Module JoinCount.Monitor

module Monitor: sig .. end

type key 

Type for identifiers of pending computations.

type ('a, 'b, 'c) t = {

Monitiors are enhancements of dynamic collectors adding the ability to access the list of pending computations.

Given a monitor m, defined as create comb y0:

• m is informed of the start of a computation by sending a message m.enter xi where xi is the input of the computation, an identifier for the computation being returned.
• m is informed of the end of a computation by sending a message m.leave (id, yi) where id is the computation identifier as previously returned by enter, and yi is the result of the computation.
• m.is_pending id returns whether the computation whose identifier is passed is pending (a computation is pending if it has been "entered" but not yet "leaved").
• m.get_pendings () returns the list of pending computations.
• m is informed that no more computation will be entered by sending a message m.finished ().

The call m.wait () will return the combined result comb y1 (comb y2 (... (comb yn y0))), once all the announced events have occurred. Observe that at most one such call is allowed.

val create : ('b -> 'c -> 'c) -> 'c -> ('a, 'b, 'c) t

create comb y0 returns a monitor for computations of type 'a -> 'b, comb being used to combine results with initial result y0.