org.jboss.jca.adapters.jdbc.util
Class LRUCachePolicy

java.lang.Object
  org.jboss.jca.adapters.jdbc.util.LRUCachePolicy

Direct Known Subclasses:

PreparedStatementCache

public class LRUCachePolicy
extends Object

Implementation of a Least Recently Used cache policy.

Version:

$Revision$

Author:

Stefano Maestri

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	lruList The linked list used to implement the LRU algorithm
protected Map	map The map holding the cached objects
protected int	maxCapacity The maximum capacity of this cache
protected int	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.
void	create() Initializes the cache, creating all required objects and initializing their values.
protected LRUCachePolicy.LRUCacheEntry	createCacheEntry(Object key, Object value) Factory method for cache entries
protected LRUCachePolicy.LRUList	createList() Factory method for the linked list used by this cache implementation.
protected Map	createMap() Create map holding entries.
void	destroy() Destroys the cache that is now unusable.
void	flush() flush
Object	get(Object key) get method
void	insert(Object key, Object o) insert
Object	peek(Object key) peek
void	remove(Object key) remove
int	size() 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

map

protected Map map

The map holding the cached objects

lruList

protected LRUCachePolicy.LRUList lruList

The linked list used to implement the LRU algorithm

maxCapacity

protected int maxCapacity

The maximum capacity of this cache

minCapacity

protected int 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.

Parameters:

min - min

max - max

See Also:

create()

Method Detail

createMap

protected Map createMap()

Create map holding entries.

Returns:

the map

create

public void create()

Initializes the cache, creating all required objects and initializing their values.

See Also:

start(), destroy()

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()

get

public Object get(Object key)

get method

Parameters:

key - key

Returns:

the value

peek

public Object peek(Object key)

peek

Parameters:

key - the key

Returns:

the value

insert

public void insert(Object key,
                   Object o)

insert

Parameters:

key - the key

o - value

remove

public void remove(Object key)

remove

Parameters:

key - the key

flush

public void flush()

flush

size

public int size()

size

Returns:

the size

createList

protected LRUCachePolicy.LRUList createList()

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

Returns:

the lru list

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.

Parameters:

entry - entry

cacheMiss

protected void cacheMiss()

Callback method called when a cache miss happens.

createCacheEntry

protected LRUCachePolicy.LRUCacheEntry createCacheEntry(Object key,
                                                        Object value)

Factory method for cache entries

Parameters:

key - key

value - value

Returns:

the entry entry