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open Stdune
open Core
open Core.O
type t =
{ mutable locked : bool
; mutable waiters : unit k Queue.t
}
let lock t k =
if t.locked then suspend (fun k -> Queue.push t.waiters k) k
else (
t.locked <- true;
k ())
let unlock t k =
assert t.locked;
match Queue.pop t.waiters with
| None ->
t.locked <- false;
k ()
| Some next -> resume next () k
let with_lock t ~f =
let* () = lock t in
finalize f ~finally:(fun () -> unlock t)
let create () = { locked = false; waiters = Queue.create () }