Send and cancel will message by apis rather than hook

src/emqx_protocol.erl

@@ -638,6 +638,9 @@ try_open_session(PState = #pstate{zone        = Zone,
     case emqx_sm:open_session(SessAttrs1) of
         {ok, SPid} ->
             {ok, SPid, false};
+        {ok, SPid, true} ->
+            emqx_delayed_publish:cancel_publish(ClientId),
+            {ok, SPid, true};
         Other -> Other
     end.
 
@@ -838,11 +841,9 @@ shutdown(Reason, PState = #pstate{connected = true,
 
 send_willmsg(undefined, _ClientId) ->
     ignore;
-send_willmsg(WillMsg = #message{topic = Topic,
-                                headers = #{'Will-Delay-Interval' := Interval} = Headers}, ClientId)
+send_willmsg(WillMsg = #message{headers = #{'Will-Delay-Interval' := Interval}}, ClientId)
             when is_integer(Interval), Interval > 0 ->
-    SendAfter = integer_to_binary(Interval),
-    emqx_broker:publish(WillMsg#message{topic = emqx_topic:join([<<"$will">>, SendAfter, Topic]), headers = Headers#{client_id => ClientId}});
+    emqx_delayed_publish:delay_publish(WillMsg, ClientId);
 send_willmsg(WillMsg, _ClientId) ->
     emqx_broker:publish(WillMsg).