perf(ready): send timing diagnostics only to staff sessions (#2190)

fluxer_gateway/src/gateway/gateway_handler_resume.erl

@@ -154,7 +154,7 @@ finalize_resume(Pid, Seq, MissedEvents, GwTimings0, State) ->
         ReplayStartedAt,
         GwTimings0
     ),
-    ResumedData = put_resumed_gateway_timings(GwTimings),
+    ResumedData = put_resumed_gateway_timings(session_is_staff(Pid), GwTimings),
     SocketPid ! {dispatch, resumed, ResumedData, Seq},
     erlang:garbage_collect(self(), [{type, major}]),
     {ok, State#{
@@ -209,9 +209,20 @@ remote_trace_meta(Operation, NodeName) ->
         _ -> #{}
     end.
 
--spec put_resumed_gateway_timings(gateway_timings:recorder()) -> map().
-put_resumed_gateway_timings(GwTimings) ->
-    #{<<"_timings_gw">> => gateway_timings_payload:finalize(GwTimings)}.
+-spec session_is_staff(pid()) -> boolean().
+session_is_staff(Pid) ->
+    try gen_server:call(Pid, {is_staff}, 5000) of
+        IsStaff when is_boolean(IsStaff) -> IsStaff;
+        _Other -> false
+    catch
+        exit:_Reason -> false
+    end.
+
+-spec put_resumed_gateway_timings(boolean(), gateway_timings:recorder()) -> map().
+put_resumed_gateway_timings(true, GwTimings) ->
+    #{<<"_timings_gw">> => gateway_timings_payload:finalize(GwTimings)};
+put_resumed_gateway_timings(false, _GwTimings) ->
+    #{}.
 
 -spec replay_missed_events([term()], pid()) -> ok.
 replay_missed_events([], _SocketPid) ->

fluxer_gateway/src/session/session.erl

@@ -96,6 +96,8 @@ init(SessionData) ->
     {reply, term(), session_state()} | {stop, normal, term(), session_state()}.
 handle_call({token_verify, Token}, _From, State) when is_binary(Token) ->
     session_lifecycle:handle_token_verify(Token, State);
+handle_call({is_staff}, _From, State) ->
+    session_lifecycle:handle_is_staff(State);
 handle_call({heartbeat_ack, Seq}, _From, State) when is_integer(Seq), Seq >= 0 ->
     session_lifecycle:handle_heartbeat_ack(Seq, State);
 handle_call({resume, Seq, SocketPid}, _From, State) when

fluxer_gateway/src/session/session_lifecycle.erl

@@ -16,6 +16,7 @@
     serialize_state/1,
     serialize_transfer_state/1,
     handle_token_verify/2,
+    handle_is_staff/1,
     handle_heartbeat_ack/2,
     handle_resume/3,
     handle_resume_offline_timeout/2,
@@ -268,6 +269,12 @@ token_hash_matches(HashedInput, TokenHash) when
 token_hash_matches(_HashedInput, _TokenHash) ->
     false.
 
+-spec handle_is_staff(session_state()) -> {reply, boolean(), session_state()}.
+handle_is_staff(#{is_staff := true} = State) ->
+    {reply, true, State};
+handle_is_staff(State) ->
+    {reply, false, State}.
+
 -spec handle_heartbeat_ack(seq(), session_state()) ->
     {reply, boolean(), session_state()}.
 handle_heartbeat_ack(Seq, #{ack_seq := AckSeq} = State) when Seq < AckSeq ->

fluxer_gateway/src/session/session_ready_dispatch.erl

@@ -61,9 +61,9 @@ dispatch_ready_to_socket(State) ->
         #{children => [PresencesSpan, UsersSpan, BuildSpan]},
         GwTimings0
     ),
-    FinalReadyData = FinalReadyData0#{
-        <<"_timings_gw">> => gateway_timings_payload:finalize(GwTimings)
-    },
+    FinalReadyData = apply_timings_visibility(
+        is_staff_session(State), GwTimings, FinalReadyData0
+    ),
     StateWithTimings = gateway_timings:put_state(GwTimings, State),
     StateAfterReady = dispatch_event(ready, FinalReadyData, StateWithTimings),
     StateAfterGuilds = dispatch_bot_guild_creates(
@@ -79,6 +79,18 @@ dispatch_ready_to_socket(State) ->
     erlang:garbage_collect(),
     {noreply, FinalState}.
 
+-spec is_staff_session(session_state()) -> boolean().
+is_staff_session(#{is_staff := true}) ->
+    true;
+is_staff_session(_State) ->
+    false.
+
+-spec apply_timings_visibility(boolean(), gateway_timings:recorder(), map()) -> map().
+apply_timings_visibility(true, GwTimings, ReadyData) ->
+    ReadyData#{<<"_timings_gw">> => gateway_timings_payload:finalize(GwTimings)};
+apply_timings_visibility(false, _GwTimings, ReadyData) ->
+    maps:without([<<"_timings">>], ReadyData).
+
 -spec build_final_ready_data(
     session_state(),
     [map()],