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findOne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方法分开.

根据这个答案,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事务
• 第二个没有考虑第一个的变化.

因此破坏了行为.

任何线索为什么@Lock没有开箱即用刷新实体经理？

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

您需要使用的entityManger transaction是Spring为你创建:

    @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);
    }

}