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Diffstat (limited to 'libjava/java/io/PipedReader.java')
| -rw-r--r-- | libjava/java/io/PipedReader.java | 361 |
1 files changed, 0 insertions, 361 deletions
diff --git a/libjava/java/io/PipedReader.java b/libjava/java/io/PipedReader.java deleted file mode 100644 index 90fc10f672d..00000000000 --- a/libjava/java/io/PipedReader.java +++ /dev/null @@ -1,361 +0,0 @@ -/* PipedReader.java -- Read portion of piped character streams. - Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc. - -This file is part of GNU Classpath. - -GNU Classpath is free software; you can redistribute it and/or modify -it under the terms of the GNU General Public License as published by -the Free Software Foundation; either version 2, or (at your option) -any later version. - -GNU Classpath 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 for more details. - -You should have received a copy of the GNU General Public License -along with GNU Classpath; see the file COPYING. If not, write to the -Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA -02110-1301 USA. - -Linking this library statically or dynamically with other modules is -making a combined work based on this library. Thus, the terms and -conditions of the GNU General Public License cover the whole -combination. - -As a special exception, the copyright holders of this library give you -permission to link this library with independent modules to produce an -executable, regardless of the license terms of these independent -modules, and to copy and distribute the resulting executable under -terms of your choice, provided that you also meet, for each linked -independent module, the terms and conditions of the license of that -module. An independent module is a module which is not derived from -or based on this library. If you modify this library, you may extend -this exception to your version of the library, but you are not -obligated to do so. If you do not wish to do so, delete this -exception statement from your version. */ - -package java.io; - -// NOTE: This implementation is very similar to that of PipedInputStream. -// If you fix a bug in here, chances are you should make a similar change to -// the PipedInputStream code. - -/** - * An input stream that reads characters from a piped writer to which it is - * connected. - * <p> - * Data is read and written to an internal buffer. It is highly recommended - * that the <code>PipedReader</code> and connected <code>PipedWriter</code> - * be part of different threads. If they are not, there is a possibility - * that the read and write operations could deadlock their thread. - * - * @specnote The JDK implementation appears to have some undocumented - * functionality where it keeps track of what thread is writing - * to pipe and throws an IOException if that thread susequently - * dies. This behaviour seems dubious and unreliable - we don't - * implement it. - * - * @author Aaron M. Renn (arenn@urbanophile.com) - */ -public class PipedReader extends Reader -{ - /** PipedWriter to which this is connected. Null only if this - * Reader hasn't been connected yet. */ - PipedWriter source; - - /** Set to true if close() has been called on this Reader. */ - boolean closed; - - /** - * The size of the internal buffer used for input/output. - */ - static final int PIPE_SIZE = 2048; - - /** - * This is the internal circular buffer used for storing chars written - * to the pipe and from which chars are read by this stream - */ - char[] buffer = new char[PIPE_SIZE]; - - /** - * The index into buffer where the next char from the connected - * <code>PipedWriter</code> will be written. If this variable is - * equal to <code>out</code>, then the buffer is full. If set to < 0, - * the buffer is empty. - */ - int in = -1; - - /** - * This index into the buffer where chars will be read from. - */ - int out = 0; - - /** Buffer used to implement single-argument read/receive */ - char[] read_buf = new char[1]; - - /** - * Creates a new <code>PipedReader</code> that is not connected to a - * <code>PipedWriter</code>. It must be connected before chars can - * be read from this stream. - */ - public PipedReader() - { - } - - /** - * This constructor creates a new <code>PipedReader</code> and connects - * it to the passed in <code>PipedWriter</code>. The stream is then - * ready for reading. - * - * @param source The <code>PipedWriter</code> to connect this stream to - * - * @exception IOException If <code>source</code> is already connected. - */ - public PipedReader(PipedWriter source) throws IOException - { - connect(source); - } - - /** - * This method connects this stream to the passed in - * <code>PipedWriter</code>. - * This stream is then ready for reading. If this stream is already - * connected or has been previously closed, then an exception is thrown - * - * @param source The <code>PipedWriter</code> to connect this stream to - * - * @exception IOException If this PipedReader or <code>source</code> - * has been connected already. - */ - public void connect(PipedWriter source) throws IOException - { - // The JDK (1.3) does not appear to check for a previously closed - // connection here. - - if (this.source != null || source.sink != null) - throw new IOException ("Already connected"); - - source.sink = this; - this.source = source; - } - - /** - * This method is used by the connected <code>PipedWriter</code> to - * write chars into the buffer. - * - * @param buf The array containing