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.

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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