com.knowgate.cache
Class LRUCachePolicy

java.lang.Object
  com.knowgate.cache.LRUCachePolicy

public final class LRUCachePolicy
extends java.lang.Object

LRU Cache Policy

Implementation of a Least Recently Used cache policy.

Nested Class Summary

class	LRUCachePolicy.LRUCacheEntry Double linked cell used as entry in the cache list.
class	LRUCachePolicy.LRUList Double queued list used to store cache entries.

Field Summary

protected LRUCachePolicy.LRUList	m_list The linked list used to implement the LRU algorithm
protected java.util.HashMap	m_map The map holding the cached objects
protected int	m_maxCapacity The maximum capacity of this cache
protected int	m_minCapacity The minimum capacity of this cache

Constructor Summary

LRUCachePolicy()
Creates a LRU cache policy object with zero cache capacity.

LRUCachePolicy(int min, int max)
Creates a LRU cache policy object with the specified minimum and maximum capacity.

Method Summary

protected void	ageOut(LRUCachePolicy.LRUCacheEntry entry) Callback method called when the cache algorithm ages out of the cache the given entry.
protected void	cacheMiss() Callback method called when a cache miss happens.
protected LRUCachePolicy.LRUCacheEntry	createCacheEntry(java.lang.Object key, java.lang.Object value, long t) Factory method for cache entries
protected LRUCachePolicy.LRUList	createList() Factory method for the linked list used by this cache implementation.
void	destroy() Destroys the cache that is now unusable.
void	flush()
java.lang.Object	get(java.lang.Object key)
void	insert(java.lang.Object key, java.lang.Object o, long t)
java.util.Set	keySet()
long	last(java.lang.Object key)
java.lang.Object	peek(java.lang.Object key)
void	remove(java.lang.Object key)
int	size()
void	start() Starts this cache that is now ready to be used.
void	stop() Stops this cache thus flush()ing all cached objects.

Methods inherited from class java.lang.Object

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

Field Detail

m_map

protected java.util.HashMap m_map

The map holding the cached objects

m_list

protected LRUCachePolicy.LRUList m_list

The linked list used to implement the LRU algorithm

m_maxCapacity

protected int m_maxCapacity

The maximum capacity of this cache

m_minCapacity

protected int m_minCapacity

The minimum capacity of this cache

Constructor Detail

LRUCachePolicy

public LRUCachePolicy()

Creates a LRU cache policy object with zero cache capacity.

See Also:

create()

LRUCachePolicy

public LRUCachePolicy(int min,
                      int max)

Creates a LRU cache policy object with the specified minimum and maximum capacity.

See Also:

create()

Method Detail

start

public void start()

Starts this cache that is now ready to be used.

See Also:

create(), stop()

stop

public void stop()

Stops this cache thus flush()ing all cached objects.
After this method is called, a call to start() will restart the cache.

See Also:

start(), destroy()

destroy

public void destroy()

Destroys the cache that is now unusable.
To have it working again it must be re-create()ed and re-start()ed.

See Also:

create()

keySet

public java.util.Set keySet()

last

public long last(java.lang.Object key)

get

public java.lang.Object get(java.lang.Object key)

peek

public java.lang.Object peek(java.lang.Object key)

insert

public void insert(java.lang.Object key,
                   java.lang.Object o,
                   long t)

remove

public void remove(java.lang.Object key)

flush

public void flush()

size

public int size()

createList

protected LRUCachePolicy.LRUList createList()

Factory method for the linked list used by this cache implementation.

ageOut

protected void ageOut(LRUCachePolicy.LRUCacheEntry entry)

Callback method called when the cache algorithm ages out of the cache the given entry.
The implementation here is removing the given entry from the cache.

cacheMiss

protected void cacheMiss()

Callback method called when a cache miss happens.

createCacheEntry

protected LRUCachePolicy.LRUCacheEntry createCacheEntry(java.lang.Object key,
                                                        java.lang.Object value,
                                                        long t)

Factory method for cache entries