/*
Copyright (c) 2008  Franklin Schmidt <fschmidt@gmail.com>

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

package fschmidt.util.java;

import java.util.Map;
import java.util.LinkedHashMap;
import java.util.Iterator;
import fschmidt.db.util.WeakCacheMap;


public class TimedCacheMap<K,V> extends WeakCacheMap<K,V> {

	private static class IdentityRef {
		private final Object obj;

		IdentityRef(Object obj) {
			this.obj = obj;
		}

		public int hashCode() {
			return System.identityHashCode(obj);
		}

		public boolean equals(Object obj) {
			return obj instanceof IdentityRef
				&& obj==((IdentityRef)obj).obj;
		}
	}

	private final long timeLimit;
	private final Map<IdentityRef,Long> vals = new LinkedHashMap<IdentityRef,Long>();

	public TimedCacheMap(long timeLimit) {
		this.timeLimit = timeLimit;
	}

	private void add(V value,long now) {
		if( value==null )
			return;
		IdentityRef ref = new IdentityRef(value);
		vals.remove(ref);
		vals.put( ref, now + timeLimit );
	}

	private void sweep(long now) {
		for( Iterator<Long> i = vals.values().iterator(); i.hasNext(); ) {
			long time = i.next();
			if( time > now )
				return;
			i.remove();
		}
	}

	public V put(K key, V value) {
		long now = System.currentTimeMillis();
		sweep(now);
		add(value,now);
		return super.put(key,value);
	}

	public V get(Object key) {
		long now = System.currentTimeMillis();
		V value = super.get(key);
		add(value,now);
		return value;
	}
}