From 35f8bbc67d82ee199ac0662db6819a476bd62d87 Mon Sep 17 00:00:00 2001
From: Simon Cruanes <simon.cruanes.2007@m4x.org>
Date: Thu, 4 Dec 2025 14:16:08 -0500
Subject: [PATCH] feat exporter: split tick/on_tick again

---
 src/core/exporter.ml | 79 +++++++-------------------------------------
 src/core/span.mli    |  6 +++-
 2 files changed, 17 insertions(+), 68 deletions(-)

diff --git a/src/core/exporter.ml b/src/core/exporter.ml
index c077cfe7..8bd96b7f 100644
--- a/src/core/exporter.ml
+++ b/src/core/exporter.ml
@@ -9,17 +9,14 @@
 open Common_
 open Opentelemetry_emitter
 
-open struct
-  module Proto = Opentelemetry_proto
-end
-
 type t = {
   emit_spans: Proto.Trace.span Emitter.t;
   emit_metrics: Proto.Metrics.metric Emitter.t;
   emit_logs: Proto.Logs.log_record Emitter.t;
-  on_tick: Cb_set.t;
-      (** Set of callbacks for "on tick". Should be triggered regularly for
-          background processing, timeout checks, etc. *)
+  on_tick: (unit -> unit) -> unit;
+  tick: unit -> unit;
+      (** Call all the callbacks registered with [on_tick]. Should be triggered
+          regularly for background processing, timeout checks, etc. *)
   cleanup: on_done:(unit -> unit) -> unit -> unit;
       (** [cleanup ~on_done ()] is called when the exporter is shut down, and is
         responsible for sending remaining batches, flushing sockets, etc.
@@ -30,12 +27,13 @@ type t = {
 
 (** Dummy exporter, does nothing *)
 let dummy () : t =
-  let on_tick = Cb_set.create () in
+  let ticker = Cb_set.create () in
   {
     emit_spans = Emitter.dummy ();
     emit_metrics = Emitter.dummy ();
     emit_logs = Emitter.dummy ();
-    on_tick;
+    on_tick = Cb_set.register ticker;
+    tick = (fun () -> Cb_set.trigger ticker);
     cleanup = (fun ~on_done () -> on_done ());
   }
 
@@ -48,72 +46,19 @@ let[@inline] send_metrics (self : t) (l : Proto.Metrics.metric list) =
 let[@inline] send_logs (self : t) (l : Proto.Logs.log_record list) =
   Emitter.emit self.emit_logs l
 
-let on_tick (self : t) f = Cb_set.register self.on_tick f
+let[@inline] on_tick (self : t) f = self.on_tick f
 
 (** Do background work. Call this regularly if the collector doesn't already
     have a ticker thread or internal timer. *)
 let tick (self : t) =
-  Cb_set.trigger self.on_tick;
-  (* also tick each emitter! *)
+  (* make sure emitters get the chance to check timeouts, flush, etc. *)
   let now = Mtime_clock.now () in
   Emitter.tick ~now self.emit_spans;
   Emitter.tick ~now self.emit_metrics;
   Emitter.tick ~now self.emit_logs;
+
+  (* call the callbacks *)
+  self.tick ();
   ()
 
 let[@inline] cleanup (self : t) ~on_done : unit = self.cleanup ~on_done ()
-
-(** Main exporter, used by the main tracing functions.
-
-    It is better to pass an explicit exporter when possible. *)
-module Main_exporter = struct
-  (* hidden *)
-  open struct
-    (* a list of callbacks automatically added to the main exporter *)
-    let on_tick_cbs_ = Alist.make ()
-
-    let exporter : t option Atomic.t = Atomic.make None
-  end
-
-  (** Set the global exporter *)
-  let set (exp : t) : unit =
-    List.iter (on_tick exp) (Alist.get on_tick_cbs_);
-    Atomic.set exporter (Some exp)
-
-  (** Remove current exporter, if any.
-      @param on_done see {!t#cleanup}, @since 0.12 *)
-  let remove ~on_done () : unit =
-    match Atomic.exchange exporter None with
-    | None -> ()
-    | Some exp ->
-      tick exp;
-      cleanup exp ~on_done
-
-  (** Is there a configured exporter? *)
-  let present () : bool = Option.is_some (Atomic.get exporter)
-
-  (** Current exporter, if any *)
-  let[@inline] get () : t option = Atomic.get exporter
-
-  let add_on_tick_callback f =
-    Alist.add on_tick_cbs_ f;
-    Option.iter (fun exp -> on_tick exp f) (get ())
-end
-
-let (set_backend [@deprecated "use `Main_exporter.set`"]) = Main_exporter.set
-
-let (remove_backend [@deprecated "use `Main_exporter.remove`"]) =
-  Main_exporter.remove
-
-let (has_backend [@deprecated "use `Main_exporter.present`"]) =
-  Main_exporter.present
-
-let (get_backend [@deprecated "use `Main_exporter.ge"]) = Main_exporter.get
-
-let with_setup_debug_backend ?(on_done = ignore) (exp : t) ?(enable = true) () f
-    =
-  if enable then (
-    Main_exporter.set exp;
-    Fun.protect ~finally:(fun () -> cleanup exp ~on_done) f
-  ) else
-    f ()
diff --git a/src/core/span.mli b/src/core/span.mli
index 34a4e858..d4722edc 100644
--- a/src/core/span.mli
+++ b/src/core/span.mli
@@ -47,6 +47,8 @@ val id : t -> Span_id.t
 
 val trace_id : t -> Trace_id.t
 
+val is_not_dummy : t -> bool
+
 val create_new :
   ?kind:kind ->
   ?id:Span_id.t ->
@@ -96,7 +98,9 @@ val add_links' : t -> (unit -> Span_link.t list) -> unit
     Note that this takes a function that produces links, and will only call it
     if there is an instrumentation backend. *)
 
-val add_attrs : t -> (unit -> Key_value.t list) -> unit
+val add_attrs : t -> Key_value.t list -> unit
+
+val add_attrs' : t -> (unit -> Key_value.t list) -> unit
 
 val set_status : t -> Span_status.t -> unit
 (** set the span status.