Merge a56dd0ec65 into 8a8aadfbb0

can be replaced with a proper cooperative lock

.ocamlformat

@@ -1,4 +1,4 @@
-version = 0.26.2
+version = 0.27.0
 profile=conventional
 margin=80
 if-then-else=k-r

dune-project

@@ -39,3 +39,14 @@
     (iostream-camlzip (>= 0.2.1))
     (logs :with-test)
     (odoc :with-doc)))
+
+(package
+  (name tiny_httpd_moonpool)
+  (synopsis "Moonpool+picos_stdio backend for Tiny_httpd")
+  (depends
+    seq
+    (tiny_httpd (= :version))
+    (moonpool (>= 0.7))
+    (moonpool-io (>= 0.7))
+    (ocaml (>= 5.0))
+    (odoc :with-doc)))

echo_mio.sh

@@ -0,0 +1,2 @@
+#!/bin/sh
+exec dune exec --display=quiet --profile=release "examples/echo_mio.exe" -- $@

examples/dune

@@ -14,6 +14,12 @@
  (modules echo vfs)
  (libraries tiny_httpd logs tiny_httpd_camlzip tiny_httpd.multipart-form-data))
 
+(executable
+ (name echo_mio)
+ (flags :standard -warn-error -a+8)
+ (modules echo_mio)
+ (libraries tiny_httpd tiny_httpd_moonpool logs))
+
 (executable
  (name writer)
  (flags :standard -warn-error -a+8)

