tests are green

lib/prometheus/error.ex

@@ -140,6 +140,18 @@ defmodule Prometheus.MissingMetricSpecKeyError do
   end
 end
 
+defmodule Prometheus.InvalidBlockArityError do
+  @moduledoc """
+  Raised when fn passed as block has more then 0 arguments
+  """
+  defexception [:args]
+
+  def message(%{args: args}) do
+    insp = Enum.map_join(args, ", ", &inspect/1)
+    "Fn with arity #{length(args)} (args: #{insp}) passed as block."
+  end
+end
+
 defmodule Prometheus.Error do
   @moduledoc false
 

lib/prometheus/injector.ex

@@ -14,7 +14,18 @@ defmodule Prometheus.Injector do
 
   # lambda
   def inject_({:fn, fn_meta, [{:->, arrow_meta, [args, do_block]}]}, callback) do
-    {:fn, fn_meta, [{:->, arrow_meta, [args, callback.(do_block)]}]}
+    case args do
+      [] ->
+        callback.({{:., [],
+                    [{:fn, fn_meta,
+                       [{:->, arrow_meta,
+                        [[], do_block]}]}]}, [],
+                   []})
+      _ ->
+        names = args
+        |> Enum.map(fn({name, _, _}) -> name end)
+        raise Prometheus.InvalidBlockArityError, args: names
+    end
   end
 
   # do_blocks can be simple calls or defs
@@ -23,7 +34,7 @@ defmodule Prometheus.Injector do
     if have_defs(do_blocks) do
       Enum.map(do_blocks, &inject_to_def(&1, callback))
     else
-      [{:do, callback.({:__block__, [], do_blocks})}]
+       callback.({:__block__, [], do_blocks})
     end
   end
 
@@ -44,7 +55,7 @@ defmodule Prometheus.Injector do
     end
   end
 
-  # single dos, or other non-block stuff like function calls
+  # single do, or other non-block stuff like function calls
   def inject_(thing, callback) do
     inject_([{:do, {:__block__, [], [thing]}}], callback)
   end
@@ -74,10 +85,10 @@ defmodule Prometheus.Injector do
   defp inject_to_def({:def, def_meta, [head, [do: body]]}, callback) do
     {:def, def_meta, [head, [do: callback.(body)]]}
   end
-  defp inject_to_def({:def, def_meta, [head, [{:do, _do_block} | rest] = all]}, callback) do
+  defp inject_to_def({:def, def_meta, [head, [{:do, _do_block} | _rest] = all]}, callback) do
     {:def, def_meta, [head, [do: callback.(
                                    quote do
                                      try unquote(all)
-                                 end)]]}
+                                   end)]]}
   end
 end

lib/prometheus/metric/counter.ex

@@ -160,6 +160,7 @@ defmodule Prometheus.Metric.Counter do
     env = __CALLER__
     Prometheus.Injector.inject(fn(block) ->
       quote do
+        require Prometheus.Error
         try do
           unquote(block)
         else

lib/prometheus/metric/gauge.ex

@@ -158,33 +158,48 @@ defmodule Prometheus.Metric.Gauge do
   end
 
   @doc """
-  Sets the gauge identified by `spec` to the number of currently executing `fun`s.
+  Sets the gauge identified by `spec` to the number of currently executing `body`s.
 
   Raises `Prometheus.UnknownMetricError` exception if a gauge
   for `spec` can't be found.<br>
   Raises `Prometheus.InvalidMetricArityError` exception if labels count mismatch.
   Raises `Prometheus.InvalidValueError` exception if fun isn't a function or block.
   """
-  defmacro track_inprogress(spec, fun) do
-    Erlang.metric_call(spec, [Erlang.ensure_fn(fun)])
-  end
-
-  defmacro track_inprogress(spec) do
-    quote do
-      @instrument {unquote(__MODULE__), :track_inprogress, unquote(spec)}
-    end
+  defmacro track_inprogress(spec, body) do
+    env = __CALLER__
+    Prometheus.Injector.inject(fn(block) ->
+      quote do
+        Prometheus.Metric.Gauge.inc(unquote(spec))
+        try do
+          unquote(block)
+        after
+          Prometheus.Metric.Gauge.dec(unquote(spec))
+        end
+      end
+    end, env, body)
   end
 
   @doc """
-  Tracks the amount of time spent executing `fun`.
+  Tracks the amount of time spent executing `body`.
 
   Raises `Prometheus.UnknownMetricError` exception if a gauge
   for `spec` can't be found.<br>
   Raises `Prometheus.InvalidMetricArityError` exception if labels count mismatch.
   Raises `Prometheus.InvalidValueError` exception if `fun` isn't a function or block.
   """
-  defmacro set_duration(spec, fun) do
-    Erlang.metric_call(spec, [Erlang.ensure_fn(fun)])
+  defmacro set_duration(spec, body) do
+    env = __CALLER__
+    Prometheus.Injector.inject(fn(block) ->
+      quote do
+        start_time = :erlang.monotonic_time()
+        try do
+          unquote(block)
+        after
+          end_time = :erlang.monotonic_time()
+          Prometheus.Metric.Gauge.set(unquote(spec), end_time - start_time)
+        end
+      end
+    end, env, body)
   end
 
