java - Spring数据CrudRepository和悲观锁

Question

我正在使用

• Spring Boot 1.4.2
• Spring Data JPA 1.10.5
• PostgreSQL 9.5 数据库

我希望在我的 Spring Data 存储库中有一个带有悲观锁的 findOne 方法，该方法与已经提供的 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);
}

这几乎行得通。

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

• 第二个等待第一个的事务提交
• 第二个不考虑第一个所做的更改。

因此破坏行为。

知道为什么 @Lock 不能立即刷新实体管理器吗？

更新

这是请求的示例代码:

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 Spring 为您创建的 entity Manager 事务:

    @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);
    }

}