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-rw-r--r--lib/stdlib/doc/src/gen_statem.xml71
-rw-r--r--lib/stdlib/src/gen_statem.erl326
-rw-r--r--lib/stdlib/test/gen_statem_SUITE.erl35
3 files changed, 104 insertions, 328 deletions
diff --git a/lib/stdlib/doc/src/gen_statem.xml b/lib/stdlib/doc/src/gen_statem.xml
index bda3ef081d..04b80d29ac 100644
--- a/lib/stdlib/doc/src/gen_statem.xml
+++ b/lib/stdlib/doc/src/gen_statem.xml
@@ -462,24 +462,6 @@ ok
</desc>
</datatype>
<datatype>
- <name name="event_predicate" />
- <desc>
- <p>
- A <c>fun()</c> of arity 2 that takes an event
- and returns a boolean.
- When used in the
- <seealso marker="#type-action">action()</seealso>
- <c>{remove_event,RemoveEventPredicate}</c>,
- the oldest event for which the predicate returns <c>true</c>
- will be removed.
- </p>
- <p>
- The predicate may <em>not</em> use a throw exception
- to return its result.
- </p>
- </desc>
- </datatype>
- <datatype>
<name name="callback_mode" />
<desc>
<p>
@@ -617,13 +599,11 @@ ok
counts just like a new in this respect.
If the value is <c>infinity</c> no timer is started.
If it is <c>0</c> the timeout event
- is immediately enqueued as the newest received.
+ is immediately enqueued as the newest received
+ (unless there are retried or inserted events to process).
Also note that it is not possible nor needed
- to cancel this timeout using the
- <seealso marker="#type-action">
- <c>action() cancel_timer</c>
- </seealso>
- since this timeout is cancelled automatically by any other event.
+ to cancel this timeout since it is cancelled automatically
+ by any other event.
</p>
</desc>
</datatype>
@@ -702,49 +682,6 @@ ok
should be used when you want to reliably distinguish
an event inserted this way from any external event.
</item>
- <tag><c>remove_event</c></tag>
- <item>
- Remove the oldest queued event
- that matches equal to <c><anno>EventType</anno></c>
- and <c><anno>EventContent</anno></c> or for which
- <c><anno>EventPredicate</anno></c>
- returns <c>true</c>. Note that <c>next_event</c>
- and <c>postpone</c> events in the same actions list
- does not get into the event queue until after all actions
- has been done so you can not remove an event that you insert
- with the same actions list. Make up your mind!
- </item>
- <tag><c>cancel_timer</c></tag>
- <item>
- Cancel the timer by calling
- <seealso marker="erts:erlang#cancel_timer/2">
- <c>erlang:cancel_timer/2</c>
- </seealso>
- with <c><anno>TimerRef</anno></c>,
- clean the process message queue from any late timeout message,
- and remove any late timeout message
- from the <c>gen_statem</c> event queue using
- <c>{remove_event,<anno>EventPredicate</anno>}</c> above.
- This is a convenience function that saves quite some
- lines of code and testing time over doing it from
- the primitives mentioned above.
- </item>
- <tag><c>demonitor</c></tag>
- <item>
- Like <c>cancel_timer</c> above but for
- <seealso marker="erts:erlang#demonitor/2">
- <c>demonitor/2</c>
- </seealso>
- with <c><anno>MonitorRef</anno></c>.
- </item>
- <tag><c>unlink</c></tag>
- <item>
- Like <c>cancel_timer</c> above but for
- <seealso marker="erts:erlang#unlink/1">
- <c>unlink/1</c>
- </seealso>
- with <c><anno>Id</anno></c>.
- </item>
</taglist>
</desc>
</datatype>
diff --git a/lib/stdlib/src/gen_statem.erl b/lib/stdlib/src/gen_statem.erl
index 29848d13a3..26f1aede6f 100644
--- a/lib/stdlib/src/gen_statem.erl
+++ b/lib/stdlib/src/gen_statem.erl
@@ -66,9 +66,6 @@
{'call',Caller :: caller()} | 'cast' |
'info' | 'timeout' | 'internal'.
--type event_predicate() :: % Return true for the event in question
- fun((event_type(), term()) -> boolean()).
-
-type callback_mode() :: 'state_functions' | 'handle_event_function'.
-type transition_option() ::
@@ -117,19 +114,7 @@
%% action() list is the first to be delivered.