   @doc """
@@ -223,4 +238,3 @@ defmodule Prometheus.Metric.Gauge do
     Erlang.metric_call(spec)
   end
 end
-

lib/prometheus/metric/histogram.ex

@@ -129,8 +129,19 @@ defmodule Prometheus.Metric.Histogram do
   Raises `Prometheus.InvalidMetricArityError` exception if labels count mismatch.
   Raises `Prometheus.InvalidValueError` exception if fun isn't a function or block.
   """
-  defmacro observe_duration(spec, fun) do
-    Erlang.metric_call(spec, [Erlang.ensure_fn(fun)])
+  defmacro observe_duration(spec, body) do
+    env = __CALLER__
+    Prometheus.Injector.inject(fn(block) ->
+      quote do
+        start_time = :erlang.monotonic_time()
+        try do
+          unquote(block)
+        after
+          end_time = :erlang.monotonic_time()
+          Prometheus.Metric.Histogram.observe(unquote(spec), end_time - start_time)
+        end
+      end
+    end, env, body)
   end
 
   @doc """

lib/prometheus/metric/summary.ex

@@ -108,8 +108,19 @@ defmodule Prometheus.Metric.Summary do
   Raises `Prometheus.InvalidMetricArityError` exception if labels count mismatch.
   Raises `Prometheus.InvalidValueError` exception if `fun` isn't a function or block.
   """
-  defmacro observe_duration(spec, fun) do
-    Erlang.metric_call(spec, [Erlang.ensure_fn(fun)])
+  defmacro observe_duration(spec, body) do
+    env = __CALLER__
+    Prometheus.Injector.inject(fn(block) ->
+      quote do
+        start_time = :erlang.monotonic_time()
+        try do
+          unquote(block)
+        after
+          end_time = :erlang.monotonic_time()
+          Prometheus.Metric.Summary.observe(unquote(spec), end_time - start_time)
+        end
+      end
+    end, env, body)
   end
 
   @doc """

test/metric/injector_test.exs → test/injector_test.exs

@@ -29,7 +29,6 @@ defmodule Prometheus.InjectorTest do
       IO.puts("fun2")
     end
 
-
     Injector.test do
       def fun3() do
         IO.puts("fun3")
@@ -51,7 +50,9 @@ defmodule Prometheus.InjectorTest do
   end
 
   test "fn" do
-    assert capture_io(Injector.test(fn () -> IO.puts("qwe") end)) ==
+    assert capture_io(fn ->
+      Injector.test(fn () -> IO.puts("qwe") end)
+    end) ==
       "before block\nqwe\nafter block\n"
   end
 

test/metric/gauge_test.exs

@@ -88,17 +88,21 @@ defmodule Prometheus.GaugeTest do
     end
 
     ## track_inprogress
-    assert_raise Prometheus.InvalidValueError,
-      "Invalid value: \"qwe\" (track_inprogress accepts only functions).",
+    assert_raise Prometheus.InvalidBlockArityError,
+      "Fn with arity 2 (args: :x, :y) passed as block.",
     fn ->
-      Gauge.track_inprogress(spec, "qwe")
+      Macro.expand(quote do
+        Gauge.track_inprogress(spec, fn(x, y) -> 1 + x + y end)
+      end, __ENV__)
     end
 
     ## set_duration
-    assert_raise Prometheus.InvalidValueError,
-      "Invalid value: \"qwe\" (set_duration accepts only functions).",
+    assert_raise Prometheus.InvalidBlockArityError,
+      "Fn with arity 2 (args: :x, :y) passed as block.",
     fn ->
-      Gauge.set_duration(spec, "qwe")
+      Macro.expand(quote do
+        Gauge.set_duration(spec, fn(x, y) -> 1 + x + y end)
+      end, __ENV__)
     end
   end
 

test/metric/histogram_test.exs

@@ -91,13 +91,6 @@ defmodule Prometheus.HistogramTest do
     fn ->
       Histogram.dobserve(spec, "qwe")
     end
-
-    ## observe_duration
-    assert_raise Prometheus.InvalidValueError,
-      "Invalid value: \"qwe\" (observe_duration accepts only functions).",
-    fn ->
-      Histogram.observe_duration(spec, "qwe")
-    end
   end
 
   test "mf/arity errors" do
@@ -178,6 +171,15 @@ defmodule Prometheus.HistogramTest do
     fn ->
       Histogram.value([name: :metric_with_label, labels: [:l1, :l2]])
     end
+
+    ## observe_duration
+    assert_raise Prometheus.InvalidBlockArityError,
+      "Fn with arity 2 (args: :x, :y) passed as block.",
+    fn ->
+      Macro.expand(quote do
+        Histogram.observe_duration(spec, fn(x, y) -> 1 + x + y end)
+      end, __ENV__)
+    end
   end
 
   test "observe" do

test/metric/summary_test.exs

@@ -67,10 +67,12 @@ defmodule Prometheus.SummaryTest do
     end
 
     ## observe_duration
-    assert_raise Prometheus.InvalidValueError,
-      "Invalid value: \"qwe\" (observe_duration accepts only functions).",
+    assert_raise Prometheus.InvalidBlockArityError,
+      "Fn with arity 2 (args: :x, :y) passed as block.",
     fn ->
-      Summary.observe_duration(spec, "qwe")
+      Macro.expand(quote do
+        Summary.observe_duration(spec, fn(x, y) -> 1 + x + y end)
+      end, __ENV__)
     end
   end