Removed RED functionnality + Refactored code (iolists)

src/statsderl.app.src

@@ -1,6 +1,6 @@
 {application, statsderl, [
   {description, "StatsD client"},
-  {vsn, "0.2"},
+  {vsn, "0.3"},
   {registered, []},
   {applications, [
     kernel,

src/statsderl.erl

@@ -2,8 +2,6 @@
 -behaviour(gen_server).
 
 -define(SERVER, ?MODULE).
--define(LOW_BACKLOG, 5000).
--define(HIGH_BACKLOG, 10000).
 
 -record(state, {
     hostname,
@@ -16,7 +14,8 @@
 %% API Function Exports
 %% ------------------------------------------------------------------
 
--export([start_link/1, increment/3, decrement/3, timing/3, timing_now/3]).
+-export([start_link/0, increment/3, decrement/3, timing/3,
+        timing_now/3]).
 
 %% ------------------------------------------------------------------
 %% gen_server Function Exports
@@ -29,51 +28,47 @@
 %% API Function Definitions
 %% ------------------------------------------------------------------
 
-start_link(BaseKey) ->
-    gen_server:start_link({local, ?SERVER}, ?MODULE, BaseKey, []).
-
-increment(Key, Magnitude, SampleRate) ->
-    Stats = io_lib:format("~s:~B|c|@~f", [Key, Magnitude, SampleRate]),
-    udp_send(Stats, SampleRate).
-
-decrement(Key, Magnitude, SampleRate) ->
-    Stats = io_lib:format("~s:-~B|c|@~f", [Key, Magnitude, SampleRate]),
-    udp_send(Stats, SampleRate).
+start_link() ->
+    gen_server:start_link({local, ?SERVER}, ?MODULE, [], []).
+
+increment(Key, Value, SampleRate) ->
+    send(increment, Key, Value, SampleRate).
+
+decrement(Key, Value, SampleRate) ->
+    send(decrement, Key, Value, SampleRate).
 
 timing(Key, Value, SampleRate) ->
-    Stats = io_lib:format("~s:~B|ms|@~f", [Key, Value, SampleRate]),
-    udp_send(Stats, SampleRate).   
+    send(timing, Key, Value, SampleRate).
 
 timing_now(Key, Timestamp, SampleRate) ->
-    Value = timer:now_diff(erlang:now(), Timestamp) div 1000,
-    timing(Key, Value, SampleRate).   
+    timing(Key, now_diff_ms(Timestamp), SampleRate).
 
 %% ------------------------------------------------------------------
 %% gen_server Function Definitions
 %% ------------------------------------------------------------------
 
-init(BaseKey) ->
+init(_Args) ->
     {ok, Hostname} = application:get_env(statsderl, hostname),
     {ok, Port} = application:get_env(statsderl, port),
+    BaseKey = case application:get_env(statsderl, base_key) of
+        {ok, Key} -> [Key, $.];
+        undefined -> <<"">>
+    end,
     {ok, Socket} = gen_udp:open(0, [{active, false}]),
     State = #state {
         hostname = Hostname,
         port = Port,
-        socket = Socket,
-        basekey = case BaseKey of
-            "" -> "";
-            _ -> [BaseKey, $.]
-        end
+        basekey = BaseKey,
+        socket = Socket
     },
     {ok, State}.
 
 handle_call(_Request, _From, State) ->
     {noreply, ok, State}.
 
-handle_cast({udp_send, Stats},
-            #state{hostname=Hostname, port=Port, socket=Socket, basekey=BaseKey}=State) ->
-    gen_udp:send(Socket, Hostname, Port, [BaseKey, Stats]),
-    decrease_backlog(),
+handle_cast({send, Packet}, State=#state{hostname=Hostname,
+        port=Port, socket=Socket, basekey=BaseKey}) ->
+    gen_udp:send(Socket, Hostname, Port, [BaseKey, Packet]),
     {noreply, State};
 handle_cast(_Msg, State) ->
     {noreply, State}.
@@ -91,51 +86,33 @@ code_change(_OldVsn, State, _Extra) ->
 %% Internal Function Definitions
 %% ------------------------------------------------------------------
 
