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/*
 * Mentawai Web Framework http://mentawai.lohis.com.br/
 * Copyright (C) 2005  Sergio Oliveira Jr. ([email protected])
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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 library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
package org.mentawai.cache;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

public class TimeoutCache extends AbstractCache implements Runnable {
    
    private final long timeout;
    
    private Thread thread = null;
    private volatile boolean bThread = true;
    
    public TimeoutCache(String name, int capacity, long timeout) {
     
        super(name, capacity);
        
        this.timeout = timeout;
        
        this.thread = new Thread(this);
        this.thread.start();
    }
    
    public void run() {
        
        while(bThread) {
            
            long now = System.currentTimeMillis();
            
            synchronized(this) {
                
                Iterator iter = map.values().iterator();
                
                while(iter.hasNext()) {
                    
                    Entry entry = (Entry) iter.next();
                    
                    if (entry.isExpired(now)) {
                        
                        iter.remove();
                        
                    }
                }
            }
            
            try {
                
                Thread.sleep(timeout);
                
            } catch(InterruptedException e) { }
        }
    }
    
    public void close() {
        
        bThread = false;
        
        thread.interrupt();
        
        thread = null;
    }
    
    protected Map createMap(int initialCapacity, float load) {
     
        return new HashMap(initialCapacity, load);
    }
    
    public synchronized Object remove(Object key) {
        
        Entry entry = (Entry) super.remove(key);
        
        if (entry != null) {
            
            return entry.value;
            
        } else {
            
            return null;
        }
    }

    public synchronized Object get(Object key) {
        
        Entry entry = (Entry) super.get(key);
        
        if (entry != null) return entry.value;
        
        return null;
    }

    public synchronized Object put(Object key, Object value) {
        
        if (map.size() == capacity && !map.containsKey(key)) {
            
            return null;
        }
        
        Entry entry = (Entry) map.put(key, new Entry(value));
        
        if (entry == null) return null;
        
        return entry.value;
    }
    
    private class Entry {
        
        long ts = System.currentTimeMillis();
        
        Object value = null;
        
        public Entry(Object value) {
            this.value = value;
        }
        
        public boolean isExpired(long now) {
            
             return now - ts >= timeout;
            
        }
    }
}    

    

    

            

    

            



    
    






    
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