examples/echo_mio.ml

@@ -0,0 +1,294 @@
+open Tiny_httpd_core
+module Log = Tiny_httpd.Log
+
+let now_ = Unix.gettimeofday
+
+let alice_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......"
+
+(* util: a little middleware collecting statistics *)
+let middleware_stat () : Server.Middleware.t * (unit -> string) =
+  let n_req = ref 0 in
+  let total_time_ = ref 0. in
+  let parse_time_ = ref 0. in
+  let build_time_ = ref 0. in
+  let write_time_ = ref 0. in
+
+  let m h req ~resp =
+    incr n_req;
+    let t1 = Request.start_time req in
+    let t2 = now_ () in
+    h req ~resp:(fun response ->
+        let t3 = now_ () in
+        resp response;
+        let t4 = now_ () in
+        total_time_ := !total_time_ +. (t4 -. t1);
+        parse_time_ := !parse_time_ +. (t2 -. t1);
+        build_time_ := !build_time_ +. (t3 -. t2);
+        write_time_ := !write_time_ +. (t4 -. t3))
+  and get_stat () =
+    Printf.sprintf
+      "%d requests (average response time: %.3fms = %.3fms + %.3fms + %.3fms)"
+      !n_req
+      (!total_time_ /. float !n_req *. 1e3)
+      (!parse_time_ /. float !n_req *. 1e3)
+      (!build_time_ /. float !n_req *. 1e3)
+      (!write_time_ /. float !n_req *. 1e3)
+  in
+  m, get_stat
+
+(* ugly AF *)
+let base64 x =
+  let ic, oc = Unix.open_process "base64" in
+  output_string oc x;
+  flush oc;
+  close_out oc;
+  let r = input_line ic in
+  ignore (Unix.close_process (ic, oc));
+  r
+
+let setup_logging () =
+  Logs.set_reporter @@ Logs.format_reporter ();
+  Logs.set_level ~all:true (Some Logs.Debug)
+
+let () =
+  Moonpool_fib.main @@ fun _ ->
+  let port_ = ref 8080 in
+  let max_conn = ref 800 in
+  let j = ref 16 in
+  Arg.parse
+    (Arg.align
+       [
+         "--port", Arg.Set_int port_, " set port";
+         "-p", Arg.Set_int port_, " set port";
+         "--debug", Arg.Unit setup_logging, " enable debug";
+         ( "--max-connections",
+           Arg.Set_int max_conn,
+           " maximum number of connections" );
+         "-j", Arg.Set_int j, " Size of thread pool";
+       ])
+    (fun _ -> raise (Arg.Bad ""))
+    "echo [option]*";
+
+  let runner = Moonpool.Ws_pool.create ~num_threads:!j () in
+  let server : Server.t =
+    Tiny_httpd_moonpool.create ~runner ~port:!port_ ~max_connections:!max_conn
+      ()
+  in
+
+  let m_stats, get_stats = middleware_stat () in
+  Server.add_middleware server ~stage:(`Stage 1) m_stats;
+
+  (* say hello *)
+  Server.add_route_handler ~meth:`GET server
+    Route.(exact "hello" @/ string @/ return)
+    (fun name _req -> Response.make_string (Ok ("hello " ^ name ^ "!\n")));
+
+  (* compressed file access *)
+  Server.add_route_handler ~meth:`GET server
+    Route.(exact "zcat" @/ string_urlencoded @/ return)
+    (fun path _req ->
+      let ic = open_in path in
+      let str = IO.Input.of_in_channel ic in
+      let mime_type =
+        try
+          let p = Unix.open_process_in (Printf.sprintf "file -i -b %S" path) in
+          try
+            let s = [ "Content-Type", String.trim (input_line p) ] in
+            ignore @@ Unix.close_process_in p;
+            s
+          with _ ->
+            ignore @@ Unix.close_process_in p;
+            []
+        with _ -> []
+      in
+      Response.make_stream ~headers:mime_type (Ok str));
+
+  (* echo request *)
+  Server.add_route_handler server
+    Route.(exact "echo" @/ return)
+    (fun req ->
+      let q =
+        Request.query req
+        |> List.map (fun (k, v) -> Printf.sprintf "%S = %S" k v)
+        |> String.concat ";"
+      in
+      Response.make_string
+        (Ok (Format.asprintf "echo:@ %a@ (query: %s)@." Request.pp req q)));
+
+  (* file upload *)
+  Server.add_route_handler_stream ~meth:`PUT server
+    Route.(exact "upload" @/ string @/ return)
+    (fun path req ->
+      Log.debug (fun k ->
+          k "start upload %S, headers:\n%s\n\n%!" path
+            (Format.asprintf "%a" Headers.pp (Request.headers req)));
+      try
+        let oc = open_out @@ "/tmp/" ^ path in
+        IO.Input.to_chan oc req.Request.body;
+        flush oc;
+        Response.make_string (Ok "uploaded file")
+      with e ->
+        Response.fail ~code:500 "couldn't upload file: %s"
+          (Printexc.to_string e));
+
+  (* protected by login *)
+  Server.add_route_handler server
+    Route.(exact "protected" @/ return)
+    (fun req ->
+      let ok =
+        match Request.get_header req "authorization" with
+        | Some v ->
+          Log.debug (fun k -> k "authenticate with %S" v);
+          v = "Basic " ^ base64 "user:foobar"
+        | None -> false
+      in
+      if ok then (
+        (* FIXME: a logout link *)
+        let s =
+          "<p>hello, this is super secret!</p><a href=\"/logout\">log out</a>"
+        in
+        Response.make_string (Ok s)
+      ) else (
+        let headers =
+          Headers.(empty |> set "www-authenticate" "basic realm=\"echo\"")
+        in
+        Response.fail ~code:401 ~headers "invalid"
+      ));
+
+  (* logout *)
+  Server.add_route_handler server
+    Route.(exact "logout" @/ return)
+    (fun _req -> Response.fail ~code:401 "logged out");
+
+  (* stats *)
+  Server.add_route_handler server
+    Route.(exact "stats" @/ return)
+    (fun _req ->
+      let stats = get_stats () in
+      Response.make_string @@ Ok stats);
+
+  Server.add_route_handler server
+    Route.(exact "alice" @/ return)
+    (fun _req -> Response.make_string (Ok alice_text));
+
+  Server.add_route_handler server
+    Route.(exact "alice10" @/ return)
+    (fun _req ->
+      let writer =
+        IO.Writer.make () ~write:(fun oc ->
+            for _i = 1 to 10 do
+              IO.Output.output_string oc alice_text;
+              IO.Output.flush oc
+            done)
+      in
+      Response.make_writer (Ok writer));
+
+  (* main page *)
+  Server.add_route_handler server
+    Route.(return)
+    (fun _req ->
+      let open Tiny_httpd_html in
+      let h =
+        html []
+          [
+            head [] [ title [] [ txt "index of echo" ] ];
+            body []
+              [
+                h3 [] [ txt "welcome!" ];
+                p [] [ b [] [ txt "endpoints are:" ] ];
+                ul []
+                  [
+                    li [] [ pre [] [ txt "/hello/:name (GET)" ] ];
+                    li []
+                      [
+                        pre []
+                          [
+                            a [ A.href "/echo/" ] [ txt "echo" ];
+                            txt " echo back query";
+                          ];
+                      ];
+                    li []
+                      [ pre [] [ txt "/upload/:path (PUT) to upload a file" ] ];
+                    li []
+                      [
+                        pre []
+                          [
+                            txt
+                              "/zcat/:path (GET) to download a file (deflate \
+                               transfer-encoding)";
+                          ];
+                      ];
+                    li []
+                      [
+                        pre []
+                          [
+                            a [ A.href "/stats/" ] [ txt "/stats/" ];
+                            txt " (GET) to access statistics";
+                          ];
+                      ];
+                    li []
+                      [
+                        pre []
+                          [
+                            a [ A.href "/vfs/" ] [ txt "/vfs" ];
+                            txt " (GET) to access a VFS embedded in the binary";
+                          ];
+                      ];
+                    li []
+                      [
+                        pre []
+                          [
+                            a [ A.href "/protected" ] [ txt "/protected" ];
+                            txt
+                              " (GET) to see a protected page (login: user, \
+                               password: foobar)";
+                          ];
+                      ];
+                    li []
+                      [
+                        pre []
+                          [
+                            a [ A.href "/logout" ] [ txt "/logout" ];
+                            txt " (POST) to log out";
+                          ];
+                      ];
+                  ];
+              ];
+          ]
+      in
+      let s = to_string_top h in
+      Response.make_string ~headers:[ "content-type", "text/html" ] @@ Ok s);
+
+  Printf.printf "listening on http://%s:%d\n%!" (Server.addr server)
+    (Server.port server);
+  match Server.run server with
+  | Ok () -> ()
+  | Error e -> raise e

