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package containers
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Semaphores

  • since 0.13
type t

A semaphore

val create : int -> t

create n creates a semaphore with initial value n.

  • raises Invalid_argument

    if n <= 0.

val get : t -> int

Current value.

val acquire : int -> t -> unit

acquire n s blocks until get s >= n, then atomically sets s := !s - n.

val release : int -> t -> unit

release n s atomically sets s := !s + n.

val with_acquire : n:int -> t -> f:(unit -> 'a) -> 'a

with_acquire ~n s ~f first acquires s with n units, calls f (), and then releases s with n units. Safely release the semaphore even if f () fails.

val wait_until_at_least : n:int -> t -> f:(unit -> 'a) -> 'a

wait_until_at_least ~n s ~f waits until get s >= n, then calls f () and returns its result. Doesn't modify the semaphore.