perf: raise default max frame size to 64 KiB

lib/config.ml

@@ -45,7 +45,7 @@ type t =
 let default =
   { (* This is effectively MAX_FRAME_SIZE, because the parser commits the frame
      * header to prevent backtracking, therefore the entire payload can fit the
-     * read buffer. The default is 16384, and can't be lower than that.
+     * read buffer. The default is 65536, and can't be lower than 16384.
      *
      * Note: h2 does not check that MAX_FRAME_SIZE is lower than 16384
      * octets. In the case that a lower value than permitted is set, peers will
@@ -57,7 +57,7 @@ let default =
      *   The initial value is 2^14 (16,384) octets. The value advertised by an
      *   endpoint MUST be between this initial value and the maximum allowed
      *   frame size (2^24-1 or 16,777,215 octets), inclusive. *)
-    read_buffer_size = Settings.default.max_frame_size
+    read_buffer_size = 0x10000
   ; (* Buffer size for request bodies *) request_body_buffer_size = 0x1000
   ; (* Buffer size for response bodies *) response_body_buffer_size = 0x1000
   ; enable_server_push = true

lib/h2.mli

@@ -665,7 +665,7 @@ module Config : sig
   type t =
     { read_buffer_size : int
       (** [read_buffer_size] specifies the size of the largest frame payload that
-        the sender is willing to receive, in octets. Defaults to [16384] *)
+        the sender is willing to receive, in octets. Defaults to [65536] *)
     ; request_body_buffer_size : int  (** Defaults to [4096] *)
     ; response_body_buffer_size : int  (** Defaults to [4096] *)
     ; enable_server_push : bool  (** Defaults to [true] *)

lib_test/test_h2_client.ml

@@ -1346,7 +1346,12 @@ module Client_connection_tests = struct
          frames)
 
   let test_fragmented_request_body_chunking () =
-    let t = create_and_handle_preface () in
+    let config =
+      { Config.default with
+        read_buffer_size = Settings.default.max_frame_size
+      }
+    in
+    let t = create_and_handle_preface ~config () in
     let request = Request.create ~scheme:"http" `POST "/" in
     let response_handler _response _response_body = () in
     let request_body =

lib_test/test_h2_server.ml

@@ -940,6 +940,7 @@ module Server_connection_tests = struct
         = { Settings.default with
             enable_push = false
           ; max_concurrent_streams = 2l
+          ; max_frame_size = Config.default.read_buffer_size
           });
       (match next_write_operation t with
       | `Write iovecs ->