ligo/src/lib_stdlib/lwt_watcher.ml

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type 'a inner_stopper = {
  id: int ;
  push: ('a option -> unit) ;
  mutable active : bool;
  input : 'a input;
}

and 'a input =
  { mutable watchers : 'a inner_stopper list;
    mutable cpt : int; }

type stopper = unit -> unit

let create_input () =
  { watchers = [];
    cpt = 0 }

let shutdown_input input =
  let { watchers ; _ } = input in
  List.iter (fun w ->
      w.active <- false ;
      w.push None
    ) watchers ;
  input.cpt <- 0 ;
  input.watchers <- []

let create_fake_stream () =
  let str, push = Lwt_stream.create () in
  str, (fun () -> push None)

let notify input info =
  List.iter (fun w -> w.push (Some info)) input.watchers

let shutdown_output output =
  if output.active then begin
    output.active <- false;
    output.push None;
    output.input.watchers <-
      List.filter (fun w -> w.id <> output.id) output.input.watchers;
  end

let create_stream input =
  input.cpt <- input.cpt + 1;
  let id = input.cpt in
  let stream, push = Lwt_stream.create () in
  let output = { id; push; input; active = true } in
  input.watchers <- output :: input.watchers;
  stream, (fun () -> shutdown_output output)

let shutdown f = f ()