anchor.diff:  -behaviour(gen_server).
   
   -define(SAMPLE_SIZE, 61).
  --define(CACHE_MAXAGE, 750000). % max age of stuff in the cache in microsecs
  +-define(STATS_MAXAGE, 750000). % max age of stats in the cache in microsecs
  +-define(TOPKEYS_MAXAGE, 5000000). % max age of topkeys in the cache in microsecs
   
   %% API
   -export([start_link/0,
  
positive.code:                                   lists:member({H, P}, Servers)
                            end, OldTopkeys),
      Now = erlang:now(),
      Cache = dict:filter(fun (_K, {TS, _V}) -> timer:now_diff(Now, TS) < ?CACHE_MAXAGE end,
                          State#state.cache),
      {noreply, State#state{vals=Vals, topkeys=Topkeys, cache=Cache}};
  handle_info(Info, State) ->
      error_logger:info_msg("Just received ~p~n", [Info]),
  
negative.code:                                         State#state.vals))}),
      {reply, Reply, State};
  handle_call(Req = {get, Hostname, Port, Count}, _From, State) ->
      {Value, Cache} = cache_lookup(Req, State#state.cache, ?STATS_MAXAGE,
                                    fun () -> do_get(Hostname, Port, Count,
                                                     State) end),
      {reply, Value, State#state{cache=Cache}};
  handle_call(Req = {get, Bucket, Count}, _From, State) ->
      {Value, Cache} = cache_lookup(Req, State#state.cache, ?STATS_MAXAGE,
                                    fun () -> do_get(Bucket, Count,
                                                     State) end),
      {reply, Value, State#state{cache=Cache}};
  handle_call(Req = {get, Count}, _From, State) ->
      {Value, Cache} = cache_lookup(Req, State#state.cache, ?STATS_MAXAGE,
                                    fun () -> do_get(Count,
                                                     State) end),
      {reply, Value, State#state{cache=Cache}};
  handle_call(Req = {get_topkeys, Bucket}, _From, State) ->
      {Value, Cache} = cache_lookup(Req, State#state.cache, ?TOPKEYS_MAXAGE,
                                    fun () -> do_get_topkeys(Bucket,
                                                             State) end),
      {reply, Value, State#state{cache=Cache}};
  