/**
* Copyright (c) 2002-2010 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.com]
*
* This file is part of Neo4j.
*
* Neo4j is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.kernel.impl.cache;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.WeakReference;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
public class WeakLruCache<K,V> extends ReferenceCache<K,V>
{
private final ConcurrentHashMap<K,WeakValue<K,V>> cache =
new ConcurrentHashMap<K,WeakValue<K,V>>();
private final WeakReferenceQueue<K,V> refQueue =
new WeakReferenceQueue<K,V>();
private final String name;
public WeakLruCache( String name )
{
this.name = name;
}
public void put( K key, V value )
{
WeakValue<K,V> ref =
new WeakValue<K,V>( key, value, (ReferenceQueue<V>) refQueue );
cache.put( key, ref );
pollClearedValues();
}
public void putAll( Map<K,V> map )
{
Map<K,WeakValue<K,V>> softMap = new HashMap<K,WeakValue<K,V>>( map.size() * 2 );
for ( Map.Entry<K, V> entry : map.entrySet() )
{
WeakValue<K,V> ref =
new WeakValue<K,V>( entry.getKey(), entry.getValue(), (ReferenceQueue<V>) refQueue );
softMap.put( entry.getKey(), ref );
}
cache.putAll( softMap );
pollClearedValues();
}
public V get( K key )
{
WeakReference<V> ref = cache.get( key );
if ( ref != null )
{
if ( ref.get() == null )
{
cache.remove( key );
}
return ref.get();
}
return null;
}
public V remove( K key )
{
WeakReference<V> ref = cache.remove( key );
if ( ref != null )
{
return ref.get();
}
return null;
}
protected void pollClearedValues()
{
WeakValue<K,V> clearedValue = refQueue.safePoll();
while ( clearedValue != null )
{
cache.remove( clearedValue.key );
clearedValue = refQueue.safePoll();
}
}
public int size()
{
return cache.size();
}
public void clear()
{
cache.clear();
}
public void elementCleaned( V value )
{
}
public String getName()
{
return name;
}
public boolean isAdaptive()
{
return true;
}
public int maxSize()
{
return -1;
}
public void resize( int newSize )
{
}
public void setAdaptiveStatus( boolean status )
{
}
}