/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2008, Red Hat Middleware LLC or third-party contributors as
* indicated by the @author tags or express copyright attribution
* statements applied by the authors. All third-party contributions are
* distributed under license by Red Hat Middleware LLC.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* 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 Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*
*/
package org.hibernate.util;
import java.io.IOException;
import java.io.Serializable;
import org.apache.commons.collections.map.LRUMap;
/**
* Cache following a "Most Recently Used" (MRU) algorithm for maintaining a
* bounded in-memory size; the "Least Recently Used" (LRU) entry is the first
* available for removal from the cache.
* <p/>
* This implementation uses a bounded MRU Map to limit the in-memory size of
* the cache. Thus the size of this cache never grows beyond the stated size.
*
* @author Steve Ebersole
*/
public class SimpleMRUCache implements Serializable {
public static final int DEFAULT_STRONG_REF_COUNT = 128;
private final int strongReferenceCount;
private transient LRUMap cache;
public SimpleMRUCache() {
this( DEFAULT_STRONG_REF_COUNT );
}
public SimpleMRUCache(int strongReferenceCount) {
this.strongReferenceCount = strongReferenceCount;
init();
}
public synchronized Object get(Object key) {
return cache.get( key );
}
public synchronized Object put(Object key, Object value) {
return cache.put( key, value );
}
public synchronized int size() {
return cache.size();
}
private void init() {
cache = new LRUMap( strongReferenceCount );
}
private void readObject(java.io.ObjectInputStream in) throws IOException, ClassNotFoundException {
in.defaultReadObject();
init();
}
public synchronized void clear() {
cache.clear();
}
}