Measure packet cache and UDP and TCP handoffs.

ebin/erldns.app

@@ -1,6 +1,6 @@
 {application,erldns,
              [{description,"Erlang Authoritative DNS Server"},
-              {vsn,"3afafd3"},
+              {vsn,"5321c5a"},
               {mod,{erldns_app,[]}},
               {applications,[kernel,stdlib,inets,crypto,ssl,folsom]},
               {start_phases,[{post_start,[]}]},

src/erldns_app.erl

@@ -52,11 +52,22 @@ get_metrics() ->
     end, folsom_metrics:get_metrics()).
 
 get_stats() ->
-  folsom_metrics:get_histogram_statistics(request_handled_histogram).
+  Histograms = [udp_handoff_histogram, tcp_handoff_histogram, request_handled_histogram],
+  lists:map(
+    fun(Name) ->
+        {Name, folsom_metrics:get_histogram_statistics(Name)}
+    end, Histograms).
 
 define_metrics() ->
+  folsom_metrics:new_histogram(udp_handoff_histogram),
+  folsom_metrics:new_histogram(tcp_handoff_histogram),
+
   folsom_metrics:new_counter(request_throttled_counter),
   folsom_metrics:new_meter(request_throttled_meter),
   folsom_metrics:new_histogram(request_handled_histogram),
 
+  folsom_metrics:new_meter(cache_hit_meter),
+  folsom_metrics:new_meter(cache_expired_meter),
+  folsom_metrics:new_meter(cache_miss_meter),
+
   folsom_metrics:get_metrics().

src/erldns_packet_cache.erl

@@ -48,11 +48,14 @@ handle_call({get_packet, Question, _Host}, _From, State) ->
       {_,T,_} = erlang:now(),
       case T > ExpiresAt of
         true ->
+          folsom_metrics:notify(cache_expired_meter, 1),
           {reply, {error, cache_expired}, State};
         false ->
+          folsom_metrics:notify(cache_hit_meter, 1),
           {reply, {ok, Response}, State}
       end;
     _ ->
+      folsom_metrics:notify(cache_miss_meter, 1),
       {reply, {error, cache_miss}, State}
   end;
 

src/erldns_tcp_server.erl

@@ -15,6 +15,9 @@
     code_change/3
   ]).
 
+% Internal API
+-export([handle_request/2]).
+
 -define(SERVER, ?MODULE).
 
 -record(state, {port, socket}).
@@ -33,9 +36,7 @@ handle_call(_Request, _From, State) ->
 handle_cast(_Message, State) ->
   {noreply, State}.
 handle_info({tcp, Socket, Bin}, State) ->
-  poolboy:transaction(tcp_worker_pool, fun(Worker) ->
-    gen_server:call(Worker, {tcp_query, Socket, Bin})
-  end),
+  folsom_metrics:histogram_timed_update(tcp_handoff_histogram, ?MODULE, handle_request, [Socket, Bin]),
   {noreply, State};
 handle_info(_Message, State) ->
   {noreply, State}.
@@ -49,4 +50,7 @@ new_connection(Socket, State) ->
 code_change(_PreviousVersion, State, _Extra) ->
   {ok, State}.
 
-
+handle_request(Socket, Bin) ->
+  poolboy:transaction(tcp_worker_pool, fun(Worker) ->
+    gen_server:call(Worker, {tcp_query, Socket, Bin})
+  end).

src/erldns_udp_server.erl

@@ -37,7 +37,7 @@ handle_info(timeout, State) ->
   %lager:info("UDP instance timed out"),
   {noreply, State};
 handle_info({udp, Socket, Host, Port, Bin}, State) ->
-  Response = handle_request(Socket, Host, Port, Bin, State),
+  Response = folsom_metrics:histogram_timed_update(udp_handoff_histogram, ?MODULE, handle_request, [Socket, Host, Port, Bin, State]),
   inet:setopts(State#state.socket, [{active, once}]),
   Response;
 handle_info(_Message, State) ->