val key_of_identifier : cache_index:int -> string -> key
val identifier_of_key : key -> string
val set_cache_layout : t -> int list -> t Lwt.t
val update : t -> key -> (value * int) option -> t
val list_keys : t -> cache_index:int -> (key * int) list option
val key_rank : t -> key -> int option
val future_cache_expectation : t -> time_in_blocks:int -> t
val cache_size : t -> cache_index:int -> int option
val cache_size_limit : t -> cache_index:int -> int option