src/core/gen/mkshims.ml

@@ -26,11 +26,6 @@ let atomic_before_412 =
 
 let atomic_after_412 = {|include Atomic|}
 
-let write_file file s =
-  let oc = open_out file in
-  output_string oc s;
-  close_out oc
-
 let () =
   let version = Scanf.sscanf Sys.ocaml_version "%d.%d.%s" (fun x y _ -> x, y) in
   print_endline

src/core/route.ml

@@ -91,3 +91,34 @@ module Private_ = struct
 end
 
 let pp out x = Format.pp_print_string out (to_string x)
+
+let rec to_url_rec : type b. Buffer.t -> (b, string) t -> b =
+ fun buf route ->
+  match route with
+  | Fire -> Buffer.contents buf
+  | Rest { url_encoded = _ } ->
+    fun str ->
+      Buffer.add_string buf str;
+      Buffer.contents buf
+  | Compose (comp, rest) ->
+    (match comp with
+    | Exact s ->
+      Buffer.add_string buf s;
+      Buffer.add_char buf '/';
+      to_url_rec buf rest
+    | Int ->
+      fun i ->
+        Printf.bprintf buf "%d/" i;
+        to_url_rec buf rest
+    | String ->
+      fun s ->
+        Printf.bprintf buf "%s/" s;
+        to_url_rec buf rest
+    | String_urlencoded ->
+      fun s ->
+        Printf.bprintf buf "%s/" (Util.percent_encode s);
+        to_url_rec buf rest)
+
+let to_url (h : ('a, string) t) : 'a =
+  let buf = Buffer.create 16 in
+  to_url_rec buf h

src/core/route.mli

@@ -1,7 +1,7 @@
 (** Routing
 
-    Basic type-safe routing of handlers based on URL paths. This is optional,
-    it is possible to only define the root handler with something like
+    Basic type-safe routing of handlers based on URL paths. This is optional, it
+    is possible to only define the root handler with something like
     {{:https://github.com/anuragsoni/routes/} Routes}.
     @since 0.6 *)
 
@@ -27,18 +27,18 @@ val return : ('a, 'a) t
 (** Matches the empty path. *)
 
 val rest_of_path : (string -> 'a, 'a) t
-(** Matches a string, even containing ['/']. This will match
-      the entirety of the remaining route.
+(** Matches a string, even containing ['/']. This will match the entirety of the
+    remaining route.
     @since 0.7 *)
 
 val rest_of_path_urlencoded : (string -> 'a, 'a) t
-(** Matches a string, even containing ['/'], and URL-decode it (piecewise).
-      This will match the entirety of the remaining route.
+(** Matches a string, even containing ['/'], and URL-decode it (piecewise). This
+    will match the entirety of the remaining route.
     @since 0.7 *)
 
 val ( @/ ) : ('a, 'b) comp -> ('b, 'c) t -> ('a, 'c) t
-(** [comp / route] matches ["foo/bar/…"] iff [comp] matches ["foo"],
-      and [route] matches ["bar/…"]. *)
+(** [comp / route] matches ["foo/bar/…"] iff [comp] matches ["foo"], and [route]
+    matches ["bar/…"]. *)
 
 val exact_path : string -> ('a, 'b) t -> ('a, 'b) t
 (** [exact_path "foo/bar/..." r] is equivalent to
@@ -53,6 +53,10 @@ val to_string : _ t -> string
 (** Print the route.
     @since 0.7 *)
 
