open Lwt

let rec iter f l =

let l = List.fold_left (fun acc a -> f a :: acc) [] l in

let l = List.rev l in

List.fold_left (fun rt t -> t >>= fun () -> rt) (Lwt.return ()) l

let rec map f l =

match l with

[] ->

return []

| v :: r ->

let t = f v in

let rt = map f r in

t >>= (fun v' ->

rt >>= (fun l' ->

return (v' :: l')))

let map_with_waiting_action f wa l =

let rec loop l =

match l with

[] ->

return []

| v :: r ->

let t = f v in

let rt = loop r in

t >>= (fun v' ->

(* Perform the specified "waiting action" for the next *)

(* item in the list. *)

if r <> [] then

wa (List.hd r)

else

();

rt >>= (fun l' ->

return (v' :: l')))

in

if l <> [] then

wa (List.hd l)

else

();

loop l

let rec map_serial f l =

match l with

[] ->

return []

| v :: r ->

f v >>= (fun v' ->

map_serial f r >>= (fun l' ->

return (v' :: l')))

let join l = iter (fun x -> x) l

type region =

{ mutable size : int;

mutable count : int;

waiters : (unit Lwt.t * int) Queue.t }

let make_region count = { size = count; count = 0; waiters = Queue.create () }

let resize_region reg sz = reg.size <- sz

let purge_region reg = Queue.clear reg.waiters

let leave_region reg sz =

try

if reg.count - sz >= reg.size then raise Queue.Empty;

let (w, sz') = Queue.take reg.waiters in

reg.count <- reg.count - sz + sz';

Lwt.wakeup w ()

with Queue.Empty ->

reg.count <- reg.count - sz

let run_in_region_1 reg sz thr =

(catch

(fun () -> thr () >>= (fun v -> leave_region reg sz; return v))

(fun e -> leave_region reg sz; fail e))

let run_in_region reg sz thr =

if reg.count >= reg.size then begin

let res = wait () in

Queue.add (res, sz) reg.waiters;

res >>= (fun () -> run_in_region_1 reg sz thr)

end else begin

reg.count <- reg.count + sz;

run_in_region_1 reg sz thr

end