athenz.shade.zts.org.glassfish.hk2.utilities.cache.LRUCache Maven / Gradle / Ivy
/*
* Copyright (c) 2012, 2018 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0, which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception, which is available at
* https://www.gnu.org/software/classpath/license.html.
*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
package athenz.shade.zts.athenz.shade.zts.org.glassfish.hk2.utilities.cache;
import athenz.shade.zts.athenz.shade.zts.org.glassfish.hk2.utilities.cache.internal.LRUCacheCheapRead;
/**
* A cache that contains a certain number of entries, and whose oldest accessed
* entries are removed when removal is necessary.
*
* @author jwells
* @param The key type for this cache
* @param The value type for this cache
*
*/
public abstract class LRUCache {
/**
* Creates a cache with the given maximum cache size
*
* @param maxCacheSize The maximum number of entries in the cache, must be greater than 2
* @return An LRUCache that can be used to quickly retrieve objects
*/
public static LRUCache createCache(int maxCacheSize) {
return new LRUCacheCheapRead(maxCacheSize);
}
/**
* Returns the value associated with the given key. If there is no
* value, returns null
*
* @param key Must be a non-null key, appropriate for use as the key to a hash map
* @return The value associated with the key, or null if there is no such value
*/
public abstract V get(K key);
/**
* Adds the given key and value pair into the cache
*
* @param key Must be a non-null key, appropriate for use as the key to a hash map
* @param value Must be a non-null value
* @return A cache entry that can be used to remove this entry from the cache. Will not return null
*/
public abstract CacheEntry put(K key, V value);
/**
* Clears all entries in the cache, for use when a known event makes the cache incorrect
*/
public abstract void releaseCache();
/**
* Returns the maximum number of entries that will be stored in this cache
*
* @return The maximum number of entries that will be stored in this cache
*/
public abstract int getMaxCacheSize();
/**
* This method will remove all cache entries for which this filter
* matches
*
* @param filter Entries in the cache that match this filter will
* be removed from the cache. If filter is null nothing
* will be removed from the cache
*/
public abstract void releaseMatching(CacheKeyFilter filter);
}