+val to_url : ('a, string) t -> 'a
+(** [to_url route args] takes a route, and turns it into a URL path.
+    @since NEXT_RELEASE *)
+
 module Private_ : sig
   val eval : string list -> ('a, 'b) t -> 'a -> 'b option
 end

src/core/server.ml

@@ -15,7 +15,6 @@ module Head_middleware = struct
   type t = { handle: 'a. 'a Request.t -> 'a Request.t }
 
   let trivial = { handle = Fun.id }
-  let[@inline] apply (self : t) req = self.handle req
   let[@inline] apply' req (self : t) = self.handle req
 
   let to_middleware (self : t) : Middleware.t =

src/html/gen/gentags.ml

@@ -1,7 +1,6 @@
 (* adapted from https://github.com/sindresorhus/html-tags (MIT licensed) *)
 
 let pf = Printf.printf
-let spf = Printf.sprintf
 
 let void =
   [

src/moonpool-io/dune

@@ -0,0 +1,6 @@
+
+
+(library
+ (name tiny_httpd_moonpool)
+ (public_name tiny_httpd_moonpool)
+ (libraries tiny_httpd moonpool moonpool.sync moonpool.fib moonpool-io))

src/moonpool-io/io_server.ml

@@ -0,0 +1,220 @@
+open Tiny_httpd_core
+module A = Atomic
+module MIO = Moonpool_io
+module Sem = Moonpool_sync.Semaphore.Counting
+module Fd = Moonpool_io.Fd
+
+module IO_helper = struct
+  module Slice = Iostream.Slice
+
+  module Output = struct
+    include IO.Output
+
+    class of_unix_fd ?(close_noerr = false) ~closed ~(buf : Slice.t) (fd : Fd.t) :
+      t =
+      object
+        inherit t_from_output ~bytes:buf.bytes ()
+
+        method private output_underlying bs i len0 =
+          let i = ref i in
+          let len = ref len0 in
+          while !len > 0 do
+            match MIO.Unix.write fd bs !i !len with
+            | 0 -> failwith "write failed"
+            | n ->
+              i := !i + n;
+              len := !len - n
+          done
+
+        method private close_underlying () =
+          if not !closed then (
+            closed := true;
+            if close_noerr then (
+              try MIO.Unix.close fd with _ -> ()
+            ) else
+              MIO.Unix.close fd
+          )
+      end
+  end
+
+  module Input = struct
+    include IO.Input
+
+    let of_unix_fd ?(close_noerr = false) ~closed ~(buf : Slice.t) (fd : Fd.t) :
+        t =
+      let eof = ref false in
+      object
+        inherit Iostream.In_buf.t_from_refill ~bytes:buf.bytes ()
+
+        method private refill (slice : Slice.t) =
+          if not !eof then (
+            slice.off <- 0;
+            let continue = ref true in
+            while !continue do
+              match
+                MIO.Unix.read fd slice.bytes 0 (Bytes.length slice.bytes)
+              with
+              | n ->
+                slice.len <- n;
+                continue := false
+            done;
+            (* Printf.eprintf "read returned %d B\n%!" !n; *)
+            if slice.len = 0 then eof := true
+          )
+
+        method close () =
+          if not !closed then (
+            closed := true;
+            eof := true;
+            if close_noerr then (
+              try MIO.Unix.close fd with _ -> ()
+            ) else
+              MIO.Unix.close fd
+          )
+      end
+  end
+end
+
+open struct
+  let get_addr_ (fd : Fd.t) =
+    match Unix.getsockname (Fd.unsafe_get fd) with
+    | Unix.ADDR_INET (addr, port) -> addr, port
+    | _ -> invalid_arg "httpd: address is not INET"
+
+  let shutdown_silent_ (fd : Fd.t) : unit =
+    try MIO.Unix.shutdown fd Unix.SHUTDOWN_ALL with _ -> ()
+
+  let close_silent_ (fd : Fd.t) : unit = try MIO.Unix.close fd with _ -> ()
+end
+
+type t = {
+  addr: string;
+  port: int;
+  buf_pool: Buf.t Pool.t;
+  slice_pool: IO.Slice.t Pool.t;
+  max_connections: int;
+  sem_max_connections: Sem.t;
+      (** semaphore to restrict the number of active concurrent connections *)
+  mutable sock: Fd.t option;  (** Socket *)
+  new_thread: (unit -> unit) -> unit;
+  timeout: float;
+  running: bool A.t; (* TODO: use an atomic? *)
+}
+
+let to_tcp_server (self : t) : IO.TCP_server.builder =
+  {
+    IO.TCP_server.serve =
+      (fun ~after_init ~handle () : unit ->
+        let sock, should_bind =
+          match self.sock with
+          | Some s ->
+            (* Because we're getting a socket from the caller (e.g. systemd) *)
+            s, false
+          | None ->
+            let sock =
