org.hibernate.engine.spi

Class BatchFetchQueue

java.lang.Object

org.hibernate.engine.spi.BatchFetchQueue

public class BatchFetchQueue
extends Object

Tracks entity and collection keys that are available for batch fetching, and the queries which were used to load entities, which can be re-used as a subquery for loading owned collections.

Author:

Gavin King, Steve Ebersole, Guenther Demetz

Constructor Summary

Constructors

Constructor and Description
BatchFetchQueue(PersistenceContext context) Constructs a queue for the given context.

Method Summary

Modifier and Type	Method and Description
void	addBatchLoadableCollection(PersistentCollection collection, CollectionEntry ce) If a CollectionEntry represents a batch loadable collection, add it to the queue.
void	addBatchLoadableEntityKey(EntityKey key) If an EntityKey represents a batch loadable entity, add it to the queue.
void	addSubselect(EntityKey key, SubselectFetch subquery) Adds a subselect fetch decriptor for the given entity key.
void	clear() Clears all entries from this fetch queue.
boolean	containsEntityKey(EntityKey key) Intended for test usage.
Serializable[]	getCollectionBatch(CollectionPersister collectionPersister, Serializable id, int batchSize) Get a batch of uninitialized collection keys for a given role
Serializable[]	getEntityBatch(EntityPersister persister, Serializable id, int batchSize, EntityMode entityMode) Get a batch of unloaded identifiers for this class, using a slightly complex algorithm that tries to grab keys registered immediately after the given key.
SubselectFetch	getSubselect(EntityKey key) Retrieve the fetch descriptor associated with the given entity key.
void	removeBatchLoadableCollection(CollectionEntry ce) After a collection was initialized or evicted, we don't need to batch fetch it anymore, remove it from the queue if necessary
void	removeBatchLoadableEntityKey(EntityKey key) After evicting or deleting or loading an entity, we don't need to batch fetch it anymore, remove it from the queue if necessary
void	removeSubselect(EntityKey key) After evicting or deleting an entity, we don't need to know the query that was used to load it anymore (don't call this after loading the entity, since we might still need to load its collections)

Methods inherited from class java.lang.Object

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

Constructor Detail

BatchFetchQueue

public BatchFetchQueue(PersistenceContext context)

Constructs a queue for the given context.

Parameters:

context - The owning context.

Method Detail

clear

public void clear()

Clears all entries from this fetch queue.

Called after flushing or clearing the session.

getSubselect

public SubselectFetch getSubselect(EntityKey key)

Retrieve the fetch descriptor associated with the given entity key.

Parameters:

key - The entity key for which to locate any defined subselect fetch.

Returns:

The fetch descriptor; may return null if no subselect fetch queued for this entity key.

addSubselect

public void addSubselect(EntityKey key,
                         SubselectFetch subquery)

Adds a subselect fetch decriptor for the given entity key.

Parameters:

key - The entity for which to register the subselect fetch.

subquery - The fetch descriptor.

removeSubselect

public void removeSubselect(EntityKey key)

After evicting or deleting an entity, we don't need to know the query that was used to load it anymore (don't call this after loading the entity, since we might still need to load its collections)

addBatchLoadableEntityKey

public void addBatchLoadableEntityKey(EntityKey key)

If an EntityKey represents a batch loadable entity, add it to the queue.

Note that the contract here is such that any key passed in should previously have been been checked for existence within the PersistenceContext; failure to do so may cause the referenced entity to be included in a batch even though it is already associated with the PersistenceContext.

removeBatchLoadableEntityKey

public void removeBatchLoadableEntityKey(EntityKey key)

After evicting or deleting or loading an entity, we don't need to batch fetch it anymore, remove it from the queue if necessary

containsEntityKey

public boolean containsEntityKey(EntityKey key)

Intended for test usage. Really has no use-case in Hibernate proper.

getEntityBatch

public Serializable[] getEntityBatch(EntityPersister persister,
                                     Serializable id,
                                     int batchSize,
                                     EntityMode entityMode)

Get a batch of unloaded identifiers for this class, using a slightly complex algorithm that tries to grab keys registered immediately after the given key.

Parameters:

persister - The persister for the entities being loaded.

id - The identifier of the entity currently demanding load.

batchSize - The maximum number of keys to return

Returns:

an array of identifiers, of length batchSize (possibly padded with nulls)

addBatchLoadableCollection

public void addBatchLoadableCollection(PersistentCollection collection,
                                       CollectionEntry ce)

If a CollectionEntry represents a batch loadable collection, add it to the queue.

removeBatchLoadableCollection

public void removeBatchLoadableCollection(CollectionEntry ce)

After a collection was initialized or evicted, we don't need to batch fetch it anymore, remove it from the queue if necessary

getCollectionBatch

public Serializable[] getCollectionBatch(CollectionPersister collectionPersister,
                                         Serializable id,
                                         int batchSize)

Get a batch of uninitialized collection keys for a given role

Parameters:

collectionPersister - The persister for the collection role.

id - A key that must be included in the batch fetch

batchSize - the maximum number of keys to return

Returns:

an array of collection keys, of length batchSize (padded with nulls)