Supervisor child pid
Roger Lipscombe
roger@REDACTED
Tue Mar 3 21:54:36 CET 2020
supervisor:get_child_spec/2 seems less brittle and more understandable.
On Tue, 3 Mar 2020 at 19:51, Zsolt Laky <zsoci@REDACTED> wrote:
>
> Dear Team,
>
> Finding a child Pid under a supervisor can be costly with the suggestion I found on the net with supervisor:which_children/1 as with a high number of children it returns a huge list with {Id, Child, Type, Modules} to find the MyChildId in.
>
> What I did is:
>
> -spec lookup(Name) -> Result when
> Name :: term(),
> Result :: {ok, pid()} | {error, not_registered}.
> lookup(Name) ->
> FakeChild = #{ id => Name,
> start => {?MODULE, ignore_start_child, []},
> restart => temporary,
> shutdown => 2000,
> type => worker,
> modules => dynamic},
> case supervisor:start_child(actor_sup, FakeChild) of
> {error, {already_started, Pid}} ->
> {ok, Pid};
> _Else -> %% {error, {ignored, _}}
> {error, not_registered}
> end.
>
> -spec ignore_start_child() ->
> {error, ignored}.
> ignore_start_child() ->
> {error, ignored}.
>
> I ask the experts if they see any pitfall I might have missed.
>
> Thanks in advance and kind regards,
> Zsolt
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