Defines contracts for transactional and concurrent access to cached {@link org.hibernate.cache.spi.access.EntityRegionAccessStrategy entity} and {@link org.hibernate.cache.spi.access.CollectionRegionAccessStrategy collection} data. Transactions pass in a timestamp indicating transaction start time which is then used to protect against concurrent access (exactly how that occurs is based on the actual access-strategy impl used). Two different implementation patterns are provided for:
Note that, for an asynchronous cache, cache invalidation must be a two step process (lock->unlock or lock->afterUpdate), since this is the only way to guarantee consistency with the database for a nontransactional cache implementation. For a synchronous cache, cache invalidation is a single step process (evict or update). Hence, these contracts ({@link org.hibernate.cache.spi.access.EntityRegionAccessStrategy} and {@link org.hibernate.cache.spi.access.CollectionRegionAccessStrategy}) define a three step process to cater 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 {@link org.hibernate.cache.spi.QueryResultsRegion}.