使用 session.save 保存对象时，Hibernate 不刷新会话？

Question

首先看一下下面的代码，我有三个主要模型来管理StoreHouse和StoreHouseInvetory，还有一个名为StoreHouseInventoryLock的模型来临时锁定/解锁一些StoreHouseInvetory当其他进程想要使用这些模型时：

public class StoreHouse {
    private String  name;
    private Double  currentAmount;
}

public class StoreHouseInventory {
    private StoreHouse  storeHouse;
    private Good        good;
    private Double      amount;
}

public class StoreHouseInventoryLock {
    private StoreHouseInventory     inventory;
    private Double                  amount;
}

@Service
public class PermitService implements IPermitService {

    @Autowired
    private IStoreHouseInventoryLockService storeHouseInventoryLockService;

    @Autowired
    private IStoreHouseService storeHouseService;

    @Override
    @Transactional
    public void addDetailToPermitFromStoreHouseInventory(long permitId, long storeHouseId, long inventoryId, double amount) {

        // do some business logic here

        /* save is simple method
         * and uses Session.save(object)
        */
        storeHouseInventoryLockService.add(inventoryId, +amount);

        // do some business logic here
        storeHouseService.syncCurrentInventory(storeHouseId);   
    }
}

@Service
public class StoreHouseService implements IStoreHouseService {

    @Autowired
    private IStoreHouseInventoryService storeHouseInventoryService;

    @Autowired
    private IStoreHouseInventoryLockService storeHouseInventoryLockService;

    @Transactional
    public void syncCurrentInventory(storeHouseId) {
        /* is a simeple method that use query like below
         * select sum(e.amount)
         *   from StoreHouseInventory
         *  where e.storeHouse.id = :storeHouseId
         */
        Double sumOfInventory = storeHouseInventoryService.sumOfInventory(storeHouseId);
        /* is a simeple method that use query like below
         * select sum(e.amount)
         *   from StoreHouseInventoryLock
         *  where e.storeHouseInventory.storeHouse.id = :storeHouseId
         */
        Double sumOfLock = storeHouseInventoryService.sumOfLock(storeHouseId);

        // load method is a simple method to load object by it's id
        // and used from Session.get(String entityName, Serializable id)
        StoreHouse storeHouse = this.load(storeHouseId);
        storeHouse.setCurrentAmount(sumOfInventory - sumOfLock);

        this.save(storeHouse);
    }
}

问题是在StoreHouseService.syncCurrentInventory中调用storeHouseInventoryService.sumOfLock时，不知道storeHouseInventoryLockService.add方法在PermitService.addDetailToPermitFromStoreHouseInventory方法中的变化，导致锁总和计算错误。

我认为这是因为当我调用 storeHouseInventoryLockService.add 时会话未刷新。如果是真的，为什么休眠在此更改期间不刷新会话？如果没有，我该怎么办？

Answer 1

由于IStoreHouseInventoryLockService.add 是从已经附加了事务的方法中调用的，因此相同的事务会传播到add 方法，因此在外部addDetailToPermitFromStoreHouseInventory 完成之前不会发生刷新。

一个快速的解决方案是使用 REQUIRES_NEW 事务传播类型标记 add 方法：

@Transactional(propagation=Propagation.REQUIRES_NEW)
public void add(..){..}

现在该方法完成后，即使有外部事务，所有持久性更改都会在退出时刷新到数据库。

Answer 2

如果当前执行的查询不与未刷新的表语句重叠，则可以安全地忽略刷新。