Source file gluten_lwt.ml

(*----------------------------------------------------------------------------
 *  Copyright (c) 2018 Inhabited Type LLC.
 *  Copyright (c) 2018 Anton Bachin
 *  Copyright (c) 2019-2020 Antonio N. Monteiro.
 *
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *  3. Neither the name of the author nor the names of his contributors
 *     may be used to endorse or promote products derived from this software
 *     without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``AS IS'' AND ANY EXPRESS
 *  OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 *  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR
 *  ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 *  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 *  OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 *  HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 *  STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 *  ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 *  POSSIBILITY OF SUCH DAMAGE.
 *---------------------------------------------------------------------------*)

open Lwt.Infix

module Buffer : sig
  type t

  val create : int -> t

  val get : t -> f:(Bigstringaf.t -> off:int -> len:int -> int) -> int

  val put
    :  t
    -> f:(Bigstringaf.t -> off:int -> len:int -> [ `Eof | `Ok of int ] Lwt.t)
    -> [ `Eof | `Ok of int ] Lwt.t
end = struct
  type t =
    { buffer : Bigstringaf.t
    ; mutable off : int
    ; mutable len : int
    }

  let create size =
    let buffer = Bigstringaf.create size in
    { buffer; off = 0; len = 0 }

  let compress t =
    if t.len = 0 then (
      t.off <- 0;
      t.len <- 0)
    else if t.off > 0 then (
      Bigstringaf.blit t.buffer ~src_off:t.off t.buffer ~dst_off:0 ~len:t.len;
      t.off <- 0)

  let get t ~f =
    let n = f t.buffer ~off:t.off ~len:t.len in
    t.off <- t.off + n;
    t.len <- t.len - n;
    if t.len = 0 then
      t.off <- 0;
    n

  let put t ~f =
    compress t;
    f t.buffer ~off:(t.off + t.len) ~len:(Bigstringaf.length t.buffer - t.len)
    >|= function
    | `Eof ->
      `Eof
    | `Ok n as ret ->
      t.len <- t.len + n;
      ret
end

include Gluten_lwt_intf

module IO_loop = struct
  let start
      : type t fd.
        (module IO with type socket = fd)
        -> (module Gluten.RUNTIME with type t = t)
        -> t
        -> read_buffer_size:int
        -> fd
        -> unit Lwt.t
    =
   fun (module Io) (module Runtime) t ~read_buffer_size socket ->
    let read_buffer = Buffer.create read_buffer_size in
    let read_loop_exited, notify_read_loop_exited = Lwt.wait () in
    let rec read_loop () =
      let rec read_loop_step () =
        match Runtime.next_read_operation t with
        | `Read ->
          Buffer.put ~f:(Io.read socket) read_buffer >>= ( function
          | `Eof ->
            Buffer.get read_buffer ~f:(fun bigstring ~off ~len ->
                Runtime.read_eof t bigstring ~off ~len)
            |> ignore;
            read_loop_step ()
          | `Ok _ ->
            Buffer.get read_buffer ~f:(fun bigstring ~off ~len ->
                Runtime.read t bigstring ~off ~len)
            |> ignore;
            read_loop_step () )
        | `Yield ->
          Runtime.yield_reader t read_loop;
          Lwt.return_unit
        | `Close ->
          Lwt.wakeup_later notify_read_loop_exited ();
          Io.shutdown_receive socket;
          Lwt.return_unit
      in
      Lwt.async (fun () ->
          Lwt.catch read_loop_step (fun exn ->
              Runtime.report_exn t exn;
              Lwt.return_unit))
    in
    let writev = Io.writev socket in
    let write_loop_exited, notify_write_loop_exited = Lwt.wait () in
    let rec write_loop () =
      let rec write_loop_step () =
        match Runtime.next_write_operation t with
        | `Write io_vectors ->
          writev io_vectors >>= fun result ->
          Runtime.report_write_result t result;
          write_loop_step ()
        | `Yield ->
          Runtime.yield_writer t write_loop;
          Lwt.return_unit
        | `Close _ ->
          Lwt.wakeup_later notify_write_loop_exited ();
          Lwt.return_unit
      in
      Lwt.async (fun () ->
          Lwt.catch write_loop_step (fun exn ->
              Runtime.report_exn t exn;
              Lwt.return_unit))
    in
    read_loop ();
    write_loop ();
    Lwt.join [ read_loop_exited; write_loop_exited ] >>= fun () ->
    Io.close socket
end

module Server (Io : IO) = struct
  module Server = Gluten.Server

  type socket = Io.socket

  type addr = Io.addr

  let create_connection_handler
      ~read_buffer_size ~protocol connection _client_addr socket
    =
    let connection = Server.create ~protocol connection in
    IO_loop.start
      (module Io)
      (module Server)
      connection
      ~read_buffer_size
      socket

  let create_upgradable_connection_handler
      ~read_buffer_size
      ~protocol
      ~create_protocol
      ~request_handler
      client_addr
      socket
    =
    let connection =
      Server.create_upgradable
        ~protocol
        ~create:create_protocol
        (request_handler client_addr)
    in
    IO_loop.start
      (module Io)
      (module Server)
      connection
      ~read_buffer_size
      socket
end

module Client (Io : IO) = struct
  module Client_connection = Gluten.Client

  type socket = Io.socket

  type t =
    { connection : Client_connection.t
    ; socket : socket
    }

  let create ~read_buffer_size ~protocol t socket =
    let connection = Client_connection.create ~protocol t in
    Lwt.async (fun () ->
        IO_loop.start
          (module Io)
          (module Client_connection)
          connection
          ~read_buffer_size
          socket);
    Lwt.return { connection; socket }

  let upgrade t protocol =
    Client_connection.upgrade_protocol t.connection protocol

  let shutdown t =
    Client_connection.shutdown t.connection;
    Io.close t.socket

  let is_closed t = Client_connection.is_closed t.connection
end