eio: reimplement some buffering

src/eio/tiny_httpd_eio.ml

@@ -15,28 +15,68 @@ let get_max_connection_ ?(max_connections = 64) () : int =
   let max_connections = max 4 max_connections in
   max_connections
 
-let read_buf_size = 4 * 1024
-let write_buf_size = 8 * 1024
+let buf_size = 16 * 1024
 
 let ic_of_flow (flow : Eio.Net.stream_socket) : IO.In_channel.t =
-  let cstruct = Cstruct.create write_buf_size in
+  let cstruct = Cstruct.create buf_size in
+  let len_slice = ref 0 in
+  let offset = ref 0 in
+
   let input buf i len =
     if len = 0 then
       0
     else (
-      let n = flow#read_into (Cstruct.sub cstruct 0 (min len write_buf_size)) in
-      Cstruct.blit_to_bytes cstruct 0 buf i n;
-      n
+      let available = ref (!len_slice - !offset) in
+      if !available = 0 then (
+        let n = flow#read_into cstruct in
+        offset := 0;
+        len_slice := n;
+        available := n
+      );
+
+      let n = min !available len in
+      if n > 0 then (
+        Cstruct.blit_to_bytes cstruct !offset buf i n;
+        offset := !offset + n;
+        n
+      ) else
+        0
     )
   in
   let close () = flow#shutdown `Receive in
   { IO.In_channel.input; close }
 
-let oc_of_flow (flow : Eio.Net.stream_socket) : IO.Out_channel.t =
+(*
+
   let output buf i len =
-    if len > 0 then (
-      let i = ref i in
-      let len = ref len in
+    let i = ref i in
+    let len = ref len in
+
+    while !len > 0 do
+      let available = Cstruct.length cstruct - !offset in
+      let n = min !len available in
+      Cstruct.blit_from_bytes buf !i cstruct !offset n;
+      offset := !offset + n;
+      i := !i + n;
+      len := !len - n;
+
+      if !offset = Cstruct.length cstruct then (
+        flow#write [ cstruct ];
+        offset := 0
+      )
+    done
+  in
+  *)
+
+let oc_of_flow (flow : Eio.Net.stream_socket) : IO.Out_channel.t =
+  (* write buffer *)
+  let wbuf = Bytes.create buf_size in
+  let offset = ref 0 in
+
+  let flush () =
+    if !offset > 0 then (
+      let i = ref 0 in
+      let len = ref !offset in
 
       let src =
         object
@@ -45,18 +85,34 @@ let oc_of_flow (flow : Eio.Net.stream_socket) : IO.Out_channel.t =
           method read_into (cstruct : Cstruct.t) : int =
             if !len = 0 then raise End_of_file;
             let n = min !len (Cstruct.length cstruct) in
-            Cstruct.blit_from_bytes buf !i cstruct 0 n;
+            Cstruct.blit_from_bytes wbuf !i cstruct 0 n;
             i := !i + n;
             len := !len - n;
             n
         end
       in
 
-      flow#copy src
+      flow#copy src;
+      offset := 0
     )
   in
+
+  let output buf i len =
+    let i = ref i in
+    let len = ref len in
+
+    while !len > 0 do
+      let available = Bytes.length wbuf - !offset in
+      let n = min !len available in
+      Bytes.blit buf !i wbuf !offset n;
+      offset := !offset + n;
+      i := !i + n;
+      len := !len - n;
+
+      if !offset = Bytes.length wbuf then flush ()
+    done
+  in
   let close () = flow#shutdown `Send in
-  let flush () = () in
   { IO.Out_channel.close; flush; output }
 
 let io_backend ?(addr = "127.0.0.1") ?(port = 8080) ?max_connections
@@ -69,13 +125,11 @@ let io_backend ?(addr = "127.0.0.1") ?(port = 8080) ?max_connections
       let clock = Eio.Stdenv.clock stdenv in
       Eio.Time.now clock
 
-    let spawn f : unit =
-      Eio.Switch.run @@ fun sub_sw -> Eio.Fiber.fork ~sw:sub_sw f
-
     let tcp_server () : IO.TCP_server.builder =
       {
         IO.TCP_server.serve =
           (fun ~after_init ~handle () : unit ->
+            (* FIXME: parse *)
             let ip_addr = Eio.Net.Ipaddr.V4.any in
             let running = Atomic.make true in
             let active_conns = Atomic.make 0 in
@@ -105,8 +159,6 @@ let io_backend ?(addr = "127.0.0.1") ?(port = 8080) ?max_connections
             after_init tcp_server;
 
             while Atomic.get running do
-              Eio.Switch.check sw;
-
               Eio.Net.accept_fork ~sw
                 ~on_error:(fun exn ->
                   H._debug (fun k ->