From f349c313689c1e0d11fbfc1f5a4e53bc33cd8d37 Mon Sep 17 00:00:00 2001
From: Simon Cruanes <simon.cruanes.2007@m4x.org>
Date: Wed, 3 Dec 2025 13:28:25 -0500
Subject: [PATCH] update opentelemetry_trace just a bit

---
 src/trace/dune                    |  6 ++-
 src/trace/opentelemetry_trace.ml  |  1 +
 src/trace/opentelemetry_trace.mli | 61 ++++++++++++++++++++-----------
 3 files changed, 46 insertions(+), 22 deletions(-)

diff --git a/src/trace/dune b/src/trace/dune
index 9606e2a5..0c815c5d 100644
--- a/src/trace/dune
+++ b/src/trace/dune
@@ -3,4 +3,8 @@
  (public_name opentelemetry.trace)
  (synopsis "Use opentelemetry as a collector for trace")
  (optional)
- (libraries opentelemetry.ambient-context trace.core opentelemetry))
+ (libraries
+  opentelemetry.ambient-context
+  trace.core
+  trace.subscriber
+  opentelemetry))
diff --git a/src/trace/opentelemetry_trace.ml b/src/trace/opentelemetry_trace.ml
index ead41826..1d2f7f34 100644
--- a/src/trace/opentelemetry_trace.ml
+++ b/src/trace/opentelemetry_trace.ml
@@ -1,6 +1,7 @@
 module Otel = Opentelemetry
 module Otrace = Trace_core (* ocaml-trace *)
 module TLS = Thread_local_storage
+module TSub = Trace_subscriber.Subscriber
 
 open struct
   let spf = Printf.sprintf
diff --git a/src/trace/opentelemetry_trace.mli b/src/trace/opentelemetry_trace.mli
index 060f4f13..eb5591fa 100644
--- a/src/trace/opentelemetry_trace.mli
+++ b/src/trace/opentelemetry_trace.mli
@@ -1,21 +1,3 @@
-module Otel := Opentelemetry
-module Otrace := Trace_core
-module TLS := Thread_local_storage
-
-module Conv : sig
-  val trace_id_of_otel : Otel.Trace_id.t -> string
-
-  val trace_id_to_otel : string -> Otel.Trace_id.t
-
-  val span_id_of_otel : Otel.Span_id.t -> int64
-
-  val span_id_to_otel : int64 -> Otel.Span_id.t
-
-  val ctx_to_otel : Otrace.explicit_span_ctx -> Otel.Span_ctx.t
-
-  val ctx_of_otel : Otel.Span_ctx.t -> Otrace.explicit_span_ctx
-end
-
 (** [opentelemetry.trace] implements a {!Trace_core.Collector} for
     {{:https://v3.ocaml.org/p/trace} ocaml-trace}.
 
@@ -43,21 +25,58 @@ end
       {!Internal.spankind_of_string} for the list of supported values.)
 
     {[
-      ocaml
       let describe () = [ Opentelemetry_trace.(spankind_key, client) ] in
       Trace_core.with_span ~__FILE__ ~__LINE__ ~data:describe "my-span"
       @@ fun _ ->
         (* ... *)
     ]} *)
 
+module Otel := Opentelemetry
+module Otrace := Trace_core
+module TLS := Thread_local_storage
+
+(** Conversions between [Opentelemetry] and [Trace_core] types *)
+module Conv : sig
+  val trace_id_of_otel : Otel.Trace_id.t -> string
+
+  val trace_id_to_otel : string -> Otel.Trace_id.t
+
+  val span_id_of_otel : Otel.Span_id.t -> int64
+
+  val span_id_to_otel : int64 -> Otel.Span_id.t
+
+  val ctx_to_otel : Otrace.explicit_span_ctx -> Otel.Span_ctx.t
+
+  val ctx_of_otel : Otel.Span_ctx.t -> Otrace.explicit_span_ctx
+end
+
+(** The extension events for {!Trace_core}. *)
+module Extensions : sig
+  type Otrace.extension_event +=
+    | Ev_link_span of Otrace.explicit_span * Otrace.explicit_span_ctx
+          (** Link the given span to the given context. The context isn't the
+              parent, but the link can be used to correlate both spans. *)
+    | Ev_record_exn of {
+        sp: Otrace.span;
+        exn: exn;
+        bt: Printexc.raw_backtrace;
+        error: bool;  (** Is this an actual internal error? *)
+      }
+          (** Record exception and potentially turn span to an error *)
+    | Ev_set_span_kind of Otrace.span * Otel.Span_kind.t
+end
+
 val on_internal_error : (string -> unit) ref
 (** Callback to print errors in the library itself (ie bugs) *)
 
 val setup : unit -> unit
 (** Install the OTEL backend as a Trace collector *)
 
-val setup_with_otel_backend : Opentelemetry.Collector.backend -> unit
-(** Same as {!setup}, but also install the given backend as OTEL backend *)
+val setup_with_otel_exporter : #Opentelemetry.Exporter.t -> unit
+(** Same as {!setup}, but using the given exporter *)
+
+val setup_with_otel_backend : #Opentelemetry.Exporter.t -> unit
+[@@deprecated "use setup_with_otel_exporter"]
 
 val collector : unit -> Trace_core.collector
 (** Make a Trace collector that uses the OTEL backend to send spans and logs *)