org.apache.jackrabbit.core.state
Class ItemStateReferenceCache

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

All Implemented Interfaces:

Dumpable, ItemStateCache

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 flusehd 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.

Constructor Summary

ItemStateReferenceCache()
Creates a new ItemStateReferenceCache that uses a LRUItemStateCache instance as internal secondary cache.

ItemStateReferenceCache(ItemStateCache cache)
Creates a new ItemStateReferenceCache that uses the specified ItemStateCache 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	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.
Set	keySet() Returns an unmodifiable set view of the keys (i.e. ItemId objects) of the cached 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.
int	size() Returns the number of entries in this cache.
Collection	values() Returns an unmodifiable collection view of the values (i.e. ItemState objects) contained in this cache.

Methods inherited from class java.lang.Object

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

Constructor Detail

ItemStateReferenceCache

public ItemStateReferenceCache()

Creates a new ItemStateReferenceCache that uses a LRUItemStateCache 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

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.

evictAll

public void evictAll()

Clears all entries from this cache.

Specified by:

evictAll in interface ItemStateCache

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.

size

public int size()

Returns the number of entries in this cache.

Specified by:

size in interface ItemStateCache

Returns:

number of entries in this cache.

keySet

public Set keySet()

Returns an unmodifiable set view of the keys (i.e. ItemId objects) of the cached entries.

Specified by:

keySet in interface ItemStateCache

Returns:

a set view of the keys of the cached entries.

values

public Collection values()

Returns an unmodifiable collection view of the values (i.e. ItemState objects) contained in this cache.

Specified by:

values in interface ItemStateCache

Returns:

a collection view of the values contained in this cache.

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