org.datanucleus.cache

Class WeakLevel2Cache

java.lang.Object

org.datanucleus.cache.WeakLevel2Cache

All Implemented Interfaces:

Serializable, Level2Cache

Direct Known Subclasses:

SoftLevel2Cache

public class WeakLevel2Cache
extends Object
implements Level2Cache

Weak referenced implementation of a Level 2 cache.

Operates with 2 maps internally. One stores all pinned objects that have been selected to be retained by user's application. The other stores all other objects. This second map is the default location where objects are placed when being added here. The second (unpinned) map stores weak references meaning that they can get garbage collected as necessary by the JVM.

Maintains collections of the classes and the identities that are to be pinned if they ever are put into the cache. These are defined by the pinAll(), pin() methods.

All mutating methods, and the get method have been synchronized to prevent conflicts.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface org.datanucleus.cache.Level2Cache

Level2Cache.PinnedClass

Field Summary

Fields

Modifier and Type	Field and Description
protected ApiAdapter	apiAdapter
protected Map	pinnedCache Pinned objects cache.
protected Collection<Level2Cache.PinnedClass>	pinnedClasses Collection of pinned classes whose objects should be pinned if they ever reach the cache.
protected Collection	pinnedIds Collection of ids whose objects should be pinned if they ever reach the cache.
protected Map	unpinnedCache Unpinned objects cache.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	WeakLevel2Cache()
	WeakLevel2Cache(NucleusContext nucleusCtx) Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Method to close the cache when no longer needed.
boolean	containsOid(Object oid) Method to check if an object with the specified id is in the cache
void	evict(Object oid) Method to evict an object from the cache.
void	evictAll() Method to evict all objects from the L2 cache.
void	evictAll(Class pcClass, boolean subclasses) Method to evict all objects of the given types from the cache.
void	evictAll(Collection oids) Method to evict the objects with the specified ids.
void	evictAll(Object[] oids) Method to evict the objects with the specified ids.
CachedPC	get(Object oid) Accessor for an object from the cache.
Map<Object,CachedPC>	getAll(Collection oids) Accessor for a collection of objects from the cache.
int	getNumberOfPinnedObjects() Accessor for the number of pinned objects in the cache.
int	getNumberOfUnpinnedObjects() Accessor for the number of unpinned objects in the cache.
int	getSize() Accessor for the total number of objects in the L2 cache.
boolean	isEmpty() Accessor for whether the cache is empty.
void	pin(Object oid) Method to pin an object to the cache.
void	pinAll(Class cls, boolean subs) Method to pin all objects of the given types.
void	pinAll(Collection oids) Method to pin all of the supplied objects
void	pinAll(Object[] oids) Method to pin all of the supplied objects
CachedPC	put(Object oid, CachedPC pc) Method to put an object in the cache.
void	putAll(Map<Object,CachedPC> objs) Method to put several objects into the cache.
void	unpin(Object oid) Method to unpin an object
void	unpinAll(Class cls, boolean subs) Method to unpin all objects of the specified types.
void	unpinAll(Collection oids) Method to unpin all of the supplied objects
void	unpinAll(Object[] oids) Method to unpin all of the specified objects

Methods inherited from class java.lang.Object

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

Field Detail

pinnedClasses

protected Collection<Level2Cache.PinnedClass> pinnedClasses

Collection of pinned classes whose objects should be pinned if they ever reach the cache.

pinnedIds

protected Collection pinnedIds

Collection of ids whose objects should be pinned if they ever reach the cache.

pinnedCache

protected Map pinnedCache

Pinned objects cache.

unpinnedCache

protected transient Map unpinnedCache

Unpinned objects cache.

apiAdapter

protected ApiAdapter apiAdapter

Constructor Detail

WeakLevel2Cache

protected WeakLevel2Cache()

WeakLevel2Cache

public WeakLevel2Cache(NucleusContext nucleusCtx)

Constructor.

Parameters:

nucleusCtx - Context

Method Detail

close

public void close()

Method to close the cache when no longer needed. Provides a hook to release resources etc.

Specified by:

close in interface Level2Cache

evict

public void evict(Object oid)

Method to evict an object from the cache.

Specified by:

evict in interface Level2Cache

Parameters:

oid - The id of the object to evict

evictAll

public void evictAll()

Method to evict all objects from the L2 cache.

