Source file caqti_lwt.ml

(* Copyright (C) 2014--2018  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 OCaml static compilation 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
 * along with this library.  If not, see <http://www.gnu.org/licenses/>.
 *)

open Caqti_prereq

module System = struct

  type 'a future = 'a Lwt.t
  let (>>=) = Lwt.(>>=)
  let (>|=) = Lwt.(>|=)
  let return = Lwt.return
  let join = Lwt.join

  module Mvar = struct
    type 'a t = 'a Lwt_mvar.t
    let create = Lwt_mvar.create_empty
    let store x v = Lwt.async (fun () -> Lwt_mvar.put v x)
    let fetch = Lwt_mvar.take
  end

  module Log = struct
    type 'a log = 'a Logs_lwt.log
    let err ?(src = default_log_src) = Logs_lwt.err ~src
    let warn ?(src = default_log_src) = Logs_lwt.warn ~src
    let info ?(src = default_log_src) = Logs_lwt.info ~src
    let debug ?(src = default_log_src) = Logs_lwt.debug ~src
  end

  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 ?(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 (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
        begin
          Lwt.catch
            (fun () -> Lwt.choose choices >|= fun _ -> false)
            (function
             | Lwt_unix.Timeout -> Lwt.return_true
             | exn -> Lwt.fail exn)
        end >>= fun timed_out ->
        Lwt.return (Lwt_unix.readable fd, Lwt_unix.writable fd, timed_out)
  end

  module Preemptive = Lwt_preemptive

end

include Caqti_connect.Make (System)

let or_fail = function
 | Ok x -> Lwt.return x
 | Error (#Caqti_error.t as err) -> Lwt.fail (Caqti_error.Exn err)