Emit runtime counter events for tracing

bin/olly.ml

@@ -96,7 +96,7 @@ let print_percentiles json output hist =
 let lost_events ring_id num =
   Printf.eprintf "[ring_id=%d] Lost %d events\n%!" ring_id num
 
-let olly ?extra ~runtime_begin ~runtime_end ~cleanup ~lifecycle ~init exec_args
+let olly ?extra ?runtime_counter ~runtime_begin ~runtime_end ~cleanup ~lifecycle ~init exec_args
     =
   let argsl = String.split_on_char ' ' exec_args in
   let executable_filename = List.hd argsl in
@@ -123,7 +123,7 @@ let olly ?extra ~runtime_begin ~runtime_end ~cleanup ~lifecycle ~init exec_args
   let cursor = Runtime_events.create_cursor (Some (tmp_dir, child_pid)) in
   let callbacks =
     Runtime_events.Callbacks.create ~runtime_begin ~runtime_end ~lifecycle
-      ~lost_events ()
+      ?runtime_counter ~lost_events ()
     |> Option.value extra ~default:Fun.id
   in
   let child_alive () =
@@ -169,14 +169,22 @@ let trace format trace_filename exec_args =
           (ts_to_us ts) ring_id ring_id;
         flush trace_file
       in
+      let runtime_counter ring_id ts counter_event i =
+        Printf.fprintf trace_file
+          "{\"name\" : \"%s\", \"ph\" : \"C\", \"ts\":%Ld,\
+           \"args\" : {\"value\" : \"%d\", \"pid\": %d, \"tid\": %d}}"
+          (Runtime_events.runtime_counter_name counter_event) (ts_to_us ts)
+          i ring_id ring_id;
+        flush trace_file
+      in
       let extra = Olly_custom_events.v_json trace_file in
       let init () =
         (* emit prefix in the tracefile *)
         Printf.fprintf trace_file "["
       in
       let cleanup () = close_out trace_file in
       olly ~extra ~runtime_begin ~runtime_end ~init ~lifecycle ~cleanup
-        exec_args
+        ~runtime_counter exec_args
   | Fuchsia ->
       let open Tracing in
       let trace_file =
@@ -209,10 +217,21 @@ let trace format trace_filename exec_args =
           ~name:(Runtime_events.runtime_phase_name phase)
           ~time:(ts |> ts_to_int |> int_to_span)
       in
+      let runtime_counter ring_id ts counter_event i =
+        let thread = doms.(ring_id) in
+        let args =
+          ["value", Trace.Arg.Int i;
+           "pid", Trace.Arg.Int ring_id;
+           "tid", Trace.Arg.Int ring_id]
+        in
+        Trace.write_counter trace_file ~thread ~args ~category:"C"
+          ~name:(Runtime_events.runtime_counter_name counter_event)
+          ~time:(ts |> ts_to_int |> int_to_span)
+      in
       let extra = Olly_custom_events.v trace_file doms in
       let init () = () in
       let cleanup () = Trace.close trace_file in
-      olly ~extra ~runtime_begin ~runtime_end ~init ~lifecycle ~cleanup
+      olly ~extra ~runtime_begin ~runtime_end ~init ~lifecycle ~runtime_counter ~cleanup
         exec_args
 
 let gc_stats json output exec_args =