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31 lines
962 B
OCaml
31 lines
962 B
OCaml
(* This file is free software, part of containers. See file "license" for more details. *)
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(** {1 Semaphores}
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@since 0.13 *)
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type t
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(** A semaphore *)
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val create : int -> t
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(** [create n] creates a semaphore with initial value [n].
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@raise Invalid_argument if [n <= 0]. *)
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val get : t -> int
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(** Current value. *)
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val acquire : int -> t -> unit
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(** [acquire n s] blocks until [get s >= n], then atomically
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sets [s := !s - n]. *)
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val release : int -> t -> unit
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(** [release n s] atomically sets [s := !s + n]. *)
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val with_acquire : n:int -> t -> f:(unit -> 'a) -> 'a
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(** [with_acquire ~n s ~f] first acquires [s] with [n] units,
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calls [f ()], and then releases [s] with [n] units.
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Safely release the semaphore even if [f ()] fails. *)
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val wait_until_at_least : n:int -> t -> f:(unit -> 'a) -> 'a
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(** [wait_until_at_least ~n s ~f] waits until [get s >= n], then calls [f ()]
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and returns its result. Doesn't modify the semaphore. *)
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