NHibernate逐出ID [英] NHibernate evict by id
问题描述
每个人都知道会话中有缓存. 通常可以通过以下两种方法清除此缓存:
Everyone knows that there is cache in session. This cache generally could be cleared by 2 methods:
- Session.Evict
- Session.Clear
第二种方法不仅删除了单个条目，还删除了所有缓存.
Second method removes all cache not only for single entry.
我有经营方法.它接收大对象的ID(来自aspx站点)，有时还接收多个ID.并在数据库中执行本机sql操作(使用具有复杂逻辑的sql-query来不加载C#中的所有数据).然后，我需要使缓存无效.因此，每个潜在的对象负载都无需数据库直接缓存.
I have business method. It receives id of large object (from aspx site) or sometimes several ids. And do native sql operation in database (using sql-query with complex logic to not load all data in C#). Then I need to invalidate cache. So every potential load of object goes without cache direct from database.
不幸的是，退出了仅接受对象.同样，其实现DefaultEvictEventListener在代码路径中也有明确的分隔符-对于代理类而不是代理类而言，是分开的.我只是尝试创建实体，手动填写id并将其传递给Evict.这是行不通的.据我了解，通过非代理类的Evict使用GetHashCode可以从缓存中查找和删除对象.因此，如果我不重写它，将无法正常工作.我有很多本机sql批处理操作，因此在所有实体对象中覆盖所有GetHashcode会产生很多工作.另外我不确定这种情况是从缓存中删除代理还是不删除代理. 更新:据我所知，覆盖GetHashCode也无济于事.找不到StatefulPersistenceContext.RemoveEntry实体，因为它使用RuntimeHelpers.GetHashCode.因此，这种解决方案甚至是不可能的
Unfortunately evict accepting only objects. Also its implementation DefaultEvictEventListener has clear separation in code path - separate for proxy and not proxied classes. I have tried simply to create entity, fill id manually and pass it to Evict. This will not works. As I understand Evict by not proxied class use GetHashCode to find and remove object from cache. So if I am not overriding it it will not works. I have a lot native sql batch operations so overriding all GetHashcode in all entities objects will create a lot of work. Also I am not sure is this case removes proxies from cache or no. Update: As far as I have tried for me overriding GetHashCode also not helped. StatefulPersistenceContext.RemoveEntry not found entity because it uses RuntimeHelpers.GetHashCode. So this solution is not even possible
使用NHibernate的来源，我产生了以下解决方案:
Using sources of NHibernate I have produced following solution:
public static class NHSessionHelper: DefaultEvictEventListener
public static void RemoveEntityFromCache(this ISession session, Type type, object entityId)
{
ISessionImplementor sessionImpl = session.GetSessionImplementation();
IPersistenceContext persistenceContext = sessionImpl.PersistenceContext;
IEntityPersister persister = sessionImpl.Factory.GetEntityPersister(type.FullName);
if (persister == null)
{
return;
}
EntityKey key = new EntityKey(entityId, persister, sessionImpl.EntityMode);
persistenceContext.RemoveProxy(key);
object entity = persistenceContext.RemoveEntity(key);
if (entity != null)
{
EntityEntry e = persistenceContext.RemoveEntry(entity);
DoEvict(entity, key, e.Persister, (IEventSource)sessionImpl);
}
}
它仅使用NHibenate实现的一部分.但是在我看来，复制代码不是一个好主意.可能还有其他想法吗?
It just uses part of NHibenate implementation. But it seem to me not good idea to duplicate code. May be anyone have other ideas?
推荐答案
如果您确定对象在缓存中，则Session.Get(id)不会命中数据库.可能最简单的方法是Evict返回的对象:
If you are sure that the object is in the cache, Session.Get(id) will not hit the db. It's probably easiest to do that and then Evict the object you get back:
Model m = Session.Get(id);
Session.Evict(m);
修改
我不清楚您是在谈论第一级缓存还是第二级缓存.上面的内容将从一级缓存中逐出.要从二级缓存中退出，请在SessionFactory上使用evict方法.
It is not clear to me if you are talking about the first-level cache or the second-level cache. The above will evict something from the first-level cache. To evict from the second-level cache, use the evict method on SessionFactory.
根据评论进行编辑
在这种情况下，您可以尝试Session.Load:
In that case, you might try Session.Load:
Model m = Session.Load(id);
Session.Evict(m);
如果m在缓存中，则Session.Load将返回您可以退出的实例.如果不是，它将返回一个代理(没有数据库命中).我的测试表明，如果您尝试逐出代理服务器，则Session.Evict不会抛出异常，因此应该可以.
If m is in the cache, Session.Load will return the instance which you can evict. If not it returns a proxy (no db hit). My tests suggest that Session.Evict will not throw if you try to evict the proxy, so this should work.
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