anchor.diff:  			ExistXNest;
   		_ ->
   			{ok, NewXNest} = xnest:start_link(),
  -			ets:insert(?TAB, [{XNestName, NewXNest}]),
  -			ets:insert(?PID_INDEX, [{NewXNest, XNestName}]),
  +			ets:insert_new(?TAB, {XNestName, NewXNest}),
  +			ets:insert_new(?PID_INDEX, {NewXNest, XNestName}),
   			NewXNest	
   	end,
   	{reply, XNest, State};
  +
  +
   handle_call(_Request, _From, State) ->
   	{reply, ignored, State}.
   
  
positive.code: %% @doc Start the xnest_manager gen_server.
  -spec start_link() -> {ok, pid()}.
  start_link() ->
  	gen_server:start_link(?MODULE, [], []).
  
  %% @doc Get the xnest by name, a new one will be created if the specfied is not exists.
  -spec get_xnest(binary()) -> {ok, pid()}.
  get_xnest(XNestName) ->
  	gen_server:call(?MODULE, {get_xnest, XNestName}).
  
  %% @doc Get current xnest number.
  -spec get_xnest_count() -> integer().
  
negative.code: -module(xnest_manager).
  -include("lager.hrl").
  -behaviour(gen_server).
  
  %% API.
  