Lookup the value for key k If the value is in the cache, return it.
Lookup the value for key k If the value is in the cache, return it. Otherwise, insert the value v and return it
Note: This method does not guarantee that v will be in the cache when it returns
the cached value keyed to k or the computed value of v
Insert the value v (keyed by k) into the cache
Insert the value v (keyed by k) into the cache
true if the value was inserted into the cache
Lookup the value for key k
Lookup the value for key k
Some(v) if the value was cached, None otherwise
Remove k from the cache
Remove k from the cache
An unbounded hash-backed cache Operations on this cache execute in O(1) time