Source file payload.ml

(*----------------------------------------------------------------------------
 *  Copyright (c) 2018 Inhabited Type LLC.
 *  Copyright (c) 2021 António Nuno Monteiro
 *
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 *     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
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module IOVec = Httpaf.IOVec

  type t =
  { faraday : Faraday.t
  ; mutable read_scheduled : bool
  ; mutable on_eof : unit -> unit
  ; mutable on_read : Bigstringaf.t -> off:int -> len:int -> unit
  }

  let default_on_eof         = Sys.opaque_identity (fun () -> ())
  let default_on_read        = Sys.opaque_identity (fun _ ~off:_ ~len:_ -> ())

  let of_faraday faraday =
    { faraday
    ; read_scheduled         = false
    ; on_eof                 = default_on_eof
    ; on_read                = default_on_read
    }

  let create buffer =
    of_faraday (Faraday.of_bigstring buffer)

  let create_empty () =
    let t = create Bigstringaf.empty in
    Faraday.close t.faraday;
    t

  let empty = create_empty ()

  let is_closed t =
    Faraday.is_closed t.faraday

  let unsafe_faraday t =
    t.faraday

  let rec do_execute_read t on_eof on_read =
    match Faraday.operation t.faraday with
    | `Yield           -> ()
    | `Close           ->
      t.read_scheduled <- false;
      t.on_eof         <- default_on_eof;
      t.on_read        <- default_on_read;
      on_eof ()
    | `Writev []       -> assert false
    | `Writev (iovec::_) ->
      t.read_scheduled <- false;
      t.on_eof         <- default_on_eof;
      t.on_read        <- default_on_read;
      let { IOVec.buffer; off; len } = iovec in
      Faraday.shift t.faraday len;
      on_read buffer ~off ~len;
      execute_read t
  and execute_read t =
    if t.read_scheduled then do_execute_read t t.on_eof t.on_read

  let schedule_read t ~on_eof ~on_read =
    if t.read_scheduled
    then failwith "Payload.schedule_read: reader already scheduled";
    if is_closed t
    then do_execute_read t on_eof on_read
    else begin
      t.read_scheduled <- true;
      t.on_eof         <- on_eof;
      t.on_read        <- on_read;
    end

  let is_read_scheduled t = t.read_scheduled

  let close t =
    Faraday.close t.faraday;
    execute_read t