/*
* Copyright 2004 Clinton Begin
*
* Licensed 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 com.ibatis.sqlmap.engine.cache.lru;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import com.ibatis.sqlmap.engine.cache.CacheController;
import com.ibatis.sqlmap.engine.cache.CacheModel;
/**
* LRU (least recently used) cache controller implementation
*/
public class LruCacheController implements CacheController {
private int cacheSize;
private Map cache;
private List keyList;
/**
* Default constructor
*/
public LruCacheController() {
this.cacheSize = 100;
this.cache = Collections.synchronizedMap(new HashMap());
this.keyList = Collections.synchronizedList(new LinkedList());
}
public int getCacheSize() {
return cacheSize;
}
public void setCacheSize(int cacheSize) {
this.cacheSize = cacheSize;
}
/**
* Configures the cache
*
* @param props Optionally can contain properties [reference-type=WEAK|SOFT|STRONG]
*/
public void setProperties(Properties props) {
String size = props.getProperty("cache-size");
if (size == null) {
size = props.getProperty("size");
}
if (size != null) {
cacheSize = Integer.parseInt(size);
}
}
/**
* Add an object to the cache
*
* @param cacheModel The cacheModel
* @param key The key of the object to be cached
* @param value The object to be cached
*/
public void putObject(CacheModel cacheModel, Object key, Object value) {
cache.put(key, value);
keyList.add(key);
if (keyList.size() > cacheSize) {
try {
Object oldestKey = keyList.remove(0);
cache.remove(oldestKey);
} catch (IndexOutOfBoundsException e) {
//ignore
}
}
}
/**
* Get an object out of the cache.
*
* @param cacheModel The cache model
* @param key The key of the object to be returned
* @return The cached object (or null)
*/
public Object getObject(CacheModel cacheModel, Object key) {
Object result = cache.get(key);
keyList.remove(key);
if (result != null) {
keyList.add(key);
}
return result;
}
public Object removeObject(CacheModel cacheModel, Object key) {
keyList.remove(key);
return cache.remove(key);
}
/**
* Flushes the cache.
*
* @param cacheModel The cache model
*/
public void flush(CacheModel cacheModel) {
cache.clear();
keyList.clear();
}
}