NHibernate second-level caching - evicting regions

Question

We have a number of cache regions set up in our nHibernate implementation. In order to avoid trouble with load balanced web servers, I want to effectively disable the caching on the pages that edit the cached data. I can write a method that clears out all my query caches, my class caches and my entity caches easily enough.

But what I really want is to clear the cache by region. sessionFactory.EvictQueries() will take a region parameter, but Evict() and EvictCollection() does not. I don't really want to throw away the whole cache here, nor do I want to maintain some sort of clumsy dictionary associating types with their cache regions. Does nHibernate have a way to ask an entity or collection what its caching settings are?

thanks

Answer 1

I've just done the same thing. For everyone's benefit, here is the method I constructed:

public void ClearCache(string regionName)
    {
        // Use your favourite IOC to get to the session factory
        var sessionFactory = ObjectFactory.GetInstance<ISessionFactory>();

        sessionFactory.EvictQueries(regionName);

        foreach (var collectionMetaData in sessionFactory.GetAllCollectionMetadata().Values)
        {
            var collectionPersister = collectionMetaData as NHibernate.Persister.Collection.ICollectionPersister;
            if (collectionPersister != null)
            {
                if ((collectionPersister.Cache != null) && (collectionPersister.Cache.RegionName == regionName))
                {
                    sessionFactory.EvictCollection(collectionPersister.Role);
                }
            }
        }

        foreach (var classMetaData in sessionFactory.GetAllClassMetadata().Values)
        {
            var entityPersister = classMetaData as NHibernate.Persister.Entity.IEntityPersister;
            if (entityPersister != null)
            {
                if ((entityPersister.Cache != null) && (entityPersister.Cache.RegionName == regionName))
                {
                    sessionFactory.EvictEntity(entityPersister.EntityName);
                }
            }
        }
    }