jdbm.helper
Class MRU<K,V>

java.lang.Object
  jdbm.helper.MRU<K,V>

All Implemented Interfaces:

CachePolicy<K,V>

public class MRU<K,V>
extends Object
implements CachePolicy<K,V>

MRU - Most Recently Used cache policy. Methods are *not* synchronized, so no concurrent access is allowed.

Author:

Alex Boisvert

Constructor Summary

MRU(int max)
Construct an MRU with a given maximum number of objects.

Method Summary

protected void	addEntry(jdbm.helper.CacheEntry entry) Add a CacheEntry.
void	addListener(CachePolicyListener listener) Add a listener to this cache policy
Enumeration<V>	elements() Enumerate elements' values in the cache
V	get(K key) Obtain an object in the cache
protected jdbm.helper.CacheEntry	purgeEntry() Purge least recently used object from the cache
void	put(K key, V value) Place an object in the cache.
void	remove(K key) Remove an object from the cache
void	removeAll() Remove all objects from the cache
protected void	removeEntry(jdbm.helper.CacheEntry entry) Remove a CacheEntry from linked list, and relink the remaining element sin the list.
void	removeListener(CachePolicyListener listener) Remove a listener from this cache policy
protected void	touchEntry(jdbm.helper.CacheEntry entry) Place entry at the end of linked list -- Most Recently Used

Methods inherited from class java.lang.Object

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

Constructor Detail

MRU

public MRU(int max)

Construct an MRU with a given maximum number of objects.

Method Detail

put

public void put(K key,
                V value)
         throws CacheEvictionException

Place an object in the cache.

Specified by:

put in interface CachePolicy<K,V>

Parameters:

key - key for the cached object

value - the cached object

Throws:

CacheEvictionException - propagated if, while evicting objects to make room for new object, an eviction listener encountered this problem.

get

public V get(K key)

Obtain an object in the cache

Specified by:

get in interface CachePolicy<K,V>

Parameters:

key - key the object was cached under

Returns:

the object if it is still in the cache, null otherwise.

remove

public void remove(K key)

Remove an object from the cache

Specified by:

remove in interface CachePolicy<K,V>

Parameters:

key - key the object was stored in the cache under.

removeAll

public void removeAll()

Remove all objects from the cache

Specified by:

removeAll in interface CachePolicy<K,V>

elements

public Enumeration<V> elements()

Enumerate elements' values in the cache

Specified by:

elements in interface CachePolicy<K,V>

addListener

public void addListener(CachePolicyListener listener)

Add a listener to this cache policy

Specified by:

addListener in interface CachePolicy<K,V>

Parameters:

listener - Listener to add to this policy

removeListener

public void removeListener(CachePolicyListener listener)

Remove a listener from this cache policy

Specified by:

removeListener in interface CachePolicy<K,V>

Parameters:

listener - Listener to remove from this policy

addEntry

protected void addEntry(jdbm.helper.CacheEntry entry)

Add a CacheEntry. Entry goes at the end of the list.

removeEntry

protected void removeEntry(jdbm.helper.CacheEntry entry)

Remove a CacheEntry from linked list, and relink the remaining element sin the list.

touchEntry

protected void touchEntry(jdbm.helper.CacheEntry entry)

Place entry at the end of linked list -- Most Recently Used

purgeEntry

protected jdbm.helper.CacheEntry purgeEntry()
                                     throws CacheEvictionException

Purge least recently used object from the cache

Returns:

recyclable CacheEntry

Throws:

CacheEvictionException