Make the metric name be the first element output

README.md

@@ -276,6 +276,7 @@ Code contributors include:
 
 ### 1.0.0
 
+* Ensure that metric name is the first element output
 * Bump dev env to modern versions of Elixir (v1.16.3) 
 * Clean up dependencies
 * Be more explicit internally with map vs. keyword list manipulation

lib/metrix.ex

@@ -60,28 +60,20 @@ defmodule Metrix do
   def count(metric, num) when is_number(num), do: count(%{}, metric, num)
   def count(metadata, metric), do: count(metadata, metric, 1)
   def count(metadata, metric, num) do
-    metadata
-    |> add("count", metric, num)
-    |> log
-
+    log(format_metric("count", metric, num), metadata)
     metadata
   end
 
   def sample(metric, value), do: sample(%{}, metric, value)
   def sample(metadata, metric, value) do
-    metadata
-    |> add("sample", metric, value)
-    |> log
-
+    log(format_metric("sample", metric, value), metadata)
     metadata
   end
 
   def measure(metric, ms) when is_number(ms), do: measure(%{}, metric, ms)
   def measure(metric, fun) when is_function(fun), do: measure(%{}, metric, fun)
   def measure(metadata, metric, ms) when is_number(ms) do
-    metadata
-    |> add("measure", metric, "#{ms}ms")
-    |> log
+    log(format_metric("measure", metric, "#{ms}ms"), metadata)
   end
   def measure(metadata, metric, fun) when is_function(fun) do
 
@@ -90,22 +82,23 @@ defmodule Metrix do
       is_function(fun, 1) -> :timer.tc(fun, [metadata])
     end
 
-    metadata
-    |> add("measure", metric, "#{service_us / 1000}ms")
-    |> log
+    log(format_metric("measure", metric, "#{service_us / 1000}ms"), metadata)
 
     ret_value
   end
 
-  defp add(list, type, metric, value) when is_list(list), do: add(Enum.into(list, %{}), type, metric, value)
-  defp add(map, type, metric, value) when is_map(map) do
-    Map.put(map, prefix_metric(type, metric), value)
+  defp format_metric(type, metric, value) do
+    Logfmt.encode(Map.put(%{}, prefix_metric(type, metric), value))
   end
 
-  defp log(values = %{}) do
-    Map.merge(values, get_context())
-    |> Logfmt.encode
-    |> write
+  defp log(formatted_metric, metadata) do
+    metadata_with_context =
+      metadata
+      |> Enum.into(%{})
+      |> Map.merge(get_context())
+      |> Logfmt.encode
+
+    write("#{formatted_metric} #{metadata_with_context}")
   end
 