chars to write to this stream - * @param offset The offset into the array to start writing from - * @param len The number of chars to write. - * - * @exception IOException If an error occurs - * @specnote This code should be in PipedWriter.write, but we - * put it here in order to support that bizarre recieve(int) - * method. - */ - void receive(char[] buf, int offset, int len) - throws IOException - { - synchronized (lock) - { - if (closed) - throw new IOException ("Pipe closed"); - - int bufpos = offset; - int copylen; - - while (len > 0) - { - try - { - while (in == out) - { - // The pipe is full. Wake up any readers and wait for them. - lock.notifyAll(); - lock.wait(); - // The pipe could have been closed while we were waiting. - if (closed) - throw new IOException ("Pipe closed"); - } - } - catch (InterruptedException ix) - { - throw new InterruptedIOException (); - } - - if (in < 0) // The pipe is empty. - in = 0; - - // Figure out how many chars from buf can be copied without - // overrunning out or going past the length of the buffer. - if (in < out) - copylen = Math.min (len, out - in); - else - copylen = Math.min (len, buffer.length - in); - - // Copy chars until the pipe is filled, wrapping if necessary. - System.arraycopy(buf, bufpos, buffer, in, copylen); - len -= copylen; - bufpos += copylen; - in += copylen; - if (in == buffer.length) - in = 0; - } - // Notify readers that new data is in the pipe. - lock.notifyAll(); - } - } - - /** - * This method reads chars from the stream into a caller supplied buffer. - * It starts storing chars at position <code>offset</code> into the - * buffer and - * reads a maximum of <code>len</code> chars. Note that this method - * can actually - * read fewer than <code>len</code> chars. The actual number of chars - * read is - * returned. A -1 is returned to indicated that no chars can be read - * because the end of the stream was reached. If the stream is already - * closed, a -1 will again be returned to indicate the end of the stream. - * <p> - * This method will block if no char is available to be read. - */ - public int read() throws IOException - { - // Method operates by calling the multichar overloaded read method - // Note that read_buf is an internal instance variable. I allocate it - // there to avoid constant reallocation overhead for applications that - // call this method in a loop at the cost of some unneeded overhead - // if this method is never called. - - int r = read(read_buf, 0, 1); - return r != -1 ? read_buf[0] : -1; - } - - /** - * This method reads characters from the stream into a caller supplied - * buffer. It starts storing chars at position <code>offset</code> into - * the buffer and reads a maximum of <code>len</code> chars. Note that - * this method can actually read fewer than <code>len</code> chars. - * The actual number of chars read is - * returned. A -1 is returned to indicated that no chars can be read - * because the end of the stream was reached - ie close() was called on the - * connected PipedWriter. - * <p> - * This method will block if no chars are available to be read. - * - * @param buf The buffer into which chars will be stored - * @param offset The index into the buffer at which to start writing. - * @param len The maximum number of chars to read. - * - * @exception IOException If <code>close()</code> was called on this Piped - * Reader. - */ - public int read(char[] buf, int offset, int len) - throws IOException - { - synchronized (lock) - { - if (source == null) - throw new IOException ("Not connected"); - if (closed) - throw new IOException ("Pipe closed"); - - // If the buffer is empty, wait until there is something in the pipe - // to read. - try - { - while (in < 0) - { - if (source.closed) - return -1; - lock.wait(); - } - } - catch (InterruptedException ix) - { - throw new InterruptedIOException(); - } - - int total = 0; - int copylen; - - while (true) - { - // Figure out how many chars from the pipe can be copied without - // overrunning in or going past the length of buf. - if (out < in) - copylen = Math.min (len, in - out); - else - copylen = Math.min (len, buffer.length - out); - - System.arraycopy (buffer, out, buf, offset, copylen); - offset += copylen; - len -= copylen; - out += copylen; - total += copylen; - - if (out == buffer.length) - out = 0; - - if (out == in) - { - // Pipe is now empty. - in = -1; - out = 0; - } - - // If output buffer is filled or the pipe is empty, we're done. - if (len == 0 || in == -1) - { - // Notify any waiting Writer that there is now space - // to write. - lock.notifyAll(); - return total; - } - } - } - } - - public boolean ready() throws IOException - { - // The JDK 1.3 implementation does not appear to check for the closed or - // unconnected stream conditions here. However, checking for a - // closed stream is explicitly required by the JDK 1.2 and 1.3 - // documentation (for Reader.close()), so we do it. - - synchronized (lock) - { - if (closed) - throw new IOException("Pipe closed"); - - if (in < 0) - return false; - - int count; - if (out < in) - count = in - out; - else - count = (buffer.length - out) - in; - - return (count > 0); - } - } - - /** - * This methods closes the stream so that no more data can be read - * from it. - * - * @exception IOException If an error occurs - */ - public void close() throws IOException - { - synchronized (lock) - { - closed = true; - // Wake any thread which may be in receive() waiting to write data. - lock.notifyAll(); - } - } -} - |