Extract timestamped telemetry events to a helper module

src/amoc_controller.erl

@@ -202,6 +202,7 @@ handle_start_scenario(Scenario, Settings, #state{status = idle} = State) ->
                                    scenario_start = StartTime,
                                    scenario_ref   = Ref,
                                    status         = running},
+            %% This simulates a span
             telemetry:execute([amoc, scenario, run, start],
                               #{monotonic_time => StartTime, system_time => erlang:system_time()},
                               #{telemetry_span_context => Ref, scenario => Scenario}),
@@ -240,9 +241,8 @@ handle_add(StartId, EndId, #state{last_user_id = LastId,
                                   scenario     = Scenario,
                                   tref         = TRef} = State) when StartId =< EndId,
                                                                      LastId < StartId ->
-    TimeStamp = erlang:monotonic_time(),
-    telemetry:execute([amoc, controller, users], #{count => EndId - StartId + 1},
-                      #{monotonic_time => TimeStamp, scenario => Scenario, type => add}),
+    amoc_telemetry:execute([controller, users], #{count => EndId - StartId + 1},
+                           #{scenario => Scenario, type => add}),
     NewUsers = lists:seq(StartId, EndId),
     NewScheduledUsers = lists:append(ScheduledUsers, NewUsers),
     NewTRef = maybe_start_timer(TRef),
@@ -255,9 +255,8 @@ handle_add(_StartId, _EndId, #state{status = Status} = State) ->
 
 -spec handle_remove(user_count(), boolean(), state()) -> handle_call_res().
 handle_remove(Count, ForceRemove, #state{status = running, scenario = Scenario}) ->
-    TimeStamp = erlang:monotonic_time(),
-    telemetry:execute([amoc, controller, users], #{count => Count},
-                      #{monotonic_time => TimeStamp, scenario => Scenario, type => remove}),
+    amoc_telemetry:execute([controller, users], #{count => Count},
+                           #{scenario => Scenario, type => remove}),
     Pids = case ets:match_object(?USERS_TABLE, '$1', Count) of
                {Objects, _} -> [Pid || {_Id, Pid} <- Objects];
                '$end_of_table' -> []
@@ -332,13 +331,15 @@ terminate_scenario(#state{scenario = Scenario,
                           scenario_ref = Ref}) ->
     case amoc_scenario:terminate(Scenario, ScenarioState) of
         {error, {Class, Reason, Stacktrace}} = Ret ->
+            %% This simulates a span
             StopTime = erlang:monotonic_time(),
             telemetry:execute([amoc, scenario, run, exception],
                               #{duration => StopTime - StartTime, monotonic_time => StopTime},
                               #{telemetry_span_context => Ref, scenario => Scenario,
                                 kind => Class, reason => Reason, stacktrace => Stacktrace}),
             Ret;
         Ret ->
+            %% This simulates a span
             StopTime = erlang:monotonic_time(),
             telemetry:execute([amoc, scenario, run, stop],
                               #{duration => StopTime - StartTime, monotonic_time => StopTime},

src/amoc_coordinator/amoc_coordinator.erl

@@ -74,8 +74,7 @@ start(Name, CoordinationPlan, Timeout) when ?IS_TIMEOUT(Timeout) ->
     Plan = normalize_coordination_plan(CoordinationPlan),
     case gen_event:start({local, Name}) of
         {ok, _} ->
-            telemetry:execute([amoc, coordinator, start], #{count => 1},
-                              #{monotonic_time => erlang:monotonic_time(), name => Name}),
+            amoc_telemetry:execute([coordinator, start], #{count => 1}, #{name => Name}),
             %% according to gen_event documentation:
             %%
             %%    When the event is received, the event manager calls
@@ -100,8 +99,7 @@ start(Name, CoordinationPlan, Timeout) when ?IS_TIMEOUT(Timeout) ->
 -spec stop(name()) -> ok.
 stop(Name) ->
     gen_event:stop(Name),
-    telemetry:execute([amoc, coordinator, stop], #{count => 1},
-                      #{monotonic_time => erlang:monotonic_time(), name => Name}).
+    amoc_telemetry:execute([coordinator, stop], #{count => 1}, #{name => Name}).
 
 %% @see add/3
 -spec add(name(), any()) -> ok.
@@ -158,15 +156,14 @@ init(CoordinationItem) ->
 -spec handle_event(Event :: term(), state()) -> {ok, state()}.
 handle_event(Event, {timeout, Name, Pid}) ->
     %% there's only one "timeout" event handler for coordinator,
-    %% so calling telemetry:execute/3 here to ensure that it's
+    %% so calling amoc_telemetry:execute/3 here to ensure that it's
     %% triggered just once per event.
     TelemetryEvent = case Event of
                          {coordinate, _} -> add;
                          reset_coordinator -> reset;
                          coordinator_timeout -> timeout
                      end,
-    telemetry:execute([amoc, coordinator, TelemetryEvent], #{count => 1},
-                      #{monotonic_time => erlang:monotonic_time(), name => Name}),
+    amoc_telemetry:execute([coordinator, TelemetryEvent], #{count => 1}, #{name => Name}),
     erlang:send(Pid, Event),
     {ok, {timeout, Name, Pid}};
 handle_event(Event, {worker, WorkerPid}) ->

src/amoc_telemetry.erl

@@ -0,0 +1,15 @@
+%% @private
+%% @copyright 2023 Erlang Solutions Ltd.
+-module(amoc_telemetry).
+
+-export([execute/3]).
+
+-spec execute(EventName, Measurements, Metadata) -> ok when
+      EventName :: telemetry:event_name(),
+      Measurements :: telemetry:event_measurements(),
+      Metadata :: telemetry:event_metadata().
+execute(Name, Measurements, Metadata) ->
+    TimeStamp = erlang:monotonic_time(),
+    NameWithAmocPrefix = [amoc | Name],
+    MetadataWithTS = Metadata#{monotonic_time => TimeStamp},
+    telemetry:execute(NameWithAmocPrefix, Measurements, MetadataWithTS).

src/amoc_throttle/amoc_throttle_controller.erl

@@ -204,14 +204,10 @@ maybe_raise_event(Name, Event) ->
     end.
 
 raise_event(Name, Event) when Event =:= request; Event =:= execute; Event =:= init ->
-    telemetry:execute([amoc, throttle, Event],
-                      #{count => 1},
-                      #{monotonic_time => erlang:monotonic_time(), name => Name}).
+    amoc_telemetry:execute([throttle, Event], #{count => 1}, #{name => Name}).
 
 report_rate(Name, RatePerMinute) ->
-    telemetry:execute([amoc, throttle, rate],
-                      #{rate => RatePerMinute},
-                      #{monotonic_time => erlang:monotonic_time(), name => Name}).
+    amoc_telemetry:execute([throttle, rate], #{rate => RatePerMinute}, #{name => Name}).
 
 -spec change_rate_and_stop_plan(name(), state()) -> state().
 change_rate_and_stop_plan(Name, State) ->