Package org.hibernate.cache.spi.access

package org.hibernate.cache.spi.access
Defines contracts for transactional and concurrent access to cached entity and collection data.

Transactions pass in a timestamp indicating transaction start time which is then used to protect against concurrent access. Exactly how that happens is based on the actual access-strategy implementation used.

Two different implementation patterns are provided for:

  • A transaction-aware cache implementation might be wrapped by a synchronous access strategy, where updates to the cache are written to the cache inside the transaction.
  • A non-transaction-aware cache would be wrapped by an asynchronous access strategy, where items are merely "soft locked" during the transaction and then updated during the "after transaction completion" phase. The soft lock is not an actual lock on the database row, it only prevents access to the cached representation of the item.

The asynchronous access strategies are: read-only, read-write and nonstrict-read-write. The only synchronous access strategy is transactional.

Note that:

  • for an asynchronous cache, cache invalidation must be a two-step process ("lock" then "unlock", or "lock" then "after update"), since this is the only way to guarantee consistency with the database for a non-transactional cache implementation, but
  • for a synchronous cache, cache invalidation may be performed in a single operation ("evict" or "update").
Hence, the contracts EntityDataAccess and CollectionDataAccess define a three-step process to allow for both models (see the individual contracts for details).

Note that query result caching does not go through an access strategy; those caches are managed directly against the underlying QueryResultsRegion.

  • Class
    Description
    AccessType
    Enumerates the policies for managing concurrent access to the shared second-level cache.
    CachedDomainDataAccess
    Base contract for accessing the underlying cached data for a particular Navigable of the user's domain model in a transactionally ACID manner.
    CollectionDataAccess
    Contract for managing transactional and concurrent access to cached collection data.
    EntityDataAccess
    Contract for managing transactional and concurrent access to cached entity data.
    NaturalIdDataAccess
    Contract for managing transactional and concurrent access to cached naturalId data.
    SoftLock
    Memento object for use by synchronous concurrency strategies
    UnknownAccessTypeException
    Indicates that an unknown AccessType external name was encountered or that an AccessType was requested that the underlying cache provider does not support.