com.mchange.v2.coalesce.AbstractWeakCoalescer Maven / Gradle / Ivy
/*
* Distributed as part of mchange-commons-java 0.2.11
*
* Copyright (C) 2015 Machinery For Change, Inc.
*
* Author: Steve Waldman
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of EITHER:
*
* 1) The GNU Lesser General Public License (LGPL), version 2.1, as
* published by the Free Software Foundation
*
* OR
*
* 2) The Eclipse Public License (EPL), version 1.0
*
* You may choose which license to accept if you wish to redistribute
* or modify this work. You may offer derivatives of this work
* under the license you have chosen, or you may provide the same
* choice of license which you have been offered here.
*
* This software 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.
*
* You should have received copies of both LGPL v2.1 and EPL v1.0
* along with this software; see the files LICENSE-EPL and LICENSE-LGPL.
* If not, the text of these licenses are currently available at
*
* LGPL v2.1: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
* EPL v1.0: http://www.eclipse.org/org/documents/epl-v10.php
*
*/
package com.mchange.v2.coalesce;
import java.util.*;
import java.lang.ref.WeakReference;
class AbstractWeakCoalescer implements Coalescer
{
Map wcoalesced;
AbstractWeakCoalescer( Map wcoalesced )
{ this.wcoalesced = wcoalesced; }
public Object coalesce( Object o )
{
//System.err.println("AbstractWeakCoalescer.coalesce( " + o + " )");
Object out = null;
WeakReference wr = (WeakReference) wcoalesced.get( o );
if ( wr != null )
out = wr.get(); //there is a conceivable race that would
//permit wr be cleared
if ( out == null )
{
wcoalesced.put( o , new WeakReference(o) );
out = o;
}
return out;
}
public int countCoalesced()
{ return wcoalesced.size(); }
public Iterator iterator()
{ return new CoalescerIterator( wcoalesced.keySet().iterator() ); }
}