{'next_event', % Insert event as the next to handle
EventType :: event_type(),
- EventContent :: term()} |
- %%
- {'remove_event', % Remove the oldest matching (=:=) event
- EventType :: event_type(), EventContent :: term()} |
- {'remove_event', % Remove the oldest event satisfying predicate
- EventPredicate :: event_predicate()} |
- %%
- {'cancel_timer', % Cancel timer and clean up mess(ages)
- TimerRef :: reference()} |
- {'demonitor', % Demonitor and clean up mess(ages)
- MonitorRef :: reference()} |
- {'unlink', % Unlink and clean up mess(ages)
- Id :: pid() | port()}.
+ EventContent :: term()}.
-type reply_action() ::
{'reply', % Reply to a caller
Caller :: caller(), Reply :: term()}.
@@ -745,11 +730,11 @@ loop_receive(Parent, Debug, #{timer := Timer} = S) ->
Msg ->
case Msg of
{system,Pid,Req} ->
+ #{hibernate := Hibernate} = S,
%% Does not return but tail recursively calls
%% system_continue/3 that jumps to loop/3
sys:handle_system_msg(
- Req, Pid, Parent, ?MODULE, Debug, S,
- maps:get(hibernate, S));
+ Req, Pid, Parent, ?MODULE, Debug, S, Hibernate);
{'EXIT',Parent,Reason} = EXIT ->
%% EXIT is not a 2-tuple and therefore
%% not an event and has no event_type(),
@@ -757,8 +742,25 @@ loop_receive(Parent, Debug, #{timer := Timer} = S) ->
?TERMINATE(exit, Reason, Debug, S, [EXIT]);
{timeout,Timer,Content} when Timer =/= undefined ->
loop_event(
- Parent, Debug, S, {timeout,Content}, undefined);
+ Parent, Debug, S, {timeout,Content});
_ ->
+ %% Cancel Timer if running
+ case Timer of
+ undefined ->
+ ok;
+ _ ->
+ case erlang:cancel_timer(Timer) of
+ TimeLeft when is_integer(TimeLeft) ->
+ ok;
+ false ->
+ receive
+ {timeout,Timer,_} ->
+ ok
+ after 0 ->
+ ok
+ end
+ end
+ end,
Event =
case Msg of
{'$gen_call',Caller,Request} ->
@@ -768,22 +770,20 @@ loop_receive(Parent, Debug, #{timer := Timer} = S) ->
_ ->
{info,Msg}
end,
- loop_event(Parent, Debug, S, Event, Timer)
+ loop_event(Parent, Debug, S, Event)
end
end.
-loop_event(Parent, Debug, S, Event, Timer) ->
+loop_event(Parent, Debug, S, Event) ->
+ %% The timer field in S is now invalid and ignored
+ %% until we get back to loop/3
NewDebug = sys_debug(Debug, S, {in,Event}),
%% Here the queue of not yet processed events is created
- loop_events(Parent, NewDebug, S, [Event], Timer).
+ loop_events(Parent, NewDebug, S, [Event]).
-%% Process first event in queue, or if there is none receive a new
-%%
-%% The loop_event* functions optimize S map handling by dismantling it,
-%% passing the parts in arguments to avoid map lookups and construct the
-%% new S map in one go on exit. Premature optimization, I know, but
-%% there were quite some map lookups repeated in different functions.
-loop_events(Parent, Debug, S, [], _Timer) ->
+%% Process first the event queue, or if it is empty
+%% loop back to receive a new event
+loop_events(Parent, Debug, S, []) ->
loop(Parent, Debug, S);
loop_events(
Parent, Debug,
@@ -791,9 +791,7 @@ loop_events(
module := Module,
state := State,
data := Data} = S,
- [{Type,Content} = Event|Events] = Q, Timer) ->
- _ = (Timer =/= undefined) andalso
- cancel_timer(Timer),
+ [{Type,Content} = Event|Events] = Q) ->
try
case CallbackMode of
state_functions ->
@@ -841,7 +839,7 @@ loop_events(
terminate(Class, Reason, Stacktrace, Debug, S, Q)
end.
-%% Interpret all callback return value variants
+%% Interpret all callback return variants
loop_event_result(
Parent, Debug,
#{callback_mode := CallbackMode, state := State, data := Data} = S,
@@ -909,7 +907,6 @@ loop_event_actions(
Hibernate = false,
Timeout = undefined,
NextEvents = [],
- P = false, % The postponed list or false if unchanged
loop_event_actions(
Parent, Debug, S, Events, Event, State, NewState, NewData,
if
@@ -918,24 +915,25 @@ loop_event_actions(
true ->
[Actions]
end,
- Postpone, Hibernate, Timeout, NextEvents, P).
+ Postpone, Hibernate, Timeout, NextEvents).
%%
+%% Process all action()s
loop_event_actions(
Parent, Debug, S, Events, Event,
State, NewState, NewData, [Action|Actions],
- Postpone, Hibernate, Timeout, NextEvents, P) ->
+ Postpone, Hibernate, Timeout, NextEvents) ->
case Action of
- %% Set options
+ %% Actions that set options
postpone ->
loop_event_actions(
Parent, Debug, S, Events, Event,
State, NewState, NewData, Actions,
- true, Hibernate, Timeout, NextEvents, P);
+ true, Hibernate, Timeout, NextEvents);
{postpone,NewPostpone} when is_boolean(NewPostpone) ->
loop_event_actions(
Parent, Debug, S, Events, Event,
State, NewState, NewData, Actions,
- NewPostpone, Hibernate, Timeout, NextEvents, P);
+ NewPostpone, Hibernate, Timeout, NextEvents);
{postpone,_} ->
?TERMINATE(
error, {bad_action,Action}, Debug, S, [Event|Events]);
@@ -943,12 +941,12 @@ loop_event_actions(
loop_event_actions(
Parent, Debug, S, Events, Event,
State, NewState, NewData, Actions,
- Postpone, true, Timeout, NextEvents, P);
+ Postpone, true, Timeout, NextEvents);
{hibernate,NewHibernate} when is_boolean(NewHibernate) ->
loop_event_actions(
Parent, Debug, S, Events, Event,
State, NewState, NewData, Actions,
- Postpone, NewHibernate, Timeout, NextEvents, P);
+ Postpone, NewHibernate, Timeout, NextEvents);
{hibernate,_} ->
?TERMINATE(
error, {bad_action,Action}, Debug, S, [Event|Events]);
@@ -956,12 +954,12 @@ loop_event_actions(
loop_event_actions(
Parent, Debug, S, Events, Event,
State, NewState, NewData, Actions,
- Postpone, Hibernate, undefined, NextEvents, P);
+ Postpone, Hibernate, undefined, NextEvents);
{timeout,Time,_} = NewTimeout when is_integer(Time), Time >= 0 ->
loop_event_actions(
Parent, Debug, S, Events, Event,
State, NewState, NewData, Actions,
- Postpone, Hibernate, NewTimeout, NextEvents, P);
+ Postpone, Hibernate, NewTimeout, NextEvents);
{timeout,_,_} ->
?TERMINATE(
error, {bad_action,Action}, Debug, S, [Event|Events]);
@@ -973,7 +971,7 @@ loop_event_actions(
loop_event_actions(
Parent, NewDebug, S, Events, Event,
State, NewState, NewData, Actions,
- Postpone, Hibernate, Timeout, NextEvents, P);
+ Postpone, Hibernate, Timeout, NextEvents);
false ->
?TERMINATE(
error, {bad_action,Action}, Debug, S, [Event|Events])
@@ -985,67 +983,25 @@ loop_event_actions(
Parent, Debug, S, Events, Event,
State, NewState, NewData, Actions,
Postpone, Hibernate, Timeout,
- [{Type,Content}|NextEvents], P);
+ [{Type,Content}|NextEvents]);
false ->
?TERMINATE(
error, {bad_action,Action}, Debug, S, [Event|Events])
end;
_ ->
- %% All others are remove actions
- case remove_fun(Action) of
- false ->
- loop_event_actions(
- Parent, Debug, S, Events, Event,
- State, NewState, NewData, Actions,
- Postpone, Hibernate, Timeout, NextEvents, P);
- undefined ->
- ?TERMINATE(
- error, {bad_action,Action}, Debug, S, [Event|Events]);
- RemoveFun when is_function(RemoveFun, 2) ->
- P0 =
- case P of
- false ->
- maps:get(postponed, S);
- _ ->
- P
- end,
- case remove_event(RemoveFun, Events, P0) of
- false ->
- loop_event_actions(
- Parent, Debug, S, Events, Event,
- State, NewState, NewData, Actions,
- Postpone, Hibernate, Timeout, NextEvents, P);
- {NewEvents,false} ->
- loop_event_actions(
- Parent, Debug, S, NewEvents, Event,
- State, NewState, NewData, Actions,
- Postpone, Hibernate, Timeout, NextEvents, P);
- {false,NewP} ->
- loop_event_actions(
- Parent, Debug, S, Events, Event,
- State, NewState, NewData, Actions,
- Postpone, Hibernate, Timeout, NextEvents,
- NewP);
- [Class,Reason,Stacktrace] ->
- terminate(
- Class, Reason, Stacktrace,
- Debug, S, [Event|Events])
- end;
- [Class,Reason,Stacktrace] ->
- terminate(
- Class, Reason, Stacktrace, Debug, S, [Event|Events])
- end
+ ?TERMINATE(
+ error, {bad_action,Action}, Debug, S, [Event|Events])
end;
+%%
+%% End of actions list
loop_event_actions(
- Parent, Debug, S, Events, Event, State, NewState, NewData, [],
- Postpone, Hibernate, Timeout, NextEvents, P) ->
- P0 =
- case P of
- false ->
- maps:get(postponed, S);
- _ ->
- P
- end,
+ Parent, Debug, #{postponed := P0} = S, Events, Event,
+ State, NewState, NewData, [],
+ Postpone, Hibernate, Timeout, NextEvents) ->
+ %%
+ %% All options have been collected and next_events are buffered.
+ %% Do the actual state transition.
+ %%
P1 = % Move current event to postponed if Postpone
case Postpone of
true ->
@@ -1053,23 +1009,12 @@ loop_event_actions(
false ->
P0
end,
- {Timer,Q1} =
- case Timeout of
- undefined ->
- {undefined,Events};
- {timeout,0,Msg} ->
- %% Pretend the timeout has just been received
- {undefined,Events ++ [{timeout,Msg}]};
- {timeout,Time,Msg} ->
- {erlang:start_timer(Time, self(), Msg),
- Events}
- end,
- {Q2,P2} = % Move all postponed events to queue if state change
+ {Q2,P} = % Move all postponed events to queue if state change
if
NewState =:= State ->
- {Q1,P1};
+ {Events,P1};
true ->
- {lists:reverse(P1, Q1),[]}
+ {lists:reverse(P1, Events),[]}
end,
%% Place next events first in queue
Q3 = lists:reverse(NextEvents, Q2),
@@ -1083,16 +1028,41 @@ loop_event_actions(
false ->
{consume,Event,NewState}
end),
- %% Loop to top; process next event
+ %% Have a peek on the event queue so we can avoid starting
+ %% the state timer unless we have to
+ {Q,Timer} =
+ case Timeout of
+ undefined ->
+ %% No state timeout has been requested
+ {Q3,undefined};
+ {timeout,Time,Msg} ->
+ %% A state timeout has been requested
+ case Q3 of
+ [] when Time =:= 0 ->
+ %% Immediate timeout - simulate it
+ %% so we do not get the timeout message
+ %% after any received event
+ {[{timeout,Msg}],undefined};
+ [] ->
+ %% Actually start a timer
+ {Q3,erlang:start_timer(Time, self(), Msg)};
+ _ ->
+ %% Do not start a timer since any queued
+ %% event cancels the state timer so we pretend
+ %% that the timer has been started and cancelled
+ {Q3,undefined}
+ end
+ end,
+ %% Loop to top of event queue loop; process next event
loop_events(
Parent, NewDebug,
S#{
state := NewState,
data := NewData,
timer := Timer,
- hibernate := Hibernate,
- postponed := P2},
- Q3, Timer).
+ postponed := P,
+ hibernate := Hibernate},
+ Q).
%%---------------------------------------------------------------------------
%% Server helpers
@@ -1125,103 +1095,6 @@ do_reply(Debug, S, Caller, Reply) ->
sys_debug(Debug, S, {out,Reply,Caller}).
-%% Remove oldest matching event from the queue(s)
-remove_event(RemoveFun, Q, P) ->
- try
- case remove_tail_event(RemoveFun, P) of
- false ->
- case remove_head_event(RemoveFun, Q) of
- false ->
- false;
- NewQ ->
- {false,NewQ}
- end;
- NewP ->
- {NewP,false}
- end
- catch
- Class:Reason ->
- [Class,Reason,erlang:get_stacktrace()]
- end.
-
-%% Do the given action and create an event removal predicate fun()
-remove_fun({remove_event,Type,Content}) ->
- fun (T, C) when T =:= Type, C =:= Content -> true;
- (_, _) -> false
- end;
-remove_fun({remove_event,RemoveFun}) when is_function(RemoveFun, 2) ->
- RemoveFun;
-remove_fun({cancel_timer,TimerRef}) ->
- try cancel_timer(TimerRef) of
- false ->
- false;
- true ->
- fun
- (info, {timeout,TRef,_})
- when TRef =:= TimerRef ->
- true;
- (_, _) ->
- false
- end
- catch
- Class:Reason ->
- [Class,Reason,erlang:get_stacktrace()]
- end;
-remove_fun({demonitor,MonitorRef}) ->
- try erlang:demonitor(MonitorRef, [flush,info]) of
- false ->
- false;
- true ->
- fun (info, {'DOWN',MRef,_,_,_})
- when MRef =:= MonitorRef->
- true;
- (_, _) ->
- false
- end
- catch
- Class:Reason ->
- [Class,Reason,erlang:get_stacktrace()]
- end;
-remove_fun({unlink,Id}) ->
- try unlink(Id) of
- true ->
- receive
- {'EXIT',Id,_} ->
- ok
- after 0 ->
- ok
- end,
- fun (info, {'EXIT',I,_})
- when I =:= Id ->
- true;
- (_, _) ->
- false
- end
- catch
- Class:Reason ->
- [Class,Reason,erlang:get_stacktrace()]
- end;
-remove_fun(_) ->
- undefined.
