ObjectDB ObjectDB

lock(entity, lockMode) - JPA EntityManager's method

void lock(
  Object entity,
  LockModeType lockMode

Lock an entity instance that is contained in the persistence context with the specified lock mode type.

If a pessimistic lock mode type is specified and the entity contains a version attribute, the persistence provider must also perform optimistic version checks when obtaining the database lock. If these checks fail, the OptimisticLockException will be thrown.

If the lock mode type is pessimistic and the entity instance is found but cannot be locked:

  • the PessimisticLockException will be thrown if the database locking failure causes transaction-level rollback
  • the LockTimeoutException will be thrown if the database locking failure causes only statement-level rollback
entity - entity instance
lockMode - lock mode
IllegalArgumentException - if the instance is not an entity or is a detached entity
TransactionRequiredException - if there is no transaction
EntityNotFoundException - if the entity does not exist in the database when pessimistic locking is performed
OptimisticLockException - if the optimistic version check fails
PessimisticLockException - if pessimistic locking fails and the transaction is rolled back
LockTimeoutException - if pessimistic locking fails and only the statement is rolled back
PersistenceException - if an unsupported lock call is made
JPA 1.0