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Terminate when ra_systems_sup exits #15782

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Terminate when ra_systems_sup exits #15782

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52 changes: 52 additions & 0 deletions deps/rabbit/src/rabbit_ra_systems.erl
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@the-mikedavis the-mikedavis Mar 19, 2026

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Using an extra gen_server just to crash the Rabbit app seems a bit hacky to me, though it works. I'm sure there must be a better way to crash Rabbit when ra_systems_sup exits.

Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,8 @@

-module(rabbit_ra_systems).

-behaviour(gen_server).

-include_lib("kernel/include/logger.hrl").

-include_lib("rabbit_common/include/logging.hrl").
Expand All @@ -20,6 +22,21 @@
ensure_started/0,
ensure_stopped/0]).

-export([start_link/0,
init/1,
handle_call/3,
handle_cast/2,
handle_info/2,
terminate/2,
code_change/3]).
-export([stop/0]).

-rabbit_boot_step({rabbit_ra_systems_monitor,
[{description, "monitor process to shut down when Ra systems exit"},
{mfa, {rabbit_sup, start_child, [?MODULE]}},
{requires, [kernel_ready]},
{cleanup, {?MODULE, stop, []}}]}).

-type ra_system_name() :: atom().

-define(COORD_WAL_MAX_SIZE_B, 64_000_000).
Expand Down Expand Up @@ -192,3 +209,38 @@ ensure_ra_system_stopped(RaSystem) ->
#{domain => ?RMQLOG_DOMAIN_GLOBAL}),
throw(Error)
end.

%% ----------------------------------------------------------------------------

start_link() ->
gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).

stop() ->
case supervisor:terminate_child(rabbit_sup, ?MODULE) of
ok -> ok = supervisor:delete_child(rabbit_sup, ?MODULE);
{error, not_found} -> ok
end.

init(_) ->
process_flag(trap_exit, true),
Pid = whereis(ra_systems_sup),
true = link(Pid),
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@dumbbell dumbbell Apr 20, 2026

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Don’t you need to unlink in the terminate/2 callback? Otherwise, stopping rabbit will kill ra_systems_sup. I know that rabbit messes with its dependencies so it might not be a problem right now. But if one day, we fix rabbit, it will be one.

{ok, Pid, hibernate}.

handle_call(_Request, _From, State) -> {noreply, State}.
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@dumbbell dumbbell Apr 20, 2026

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This will leave the caller waiting for a reply, until timeout if it set one. I think you can reply with an ok just to avoid that. What do you think?


handle_cast(_Msg, State) -> {noreply, State}.

handle_info({'EXIT', RaSystemsSup, Reason} = E, RaSystemsSup) ->
?LOG_ERROR(
?MODULE_STRING ": Ra system supervisor exited with reason ~tp~n",
[Reason],
#{domain => ?RMQLOG_DOMAIN_GLOBAL}),
exit(E);
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@dumbbell dumbbell Apr 20, 2026

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What about returning {stop, Reason, State}? Would it have a different behaviour compared to exiting?

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@the-mikedavis the-mikedavis Apr 20, 2026

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Yeah actually, Rabbit doesn't exit unless we use exit/1 here. With {stop, Reason, State} Rabbit keeps going. I'm not really sure why. This is the part that seems pretty hacky to me 😅

handle_info(_Info, State) -> {noreply, State}.

terminate(_, RaSystemsSup) ->
true = unlink(RaSystemsSup),
ok.

code_change(_OldVsn, State, _Extra) -> {ok, State}.
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