+              Unix.socket
+                (if Util.is_ipv6_str self.addr then
+                  Unix.PF_INET6
+                else
+                  Unix.PF_INET)
+                Unix.SOCK_STREAM 0
+            in
+            let fd = Fd.create sock in
+            fd, true (* Because we're creating the socket ourselves *)
+        in
+        MIO.Unix.set_nonblock sock;
+        MIO.Unix.setsockopt_optint sock Unix.SO_LINGER None;
+        if should_bind then (
+          let inet_addr = Unix.inet_addr_of_string self.addr in
+          MIO.Unix.setsockopt sock Unix.SO_REUSEADDR true;
+          MIO.Unix.bind sock (Unix.ADDR_INET (inet_addr, self.port));
+          let n_listen = 2 * self.max_connections in
+          MIO.Unix.listen sock n_listen
+        );
+
+        self.sock <- Some sock;
+
+        let tcp_server =
+          {
+            IO.TCP_server.stop = (fun () -> Atomic.set self.running false);
+            running = (fun () -> Atomic.get self.running);
+            active_connections =
+              (fun () ->
+                self.max_connections - Sem.get_value self.sem_max_connections);
+            endpoint =
+              (fun () ->
+                let addr, port = get_addr_ sock in
+                Unix.string_of_inet_addr addr, port);
+          }
+        in
+        after_init tcp_server;
+
+        (* how to handle a single client *)
+        let handle_client_ (client_sock : Fd.t) (client_addr : Unix.sockaddr) :
+            unit =
+          Log.debug (fun k ->
+              k "t[%d]: serving new client on %s"
+                (Thread.id @@ Thread.self ())
+                (Util.show_sockaddr client_addr));
+
+          MIO.Unix.set_nonblock client_sock;
+          MIO.Unix.setsockopt client_sock Unix.TCP_NODELAY true;
+          MIO.Unix.(setsockopt_float client_sock SO_RCVTIMEO self.timeout);
+          MIO.Unix.(setsockopt_float client_sock SO_SNDTIMEO self.timeout);
+
+          Pool.with_resource self.slice_pool @@ fun ic_buf ->
+          Pool.with_resource self.slice_pool @@ fun oc_buf ->
+          let closed = ref false in
+
+          let oc =
+            new IO_helper.Output.of_unix_fd
+              ~close_noerr:true ~closed ~buf:oc_buf client_sock
+          in
+          let ic =
+            IO_helper.Input.of_unix_fd ~close_noerr:true ~closed ~buf:ic_buf
+              client_sock
+          in
+          handle.handle ~client_addr ic oc
+        in
+
+        MIO.Unix.set_nonblock sock;
+        while Atomic.get self.running do
+          match MIO.Unix.accept sock with
+          | client_sock, client_addr ->
+            (* limit concurrency *)
+            Sem.acquire self.sem_max_connections;
+            self.new_thread (fun () ->
+                try
+                  handle_client_ client_sock client_addr;
+                  Log.debug (fun k ->
+                      k "t[%d]: done with client on %s, exiting"
+                        (Thread.id @@ Thread.self ())
+                      @@ Util.show_sockaddr client_addr);
+                  shutdown_silent_ client_sock;
+                  close_silent_ client_sock;
+                  Sem.release self.sem_max_connections
+                with e ->
+                  let bt = Printexc.get_raw_backtrace () in
+                  shutdown_silent_ client_sock;
+                  close_silent_ client_sock;
+                  Sem.release self.sem_max_connections;
+                  Log.error (fun k ->
+                      k
+                        "@[<v>Handler: uncaught exception for client %s:@ %s@ \
+                         %s@]"
+                        (Util.show_sockaddr client_addr)
+                        (Printexc.to_string e)
+                        (Printexc.raw_backtrace_to_string bt)))
+          | exception e ->
+            Log.error (fun k ->
+                k "Unix.accept raised an exception: %s" (Printexc.to_string e));
+            Atomic.set self.running false
+        done;
+
+        (* Wait for all threads to be done: this only works if all threads are done. *)
+        MIO.Unix.close sock;
+        while Sem.get_value self.sem_max_connections < self.max_connections do
+          Sem.acquire self.sem_max_connections
+        done;
+        ());
+  }

