add after_shutdown to ocurl-lwt client

src/client-ocurl-lwt/opentelemetry_client_ocurl_lwt.ml

@@ -90,12 +90,13 @@ let create_exporter ?(config = Config.make ()) () =
 
 let create_backend = create_exporter
 
-let setup_ ?config () : unit =
+let setup_ ?config () : Exporter.t =
   let exp = create_backend ?config () in
   Main_exporter.set exp;
-  ()
+  exp
 
-let setup ?config ?(enable = true) () = if enable then setup_ ?config ()
+let setup ?config ?(enable = true) () =
+  if enable then ignore (setup_ ?config () : Exporter.t)
 
 let remove_exporter () : unit Lwt.t =
   let done_fut, done_u = Lwt.wait () in
@@ -104,18 +105,21 @@ let remove_exporter () : unit Lwt.t =
 
 let remove_backend = remove_exporter
 
-let with_setup ?(config = Config.make ()) ?(enable = true) () f : _ Lwt.t =
+let with_setup ?(after_shutdown = ignore) ?(config = Config.make ())
-  if enable then (
+    ?(enable = true) () f : _ Lwt.t =
+  if enable then
     let open Lwt.Syntax in
-    setup_ ~config ();
+    let exp = setup_ ~config () in
 
     Lwt.catch
       (fun () ->
         let* res = f () in
         let+ () = remove_backend () in
+        after_shutdown exp;
         res)
       (fun exn ->
         let* () = remove_backend () in
+        after_shutdown exp;
         Lwt.reraise exn)
-  ) else
+  else
     f ()

src/client-ocurl-lwt/opentelemetry_client_ocurl_lwt.mli

@@ -32,6 +32,11 @@ val remove_backend : unit -> unit Lwt.t
     @since NEXT_RELEASE *)
 
 val with_setup :
-  ?config:Config.t -> ?enable:bool -> unit -> (unit -> 'a Lwt.t) -> 'a Lwt.t
+  ?after_shutdown:(Opentelemetry.Exporter.t -> unit) ->
+  ?config:Config.t ->
+  ?enable:bool ->
+  unit ->
+  (unit -> 'a Lwt.t) ->
+  'a Lwt.t
 (** [with_setup () f] is like [setup(); f()] but takes care of cleaning up after
     [f()] returns See {!setup} for more details. *)

tests/bin/emit1_ocurl_lwt.ml

@@ -170,8 +170,18 @@ let () =
     Printf.printf "\ndone. %d spans in %.4fs (%.4f/s)\n%!" (Atomic.get num_tr)
       elapsed n_per_sec
   in
+  let after_exp_shutdown exp =
+    (* print some stats *)
+    if !final_stats then (
+      let ms = OT.Exporter.self_metrics exp in
+      Format.eprintf "@[exporter metrics:@ %a@]@."
+        (Format.pp_print_list Opentelemetry.Metrics.pp)
+        ms
+    )
+  in
 
   Lwt_main.run
   @@
   let@ () = Fun.protect ~finally in
   Opentelemetry_client_ocurl_lwt.with_setup ~config () run
+    ~after_shutdown:after_exp_shutdown