   defp prefix_metric(type, metric) do

test/metrix_test.exs

@@ -25,6 +25,7 @@ defmodule MetrixTest do
       for metadata <- [%{"meta" => "data"}, [meta: "data"]] do
         for event <- ["event_name", :event_name] do
           output = line(fn -> Metrix.count(metadata, event) end)
+          assert matches_count?(output, event)
           assert output |> String.contains?("count#event_name=1")
           assert output |> String.contains?("meta=data")
           line(fn -> assert Metrix.count(metadata, event) == metadata end)
@@ -42,7 +43,7 @@ defmodule MetrixTest do
       for metadata <- [%{"meta" => "data"}, [meta: "data"]] do
         for event <- ["event_name", :event_name] do
           output = line(fn -> Metrix.count(metadata, event, 23) end)
-          assert output |> String.contains?("count#event_name=23")
+          assert matches_count?(output, event)
           assert output |> String.contains?("meta=data")
           line(fn -> assert Metrix.count(metadata, event, 1) == metadata end)
         end
@@ -55,6 +56,7 @@ defmodule MetrixTest do
         for metadata <- [%{"meta" => "data"}, [meta: "data"]] do
           for event <- ["event_name", :event_name] do
             output = line(fn -> Metrix.count(metadata, event, 23) end)
+            assert matches_count?(output, event)
             assert output |> String.contains?("count#event_name=23")
             assert output |> String.contains?("meta=data")
             assert output |> String.contains?("context=global")
@@ -84,6 +86,7 @@ defmodule MetrixTest do
       for metadata <- [%{"meta" => "data"}, [meta: "data"]] do
         for event <- ["event_name", :event_name] do
           output = line(fn -> Metrix.sample metadata, event, "13.4mb" end)
+          assert matches_sample?(output, event)
           assert output |> String.contains?("sample#event_name=13.4mb")
           assert output |> String.contains?("meta=data")
           line(fn -> assert Metrix.sample(metadata, event, "13.4mb") == metadata end)
@@ -97,6 +100,7 @@ defmodule MetrixTest do
         for metadata <- [%{"meta" => "data"}, [meta: "data"]] do
           for event <- ["event_name", :event_name] do
             output = line(fn -> Metrix.sample(metadata, event, "13.4mb") end)
+            assert matches_sample?(output, event)
             assert output |> String.contains?("sample#event_name=13.4mb")
             assert output |> String.contains?("meta=data")
             assert output |> String.contains?("context=global")
@@ -156,22 +160,22 @@ defmodule MetrixTest do
     test "with map metadata passed to function" do
       metadata = %{"meta" => "data"}
       output = line(fn -> Metrix.measure(metadata, "event.name", fn %{"meta" => _data} -> :timer.sleep(1) end) end)
-      assert matches_measure?(output), "Unexpected output format \"#{output}\""
+      assert matches_measure?(output, "event.name"), "Unexpected output format \"#{output}\""
       assert output |> String.contains?("meta=data")
     end
 
     test "with keyword list metadata passed to function" do
       metadata = [meta: "data"]
       output = line(fn -> Metrix.measure(metadata, "event.name", fn [meta: _data] -> :timer.sleep(1) end) end)
-      assert matches_measure?(output), "Unexpected output format \"#{output}\""
+      assert matches_measure?(output, "event.name"), "Unexpected output format \"#{output}\""
       assert output |> String.contains?("meta=data")
     end
 
     test "with metadata and global context" do
       Metrix.add_context %{"meta" => "data_global"}
       for metadata <- [%{"meta" => "data"}, [meta: "data"]] do
         output = line(fn -> Metrix.measure metadata, "event.name", fn -> :timer.sleep(1) end end)
-        assert matches_measure?(output), "Unexpected output format \"#{output}\""
+        assert matches_measure?(output, "event.name"), "Unexpected output format \"#{output}\""
         assert output |> String.contains?("meta=data")
       end
     end
@@ -180,7 +184,7 @@ defmodule MetrixTest do
       Metrix.add_context %{"meta" => "data_global"}
       for metadata <- [%{"meta" => "data"}, [meta: "data"]] do
         output = line(fn -> Metrix.measure metadata, "event.name", 78 end)
-        assert matches_measure?(output), "Unexpected output format \"#{output}\""
+        assert matches_measure?(output, "event.name"), "Unexpected output format \"#{output}\""
         assert output |> String.contains?("meta=data")
         assert output |> String.contains?("=78ms"), "Incorrect measurement value"
       end

test/test_helper.exs

@@ -10,10 +10,19 @@ defmodule MetrixTestHelper do
   def line(fun), do: capture_log(fun) |> String.trim
   def silence(fun), do: capture_log(fun); nil
 
-  def matches_measure?(output), do: matches_measure?(output, "event.name")
   def matches_measure?(output, event), do: matches_measure?(output, event, "")
   def matches_measure?(output, event, prefix) do
-    Regex.match?(~r/measure##{prefix}#{event}=[0-9]+\.*+[0-9]+ms/u, output)
+    Regex.match?(~r/^measure##{prefix}#{event}=[0-9]+\.*+[0-9]+ms/u, output)
+  end
+
+  def matches_count?(output, event), do: matches_count?(output, event, "")
+  def matches_count?(output, event, prefix) do
+    Regex.match?(~r/^count##{prefix}#{event}=[0-9]+/u, output)
+  end
+
+  def matches_sample?(output, event), do: matches_sample?(output, event, "")
+  def matches_sample?(output, event, prefix) do
+    Regex.match?(~r/^sample##{prefix}#{event}=[0-9]+/u, output)
   end
 
   # All the machinations needed to start an app with a known config