add Any_signal_l; modify Exporter to use Aswitch

src/core/any_signal_l.ml

@@ -0,0 +1,20 @@
+(** Any kind of lists of signals *)
+
+open Common_
+
+type t =
+  | Spans of Span.t list
+  | Metrics of Metrics.t list
+  | Logs of Log_record.t list
+
+open struct
+  let pp_sep out () = Format.fprintf out ";@ "
+
+  let pp_list ppx out l =
+    Format.fprintf out "[@[%a@]]" (Format.pp_print_list ~pp_sep ppx) l
+end
+
+let pp out = function
+  | Spans s -> pp_list Proto.Trace.pp_span out s
+  | Metrics m -> pp_list Proto.Metrics.pp_metric out m
+  | Logs l -> pp_list Proto.Logs.pp_log_record out l

src/core/exporter.ml

@@ -10,6 +10,8 @@ open Common_
 open Opentelemetry_emitter
 
 type t = {
+  active: unit -> Aswitch.t;
+      (** Is the exporer currently active? After shutdown this is turned off. *)
   emit_spans: Proto.Trace.span Emitter.t;
   emit_metrics: Proto.Metrics.metric Emitter.t;
   emit_logs: Proto.Logs.log_record Emitter.t;
@@ -17,24 +19,26 @@ type t = {
   tick: unit -> unit;
       (** Call all the callbacks registered with [on_tick]. Should be triggered
           regularly for background processing, timeout checks, etc. *)
-  shutdown: on_done:(unit -> unit) -> unit -> unit;
-      (** [shutdown ~on_done ()] is called when the exporter is shut down, and is
-        responsible for sending remaining batches, flushing sockets, etc.
-        @param on_done
-          callback invoked after the shutdown is done. @since 0.12 *)
+  shutdown: unit -> unit;
+      (** [shutdown ()] is called when the exporter is shut down, and is
+          responsible for sending remaining batches, flushing sockets, etc. To
+          know when shutdown is complete, register callbacks on [active].
+          @since 0.12 *)
 }
 (** Main exporter interface. *)
 
 (** Dummy exporter, does nothing *)
 let dummy () : t =
   let ticker = Cb_set.create () in
+  let active, trigger = Aswitch.create () in
   {
+    active = (fun () -> active);
     emit_spans = Emitter.dummy;
     emit_metrics = Emitter.dummy;
     emit_logs = Emitter.dummy;
     on_tick = Cb_set.register ticker;
     tick = (fun () -> Cb_set.trigger ticker);
-    shutdown = (fun ~on_done () -> on_done ());
+    shutdown = (fun () -> Aswitch.turn_off trigger);
   }
 
 let[@inline] send_trace (self : t) (l : Proto.Trace.span list) =
@@ -61,6 +65,11 @@ let tick (self : t) =
   self.tick ();
   ()
 
-let[@inline] shutdown (self : t) ~on_done : unit = self.shutdown ~on_done ()
+let[@inline] active self : Aswitch.t = self.active ()
+
+(** [on_stop e f] calls [f()] when [e] stops, or now if it's already stopped *)
+let on_stop self f = Aswitch.on_turn_off (self.active ()) f
+
+let[@inline] shutdown (self : t) : unit = self.shutdown ()
 
 let (cleanup [@deprecated "use shutdown instead"]) = shutdown