org.apache.jackrabbit.core.state
Class ItemStateReferenceCache

java.lang.Object
  org.apache.jackrabbit.core.state.ItemStateReferenceCache

All Implemented Interfaces:

ItemStateCache, Dumpable

public class ItemStateReferenceCache
extends Object
implements ItemStateCache, Dumpable

ItemStateReferenceCache internally consists of 2 components:

• an ItemStateReferenceMap serving as the primary (or main) cache; it holds weak references to ItemState instances. This ItemStateCache implementation directly represents the contents of the primary cache, i.e. isCached(ItemId), retrieve(ItemId)}, #size() etc. only refer to the contents of the primary cache.
• an ItemStateCache implementing a custom eviction policy and serving as the secondary (or auxiliary) cache; entries that are automatically flushed from this secondary cache through its eviction policy (LRU, etc.) will be indirectly flushed from the primary (reference) cache by the garbage collector if they are thus rendered weakly reachable.

This implementation of ItemStateCache is thread-safe.

Constructor Summary

ItemStateReferenceCache(ItemStateCache cache)
Creates a new ItemStateReferenceCache that uses the specified ItemStateCache instance as internal secondary cache.

ItemStateReferenceCache(ItemStateCacheFactory cacheFactory)
Creates a new ItemStateReferenceCache that uses a MLRUItemStateCache instance as internal secondary cache.

Method Summary

void	cache(ItemState state) Stores the specified ItemState object in the map using its ItemId as the key.
void	dispose() Informs the cache that it is no longer in use.
void	dump(PrintStream ps) Dumps the state of this instance in a human readable format for diagnostic purposes.
void	evict(ItemId id) Removes the ItemState object with the specified id from this cache if it is present.
void	evictAll() Clears all entries from this cache.
boolean	isCached(ItemId id) Returns true if this cache contains an ItemState object with the specified id.
boolean	isEmpty() Returns true if this cache contains no entries.
ItemState	retrieve(ItemId id) Returns the ItemState object with the specified id if it is present or null if no entry exists with that id.
ItemState[]	retrieveAll() Returns all the cached item states.
void	update(ItemId id) Informs the cache that the item was modified and the cache might need to recalculate the items caching weight.

Methods inherited from class java.lang.Object

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

Constructor Detail

ItemStateReferenceCache

public ItemStateReferenceCache(ItemStateCacheFactory cacheFactory)

Creates a new ItemStateReferenceCache that uses a MLRUItemStateCache instance as internal secondary cache.

ItemStateReferenceCache

public ItemStateReferenceCache(ItemStateCache cache)

Creates a new ItemStateReferenceCache that uses the specified ItemStateCache instance as internal secondary cache.

Parameters:

cache - secondary cache implementing a custom eviction policy

Method Detail

isCached

public boolean isCached(ItemId id)

Returns true if this cache contains an ItemState object with the specified id.

Specified by:

isCached in interface ItemStateCache

Parameters:

id - id of ItemState object whose presence should be tested.

Returns:

true if there's a corresponding cache entry, otherwise false.

retrieve

public ItemState retrieve(ItemId id)

Returns the ItemState object with the specified id if it is present or null if no entry exists with that id.

Specified by:

retrieve in interface ItemStateCache

Parameters:

id - the id of the ItemState object to be returned.

Returns:

the ItemState object with the specified id or or null if no entry exists with that id

retrieveAll

public ItemState[] retrieveAll()

Returns all the cached item states.

Specified by:

retrieveAll in interface ItemStateCache

Returns:

newly allocated item state array

cache

public void cache(ItemState state)

Stores the specified ItemState object in the map using its ItemId as the key.

Specified by:

cache in interface ItemStateCache

Parameters:

state - the ItemState object to cache

evict

public void evict(ItemId id)

Removes the ItemState object with the specified id from this cache if it is present.

Specified by:

evict in interface ItemStateCache

Parameters:

id - the id of the ItemState object which should be removed from this cache.

dispose

public void dispose()

Informs the cache that it is no longer in use.

Specified by:

dispose in interface ItemStateCache

evictAll

public void evictAll()

Clears all entries from this cache.

Specified by:

evictAll in interface ItemStateCache

update

public void update(ItemId id)

Informs the cache that the item was modified and the cache might need to recalculate the items caching weight.

Specified by:

update in interface ItemStateCache

Parameters:

id - the id of the item that was modified.

isEmpty

public boolean isEmpty()

Returns true if this cache contains no entries.

Specified by:

isEmpty in interface ItemStateCache

Returns:

true if this cache contains no entries.

dump

public void dump(PrintStream ps)

Dumps the state of this instance in a human readable format for diagnostic purposes.

Specified by:

dump in interface Dumpable

Parameters:

ps - stream to dump state to