-udp_send(Stats, SampleRate) ->
-    case sample(SampleRate) of
+send(Method, Key, Value, SampleRate) ->
+    random:seed(erlang:now()),
+    case random:uniform() =< SampleRate of
         true ->
-            increase_backlog(),
-            gen_server:cast(?MODULE, {udp_send, Stats});
+            Packet = generate_packet(Method, Key, Value, SampleRate),
+            gen_server:cast(?MODULE, {send, Packet});
         false ->
             ok
     end.
 
-sample(SampleRate) ->
-    case red() of
-        true ->
-            false;
-        false ->
-            random:seed(erlang:now()),
-            random:uniform() =< SampleRate
-    end.
-
-%% ------------------------------------------------------------------
-%% Random Early Drop
-%% http://en.wikipedia.org/wiki/Random_early_detection
-%% ------------------------------------------------------------------
-
-red() ->
-    Requests = ets:lookup_element(statsderl, backlog, 2),
-    case Requests of
-        _ when ?LOW_BACKLOG >= Requests->
-            false;
-        _ when Requests >= ?HIGH_BACKLOG ->
-            true;
-        _ ->
-            random_drop_function(Requests)
-    end.
-
-random_drop_function(Requests) ->
-    Distribution = ?HIGH_BACKLOG - Requests,
-    case erlang:phash2({self(), now()}, Distribution) + 1 of
-        Distribution ->
-            true;
-        _ ->
-            false
-    end.
-
-increase_backlog() ->
-    ets:update_counter(statsderl, backlog, 1).
-
-decrease_backlog() ->
-    ets:update_counter(statsderl, backlog, -1).
+now_diff_ms(Timestamp) ->
+    timer:now_diff(os:timestamp(), Timestamp) div 1000.
+
+generate_packet(Method, Key, Value, SampleRate) ->
+    BinSampleRate =
+        case SampleRate >= 1 of
+            true ->
+                <<"">>;
+            false ->
+                [<<"|@">>, io_lib:format("~.3f", [SampleRate])]
+        end,
+    BinValue = list_to_binary(integer_to_list(Value)),
+    case Method of
+        increment ->
+            [Key, <<":">>, BinValue, <<"|c">>, BinSampleRate];
+        decrement ->
+            [Key, <<":-">>, BinValue, <<"|c">>, BinSampleRate];
+        timing ->
+            [Key, <<":">>, BinValue, <<"|ms">>, BinSampleRate]
+    end.

src/statsderl_sup.erl

@@ -10,31 +10,18 @@
 -export([init/1]).
 
 %% Helper macro for declaring children of supervisor
--define(CHILD(I, Type, Args), {I, {I, start_link, Args}, permanent, 5000, Type, [I]}).
+-define(CHILD(I, Type), {I, {I, start_link, []}, permanent, 5000, Type, [I]}).
 
 %% ===================================================================
 %% API functions
 %% ===================================================================
 
 start_link() ->
-    init_red(),
-    BaseKey = case application:get_env(statsderl, base_key) of
-        {ok, Key} -> Key;
-        undefined -> ""
-    end,
-    supervisor:start_link({local, ?MODULE}, ?MODULE, BaseKey).
+    supervisor:start_link({local, ?MODULE}, ?MODULE, []).
 
 %% ===================================================================
 %% Supervisor callbacks
 %% ===================================================================
 
-init(BaseKey) ->
-    {ok, { {one_for_one, 5, 10}, [?CHILD(statsderl, worker, [BaseKey])]} }.
-
-%% ------------------------------------------------------------------
-%% Internal Function Definitions
-%% ------------------------------------------------------------------
-
-init_red() ->
-    statsderl = ets:new(statsderl, [set, public, named_table, {read_concurrency, true}]),
-    true = ets:insert(statsderl, {backlog, 0}).
+init(_Args) ->
+    {ok, { {one_for_one, 5, 10}, [?CHILD(statsderl, worker)]} }.