Add distribution method

lib/github/statsd.rb

@@ -91,6 +91,7 @@ def namespace=(namespace)
     TIMING_TYPE = "ms".freeze
     GAUGE_TYPE = "g".freeze
     HISTOGRAM_TYPE = "h".freeze
+    DISTRIBUTION_TYPE = "d".freeze
 
     def initialize(client_class = nil)
       @shards = []
@@ -187,6 +188,11 @@ def time(stat, sample_rate=1)
     # statsd server then uses the sample_rate to correctly track the average
     # for the stat.
     def histogram(stat, value, sample_rate=1); send stat, value, HISTOGRAM_TYPE, sample_rate end
+
+    # A modified gauge that submits a distribution of values over a sample period.
+    # Arithmetic and statistical calculations (percetiles, average, etc.) on the data set
+    # are peformed server side rather than client side like a histogram.
+    def distribution(stat, value, sample_rate=1); send stat, value, DISTRIBUTION_TYPE, sample_rate end
 
     private
     def sampled(sample_rate)

spec/statsd_spec.rb

@@ -68,6 +68,13 @@ class << @statsd
     end
   end
 
+  describe "#distribution" do
+    it "should format the message according to the statsd spec" do
+      @statsd.distribution('foobar', 500)
+      @statsd.shards.first.recv.must_equal ["foobar:500|d"]
+    end
+  end
+
   describe "#time" do
     it "should format the message according to the statsd spec" do
       @statsd.time('foobar') { sleep(0.001); 'test' }