Package org.datanucleus.cache

Class AbstractReferencedLevel2Cache

  • All Implemented Interfaces:
    Serializable, Level2Cache
    Direct Known Subclasses:
    SoftLevel2Cache, WeakLevel2Cache
    public abstract class AbstractReferencedLevel2Cache
extends Object
implements Level2Cache
    Abstract referenced implementation of a Level 2 cache, to be used as the base for weak/soft variants.

    Operates with 3 maps internally. One stores all pinned objects that have been selected to be retained by user's application. The second stores all other objects, and is the default location where objects are placed when being added here, using weak references meaning that they can get garbage collected as necessary by the JVM. The third stores objects keyed by the unique key that they relate to.

    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

    • Field Detail

      • pinnedClasses

        protected Collection<org.datanucleus.cache.AbstractReferencedLevel2Cache.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.

      • unpinnedCache

        protected transient Map<Object,​CachedPC> unpinnedCache
        Unpinned objects cache.

    • Constructor Detail

      • AbstractReferencedLevel2Cache

        protected AbstractReferencedLevel2Cache()

      • AbstractReferencedLevel2Cache

        public AbstractReferencedLevel2Cache​(NucleusContext nucleusCtx)
        Constructor.
        Parameters:
        nucleusCtx - Context

    • Method Detail

      • initialiseCaches

        protected abstract void initialiseCaches()

      • 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

      • get

        public CachedPC get​(Object oid)
        Accessor for an object from the cache. The returned object will not have a StateManager connected. This is because data stored in the Level 2 cache is StateManager 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.
        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.

      • getUnique

        public CachedPC getUnique​(CacheUniqueKey key)
        Description copied from interface: Level2Cache
        Method to retrieve the id represented by the specified unique key.
        Specified by:
        getUnique in interface Level2Cache
        Parameters:
        key - Unique key
        Returns:
        The "identity" of the object that this unique key represents

      • putUnique

        public CachedPC putUnique​(CacheUniqueKey key,
                          CachedPC pc)
        Description copied from interface: Level2Cache
        Method to store a persistable object for this unique key.
        Specified by:
        putUnique in interface Level2Cache
        Parameters:
        key - The unique key
        pc - The representation of the persistable object to cache
        Returns:
        The previous object for this unique key if one was present, otherwise null

      • putUniqueAll

        public void putUniqueAll​(Map<CacheUniqueKey,​CachedPC> objs)
        Description copied from interface: Level2Cache
        Method to put several objects into the cache.
        Specified by:
        putUniqueAll in interface Level2Cache
        Parameters:
        objs - Map of cacheable object keyed by the unique keys.

      • removeUnique

        public void removeUnique​(CacheUniqueKey key)
        Description copied from interface: Level2Cache
        Method to remove any object cached against the provided unique key.
        Specified by:
        removeUnique in interface Level2Cache
        Parameters:
        key - Unique key

      • 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