Merge pull request #8522 from ieQu1/dispatch-shared-sub-over-gen-rpc

fix(shared_sub): Use gen_rpc to send shared_sub payloads

src/emqx_shared_sub.erl

@@ -164,27 +164,24 @@ ack_enabled() ->
 
 do_dispatch(SubPid, _Group, Topic, Msg, _Type) when SubPid =:= self() ->
     %% Deadlock otherwise
-    SubPid ! {deliver, Topic, Msg},
-    ok;
+    send(SubPid, Topic, {deliver, Topic, Msg});
 %% return either 'ok' (when everything is fine) or 'error'
 do_dispatch(SubPid, _Group, Topic, #message{qos = ?QOS_0} = Msg, _Type) ->
     %% For QoS 0 message, send it as regular dispatch
-    SubPid ! {deliver, Topic, Msg},
-    ok;
+    send(SubPid, Topic, {deliver, Topic, Msg});
 do_dispatch(SubPid, Group, Topic, Msg, Type) ->
     case ack_enabled() of
         true ->
             dispatch_with_ack(SubPid, Group, Topic, Msg, Type);
         false ->
-            SubPid ! {deliver, Topic, Msg},
-            ok
+            send(SubPid, Topic, {deliver, Topic, Msg})
     end.
 
 dispatch_with_ack(SubPid, Group, Topic, Msg, Type) ->
     %% For QoS 1/2 message, expect an ack
     Ref = erlang:monitor(process, SubPid),
     Sender = self(),
-    SubPid ! {deliver, Topic, with_group_ack(Msg, Group, Type, Sender, Ref)},
+    send(SubPid, Topic, {deliver, Topic, with_group_ack(Msg, Group, Type, Sender, Ref)}),
     Timeout = case Msg#message.qos of
                   ?QOS_1 -> timer:seconds(?SHARED_SUB_QOS1_DISPATCH_TIMEOUT_SECONDS);
                   ?QOS_2 -> infinity
@@ -210,6 +207,15 @@ dispatch_with_ack(SubPid, Group, Topic, Msg, Type) ->
         _ = erlang:demonitor(Ref, [flush])
     end.
 
+send(Pid, Topic, Msg) ->
+    Node = node(Pid),
+    if Node =:= node() ->
+            Pid ! Msg;
+       true ->
+            emqx_rpc:cast(Topic, Node, erlang, send, [Pid, Msg])
+    end,
+    ok.
+
 with_group_ack(Msg, Group, Type, Sender, Ref) ->
     emqx_message:set_headers(#{shared_dispatch_ack => {Sender, old_ref(Type, Group, Ref)}}, Msg).