Question

我正在使用

Spring Boot 1.4.2
Spring Data JPA 1.10.5
PostgreSQL 9.5数据库

我想在我的Spring Data存储库中使用带有悲观锁的findOne方法，该方法与已提供的findOne方法分开。

关注this answer我写道：

public interface RegistrationRepository extends CrudRepository<Registration, Long> {
    @Lock(LockModeType.PESSIMISTIC_WRITE)
    @Query("select r from Registration r where r.id = ?1")
    Registration findOnePessimistic(Long id);
}

这几乎可行。

不幸的是，这不会刷新实体管理器缓存中我的实体的先前实例。我有两个并发请求更新我的注册状态

第二个等待第一个提交的交易
第二个不会考虑第一个所做的更改。

因此破坏了行为。

为什么@Lock没有开箱即用的任何线索刷新实体管理器？

更新

以下是请求的示例代码：

public interface RegistrationRepository extends CrudRepository<Registration, Long> {

    @Lock(LockModeType.PESSIMISTIC_WRITE)
    @Query("select r from registration_table r where r.id = ?1")
    Registration findOnePessimistic(Long id);

}

public void RegistrationService {

    @Transactional
    public void doSomething(long id){
        // Both threads read the same version of the data 
        Registration registrationQueriedTheFirstTime = registrationRepository.findOne(id);

        // First thread gets the lock, second thread waits for the first thread to have committed
        Registration registration = registrationRepository.findOnePessimistic(id);
        // I need this to have this statement, otherwise, registration.getStatus() contains the value not yet updated by the first thread
        entityManager.refresh(registration);

        registration.setStatus(newStatus);
        registrationRepository.save(registration);
    }
}

Answer 1

您需要使用entityManger transaction为您创建的Spring：

    @Transactional
    public void doSomething(long id){
        // Both threads read the same version of the data 
        Registration registrationQueriedTheFirstTime = registrationRepository.findOne(id);

        // First thread gets the lock, second thread waits for the first thread to have committed
        Registration registration = registrationRepository.findOnePessimistic(id);
        // I need this to have this statement, otherwise, registration.getStatus() contains the value not yet updated by the first thread
        entityManager.refresh(registration);

        EntityManager em = EntityManagerFactoryUtils.getTransactionalEntityManager(<Your entity manager factory>);
        em.refresh(registration);
        registration.setStatus(newStatus);
        registrationRepository.save(registration);
    }

}

Spring数据CrudRepository和悲观锁

1 个答案: