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stdlib: optimise gen_statem by caching callback function #7419

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merged 2 commits into from
Jul 3, 2023
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stdlib: optimise gen_statem by caching callback function #7419

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stdlib: optimise gen_statem by caching callback function
NelsonVides Jun 19, 2023
07eff3b
Rework the Module:handle_event/4 caching suggestion
RaimoNiskanen Jun 21, 2023
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39 changes: 23 additions & 16 deletions lib/stdlib/src/gen_statem.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -127,6 +127,13 @@

-type callback_mode_result() ::
callback_mode() | [callback_mode() | state_enter()].

-type handle_event_enter_fun() :: fun(('enter', OldState :: state(), CurrentState, data()) ->
state_enter_result(CurrentState)).
-type handle_event_event_fun() :: fun((event_type(), event_content(), state(), data()) ->
event_handler_result(state())).
-type handle_event_fun() :: handle_event_enter_fun() | handle_event_event_fun().
-type callback_mode_internal() :: 'state_functions' | {'handle_event_function', handle_event_fun()}.
-type callback_mode() :: 'state_functions' | 'handle_event_function'.
-type state_enter() :: 'state_enter'.

Expand Down Expand Up @@ -415,13 +422,13 @@
%% - return true if the value is of the type, false otherwise
-compile(
{inline,
[callback_mode/1, state_enter/1,
[callback_mode_internal/2, state_enter/1,
event_type/1, from/1, timeout_event_type/1]}).
%%
callback_mode(CallbackMode) ->
callback_mode_internal(CallbackMode, CallbackModule) ->
case CallbackMode of
state_functions -> true;
handle_event_function -> true;
state_functions -> {true, state_functions};
handle_event_function -> {true, {handle_event_function, fun CallbackModule:handle_event/4}};
_ -> false
end.
%%
Expand Down Expand Up @@ -492,7 +499,7 @@ event_type(Type) ->
end).

-record(params,
{callback_mode = state_functions :: callback_mode(),
{callback_mode = state_functions :: callback_mode_internal(),
state_enter = false :: boolean(),
parent :: pid(),
modules = [?MODULE] :: nonempty_list(module()),
Expand Down Expand Up @@ -1375,8 +1382,8 @@ loop_state_callback(
case CallbackMode of
state_functions ->
Module:State(Type, Content, Data);
handle_event_function ->
Module:handle_event(Type, Content, State, Data)
{handle_event_function, HandleEvent} ->
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As there's only two options and any errors to that effect should've been caught before we got here, can't we skip the wrapping tuple for HandleEvent and just call it directly?

@RaimoNiskanen ?

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More than happy to do it that way ofc, just let me know if I should – asking because Raimo's been tagged so maybe we want his opinion first (?)

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That is a good idea

HandleEvent(Type, Content, State, Data)
end
of
Result ->
Expand Down Expand Up @@ -2471,19 +2478,19 @@ callback_mode_result(P, Modules, CallbackModeResult) ->
listify(CallbackModeResult), undefined, false).
%%
callback_mode_result(
P, Modules, CallbackModeResult,
[H|T], CallbackMode, StateEnter) ->
case callback_mode(H) of
true ->
P, [Module | _] = Modules, CallbackModeResult,
[H|T], CurrentCallbackMode, StateEnter) ->
case callback_mode_internal(H, Module) of
{true, InternalCallbackMode} ->
callback_mode_result(
P, Modules, CallbackModeResult,
T, H, StateEnter);
T, InternalCallbackMode, StateEnter);
false ->
case state_enter(H) of
true ->
callback_mode_result(
P, Modules, CallbackModeResult,
T, CallbackMode, true);
T, CurrentCallbackMode, true);
false ->
{error,
{bad_return_from_callback_mode, CallbackModeResult},
Expand All @@ -2492,16 +2499,16 @@ callback_mode_result(
end;
callback_mode_result(
P, Modules, CallbackModeResult,
[], CallbackMode, StateEnter) ->
[], CurrentCallbackMode, StateEnter) ->
if
CallbackMode =:= undefined ->
CurrentCallbackMode =:= undefined ->
{error,
{bad_return_from_callback_mode, CallbackModeResult},
?STACKTRACE()};
true ->
P#params{
modules = Modules,
callback_mode = CallbackMode,
callback_mode = CurrentCallbackMode,
state_enter = StateEnter}
end.

Expand Down