Sample app illustrating httpaf chunked encoding issue

lwt_echo_post.ml

open Base
open Lwt.Infix
module Arg = Caml.Arg

open Httpaf_lwt_unix
module Reqd = Httpaf.Reqd
module Request = Httpaf.Request
module Headers = Httpaf.Headers
module Response = Httpaf.Response
module Body = Httpaf.Body

let text = "CHAPTER I. Down the Rabbit-Hole  Alice was beginning to get very tired of sitting by her sister on the bank, and of having nothing to do: once or twice she had peeped into the book her sister was reading, but it had no pictures or conversations in it, <and what is the use of a book,> thought Alice <without pictures or conversations?> So she was considering in her own mind (as well as she could, for the hot day made her feel very sleepy and stupid), whether the pleasure of making a daisy-chain would be worth the trouble of getting up and picking the daisies, when suddenly a White Rabbit with pink eyes ran close by her. There was nothing so very remarkable in that; nor did Alice think it so very much out of the way to hear the Rabbit say to itself, <Oh dear! Oh dear! I shall be late!> (when she thought it over afterwards, it occurred to her that she ought to have wondered at this, but at the time it all seemed quite natural); but when the Rabbit actually took a watch out of its waistcoat-pocket, and looked at it, and then hurried on, Alice started to her feet, for it flashed across her mind that she had never before seen a rabbit with either a waistcoat-pocket, or a watch to take out of it, and burning with curiosity, she ran across the field after it, and fortunately was just in time to see it pop down a large rabbit-hole under the hedge. In another moment down went Alice after it, never once considering how in the world she was to get out again. The rabbit-hole went straight on like a tunnel for some way, and then dipped suddenly down, so suddenly that Alice had not a moment to think about stopping herself before she found herself falling down a very deep well. Either the well was very deep, or she fell very slowly, for she had plenty of time as she went down to look about her and to wonder what was going to happen next. First, she tried to look down and make out what she was coming to, but it was too dark to see anything; then she looked at the sides of the well, and noticed that they were filled with cupboards......\n"
let text = Bigstringaf.of_string ~off:0 ~len:(String.length text) text

let benchmark =
  let headers = Headers.of_list ["transfer-encoding", "chunked"] in
  let handler reqd =
    let { Request.target; _ } = Reqd.request reqd in
    let request_body          = Reqd.request_body reqd in
    Body.close_reader request_body;
    match target with
    | "/" ->
      let response = (Response.create ~headers `OK) in
      let response_body = Reqd.respond_with_streaming reqd response in
      let rec write_loop x =
        if x = 0 then begin
          Body.close_writer response_body;
        end else begin
          for i = 1 to 100 do
            Body.schedule_bigstring response_body text;
          done;
          Body.flush response_body (fun () -> write_loop (x - 1))
        end
      in
      write_loop 100
    | _   -> Reqd.respond_with_string reqd (Response.create `Not_found) "Route not found"
  in
  handler
;;

let request_handler (_ : Unix.sockaddr) = benchmark
let error_handler (_ : Unix.sockaddr) = Httpaf_examples.Server.error_handler

let main port =
  let listen_address = Unix.(ADDR_INET (inet_addr_loopback, port)) in
  Lwt.async (fun () ->
    Lwt_io.establish_server_with_client_socket
      listen_address
      (Server.create_connection_handler ~request_handler ~error_handler)
    >|= fun _server ->
      Stdio.printf "Listening on port %i and echoing POST requests.\n" port;
      Stdio.printf "To send a POST request, try one of the following\n\n";
      Stdio.printf "  echo \"Testing echo POST\" | dune exec examples/async/async_post.exe\n";
      Stdio.printf "  echo \"Testing echo POST\" | dune exec examples/lwt/lwt_post.exe\n";
      Stdio.printf "  echo \"Testing echo POST\" | curl -XPOST --data @- http://localhost:%d\n\n%!" port);
  let forever, _ = Lwt.wait () in
  Lwt_main.run forever
;;

let () =
  let port = ref 8080 in
  Arg.parse
    ["-p", Arg.Set_int port, " Listening port number (8080 by default)"]
    ignore
    "Echoes POST requests. Runs forever.";
  main !port
;;