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module Schedulable = struct
(* A monad representing computation that can be cooperatively scheduled. Computations can yield, and fork (Choice). *)
type 'a t =
| Stop
| Now of 'a
| Yield of Prio.metrics * (unit -> 'a t)
| Choice of 'a t * 'a t
let[@inline] return x : _ t = Now x
let rec bind (mx : 'a t) (f : 'a -> 'b t) : 'b t =
match mx with
| Stop -> Stop
| Now v -> f v
| Yield (prio, step) -> Yield (prio, fun () -> bind (step ()) f)
| Choice (a, b) ->
(* cps to make it tail rec *)
Choice (bind a f, bind b f)
let[@inline] ( let* ) mx f = bind mx f
let[@inline] map f x =
let* x in
return (f x)
let[@inline] ( let+ ) x f = map f x
let[@inline] yield prio = Yield (prio, Fun.const (Now ()))
let[@inline] choose a b = Choice (a, b)
let stop = Stop
end
module Make (Work_datastructure : Prio.S) = struct
(* A scheduler for Schedulable values. *)
type 'a work_queue = (unit -> 'a Schedulable.t) Work_datastructure.t
type 'a t = { work_queue : 'a work_queue } [@@unboxed]
let[@inline] init () =
let work_queue = Work_datastructure.make () in
{ work_queue }
let[@inline] add_init_task sched task =
Work_datastructure.push task Prio.dummy sched.work_queue
let work sched at_worker_value =
let rec inner (t : _ Schedulable.t) write_back =
match t with
| Stop -> ()
| Now x -> at_worker_value x
| Yield (prio, f) -> write_back (prio, f)
| Choice (m1, m2) ->
inner m1 write_back;
inner m2 write_back
in
Work_datastructure.work_while
(fun f write_back -> inner (f ()) write_back)
sched.work_queue
let spawn_worker sched
~(at_worker_value : close_work_queue:(unit -> unit) -> 'a -> unit)
~at_worker_init ~finally =
at_worker_init ();
Domain.spawn (fun () ->
Fun.protect ~finally (fun () ->
try
work sched
(at_worker_value ~close_work_queue:(fun () ->
Work_datastructure.close sched.work_queue ) )
with e ->
let e_s = Printexc.to_string e in
let bt = Printexc.get_raw_backtrace () in
let bt_s = Printexc.raw_backtrace_to_string bt in
let bt_s =
if String.equal "" bt_s then
"use OCAMLRUNPARAM=b to get the backtrace"
else bt_s
in
Log.err (fun m ->
m "a worker ended with exception %s, backtrace is: @\n@[<v>%s@]" e_s
bt_s );
Printexc.raise_with_backtrace e bt ) )
end