From 41e650d461b453b4870c4abba0456e8d32229efa Mon Sep 17 00:00:00 2001
From: Simon Cruanes <simon.cruanes.2007@m4x.org>
Date: Wed, 10 Dec 2025 08:46:20 -0500
Subject: [PATCH] perf batch: try to improve hotpath

in particular, no need to look at the clock when checking if the batch
is full
---
 src/client/batch.ml | 37 +++++++++++++++++++++----------------
 1 file changed, 21 insertions(+), 16 deletions(-)

diff --git a/src/client/batch.ml b/src/client/batch.ml
index 00029f74..e5f7c88f 100644
--- a/src/client/batch.ml
+++ b/src/client/batch.ml
@@ -46,7 +46,12 @@ let make ?(batch = 100) ?high_watermark ?now ?timeout () : _ t =
     high_watermark;
   }
 
+(** passed to ignore timeout *)
+let mtime_dummy_ = Mtime.min_stamp
+
 let timeout_expired_ ~now ~timeout (self : _ state) : bool =
+  now <> mtime_dummy_
+  &&
   match timeout with
   | Some t ->
     let elapsed = Mtime.span now self.start in
@@ -56,7 +61,7 @@ let timeout_expired_ ~now ~timeout (self : _ state) : bool =
 (** Big enough to send? *)
 let[@inline] is_full_ ~batch (self : _ state) : bool = self.size >= batch
 
-let pop_if_ready ?(force = false) ~now (self : _ t) : _ list option =
+let pop_if_ready_ ~force ~now (self : _ t) : _ list option =
   let rev_batch_opt =
     (* update state. When uncontended this runs only once. *)
     Util_atomic.update_cas self.st @@ fun state ->
@@ -84,6 +89,9 @@ let pop_if_ready ?(force = false) ~now (self : _ t) : _ list option =
     (* Reverse the list to retrieve the FIFO order. *)
     Some (List.rev batch)
 
+let pop_if_ready ?(force = false) ~now (self : _ t) : _ list option =
+  pop_if_ready_ ~force ~now self
+
 let push (self : _ t) elems : [ `Dropped | `Ok ] =
   if elems = [] then
     `Ok
@@ -119,6 +127,12 @@ let[@inline] push' self elems = ignore (push self elems : [ `Dropped | `Ok ])
 
 open Opentelemetry_emitter
 
+(** Emit current batch, if the conditions are met *)
+let maybe_emit_ (self : _ t) ~(e : _ Emitter.t) ~now : unit =
+  match pop_if_ready self ~force:false ~now with
+  | None -> ()
+  | Some l -> Emitter.emit e l
+
 let wrap_emitter (self : _ t) (e : _ Emitter.t) : _ Emitter.t =
   (* we need to be able to close this emitter before we close [e]. This
      will become [true] when we close, then we call [Emitter.flush_and_close e],
@@ -141,18 +155,10 @@ let wrap_emitter (self : _ t) (e : _ Emitter.t) : _ Emitter.t =
     )
   in
 
-  let maybe_emit ~now =
-    if not (Atomic.get closed_here) then (
-      match pop_if_ready self ~force:false ~now with
-      | None -> ()
-      | Some l -> Emitter.emit e l
-    )
-  in
-
   let tick ~now =
     if not (Atomic.get closed_here) then (
       (* first, check if batch has timed out *)
-      maybe_emit ~now;
+      maybe_emit_ self ~e ~now;
 
       (* only then, tick the underlying emitter *)
       Emitter.tick e ~now
@@ -160,14 +166,13 @@ let wrap_emitter (self : _ t) (e : _ Emitter.t) : _ Emitter.t =
   in
 
   let emit l =
-    if l <> [] && (not (Atomic.get closed_here)) && e.enabled () then (
+    if l <> [] && not (Atomic.get closed_here) then (
       push' self l;
 
-      (* TODO: it'd be nice if we checked only for size here, not
-        for timeout. The [tick] function is enough for timeouts,
-        whereas [emit] is in the hot path of every single span/metric/log *)
-      let now = Mtime_clock.now () in
-      maybe_emit ~now
+      (* we only check for size here, not for timeout. The [tick] function is
+         enough for timeouts, whereas [emit] is in the hot path of every single
+         span/metric/log *)
+      maybe_emit_ self ~e ~now:mtime_dummy_
     )
   in