libjava/java/io/PipedOutputStream.java

// PipedOutputStream.java - Write bytes to a pipe.

/* Copyright (C) 1998, 1999  Cygnus Solutions

   This file is part of libgcj.

This software is copyrighted work licensed under the terms of the
Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
details.  */

package java.io;

/**
 * @author Tom Tromey <tromey@cygnus.com>
 * @date September 24, 1998 
 */

/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
 * "The Java Language Specification", ISBN 0-201-63451-1
 * Status:  Believed complete and correct.
 */

public class PipedOutputStream extends OutputStream
{
  public void close () throws IOException
  {
    closed = true;

    // Notify PipedInputStream that there is no more data to be had.
    destination.receive(-1);
  }

  public void connect (PipedInputStream dest) throws IOException
  {
    if (closed)
      throw new IOException("pipe closed");

    if (destination != null)
      if (destination == dest)
	return;
      else
        throw new IOException("pipe already connected");

    destination = dest;
    try
    {
      dest.connect(this);
    }
    catch (IOException ex)
    {
      destination = null;
      throw ex;
    }
  }

  public synchronized void flush () throws IOException
  {
    // There doesn't seem to be anything to do here.

    // TBD: Should this maybe do a notifyAll as a way for the user
    // to wake up the input stream to check for bytes to read?  Shouldn't
    // be necessary but if there aren't any bytes, other threads will just
    // go blocak again anyway so it wouldn't hurt.
  }

  public PipedOutputStream ()
  {
    closed = false;
  }

  public PipedOutputStream (PipedInputStream dest) throws IOException
  {
    closed = false;
    connect (dest);
  }

  public void write (int oneByte) throws IOException
  {
    if (closed)
      throw new IOException ();
    destination.receive(oneByte);
  }

  // This is mentioned in the JCL book, but we don't really need it.
  // If there were a corresponding receive() method on
  // PipedInputStream then we could get better performance using
  // this.
  // public void write (byte[] buffer, int offset, int count)
  // throws IOException;

  // Instance variables.
  private PipedInputStream destination;
  private boolean closed;
}