refactor(emqx_machine): supervise terminator

apps/emqx_machine/src/emqx_machine_app.erl

@@ -24,9 +24,7 @@
 
 start(_Type, _Args) ->
     ok = emqx_machine:start(),
-    {ok, Sup} = emqx_machine_sup:start_link(),
+    emqx_machine_sup:start_link().
-    ok = emqx_machine_terminator:start(),
-    {ok, Sup}.
 
 stop(_State) ->
     ok.

apps/emqx_machine/src/emqx_machine_sup.erl

@@ -29,18 +29,19 @@ start_link() ->
     supervisor:start_link({local, ?MODULE}, ?MODULE, []).
 
 init([]) ->
-    GlobalGC = child_worker(emqx_global_gc, []),
+    GlobalGC = child_worker(emqx_global_gc, [], permanent),
-    Children = [GlobalGC],
+    Terminator = child_worker(emqx_machine_terminator, [], transient),
-    SupFlags = #{strategy => one_for_all,
+    Children = [GlobalGC, Terminator],
+    SupFlags = #{strategy => one_for_one,
                  intensity => 100,
                  period => 10
                 },
     {ok, {SupFlags, Children}}.
 
-child_worker(M, Args) ->
+child_worker(M, Args, Restart) ->
     #{id       => M,
       start    => {M, start_link, Args},
-      restart  => permanent,
+      restart  => Restart,
       shutdown => 5000,
       type     => worker,
       modules  => [M]

apps/emqx_machine/src/emqx_machine_terminator.erl

@@ -18,7 +18,7 @@
 
 -behaviour(gen_server).
 
--export([ start/0
+-export([ start_link/0
         , graceful/0
         , graceful_wait/0
         , is_running/0
@@ -36,10 +36,8 @@
 %% @doc This API is called to shutdown the Erlang VM by RPC call from remote shell node.
 %% The shutown of apps is delegated to a to a process instead of doing it in the RPC spawned
 %% process which has a remote group leader.
-start() ->
+start_link() ->
-    {ok, _} = gen_server:start_link({local, ?TERMINATOR}, ?MODULE, [], []),
+    {ok, _} = gen_server:start_link({local, ?TERMINATOR}, ?MODULE, [], []).
-    %% NOTE: Do not link this process under any supervision tree
-    ok.
 
 is_running() -> is_pid(whereis(?TERMINATOR)).