Initial revision

From-SVN: r102074

libjava/classpath/java/io/PipedOutputStream.java

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+/* PipedOutputStream.java -- Write portion of piped streams.
+   Copyright (C) 1998, 2000, 2001, 2003 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 PipedWriter.  If you 
+// fix a bug in here, chances are you should make a similar change to the 
+// PipedWriter code.
+
+/**
+  * This class writes its bytes to a <code>PipedInputStream</code> to 
+  * which it is connected.
+  * <p>
+  * It is highly recommended that a <code>PipedOutputStream</code> and its
+  * connected <code>PipedInputStream</code> be in different threads.  If 
+  * they are in the same thread, read and write operations could deadlock
+  * the thread.
+  *
+  * @author Aaron M. Renn (arenn@urbanophile.com)
+  */
+public class PipedOutputStream extends OutputStream
+{
+  /** Target PipedInputStream to which this is connected. Null only if this 
+    * OutputStream hasn't been connected yet. */
+  PipedInputStream sink;
+  
+  /** Set to true if close() has been called on this OutputStream. */
+  boolean closed;
+  
+  /** 
+    * Create an unconnected PipedOutputStream.  It must be connected
+    * to a <code>PipedInputStream</code> using the <code>connect</code>
+    * method prior to writing any data or an exception will be thrown.
+    */
+  public PipedOutputStream()
+  {
+  }
+
+  /**
+     * Create a new <code>PipedOutputStream</code> instance
+    * to write to the specified <code>PipedInputStream</code>.  This stream
+    * is then ready for writing.
+    *
+    * @param sink The <code>PipedInputStream</code> to connect this stream to.
+    *
+    * @exception IOException If <code>sink</code> has already been connected 
+    *                        to a different PipedOutputStream.
+    */
+  public PipedOutputStream(PipedInputStream sink) throws IOException
+  {
+    sink.connect(this);
+  }
+
+  /**
+    * Connects this object to the specified <code>PipedInputStream</code> 
+    * object.  This stream will then be ready for writing.
+    *
+    * @param sink The <code>PipedInputStream</code> to connect this stream to
+    *
+    * @exception IOException If the stream has not been connected or has
+    *                        been closed.
+    */
+  public void connect(PipedInputStream sink) throws IOException
+  {
+    if (this.sink != null || sink.source != null)
+      throw new IOException ("Already connected");
+    sink.connect(this);
+  }
+
+  /**
+    * Write a single byte of date to the stream.  Note that this method will 
+    * block if the <code>PipedInputStream</code> to which this object is 
+    * connected has a full buffer.
+    *
+    * @param b The byte of data to be written, passed as an <code>int</code>.
+    *
+    * @exception IOException If the stream has not been connected or has
+    *                        been closed.
+    */  
+  public void write(int b) throws IOException
+  {
+    if (sink == null)
+      throw new IOException ("Not connected");
+    if (closed)
+      throw new IOException ("Pipe closed");
+      
+    sink.receive (b);
+  }
+  
+  /**
+    * This method writes <code>len</code> bytes of data from the byte array
+    * <code>buf</code> starting at index <code>offset</code> in the array
+    * to the stream.  Note that this method will block if the  
+    * <code>PipedInputStream</code> to which this object is connected has
+    * a buffer that cannot hold all of the bytes to be written.
+    *
+    * @param buffer The array containing bytes to write to the stream.
+    * @param offset The index into the array to start writing bytes from.
+    * @param len The number of bytes to write.
+    *
+    * @exception IOException If the stream has not been connected or has
+    *                        been closed.
+    */
+  public void write(byte[] buffer, int offset, int len) throws IOException
+  {
+    if (sink == null)
+      throw new IOException ("Not connected");
+    if (closed)
+      throw new IOException ("Pipe closed");
+      
+    sink.receive(buffer, offset, len);
+  }
+
+  /**
+    * This method does nothing.
+    *
+    * @exception IOException If the stream is closed.
+    * @specnote You'd think that this method would block until the sink
+    *           had read all available data. Thats not the case - this method
+    *           appears to be a no-op?
+    */
+  public void flush() throws IOException
+  {
+  }
+  
+  /**
+    * This method closes this stream so that no more data can be written
+    * to it. Any further attempts to write to this stream may throw an
+    * exception
+    *
+    * @exception IOException If an error occurs
+    */
+  public void close() throws IOException
+  {
+    // A close call on an unconnected PipedOutputStream has no effect.
+    if (sink != null)
+      {
+	closed = true;
+	// Notify any waiting readers that the stream is now closed.
+	synchronized (sink)
+	{	  
+	  sink.notifyAll();
+	}
+      }
+  }
+}