feat client: add Exporter_add_batching

src/client/client_config.mli

@@ -19,8 +19,8 @@ type t = private {
       (** Batch metrics? If [Some i], then this produces batches of (at most)
           [i] items. If [None], there is no batching.
 
-          Note that traces and metrics are batched separately. Default [None].
-      *)
+          Note that traces and metrics are batched separately. Default
+          [Some 20]. *)
   batch_logs: int option;
       (** Batch logs? See {!batch_metrics} for details. Default [Some 400] *)
   batch_timeout_ms: int;

src/client/exporter_add_batching.ml

@@ -0,0 +1,25 @@
+(** Add batching to emitter based on client config *)
+
+open Common_
+
+open struct
+  let add_batch ~timeout batch (emitter : 'a OTEL.Emitter.t) : 'a OTEL.Emitter.t
+      =
+    let b = Batch.make ~batch ~timeout () in
+    Batch.wrap_emitter b emitter
+end
+
+let add_batching ~(config : Client_config.t) (exp : OTEL.Exporter.t) :
+    OTEL.Exporter.t =
+  let timeout = Mtime.Span.(config.batch_timeout_ms * ms) in
+  let add_batch_opt (b : int option) e =
+    match b with
+    | None -> e
+    | Some b -> add_batch ~timeout b e
+  in
+
+  let emit_spans = add_batch_opt config.batch_traces exp.emit_spans in
+  let emit_metrics = add_batch_opt config.batch_metrics exp.emit_metrics in
+  let emit_logs = add_batch_opt config.batch_logs exp.emit_logs in
+
+  { exp with emit_spans; emit_metrics; emit_logs }