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package org.apache.velocity.runtime.resource;
/*
* 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.
*/
import org.apache.velocity.runtime.RuntimeConstants;
import org.apache.velocity.runtime.RuntimeServices;
import org.slf4j.Logger;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Map.Entry;
import java.util.concurrent.ConcurrentHashMap;
/**
* Default implementation of the resource cache for the default
* ResourceManager. The cache uses a least recently used (LRU)
* algorithm, with a maximum size specified via the
* resource.manager.cache.size
property (identified by the
* {@link
* org.apache.velocity.runtime.RuntimeConstants#RESOURCE_MANAGER_DEFAULTCACHE_SIZE}
* constant). This property get be set to 0
or less for
* a greedy, unbounded cache (the behavior from pre-v1.5).
*
* @author Geir Magnusson Jr.
* @author Daniel Rall
* @version $Id$
*/
public class ResourceCacheImpl implements ResourceCache
{
/**
* A simple LRU Map based on {@link LinkedHashSet}.
*
* @param The key type of the map.
* @param The value type of the map.
*/
private static class LRUMap extends LinkedHashMap{
/**
* The serial version uid;
*/
private static final long serialVersionUID = 5889225121697975043L;
/**
* The size of the cache.
*/
private int cacheSize;
/**
* Constructor.
*
* @param cacheSize The size of the cache. After reaching this size, the
* eldest-accessed element will be erased.
*/
public LRUMap(int cacheSize)
{
this.cacheSize = cacheSize;
}
/** {@inheritDoc} */
@Override
protected boolean removeEldestEntry(Entry eldest)
{
return size() > cacheSize;
}
}
/**
* Cache storage, assumed to be thread-safe.
*/
protected Map