Global sample rate

README.md

@@ -79,6 +79,12 @@ Sampling is supported via the `:sample_rate` option:
 MyApp.Statix.increment("page_view", 1, sample_rate: 0.5)
 ```
 
+Or by setting global `:sample_rate` in config:
+```elixir
+config :statix,
+  sample_rate: 0.1
+```
+
 The UDP packet will only be sent to the server about half of the time,
 but the resulting value will be adjusted on the server according to the given sample rate.
 
@@ -113,6 +119,7 @@ The defaults are:
 * prefix: `nil`
 * host: `"127.0.0.1"`
 * port: `8125`
+* sample_rate: `1.0`
 
 __Note:__ by default, configuration is evaluated once, at compile time.
 If you plan using other configuration at runtime, you must specify the `:runtime_config` option:

lib/statix.ex

@@ -236,10 +236,12 @@ defmodule Statix do
       if Keyword.get(opts, :runtime_config, false) do
         quote do
           @statix_header_key Module.concat(__MODULE__, :__statix_header__)
+          @statix_sample_rate_key Module.concat(__MODULE__, :__statix_sample_rate__)
 
           def connect() do
             conn = Statix.new_conn(__MODULE__)
             Application.put_env(:statix, @statix_header_key, conn.header)
+            Application.put_env(:statix, @statix_sample_rate_key, conn.sample_rate)
 
             Statix.open_conn(conn)
             :ok
@@ -248,7 +250,8 @@ defmodule Statix do
           @compile {:inline, [current_conn: 0]}
           defp current_conn() do
             header = Application.fetch_env!(:statix, @statix_header_key)
-            %Statix.Conn{header: header, sock: __MODULE__}
+            sample_rate = Application.fetch_env!(:statix, @statix_sample_rate_key)
+            %Statix.Conn{header: header, sock: __MODULE__, sample_rate: sample_rate}
           end
         end
       else
@@ -320,10 +323,10 @@ defmodule Statix do
 
   @doc false
   def new_conn(module) do
-    {host, port, prefix} = load_config(module)
-    conn = Conn.new(host, port)
+    {host, port, prefix, sample_rate} = load_config(module)
+    conn = Conn.new(host, port, sample_rate)
     header = IO.iodata_to_binary([conn.header | prefix])
-    %{conn | header: header, sock: module}
+    %{conn | header: header, sock: module, sample_rate: sample_rate}
   end
 
   @doc false
@@ -335,7 +338,7 @@ defmodule Statix do
   @doc false
   def transmit(conn, type, key, val, options)
       when (is_binary(key) or is_list(key)) and is_list(options) do
-    sample_rate = Keyword.get(options, :sample_rate)
+    sample_rate = Keyword.get(options, :sample_rate, conn.sample_rate)
     if is_nil(sample_rate) or sample_rate >= :rand.uniform() do
       Conn.transmit(conn, type, key, to_string(val), options)
     else
@@ -353,8 +356,9 @@ defmodule Statix do
 
     host = Keyword.get(env, :host, "127.0.0.1")
     port = Keyword.get(env, :port, 8125)
+    sample_rate = Keyword.get(env, :sample_rate, 1.0)
     prefix = build_prefix(prefix1, prefix2)
-    {host, port, prefix}
+    {host, port, prefix, sample_rate}
   end
 
   defp build_prefix(part1, part2) do

lib/statix/conn.ex

@@ -1,18 +1,18 @@
 defmodule Statix.Conn do
   @moduledoc false
 
-  defstruct [:sock, :header]
+  defstruct [:sock, :header, :sample_rate]
 
   alias Statix.Packet
 
-  def new(host, port) when is_binary(host) do
-    new(string_to_charlist(host), port)
+  def new(host, port, sample_rate) when is_binary(host) do
+    new(string_to_charlist(host), port, sample_rate)
   end
 
-  def new(host, port) when is_list(host) or is_tuple(host) do
+  def new(host, port, sample_rate) when is_list(host) or is_tuple(host) do
     {:ok, addr} = :inet.getaddr(host, :inet)
     header = Packet.header(addr, port)
-    %__MODULE__{header: header}
+    %__MODULE__{header: header, sample_rate: sample_rate}
   end
 
   def open(%__MODULE__{} = conn) do
@@ -32,7 +32,7 @@ defmodule Statix.Conn do
       {:inet_reply, _port, status} -> status
     end
   end
-  
+
   if Version.match?(System.version(), ">= 1.3.0") do
     defp string_to_charlist(string), do: String.to_charlist(string)
   else