ReferenceCountedDirectByteBuffer.java

/*
 * Created on Jan 26, 2007
 * Created by Paul Gardner
 * Copyright (C) 2007 Aelitis, All Rights Reserved.
 *
 * This program 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
 * of the License, or (at your option) any later version.
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 * 
 * AELITIS, SAS au capital de 63.529,40 euros
 * 8 Allee Lenotre, La Grille Royale, 78600 Le Mesnil le Roi, France.
 *
 */


package org.gudy.azureus2.core3.util;

import java.nio.ByteBuffer;

public class 
ReferenceCountedDirectByteBuffer
	extends DirectByteBuffer
{
	private DirectByteBuffer	basis;
	
	private int	ref_count = 1;
	
	protected
	ReferenceCountedDirectByteBuffer(
		DirectByteBuffer	_basis )
	{
		this( _basis.getBufferInternal());
		
		basis	= _basis;
	}
	
	protected
	ReferenceCountedDirectByteBuffer(
		ByteBuffer		_buffer )
	{
		super( _buffer );
	}
	
	public ReferenceCountedDirectByteBuffer
	duplicate(
		int		offset,
		int		length )
	{
		ByteBuffer	duplicate = getBufferInternal().duplicate();
		
		duplicate.position( duplicate.position() + offset );
		
		duplicate.limit(  duplicate.position() + length );
		
		ReferenceCountedDirectByteBuffer res = new ReferenceCountedDirectByteBufferDuplicate( duplicate );
		
		return( res );
	}

	public void
	incrementReferenceCount()
	{
		synchronized( this ){
			
			ref_count++;
			
			// System.out.println( "" + this + ": rc=" + ref_count );
		}
	}
	
	public void
	decrementReferenceCount()
	{
		synchronized( this ){
				
			ref_count--;
			
			// System.out.println( "" + this + ": rc=" + ref_count );
			
			if ( ref_count == 0 ){
				
				basis.returnToPool();
			}
		}	
	}
	
	public int
	getReferenceCount()
	{
		return( ref_count );
	}
	
	public void 
	returnToPool() 
	{
		decrementReferenceCount();
	}
	
	protected class
	ReferenceCountedDirectByteBufferDuplicate
		extends ReferenceCountedDirectByteBuffer
	{
		protected 
		ReferenceCountedDirectByteBufferDuplicate(
			ByteBuffer		owner )
		{
			super( owner );
			
			incrementReferenceCount();
		}
		
		public ReferenceCountedDirectByteBuffer
		duplicate(
			int		offset,
			int		length )
		{
//			Debug.out( "dup dup" );
			
			return( null );
		}
		
		public void 
		returnToPool()
		{
			decrementReferenceCount();
		}
		
		public void
		incrementReferenceCount()
		{
			ReferenceCountedDirectByteBuffer.this.incrementReferenceCount();
		}
		
		public void
		decrementReferenceCount()
		{
			ReferenceCountedDirectByteBuffer.this.decrementReferenceCount();
		}
	}
}