feat: use a pbrt encoder pool in client-ocurl

src/client-ocurl/opentelemetry_client_ocurl.ml

@@ -94,6 +94,7 @@ end = struct
     stop: bool Atomic.t;
     cleaned: bool Atomic.t;  (** True when we cleaned up after closing *)
     config: Config.t;
+    encoder_pool: Pbrt.Encoder.t Rpool.t;
     send_q: To_send.t Sync_queue.t;  (** Queue for the send worker threads *)
     traces: Proto.Trace.span Batch.t;
     logs: Proto.Logs.log_record Batch.t;
@@ -173,7 +174,11 @@ end = struct
         Self_trace.with_ ~kind:Span_kind_producer name
           ~attrs:[ "n", `Int (List.length signals) ]
       in
-      let msg = conv signals in
+      let msg : string =
+        (* borrow encoder from buffer pool and turn [signals] into bytes *)
+        let@ encoder = Rpool.with_resource self.encoder_pool in
+        conv ?encoder:(Some encoder) signals
+      in
       ignore (Atomic.fetch_and_add n_bytes_sent (String.length msg) : int);
       send_http_ ~stop ~config ~url client msg
     in
@@ -199,12 +204,19 @@ end = struct
 
   let create_state ~stop ~config () : state =
     let n_send_threads = max 2 config.Config.bg_threads in
+    let encoder_pool =
+      Rpool.create
+        ~mk_item:(fun () -> Pbrt.Encoder.create ~size:1024 ())
+        ~max_size:32 ~clear:Pbrt.Encoder.reset ()
+    in
+
     let self =
       {
         stop;
         config;
         send_threads = [||];
         send_q = Sync_queue.create ();
+        encoder_pool;
         cleaned = Atomic.make false;
         traces = Batch.make ~batch:batch_max_size_ ~timeout:batch_timeout_ ();
         logs = Batch.make ~batch:batch_max_size_ ~timeout:batch_timeout_ ();
@@ -239,21 +251,28 @@ end = struct
         in
         To_send.Send_trace [ traces ])
 
+  let[@inline] push_to_batch b e =
+    if e <> [] then (
+      match Batch.push b e with
+      | `Ok -> ()
+      | `Dropped -> Atomic.incr n_dropped
+    )
+
   let create ~stop ~config () : #t =
     let open Opentelemetry_util in
     let st = create_state ~stop ~config () in
     let ticker = Cb_set.create () in
     object (self : #t)
       method send_trace spans =
-        Batch.push' st.traces spans;
+        push_to_batch st.traces spans;
         maybe_send_traces st ~force:false
 
       method send_metrics m =
-        Batch.push' st.metrics m;
+        push_to_batch st.metrics m;
         maybe_send_metrics st ~force:false
 
       method send_logs m =
-        Batch.push' st.logs m;
+        push_to_batch st.logs m;
         maybe_send_logs st ~force:false
 
       method add_on_tick_callback cb = Cb_set.register ticker cb