-
-
-%% Cancel a timer and clense the process mailbox returning
-%% false if no such timer message can arrive after this or
-%% true otherwise
-cancel_timer(TimerRef) ->
- case erlang:cancel_timer(TimerRef) of
- TimeLeft when is_integer(TimeLeft) ->
- false;
- false ->
- receive
- {timeout,TimerRef,_} ->
- false
- after 0 ->
- true
- end
- end.
-
-
terminate(
Class, Reason, Stacktrace, Debug,
#{module := Module,
@@ -1350,30 +1223,3 @@ format_status_default(Opt, State, Data) ->
_ ->
[{data,[{"State",SSD}]}]
end.
-
-%%---------------------------------------------------------------------------
-%% Farily general helpers
-
-%% Return the modified list where the first element that satisfies
-%% the RemoveFun predicate is removed, or false if no such element exists.
-remove_head_event(_RemoveFun, []) ->
- false;
-remove_head_event(RemoveFun, [{Tag,Content}|Events]) ->
- case RemoveFun(Tag, Content) of
- false ->
- remove_head_event(RemoveFun, Events);
- true ->
- Events
- end.
-
-%% Return the modified list where the last element that satisfies
-%% the RemoveFun predicate is removed, or false if no such element exists.
-remove_tail_event(_RemoveFun, []) ->
- false;
-remove_tail_event(RemoveFun, [{Tag,Content} = Event|Events]) ->
- case remove_tail_event(RemoveFun, Events) of
- false ->
- RemoveFun(Tag, Content) andalso Events;
- NewEvents ->
- [Event|NewEvents]
- end.
diff --git a/lib/stdlib/test/gen_statem_SUITE.erl b/lib/stdlib/test/gen_statem_SUITE.erl
index 268b45a0e7..38aab752b8 100644
--- a/lib/stdlib/test/gen_statem_SUITE.erl
+++ b/lib/stdlib/test/gen_statem_SUITE.erl
@@ -1210,29 +1210,22 @@ idle(Type, Content, Data) ->
end.
timeout(timeout, idle, {From,Time}) ->
- TRef2 = erlang:start_timer(Time, self(), ok),
- TRefC1 = erlang:start_timer(Time, self(), cancel1),
- TRefC2 = erlang:start_timer(Time, self(), cancel2),
- {next_state,timeout2,{From,Time,TRef2},
- [{cancel_timer, TRefC1},
- {next_event,internal,{cancel_timer,TRefC2}}]};
-timeout(_, _, Data) ->
- {keep_state,Data}.
-
-timeout2(
- internal, {cancel_timer,TRefC2}, {From,Time,TRef2}) ->
- Time4 = Time * 4,
- receive after Time4 -> ok end,
- {next_state,timeout3,{From,TRef2},
- [{cancel_timer,TRefC2}]};
-timeout2(_, _, Data) ->
- {keep_state,Data}.
-
-timeout3(info, {timeout,TRef2,Result}, {From,TRef2}) ->
+ TRef = erlang:start_timer(Time, self(), ok),
+ {next_state,timeout2,{From,TRef},
+ [{timeout,1,should_be_cancelled},
+ postpone]}; % Should cancel state timeout
+timeout(_, _, _) ->
+ keep_state_and_data.
+
+timeout2(timeout, idle, _) ->
+ keep_state_and_data;
+timeout2(timeout, Reason, _) ->
+ {stop,Reason};
+timeout2(info, {timeout,TRef,Result}, {From,TRef}) ->
gen_statem:reply([{reply,From,Result}]),
{next_state,idle,state};
-timeout3(_, _, Data) ->
- {keep_state,Data}.
+timeout2(_, _, _) ->
+ {keep_state_and_data,[]}.
wfor_conf({call,From}, confirm, Data) ->
{next_state,connected,Data,
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-25 01:29:25 +0000