src/moonpool-io/tiny_httpd_moonpool.ml

@@ -0,0 +1,52 @@
+include Tiny_httpd
+module Fd = Io_server.Fd
+
+open struct
+  let get_max_connection_ ?(max_connections = 64) () : int =
+    let max_connections = max 4 max_connections in
+    max_connections
+
+  let clear_slice (slice : IO.Slice.t) =
+    Bytes.fill slice.bytes 0 (Bytes.length slice.bytes) '\x00';
+    slice.off <- 0;
+    slice.len <- 0
+end
+
+let create ?max_connections ?(timeout = 0.0) ?buf_size
+    ?(get_time_s = Unix.gettimeofday) ?(addr = "127.0.0.1") ?(port = 8080)
+    ?(sock : Fd.t option) ?middlewares ~(runner : Moonpool.Runner.t) () : t =
+  let new_thread f =
+    ignore (Moonpool_fib.spawn_top ~on:runner f : _ Moonpool_fib.t)
+  in
+  let max_connections = get_max_connection_ ?max_connections () in
+  let server =
+    {
+      Io_server.addr;
+      new_thread;
+      buf_pool =
+        Pool.create ~clear:Buf.clear_and_zero
+          ~mk_item:(fun () -> Buf.create ?size:buf_size ())
+          ();
+      slice_pool =
+        Pool.create ~clear:clear_slice
+          ~mk_item:
+            (let buf_size = Option.value buf_size ~default:4096 in
+             fun () -> IO.Slice.create buf_size)
+          ();
+      running = Atomic.make true;
+      port;
+      sock;
+      max_connections;
+      sem_max_connections = Io_server.Sem.make max_connections;
+      timeout;
+    }
+  in
+  let tcp_server_builder = Io_server.to_tcp_server server in
+  let module B = struct
+    let init_addr () = addr
+    let init_port () = port
+    let get_time_s = get_time_s
+    let tcp_server () = tcp_server_builder
+  end in
+  let backend = (module B : IO_BACKEND) in
+  Server.create_from ?buf_size ?middlewares ~backend ()

src/ws/tiny_httpd_ws.ml

@@ -1,5 +1,26 @@
 open Common_ws_
 
+module With_lock = struct
+  type t = { with_lock: 'a. (unit -> 'a) -> 'a }
+  type builder = unit -> t
+
+  let default_builder : builder =
+   fun () ->
+    let mutex = Mutex.create () in
+    {
+      with_lock =
+        (fun f ->
+          Mutex.lock mutex;
+          try
+            let x = f () in
+            Mutex.unlock mutex;
+            x
+          with e ->
+            Mutex.unlock mutex;
+            raise e);
+    }
+end
+
 type handler = unit Request.t -> IO.Input.t -> IO.Output.t -> unit
 
 module Frame_type = struct
@@ -52,10 +73,10 @@ module Writer = struct
     mutable offset: int;  (** number of bytes already in [buf] *)
     oc: IO.Output.t;
     mutable closed: bool;
-    mutex: Mutex.t;
+    mutex: With_lock.t;
   }
 
-  let create ?(buf_size = 16 * 1024) ~oc () : t =
+  let create ?(buf_size = 16 * 1024) ~with_lock ~oc () : t =
     {
       header = Header.create ();
       header_buf = Bytes.create 16;
@@ -63,19 +84,9 @@ module Writer = struct
       offset = 0;
       oc;
       closed = false;
-      mutex = Mutex.create ();
+      mutex = with_lock;
     }
 
-  let[@inline] with_mutex_ (self : t) f =
-    Mutex.lock self.mutex;
-    try
-      let x = f () in
-      Mutex.unlock self.mutex;
-      x
-    with e ->
-      Mutex.unlock self.mutex;
-      raise e
-
   let[@inline] close self = self.closed <- true
   let int_of_bool : bool -> int = Obj.magic
 
@@ -142,7 +153,7 @@ module Writer = struct
     if self.offset = Bytes.length self.buf then really_output_buf_ self
 
   let send_pong (self : t) : unit =
-    let@ () = with_mutex_ self in
+    let@ () = self.mutex.with_lock in
     self.header.fin <- true;
     self.header.ty <- Frame_type.pong;
     self.header.payload_len <- 0;
@@ -151,7 +162,7 @@ module Writer = struct
     write_header_ self
 
   let output_char (self : t) c : unit =
-    let@ () = with_mutex_ self in
+    let@ () = self.mutex.with_lock in
     let cap = Bytes.length self.buf - self.offset in
     (* make room for [c] *)
     if cap = 0 then really_output_buf_ self;
@@ -161,7 +172,7 @@ module Writer = struct
     if cap = 1 then really_output_buf_ self
 
   let output (self : t) buf i len : unit =
-    let@ () = with_mutex_ self in
+    let@ () = self.mutex.with_lock in
     let i = ref i in
     let len = ref len in
     while !len > 0 do
@@ -179,7 +190,7 @@ module Writer = struct
     flush_if_full self
 
   let flush self : unit =
-    let@ () = with_mutex_ self in
+    let@ () = self.mutex.with_lock in
     flush_ self
 end
 
