builder-web/http_status_middleware/http_status_metrics.ml

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2021-06-08 12:36:53 +00:00
open Lwt.Infix
let create ~f =
let data : (string, int) Hashtbl.t = Hashtbl.create 7 in
(fun x ->
let key = f x in
let cur = match Hashtbl.find_opt data key with
| None -> 0
| Some x -> x
in
Hashtbl.replace data key (succ cur)),
(fun () ->
let data, total =
Hashtbl.fold (fun key value (acc, total) ->
(Metrics.uint key value :: acc), value + total)
data ([], 0)
in
Metrics.uint "total" total :: data)
let counter_metrics ~f name =
let open Metrics in
let doc = "Counter metrics" in
let incr, get = create ~f in
let data thing = incr thing; Data.v (get ()) in
Src.v ~doc ~tags:Metrics.Tags.[] ~data name
let add_http_status =
let f = function
| #Dream.informational -> "1xx"
| #Dream.successful -> "2xx"
| #Dream.redirection -> "3xx"
| #Dream.client_error -> "4xx"
| #Dream.server_error -> "5xx"
| `Status c -> Printf.sprintf "%dxx" (c / 100)
in
let src = counter_metrics ~f "http_response" in
(fun r -> Metrics.add src (fun x -> x) (fun d -> d r))
let handle next_handler req =
next_handler req >|= fun response ->
add_http_status (Dream.status response);
response