Spring

Question

我正在 Spring 和 Hibernate 工作。我有一个要求，我需要通过向其中添加一个数字来更新特定字段。由于多个线程可以同时执行它，在更新时我用旧值检查字段值。因此，如果没有任何更新，则意味着它已被其他线程递增，我们将触发重试。

公司服务

public Company getAndIncrementRequestId(final int companyId, int retry) throws Exception {
    Optional<Company> companyOptional = companyRepository.findById(companyId);
    if (!companyOptional.isPresent()) {
        throw new EntityNotFoundException("Company not found for given id" + companyId);
    }

    Company company = companyOptional.get();
    int oldRequestId = company.getRequestId();
    int requestId;
    if (oldRequestId == Integer.MAX_VALUE) {
        requestId = 1;
    } else {
        requestId = oldRequestId + 1;
    }
    company.setRequestId(requestId); //--------------------------> PROBLEM
    int result = companyRepository.updateRequestId(companyId, requestId, oldRequestId);
    if (result == 0) {
        if (retry < 0) {
            throw new Exception("Unable to get requestId");
        }
        LOG.warn("Retrying since there was some update on requestId by some other thread");
        try {
            TimeUnit.MILLISECONDS.sleep(100);
        } catch (InterruptedException e) {
            LOG.warn("Unexpected InterruptException occurred while trying to get requestId");
        }
        return getAndIncrementRequestId(companyId, retry - 1);
    }
    return company;
}

公司资料库

@Transactional
public interface CompanyRepository extends CrudRepository<Company, Integer> {
    Optional<Company> findById(String id);

    @Modifying(clearAutomatically = true)
    @Query("update Company c set c.requestId = :requestId WHERE c.id = :companyId AND c.requestId = :oldRequestId")
    int updateRequestId(@Param("companyId") Integer companyId, @Param("requestId") Integer requestId,@Param("oldRequestId") Integer oldRequestId);
}

但是服务中的上述代码将触发两个休眠更新，一个将 requestId 设置为最新的 requestId，另一个是实际更新。将 show-sql 设置为 true.

后可以在日志中观察到两个查询

但是如果行，

company.setRequestId(requestId);

在 companyRepository.updateRequestId() 之后向下移动它工作正常。

工作公司服务

public Company getAndIncrementRequestId(final int companyId, int retry) throws Exception {
    Optional<Company> companyOptional = companyRepository.findById(companyId);
    if (!companyOptional.isPresent()) {
        throw new EntityNotFoundException("Company not found for given id" + companyId);
    }

    Company company = companyOptional.get();
    int oldRequestId = company.getRequestId();
    int requestId;
    if (oldRequestId == Integer.MAX_VALUE) {
        requestId = 1;
    } else {
        requestId = oldRequestId + 1;
    }

    int result = companyRepository.updateRequestId(companyId, requestId, oldRequestId);
    if (result == 0) {
        if (retry < 0) {
            throw new Exception("Unable to get requestId");
        }
        LOG.warn("Retrying since there was some update on requestId by some other thread");
        try {
            TimeUnit.MILLISECONDS.sleep(100);
        } catch (InterruptedException e) {
            LOG.warn("Unexpected InterruptException occurred while trying to get requestId");
        }
        return getAndIncrementRequestId(companyId, retry - 1);
    }
    company.setRequestId(requestId); //--------------------------> PROBLEM DOES NOT EXISTS
    return company;
}

请问我的问题是，当我什至没有通过实体公司的任何地方时，为什么会有两个查询..？

Answer 1

这是因为当您执行 "companyRepository.findById(companyId);" 时，返回的公司返回 managed 状态。因此，在案例 1 中，当您在调用 "companyRepository.updateRequestId(companyId, requestId, oldRequestId);" 之前设置请求 ID 时，将在公司存储库中创建一个事务对象，该对象执行托管实体的所有未决更新以及方法 "updateRequestId" 的查询被解雇。在第二种情况下，由于您在调用 "companyRepository.updateRequestId(companyId, requestId, oldRequestId);" 之后编写了 set 语句，这就是为什么对托管对象的更新永远不会被触发，因为它没有获得任何事务

Spring - 执行了两个休眠更新查询而不是一个

Spring - Two hibernate update queries are executed instead of one

java

orm

hibernate

spring-transactions