anchor.diff:  
   -define(SERVER, ?MODULE).
   
  +-type backend_conns() :: #{inet:ip4_address() => [#ip_vs_conn{}]}.
  +
   -record(state, {
  -          conns = maps:new() :: conn_map()
  +          conns = maps:new() :: conn_map(),
  +          backend_conns = maps:new() :: backend_conns()
       }).
   
   -spec(start_link() ->
  
positive.code: get_p99s(Conns, Metrics) ->
      lists:flatmap(fun (M) -> get_p99_updates(Conns, M) end, Metrics).
  
  get_p99_updates(Conns, {netlink,tcp_metrics,_, _, _, {get,_,_,Attrs}}) ->
      match_metrics(Conns, proplists:get_value(d_addr, Attrs), proplists:get_value(vals, Attrs)).
  
  match_metrics(_, undefined, _) -> [];
  match_metrics(_, _, undefined) -> [];
  match_metrics(Conns, Addr, Vals) -> match_conn(maps:get(Addr, Conns, undefined),
                                                 proplists:get_value(rtt_us, Vals), 
                                                 proplists:get_value(rtt_var_us, Vals)).
  match_conn(undefined, _, _) -> [];
  match_conn(_, undefined, _) -> [];
  
negative.code:     {noreply, NewState :: #state{}, timeout() | hibernate} |
      {stop, Reason :: term(), NewState :: #state{}}).
  handle_info(push_metrics, State = #state{}) ->
      {NewConns, NewBCs} = check_connections(State#state.conns, State#state.backend_conns),
      erlang:send_after(splay_ms(), self(), push_metrics),
      {noreply, State#state{conns = NewConns, backend_conns = NewBCs}};
  handle_info(_Info, State) ->
      {noreply, State}.
  
  