/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.kahadb.util;
import java.util.LinkedHashMap;
import java.util.Map;
/**
* A Simple LRU Cache
*
* @version $Revision: 712224 $
* @param <K>
* @param <V>
*/
public class LRUCache<K, V> extends LinkedHashMap<K, V> {
private static final long serialVersionUID = -342098639681884413L;
protected int maxCacheSize = 10000;
/**
* Default constructor for an LRU Cache The default capacity is 10000
*/
public LRUCache() {
this(0,10000, 0.75f, true);
}
/**
* Constructs a LRUCache with a maximum capacity
*
* @param maximumCacheSize
*/
public LRUCache(int maximumCacheSize) {
this(0, maximumCacheSize, 0.75f, true);
}
/**
* Constructs an empty <tt>LRUCache</tt> instance with the specified
* initial capacity, maximumCacheSize,load factor and ordering mode.
*
* @param initialCapacity the initial capacity.
* @param maximumCacheSize
* @param loadFactor the load factor.
* @param accessOrder the ordering mode - <tt>true</tt> for access-order,
* <tt>false</tt> for insertion-order.
* @throws IllegalArgumentException if the initial capacity is negative or
* the load factor is non-positive.
*/
public LRUCache(int initialCapacity, int maximumCacheSize, float loadFactor, boolean accessOrder) {
super(initialCapacity, loadFactor, accessOrder);
this.maxCacheSize = maximumCacheSize;
}
/**
* @return Returns the maxCacheSize.
*/
public int getMaxCacheSize() {
return maxCacheSize;
}
/**
* @param maxCacheSize The maxCacheSize to set.
*/
public void setMaxCacheSize(int maxCacheSize) {
this.maxCacheSize = maxCacheSize;
}
protected boolean removeEldestEntry(Map.Entry<K,V> eldest) {
return size() > maxCacheSize;
}
}
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