it.cnr.isti.hpc.structure

Class LRUCache<K,V>

java.lang.Object

it.cnr.isti.hpc.structure.LRUCache<K,V>

public class LRUCache<K,V>
extends Object

An LRU cache, based on LinkedHashMap.

This cache has a fixed maximum number of elements (cacheSize). If the cache is full and another entry is added, the LRU (least recently used) entry is dropped.

This class is thread-safe. All methods of this class are synchronized.

Author: Christian d'Heureuse, Inventec Informatik AG, Zurich, Switzerland
Multi-licensed: EPL / LGPL / GPL / AL / BSD.

Constructor Summary

Constructors

Constructor and Description
LRUCache(int cacheSize) Creates a new LRU cache.

Method Summary

Methods

Modifier and Type	Method and Description
void	clear() Clears the cache.
boolean	containsKey(K k)
V	get(K key) Retrieves an entry from the cache. The retrieved entry becomes the MRU (most recently used) entry.
Collection<Map.Entry<K,V>>	getAll() Returns a Collection that contains a copy of all cache entries.
double	hitRate()
void	put(K key, V value) Adds an entry to this cache.
int	usedEntries() Returns the number of used entries in the cache.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LRUCache

public LRUCache(int cacheSize)

Creates a new LRU cache.

Parameters:

cacheSize - the maximum number of entries that will be kept in this cache.

Method Detail

get

public V get(K key)

Retrieves an entry from the cache.
The retrieved entry becomes the MRU (most recently used) entry.

Parameters:

key - the key whose associated value is to be returned.

Returns:

the value associated to this key, or null if no value with this key exists in the cache.

put

public void put(K key,
       V value)

Adds an entry to this cache. The new entry becomes the MRU (most recently used) entry. If an entry with the specified key already exists in the cache, it is replaced by the new entry. If the cache is full, the LRU (least recently used) entry is removed from the cache.

Parameters:

key - the key with which the specified value is to be associated.

value - a value to be associated with the specified key.

clear

public void clear()

Clears the cache.

usedEntries

public int usedEntries()

Returns the number of used entries in the cache.

Returns:

the number of entries currently in the cache.

containsKey

public boolean containsKey(K k)

hitRate

public double hitRate()

getAll

public Collection<Map.Entry<K,V>> getAll()

Returns a Collection that contains a copy of all cache entries.

Returns:

a Collection with a copy of the cache content.