/*************************************************************************************
 Copyright (c) 2006. Centre for e-Science. Lancaster University. United Kingdom.

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.

 *************************************************************************************/
package uk.ac.lancs.e_science.sakai.tools.blogger.cacheForImages;

import java.util.ArrayList;
import java.util.Date;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.TimerTask;

public class DeadReferencesRecolector extends TimerTask{
	private CacheForImages cache;
	private static long TIME=1000*60*60*3; //those elements that are not accessed in the last three hours will be deleted
	public DeadReferencesRecolector(CacheForImages cache){
		this.cache = cache;
	}
	public void run(){
		long currentMilliseconds = new Date().getTime();
		Hashtable table = cache.getTable();
		Enumeration elements = table.elements();
		ArrayList toDeleting = new ArrayList();
		while (elements.hasMoreElements()){
			CacheForImagesEntry entry = (CacheForImagesEntry)elements.nextElement();
			if (currentMilliseconds-entry.getMilliseconds()<TIME)
				toDeleting.add(entry);
		}
		Iterator it = toDeleting.iterator();
		while (it.hasNext()){
			CacheForImagesEntry entry=(CacheForImagesEntry)it.next();
			cache.removeImage(entry.getImage().getIdImage());
		}

		
	}

}
