Don't request the whole MUC room state in get_room_occupants_number command (#3684) (#1964)

src/mod_muc_admin.erl

@@ -1050,8 +1050,8 @@ get_room_occupants(Pid) ->
 get_room_occupants_number(Room, Host) ->
     case get_room_pid(Room, Host) of
 	Pid when is_pid(Pid )->
-	    S = get_room_state(Pid),
-	    maps:size(S#state.users);
+	    {ok, #{occupants_number := N}} = mod_muc_room:get_info(Pid),
+	    N;
 	_ ->
 	    throw({error, room_not_found})
     end.

src/mod_muc_room.erl

@@ -49,6 +49,7 @@
 	 get_config/1,
 	 set_config/2,
 	 get_state/1,
+	 get_info/1,
 	 change_item/5,
 	 change_item_async/5,
 	 config_reloaded/1,
@@ -217,6 +218,17 @@ get_state(Pid) ->
 	    {error, notfound}
     end.
 
+-spec get_info(pid()) -> {ok, #{occupants_number => integer()}} |
+                         {error, notfound | timeout}.
+get_info(Pid) ->
+    try
+        {ok, p1_fsm:sync_send_all_state_event(Pid, get_info)}
+    catch _:{timeout, {p1_fsm, _, _}} ->
+	    {error, timeout};
+	  _:{_, {p1_fsm, _, _}} ->
+	    {error, notfound}
+    end.
+
 -spec subscribe(pid(), jid(), binary(), [binary()]) -> {ok, [binary()]} | {error, binary()}.
 subscribe(Pid, JID, Nick, Nodes) ->
     try p1_fsm:sync_send_all_state_event(Pid, {muc_subscribe, JID, Nick, Nodes})
@@ -721,6 +733,10 @@ handle_sync_event(get_config, _From, StateName,
 handle_sync_event(get_state, _From, StateName,
 		  StateData) ->
     {reply, {ok, StateData}, StateName, StateData};
+handle_sync_event(get_info, _From, StateName,
+		  StateData) ->
+    Result = #{occupants_number => maps:size(StateData#state.users)},
+    {reply, Result, StateName, StateData};
 handle_sync_event({change_config, Config}, _From,
 		  StateName, StateData) ->
     {result, undefined, NSD} = change_config(Config, StateData),