Cleaned up selection of librato metics

lib/metriks/reporter/librato_metrics.rb

@@ -15,6 +15,12 @@ def initialize(email, token, options = {})
       @registry  = options[:registry] || Metriks::Registry.default
       @time_tracker = Metriks::TimeTracker.new(options[:interval] || 60)
       @on_error  = options[:on_error] || proc { |ex| }
+
+      if options[:only] and options[:except]
+        raise 'Can only specify one of :only or :except'
+      end
+      @only     = options[:only] || []
+      @except   = options[:except] || []
     end
 
     def start
@@ -43,7 +49,7 @@ def restart
       start
     end
 
-    def write
+    def prepare_metrics
       gauges = []
       @registry.each do |name, metric|
         gauges << case metric
@@ -84,9 +90,13 @@ def write
       end
 
       gauges.flatten!
+      gauges
+    end
 
+    def write
+      gauges = prepare_metrics
       unless gauges.empty?
-        submit(form_data(gauges.flatten))
+        submit(form_data(gauges))
       end
     end
 
@@ -146,6 +156,15 @@ def prepare_metric(base_name, metric, keys, snapshot_keys = [])
         base_name = "#{@prefix}.#{base_name}"
       end
 
+      if @only.any?
+        keys = keys & @only
+        snapshot_keys = snapshot_keys & @only
+      end
+      if @except.any?
+        keys = keys - @except
+        snapshot_keys = snapshot_keys - @except
+      end
+
       keys.flatten.each do |key|
         name = key.to_s.gsub(/^get_/, '')
         value = metric.send(key)

test/librato_metrics_reporter_test.rb

@@ -31,4 +31,23 @@ def test_write
 
     @reporter.write
   end
-end
+
+  def assert_generated(count, options)
+    @registry.timer('timer.testing').update(1.5)
+
+    metrics = build_reporter(options).prepare_metrics
+    assert_equal(count, metrics.length)
+  end
+
+  def test_no_filters
+    assert_generated(11, {})
+  end
+
+  def test_only
+    assert_generated(2, {:only => [:count, :median]})
+  end
+
+  def test_except
+    assert_generated(9, {:except => [:count, :median]})
+  end
+end