect(java.io.PipedWriter)
+ * connected}. It must be {@linkplain java.io.PipedWriter#connect(
+ * java.io.PipedReader) connected} to a <code>PipedWriter</code>
+ * before being used.
+ */
+ public PipedReader() {
+ initPipe(DEFAULT_PIPE_SIZE);
+ }
+
+ /**
+ * Creates a <code>PipedReader</code> so that it is not yet
+ * {@link #connect(java.io.PipedWriter) connected} and uses
+ * the specified pipe size for the pipe's buffer.
+ * It must be {@linkplain java.io.PipedWriter#connect(
+ * java.io.PipedReader) connected} to a <code>PipedWriter</code>
+ * before being used.
+ *
+ * @param pipeSize the size of the pipe's buffer.
+ * @exception IllegalArgumentException if <code>pipeSize <= 0</code>.
+ * @since 1.6
+ */
+ public PipedReader(int pipeSize) {
+ initPipe(pipeSize);
+ }
+
+ private void initPipe(int pipeSize) {
+ if (pipeSize <= 0) {
+ throw new IllegalArgumentException("Pipe size <= 0");
+ }
+ buffer = new char[pipeSize];
+ }
+
+ /**
+ * Causes this piped reader to be connected
+ * to the piped writer <code>src</code>.
+ * If this object is already connected to some
+ * other piped writer, an <code>IOException</code>
+ * is thrown.
+ * <p>
+ * If <code>src</code> is an
+ * unconnected piped writer and <code>snk</code>
+ * is an unconnected piped reader, 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 writer to connect to.
+ * @exception IOException if an I/O error occurs.
+ */
+ public void connect(PipedWriter src) throws IOException {
+ src.connect(this);
+ }
+
+ /**
+ * Receives a char of data. This method will block if no input is
+ * available.
+ */
+ synchronized void receive(int c) 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");
+ }
+
+ writeSide = Thread.currentThread();
+ while (in == out) {
+ if ((readSide != null) && !readSide.isAlive()) {
+ throw new IOException("Pipe broken");
+ }
+ /* full: kick any waiting readers */
+ notifyAll();
+ try {
+ wait(1000);
+ } catch (InterruptedException ex) {
+ throw new java.io.InterruptedIOException();
+ }
+ }
+ if (in < 0) {
+ in = 0;
+ out = 0;
+ }
+ buffer[in++] = (char) c;
+ if (in >= buffer.length) {
+ in = 0;
+ }
+ }
+
+ /**
+ * Receives data into an array of characters. This method will
+ * block until some input is available.
+ */
+ synchronized void receive(char c[], int off, int len) throws IOException {
+ while (--len >= 0) {
+ receive(c[off++]);
+ }
+ }
+
+ /**
+ * Notifies all waiting threads that the last character of data has been
+ * received.
+ */
+ synchronized void receivedLast() {
+ closedByWriter = true;
+ notifyAll();
+ }
+
+ /**
+ * Reads the next character of data from this piped stream.
+ * If no character is available because the end of the stream
+ * has been reached, the value <code>-1</code> is returned.
+ * This method blocks until input data is available, the end of
+ * the stream is detected, or an exception is thrown.
+ *
+ * @return the next character of data, or <code>-1</code> if the end of the
+ * stream is reached.
+ * @exception IOException if the pipe is
+ * <a href=PipedInputStream.html#BROKEN> <code>broken</code></a>,
+ * {@link #connect(java.io.PipedWriter) unconnected}, closed,
+ * or 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++];
+ if (out >= buffer.length) {
+ out = 0;
+ }
+ if (in == out) {
+ /* now empty */
+ in = -1;
+ }
+ return ret;
+ }
+
+ /**
+ * Reads up to <code>len</code> characters of data from this piped
+ * stream into an array of characters. Less than <code>len</code> characters
+ * will be read if the end of the data stream is reached or if
+ * <code>len</code> exceeds the pipe's buffer size. This method
+ * blocks until at least one character of input is available.
+ *
+ * @param cbuf the buffer into which the data is read.
+ * @param off the start offset of the data.
+ * @param len the maximum number of characters read.
+ * @return the total number of characters read into the buffer, or
+ * <code>-1</code> if there is no more data because the end of
+ * the stream has been reached.
+ * @exception IOException if the pipe is
+ * <a href=PipedInputStream.html#BROKEN> <code>broken</code></a>,
+ * {@link #connect(java.io.PipedWriter) unconnected}, closed,
+ * or an I/O error occurs.
+ */
+ public synchronized int read(char cbuf[], int off, int len) 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");
+ }
+
+ if ((off < 0) || (off > cbuf.length) || (len < 0) ||
+ ((off + len) > cbuf.length) || ((off + len) < 0)) {
+ throw new IndexOutOfBoundsException();
+ } else if (len == 0) {
+ return 0;
+ }
+
+ /* possibly wait on the first character */
+ int c = read();
+ if (c < 0) {
+ return -1;
+ }
+ cbuf[off] = (char)c;
+ int rlen = 1;
+ while ((in >= 0) && (--len > 0)) {
+ cbuf[off + rlen] = buffer[out++];
+ rlen++;
+ if (out >= buffer.length) {
+ out = 0;
+ }
+ if (in == out) {
+ /* now empty */
+ in = -1;
+ }
+ }
+ return rlen;
+ }
+
+ /**
+ * Tell whether this stream is ready to be read. A piped character
+ * stream is ready if the circular buffer is not empty.
+ *
+ * @exception IOException if the pipe is
+ * <a href=PipedInputStream.html#BROKEN> <code>broken</code></a>,
+ * {@link #connect(java.io.PipedWriter) unconnected}, or closed.
+ */
+ public synchronized boolean ready() 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");
+ }
+ if (in < 0) {
+ return false;
+ } else {
+ return true;
+ }
+ }
+
+ /**
+ * Closes this piped stream and releases any system resources
+ * associated with the stream.
+ *
+ * @exception IOException if an I/O error occurs.
+ */
+ public void close() throws IOException {
+ in = -1;
+ closedByReader = true;
+ }
+}