001package org.apache.commons.jcs.engine.memory.mru; 002 003/* 004 * Licensed to the Apache Software Foundation (ASF) under one 005 * or more contributor license agreements. See the NOTICE file 006 * distributed with this work for additional information 007 * regarding copyright ownership. The ASF licenses this file 008 * to you under the Apache License, Version 2.0 (the 009 * "License"); you may not use this file except in compliance 010 * with the License. You may obtain a copy of the License at 011 * 012 * http://www.apache.org/licenses/LICENSE-2.0 013 * 014 * Unless required by applicable law or agreed to in writing, 015 * software distributed under the License is distributed on an 016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 017 * KIND, either express or implied. See the License for the 018 * specific language governing permissions and limitations 019 * under the License. 020 */ 021 022import java.io.IOException; 023 024import org.apache.commons.jcs.engine.behavior.ICacheElement; 025import org.apache.commons.jcs.engine.memory.AbstractDoubleLinkedListMemoryCache; 026import org.apache.commons.jcs.engine.memory.util.MemoryElementDescriptor; 027 028/** 029 * The most recently used items move to the front of the list and get spooled to disk if the cache 030 * hub is configured to use a disk cache. 031 */ 032public class MRUMemoryCache<K, V> 033 extends AbstractDoubleLinkedListMemoryCache<K, V> 034{ 035 /** 036 * Adds the item to the front of the list. A put doesn't count as a usage. 037 * <p> 038 * It's not clear if the put operation should be different. Perhaps this should remove the oldest 039 * if full, and then put. 040 * <p> 041 * @param ce 042 * @return MemoryElementDescriptor the new node 043 * @throws IOException 044 */ 045 @Override 046 protected MemoryElementDescriptor<K, V> adjustListForUpdate( ICacheElement<K, V> ce ) 047 throws IOException 048 { 049 return addFirst( ce ); 050 } 051 052 /** 053 * Makes the item the last in the list. 054 * <p> 055 * @param me 056 */ 057 @Override 058 protected void adjustListForGet( MemoryElementDescriptor<K, V> me ) 059 { 060 list.makeLast( me ); 061 } 062}