org.glassfish.hk2.utilities.cache.LRUCache Maven / Gradle / Ivy
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package org.glassfish.hk2.utilities.cache;
import 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);
}