Package org.hibernate.engine.spi

Class BatchFetchQueue

  • public class BatchFetchQueue
extends Object
    Keeps track of:
    • entity and collection keys that are available for batch fetching
    • details related to queries which load entities with sub-select-fetchable collections

    • 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 descriptor 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.

      • getBatchLoadableEntityIds

        public Object[] getBatchLoadableEntityIds​(EntityMappingType entityDescriptor,
                                          Object loadingId,
                                          int maxBatchSize)
        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.

      • 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 Object[] getCollectionBatch​(CollectionPersister collectionPersister,
                                   Object 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)