Implementing Model-level caching

Question

I was posting some comments in a related question about MVC caching and some questions about actual implementation came up. How does one implement a Model-level cache that works

Answer 1

What we did, was building a cache layer as a replacement to the loading function of the MVC. This way, only the actual model calls that we want, will be cached. If no caching is necessary or unwanted, the normal way of calling a model from the controller is being used.

If a model is being called through the cachelayer, together with it's eventual parameters, the cache layer will first verify the requested data against the cache pool and return it if still valid. If so, the actual model is not loaded and cached data is just returned to the controller. If not, the model is called as it normally would be.

It's really great to have the possibility of doing this in a layer above the model, since it becomes very easy to introduce the usage of semaphore locks on a per-query / per-model level, to reduce server loads even further.

The biggest advantage to me is though the fact that the models are designed as intended and contains nothing but pure database queries. This way, it is possible to modify a model in production without end users even noticing (assuming that the requested data that a model delivers does not need recreation during the update time, of course.. )

Update: We have also implemented namespacing inside our cachelayer on two levels, a per-model basis and an optional group-basis. Thanks to that, we can easily invalidate all previously invalidate all cached data that comes from a model upon update or deletion in the database.