AbstractKeyBasedCache requires a read-only sub-type to implement only Get(Object) and GetKeysEnumerator()()()() methods, and a read-write sub-type to additionally implement only Insert(Object, Object, Int64) and Remove(Object).

A number of the methods have implementations provided, but are extremely inefficient for caches that contain large amounts of data, including Clear()()()(), Contains(Object) and Count. Furthermore, if any of a number of method implementations has any cost of returning an "old value", then the InsertAll(IDictionary) and RemoveBlind(Object) methods should also be implemented.