@@ -187,8 +198,8 @@ module Reader = struct
   type state =
     | Begin  (** At the beginning of a frame *)
     | Reading_frame of { mutable remaining_bytes: int; mutable num_read: int }
-        (** Currently reading the payload of a frame with [remaining_bytes]
-        left to read from the underlying [ic] *)
+        (** Currently reading the payload of a frame with [remaining_bytes] left
+            to read from the underlying [ic] *)
     | Close
 
   type t = {
@@ -390,8 +401,8 @@ module Reader = struct
     )
 end
 
-let upgrade ic oc : _ * _ =
-  let writer = Writer.create ~oc () in
+let upgrade ?(with_lock = With_lock.default_builder ()) ic oc : _ * _ =
+  let writer = Writer.create ~with_lock ~oc () in
   let reader = Reader.create ~ic ~writer () in
   let ws_ic : IO.Input.t =
     object
@@ -414,9 +425,11 @@ let upgrade ic oc : _ * _ =
   in
   ws_ic, ws_oc
 
-(** Turn a regular connection handler (provided by the user) into a websocket upgrade handler *)
+(** Turn a regular connection handler (provided by the user) into a websocket
+    upgrade handler *)
 module Make_upgrade_handler (X : sig
   val accept_ws_protocol : string -> bool
+  val with_lock : With_lock.builder
   val handler : handler
 end) : Server.UPGRADE_HANDLER with type handshake_state = unit Request.t =
 struct
@@ -461,7 +474,8 @@ struct
     try Ok (handshake_ req) with Bad_req s -> Error s
 
   let handle_connection req ic oc =
-    let ws_ic, ws_oc = upgrade ic oc in
+    let with_lock = X.with_lock () in
+    let ws_ic, ws_oc = upgrade ~with_lock ic oc in
     try X.handler req ws_ic ws_oc
     with Close_connection ->
       Log.debug (fun k -> k "websocket: requested to close the connection");
@@ -469,9 +483,11 @@ struct
 end
 
 let add_route_handler ?accept ?(accept_ws_protocol = fun _ -> true) ?middlewares
-    (server : Server.t) route (f : handler) : unit =
+    ?(with_lock = With_lock.default_builder) (server : Server.t) route
+    (f : handler) : unit =
   let module M = Make_upgrade_handler (struct
     let handler = f
+    let with_lock = with_lock
     let accept_ws_protocol = accept_ws_protocol
   end) in
   let up : Server.upgrade_handler = (module M) in

src/ws/tiny_httpd_ws.mli

@@ -1,30 +1,60 @@
 (** Websockets for Tiny_httpd.
 
-    This sub-library ([tiny_httpd.ws]) exports a small implementation
-    for a websocket server. It has no additional dependencies.
-    *)
+    This sub-library ([tiny_httpd.ws]) exports a small implementation for a
+    websocket server. It has no additional dependencies. *)
+
+(** Synchronization primitive used to allow both the reader to reply to "ping",
+    and the handler to send messages, without stepping on each other's toes.
+
+    @since NEXT_RELEASE *)
+module With_lock : sig
+  type t = { with_lock: 'a. (unit -> 'a) -> 'a }
+  (** A primitive to run the callback in a critical section where others cannot
+      run at the same time.
+
+      The default is a mutex, but that works poorly with thread pools so it's
+      possible to use a semaphore or a cooperative mutex instead. *)
+
+  type builder = unit -> t
+
+  val default_builder : builder
+  (** Lock using [Mutex]. *)
+end
 
 type handler = unit Request.t -> IO.Input.t -> IO.Output.t -> unit
 (** Websocket handler *)
 
