mte/unikernel/duniverse/ocaml-caqti/caqti-lwt/lib-unix/system_unix.ml
2025-11-11 02:07:51 +01:00

44 lines
1.7 KiB
OCaml

(* Copyright (C) 2023 Petter A. Urkedal <paurkedal@gmail.com>
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or (at your
* option) any later version, with the LGPL-3.0 Linking Exception.
*
* This library is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* and the LGPL-3.0 Linking Exception along with this library. If not, see
* <http://www.gnu.org/licenses/> and <https://spdx.org>, respectively.
*)
open Lwt.Infix
module Preemptive = Lwt_preemptive
module Unix = struct
type file_descr = Lwt_unix.file_descr
let wrap_fd f fd = f (Lwt_unix.of_unix_file_descr fd)
let poll ~stdenv:() ?(read = false) ?(write = false) ?timeout fd =
let choices = []
|> (fun acc -> if read then Lwt_unix.wait_read fd :: acc else acc)
|> (fun acc -> if write then Lwt_unix.wait_write fd :: acc else acc)
|> Option.fold
~none:Fun.id ~some:(fun t acc -> Lwt_unix.timeout t :: acc) timeout
in
if choices = [] then
Lwt.fail_invalid_arg "Caqti_lwt.Unix.poll: No operation specified."
else
Lwt.catch
(fun () -> Lwt.choose choices >|= fun _ -> false)
(function
| Lwt_unix.Timeout -> Lwt.return_true
| exn -> Lwt.fail exn)
>|= fun timed_out ->
(Lwt_unix.readable fd, Lwt_unix.writable fd, timed_out)
end