Confused as to how caching is designed

I'm looking at the orchard cms source code, specifically in the /src/orchard/caching folder.

Can someone give me a high level explanation of the architecture?

There 开发者_Go百科are so many classes here which I can't get my head around.

acquirecontext, cachemodule signal, weak, defaultasynchtokenprovider, etc.

The idea here is just to wrap the ASP.NET cache under an API that is aware of Orchard specificity such as multi-tenancy: both cache items and signals that could invalidate them need to be at the tenant level while keeping the API transparently oblivious to these details. I wrote a short post a while ago to show how to use it: http://weblogs.asp.net/bleroy/archive/2011/02/16/caching-items-in-orchard.aspx