Interface Level2Cache
- All Superinterfaces:
Serializable
- All Known Implementing Classes:
AbstractLevel2Cache
,AbstractReferencedLevel2Cache
,JavaxCacheLevel2Cache
,NullLevel2Cache
,SoftLevel2Cache
,WeakLevel2Cache
The L2 cache stores an object of type org.datanucleus.cache.CachedPC and is keyed by the identity of the object. The CachedPC contains the values of fields of a persistable object, together with the indicators for which fields are loaded. The relation field values do not store actual objects; they store the identities of the related objects. For example if an object X has a 1-1 relation with another persistable object Y then in the relation field values for X for that field we store the identity of Y. Similarly if the field is a Collection, then the relation field values will be a Collection of identities of the related objects. This provides isolation of each object in the L2 cache (so objects aren't storing references to other objects and so allowing garbage collection etc).
Objects are stored in the L2 cache in the following situations
- An object is retrieved (from the datastore) within a transaction, and it is stored in the L2 cache if no object with that identity already exists there.
- At commit() of the transaction any object that has been modified during that transaction will be stored/updated in the L2 cache if its persistable object is still in memory in the PM/EM (could have been garbage collected since flushing)
Each class can be configured to be cacheable or not. The default for a persistable class is to be cacheable. Configuration is performed via annotations or XML metadata. If a class is not cacheable then objects of that type aren't stored in the L2 cache.
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Method Summary
Modifier and TypeMethodDescriptionvoid
close()
Method to close the cache when no longer needed.boolean
containsOid
(Object oid) Accessor for whether an object with the specified id is in the cachevoid
Evict the parameter instance from the second-level cache.void
evictAll()
Evict the parameter instances from the second-level cache.void
Evict the parameter instances from the second-level cache.void
Evict the parameter instances from the second-level cache.void
evictAll
(Collection oids) Evict the parameter instances from the second-level cache.Accessor for an object from the cache.getAll
(Collection oids) Accessor for a collection of objects from the cache.default int
Accessor for the number of pinned objects in the cache.default int
Accessor for the number of unpinned objects in the cache.default int
getSize()
Accessor for the total number of objects in the L2 cache.default CachedPC
getUnique
(CacheUniqueKey key) Method to retrieve the id represented by the specified unique key.default boolean
isEmpty()
Accessor for whether the cache is empty.default void
Pin the parameter instance in the second-level cache.default void
Pin instances in the second-level cache.default void
Pin the parameter instances in the second-level cache.default void
pinAll
(Collection oids) Pin the parameter instances in the second-level cache.Method to put an object in the cache.default void
Method to put several objects into the cache.default CachedPC
putUnique
(CacheUniqueKey key, CachedPC pc) Method to store a persistable object for this unique key.default void
putUniqueAll
(Map<CacheUniqueKey, CachedPC> objs) Method to put several objects into the cache.default void
Method to remove any object cached against the provided unique key.default void
Unpin the parameter instance from the second-level cache.default void
Unpin instances from the second-level cache.default void
Unpin the parameter instance from the second-level cache.default void
unpinAll
(Collection oids) Unpin the parameter instances from the second-level cache.
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Method Details
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close
void close()Method to close the cache when no longer needed. Provides a hook to release resources etc. -
evict
Evict the parameter instance from the second-level cache.- Parameters:
oid
- the object id of the instance to evict.
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evictAll
void evictAll()Evict the parameter instances from the second-level cache. All instances in the PersistenceManager's cache are evicted from the second-level cache. -
evictAll
Evict the parameter instances from the second-level cache.- Parameters:
oids
- the object ids of the instance to evict.
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evictAll
Evict the parameter instances from the second-level cache.- Parameters:
oids
- the object ids of the instance to evict.
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evictAll
Evict the parameter instances from the second-level cache.- Parameters:
pcClass
- the class of instances to evictsubclasses
- if true, evict instances of subclasses also
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getSize
default int getSize()Accessor for the total number of objects in the L2 cache.- Returns:
- Number of objects
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get
Accessor for an object from the cache.- Parameters:
oid
- The Object ID- Returns:
- The L2 cacheable object
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getAll
Accessor for a collection of objects from the cache.- Parameters:
oids
- The Object IDs- Returns:
- Map of the objects, keyed by the oids that are found
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put
Method to put an object in the cache.- Parameters:
oid
- The Object id for this object (see StateManager.getInternalObjectId)pc
- The L2-cacheable persistable object- Returns:
- The value previously associated with this oid
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putAll
Method to put several objects into the cache.- Parameters:
objs
- Map of cacheable object keyed by its oid.
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isEmpty
default boolean isEmpty()Accessor for whether the cache is empty.- Returns:
- Whether it is empty.
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containsOid
Accessor for whether an object with the specified id is in the cache- Parameters:
oid
- The object id- Returns:
- Whether it is in the cache
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getUnique
Method to retrieve the id represented by the specified unique key.- Parameters:
key
- Unique key- Returns:
- The "identity" of the object that this unique key represents
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putUnique
Method to store a persistable object for this unique key.- Parameters:
key
- The unique keypc
- The representation of the persistable object to cache- Returns:
- The previous object for this unique key if one was present, otherwise null
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putUniqueAll
Method to put several objects into the cache.- Parameters:
objs
- Map of cacheable object keyed by the unique keys.
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removeUnique
Method to remove any object cached against the provided unique key.- Parameters:
key
- Unique key
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pin
Pin the parameter instance in the second-level cache.- Parameters:
oid
- the object id of the instance to pin.
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pinAll
Pin the parameter instances in the second-level cache.- Parameters:
oids
- the object ids of the instances to pin.
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pinAll
Pin the parameter instances in the second-level cache.- Parameters:
oids
- the object ids of the instances to pin.
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pinAll
Pin instances in the second-level cache.- Parameters:
pcClass
- the class of instances to pinsubclasses
- if true, pin instances of subclasses also
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unpin
Unpin the parameter instance from the second-level cache.- Parameters:
oid
- the object id of the instance to unpin.
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unpinAll
Unpin the parameter instances from the second-level cache.- Parameters:
oids
- the object ids of the instance to evict.
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unpinAll
Unpin the parameter instance from the second-level cache.- Parameters:
oids
- the object id of the instance to evict.
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unpinAll
Unpin instances from the second-level cache.- Parameters:
pcClass
- the class of instances to unpinsubclasses
- if true, unpin instances of subclasses also
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getNumberOfPinnedObjects
default int getNumberOfPinnedObjects()Accessor for the number of pinned objects in the cache.- Returns:
- Number of pinned objects
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getNumberOfUnpinnedObjects
default int getNumberOfUnpinnedObjects()Accessor for the number of unpinned objects in the cache.- Returns:
- Number of unpinned objects
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