Specified by:

evictAll in interface Level2Cache

evictAll

public void evictAll(Class pcClass,
            boolean subclasses)

Method to evict all objects of the given types from the cache.

Specified by:

evictAll in interface Level2Cache

Parameters:

pcClass - The class to evict

subclasses - Whether to also evict subclasses

evictAll

public void evictAll(Collection oids)

Method to evict the objects with the specified ids.

Specified by:

evictAll in interface Level2Cache

Parameters:

oids - The ids of the objects to evict

evictAll

public void evictAll(Object[] oids)

Method to evict the objects with the specified ids.

Specified by:

evictAll in interface Level2Cache

Parameters:

oids - The ids of the objects to evict

pin

public void pin(Object oid)

Method to pin an object to the cache.

Specified by:

pin in interface Level2Cache

Parameters:

oid - The id of the object to pin

pinAll

public void pinAll(Class cls,
          boolean subs)

Method to pin all objects of the given types.

Specified by:

pinAll in interface Level2Cache

Parameters:

cls - The class

subs - Whether to include subclasses

pinAll

public void pinAll(Collection oids)

Method to pin all of the supplied objects

Specified by:

pinAll in interface Level2Cache

Parameters:

oids - The Object ids to pin

pinAll

public void pinAll(Object[] oids)

Method to pin all of the supplied objects

Specified by:

pinAll in interface Level2Cache

Parameters:

oids - The object ids to pin

unpin

public void unpin(Object oid)

Method to unpin an object

Specified by:

unpin in interface Level2Cache

Parameters:

oid - The object id

unpinAll

public void unpinAll(Class cls,
            boolean subs)

Method to unpin all objects of the specified types.

Specified by:

unpinAll in interface Level2Cache

Parameters:

cls - Base class

subs - Whether to include subclasses

unpinAll

public void unpinAll(Collection oids)

Method to unpin all of the supplied objects

Specified by:

unpinAll in interface Level2Cache

Parameters:

oids - The object ids to unpin

unpinAll

public void unpinAll(Object[] oids)

Method to unpin all of the specified objects

Specified by:

unpinAll in interface Level2Cache

Parameters:

oids - The object ids to unpin

get

public CachedPC get(Object oid)

Accessor for an object from the cache. The returned object will not have a ObjectProvider connected. This is because data stored in the Level 2 cache is ObjectProvider and PersistenceManager independent.

Specified by:

get in interface Level2Cache

Parameters:

oid - The Object ID

Returns:

The L2 cacheable object

getAll

public Map<Object,CachedPC> getAll(Collection oids)

Description copied from interface: Level2Cache

Accessor for a collection of objects from the cache.

Specified by:

getAll in interface Level2Cache

Parameters:

oids - The Object IDs

Returns:

Map of the objects, keyed by the oids that are found

getNumberOfPinnedObjects

public int getNumberOfPinnedObjects()

Accessor for the number of pinned objects in the cache.

Specified by:

getNumberOfPinnedObjects in interface Level2Cache

Returns:

Number of pinned objects

getNumberOfUnpinnedObjects

public int getNumberOfUnpinnedObjects()

Accessor for the number of unpinned objects in the cache.

Specified by:

getNumberOfUnpinnedObjects in interface Level2Cache

Returns:

Number of unpinned objects

getSize

public int getSize()

Accessor for the total number of objects in the L2 cache.

Specified by:

getSize in interface Level2Cache

Returns:

Number of objects

putAll

public void putAll(Map<Object,CachedPC> objs)

Description copied from interface: Level2Cache

Method to put several objects into the cache.

Specified by:

putAll in interface Level2Cache

Parameters:

objs - Map of cacheable object keyed by its oid.

put

public CachedPC put(Object oid,
           CachedPC pc)

Method to put an object in the cache. Note that the pc object being passed in must NOT have a ObjectProvider connected. Data stored in the Level 2 cache has to be independent of PersistenceManager and ObjectProvider.

Specified by:

put in interface Level2Cache

Parameters:

oid - The Object id for this object

pc - The cacheable object

Returns:

The value previously associated with this oid

containsOid

public boolean containsOid(Object oid)

Method to check if an object with the specified id is in the cache

Specified by:

containsOid in interface Level2Cache

Parameters:

oid - The object ID

Returns:

Whether it is present

isEmpty

public boolean isEmpty()

Accessor for whether the cache is empty.

Specified by:

isEmpty in interface Level2Cache

Returns:

Whether it is empty.