org.jboss.jca.adapters.jdbc.util
Class LRUCache<K,V>

java.lang.Object
  org.jboss.jca.adapters.jdbc.util.LRUCache<K,V>

Type Parameters:

K - The key

V - The value

K - The key

V - The value

All Implemented Interfaces:

Cache<K,V>

public class LRUCache<K,V>
extends Object
implements Cache<K,V>

Implementation of a Least Recently Used cache policy.

Author:

Simone Bordet

Nested Class Summary

class	LRUCache.LRUCacheEntry<K,V> Double linked cell used as entry in the cache list.
class	LRUCache.LRUList Double queued list used to store cache entries.

Constructor Summary

LRUCache(int max)
Creates a LRU cache

Method Summary

void	flush() Flushes the cached objects from the cache.
V	get(K key) Returns the object paired with the specified key if it's present in the cache, otherwise must return null.
void	insert(K key, V o) Inserts the specified object into the cache following the implemented policy.
V	peek(K key) Returns the object paired with the specified key if it's present in the cache, otherwise must return null.
void	remove(K key) Remove the cached object paired with the specified key.
void	setListener(CacheListener listener) Set the cache listener
int	size() The cache size

Methods inherited from class java.lang.Object

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

Constructor Detail

LRUCache

public LRUCache(int max)

Creates a LRU cache

Parameters:

max - The maximum number of entries

Method Detail

get

public V get(K key)

Returns the object paired with the specified key if it's present in the cache, otherwise must return null.
Implementations of this method must have complexity of order O(1). Differently from Cache.peek(K) this method not only return whether the object is present in the cache or not, but also applies the implemented policy that will "refresh" the cached object in the cache, because this cached object was really requested.

Specified by:

get in interface Cache<K,V>

Parameters:

key - the key paired with the object

Returns:

the object

See Also:

Cache.peek(K)

peek

public V peek(K key)

Returns the object paired with the specified key if it's present in the cache, otherwise must return null.
Implementations of this method must have complexity of order O(1). This method should not apply the implemented caching policy to the object paired with the given key, so that a client can query if an object is cached without "refresh" its cache status. Real requests for the object must be done using Cache.get(K).

Specified by:

peek in interface Cache<K,V>

Parameters:

key - the key paired with the object

Returns:

the object

See Also:

Cache.get(K)

insert

public void insert(K key,
                   V o)

Inserts the specified object into the cache following the implemented policy.
Implementations of this method must have complexity of order O(1).

Specified by:

insert in interface Cache<K,V>

Parameters:

key - the key paired with the object

o - the object to cache

See Also:

Cache.remove(K)

remove

public void remove(K key)

Remove the cached object paired with the specified key.
Implementations of this method must have complexity of order O(1).

Specified by:

remove in interface Cache<K,V>

Parameters:

key - the key paired with the object

See Also:

Cache.insert(K, V)

flush

public void flush()

Flushes the cached objects from the cache.

Specified by:

flush in interface Cache<K,V>

size

public int size()

The cache size

Specified by:

size in interface Cache<K,V>

Returns:

the size of the cache

setListener

public void setListener(CacheListener listener)

Set the cache listener

Specified by:

setListener in interface Cache<K,V>

Parameters:

listener - The listener