-val upgrade : IO.Input.t -> IO.Output.t -> IO.Input.t * IO.Output.t
-(** Upgrade a byte stream to the websocket framing protocol. *)
+val upgrade :
+  ?with_lock:With_lock.t ->
+  IO.Input.t ->
+  IO.Output.t ->
+  IO.Input.t * IO.Output.t
+(** Upgrade a byte stream to the websocket framing protocol.
+    @param with_lock
+      if provided, use this to prevent reader and writer to compete on sending
+      frames. since NEXT_RELEASE. *)
 
 exception Close_connection
-(** Exception that can be raised from IOs inside the handler,
-    when the connection is closed from underneath. *)
+(** Exception that can be raised from IOs inside the handler, when the
+    connection is closed from underneath. *)
 
 val add_route_handler :
   ?accept:(unit Request.t -> (unit, int * string) result) ->
   ?accept_ws_protocol:(string -> bool) ->
   ?middlewares:Server.Head_middleware.t list ->
+  ?with_lock:With_lock.builder ->
   Server.t ->
   (Server.upgrade_handler, Server.upgrade_handler) Route.t ->
   handler ->
   unit
 (** Add a route handler for a websocket endpoint.
-    @param accept_ws_protocol decides whether this endpoint accepts the websocket protocol
-    sent by the client. Default accepts everything. *)
+    @param accept_ws_protocol
+      decides whether this endpoint accepts the websocket protocol sent by the
+      client. Default accepts everything.
+    @param with_lock
+      if provided, use this to synchronize writes between the frame reader
+      (replies "pong" to "ping") and the handler emitting writes. since
+      NEXT_RELEASE. *)
 
 (**/**)
 

src/ws/tiny_httpd_ws_stubs.c

@@ -8,7 +8,7 @@ CAMLprim value tiny_httpd_ws_apply_masking(value _mask_key, value _mask_offset,
   CAMLparam5(_mask_key, _mask_offset, _buf, _offset, _len);
 
   char const *mask_key = String_val(_mask_key);
-  char *buf = Bytes_val(_buf);
+  unsigned char *buf = Bytes_val(_buf);
   intnat mask_offset = Int_val(_mask_offset);
   intnat offset = Int_val(_offset);
   intnat len = Int_val(_len);

tests/dune

@@ -19,6 +19,27 @@
  (action
   (diff echo1.expect echo1.out)))
 
+(rule
+ (targets echo_mio1.out)
+ (deps
+  (:bin ../examples/echo_mio.exe))
+ (locks /port)
+ (enabled_if
+  (= %{system} "linux"))
+ (package tiny_httpd_moonpool)
+ (action
+  (with-stdout-to
+   %{targets}
+   (run ./echo_mio1.sh %{bin}))))
+
+(rule
+ (alias runtest)
+ (package tiny_httpd_moonpool)
+ (enabled_if
+  (= %{system} "linux"))
+ (action
+  (diff echo_mio1.expect echo_mio1.out)))
+
 (rule
  (targets sse_count.out)
  (deps

tests/echo_mio1.expect

@@ -0,0 +1,10 @@
+listening on http://127.0.0.1:8085
+test moonpool_io
+echo:
+{meth=GET; host=localhost:8085;
+ headers=[user-agent: test
+          accept: */*
+          host: localhost:8085];
+ path="/echo/?a=b&c=d"; body=""; path_components=["echo"];
+ query=["c","d";"a","b"]}
+(query: "c" = "d";"a" = "b")

tests/echo_mio1.sh

@@ -0,0 +1,12 @@
+#!/usr/bin/env sh
+
+ECHO=$1
+PORT=8085
+
+"$ECHO" -p $PORT &
+PID=$!
+sleep 0.1
+echo "test moonpool_io"
+curl -N "http://localhost:${PORT}/echo/?a=b&c=d" -H user-agent:test --max-time 5
+
+kill $PID

tiny_httpd_moonpool.opam

@@ -0,0 +1,35 @@
+# This file is generated by dune, edit dune-project instead
+opam-version: "2.0"
+version: "0.17"
+synopsis: "Moonpool+picos_stdio backend for Tiny_httpd"
+maintainer: ["c-cube"]
+authors: ["c-cube"]
+license: "MIT"
+homepage: "https://github.com/c-cube/tiny_httpd/"
+bug-reports: "https://github.com/c-cube/tiny_httpd/issues"
+depends: [
+  "dune" {>= "2.9"}
+  "seq"
+  "tiny_httpd" {= version}
+  "moonpool" {>= "0.7"}
+  "moonpool-io" {>= "0.7"}
+  "ocaml" {>= "5.0"}
+  "odoc" {with-doc}
+]
+build: [
+  ["dune" "subst"] {dev}
+  [
+    "dune"
+    "build"
+    "-p"
+    name
+    "-j"
+    jobs
+    "--promote-install-files=false"
+    "@install"
+    "@runtest" {with-test}
+    "@doc" {with-doc}
+  ]
+  ["dune" "install" "-p" name "--create-install-files" name]
+]
+dev-repo: "git+https://github.com/c-cube/tiny_httpd.git"