LRUCache.java

/* (c) 2014 Open Source Geospatial Foundation - all rights reserved
 * (c) 2001 - 2013 OpenPlans
 * This code is licensed under the GPL 2.0 license, available at the root
 * application directory.
 */


package org.geoserver.security.auth;

import java.util.LinkedHashMap;
import java.util.Map;

/**
 * Class implementing a LRU (last recently used) cache
 * based on {@link LinkedHashMap}
 * 
 * @author christian
 *
 * @param <K>
 * @param <V>
 */
public class LRUCache<K,V> extends LinkedHashMap<K, V> {

    private static final long serialVersionUID = 1L;

    private final int capacity;
    private long accessCount = 0;
    private long hitCount = 0;

    public LRUCache(int capacity)
    {
      super(capacity + 1, 1.1f, true);
      this.capacity = capacity;
    }

    @Override
    public V get(Object key)
    {
      accessCount++;
      if (containsKey(key))
      {
        hitCount++;
      }
      return super.get(key);
      
    }

    @Override
    protected boolean removeEldestEntry(Map.Entry<K,V> eldest)
    {
      return size() > capacity;
    }

    public long getAccessCount()
    {
      return accessCount;
    }

    public long getHitCount()
    {
      return hitCount;
    }
}