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diff --git a/lib/prometheus/metric.ex b/lib/prometheus/metric.ex
index e1ff485..b5ac261 100644
--- a/lib/prometheus/metric.ex
+++ b/lib/prometheus/metric.ex
@@ -1,123 +1,146 @@
defmodule Prometheus.Metric do
- @moduledoc false
+ @moduledoc """
+
+ Prometheus metrics shortcuts.
+
+ Aliases and requires respective metric modules so they are
+ accessible without `Prometheus.Metric` prefix.
+
+ Allows to automatically setup metrics with
+ `@<type`> attributes. Metrics will be declared in
+ the `@on_load` callback. If the module already
+ has `@on_laod` callback, metrics will be declared
+ iff the callback returns `:ok`.
+
+ iex(1)> defmodule MyCoolModule do
+ ...(1)> use Prometheus.Metric
+ ...(1)>
+ ...(1)> @counter name: :test_counter3, labels: [], help: "qwe"
+ ...(1)> end
+ iex(2)> require Prometheus.Metric.Counter
+ Prometheus.Metric.Counter
+ iex(3)> Prometheus.Metric.Counter.value(:test_counter3)
+ 0
+
+ """
@metrics [:counter, :gauge, :boolean, :summary, :histogram]
defmacro __using__(_opts) do
module_name = __CALLER__.module
quote do
alias Prometheus.Metric.{Counter,Gauge,Histogram,Summary,Boolean}
require Prometheus.Metric.{Counter,Gauge,Histogram,Summary,Boolean}
unquote_splicing(
for metric <- @metrics do
quote do
Module.register_attribute unquote(module_name), unquote(metric), accumulate: true
end
end)
@before_compile unquote(__MODULE__)
end
end
defmacro __before_compile__(env) do
quote do
def __declare_prometheus_metrics__() do
unquote_splicing(
for metric <- @metrics do
declarations = Module.get_attribute(env.module, metric)
Module.delete_attribute(env.module, metric)
quote do
unquote_splicing(
for params <- declarations do
emit_create_metric(metric, params)
end)
:ok
end
end)
end
unquote(
case get_on_load_attribute(env.module) do
nil ->
quote do
@on_load :__declare_prometheus_metrics__
end
on_load ->
Module.delete_attribute(env.module, :on_load)
Module.put_attribute(env.module, :on_load, :__prometheus_on_load_override__)
quote do
def __prometheus_on_load_override__() do
case unquote(on_load)() do
:ok -> __declare_prometheus_metrics__()
result -> result
end
end
end
end)
end
end
defp get_on_load_attribute(module) do
case Module.get_attribute(module, :on_load) do
[] ->
nil
nil ->
nil
atom when is_atom(atom) ->
atom
{atom, 0} when is_atom(atom) ->
atom
[{atom, 0}] when is_atom(atom) ->
atom
other ->
raise ArgumentError,
"expected the @on_load attribute to be an atom or a " <>
"{atom, 0} tuple, got: #{inspect(other)}"
end
end
defp emit_create_metric(:counter, params) do
quote do
Prometheus.Metric.Counter.declare(unquote(params))
end
end
defp emit_create_metric(:gauge, params) do
quote do
Prometheus.Metric.Gauge.declare(unquote(params))
end
end
defp emit_create_metric(:boolean, params) do
quote do
Prometheus.Metric.Boolean.declare(unquote(params))
end
end
defp emit_create_metric(:summary, params) do
quote do
Prometheus.Metric.Summary.declare(unquote(params))
end
end
defp emit_create_metric(:histogram, params) do
quote do
Prometheus.Metric.Histogram.declare(unquote(params))
end
end
defmacro ct_parsable_spec?(spec) do
quote do
is_list(unquote(spec)) or is_atom(unquote(spec))
end
end
def parse_spec(spec) when is_list(spec) do
registry = Keyword.get(spec, :registry, :default)
name = Keyword.fetch!(spec, :name)
labels = Keyword.get(spec, :labels, [])
{registry, name, labels}
end
def parse_spec(spec) when is_atom(spec) do
{:default, spec, []}
end
end
diff --git a/test/metric_test.exs b/test/metric_test.exs
index f0b6e86..53871c3 100644
--- a/test/metric_test.exs
+++ b/test/metric_test.exs
@@ -1,65 +1,68 @@
defmodule Prometheus.MetricTest do
use Prometheus.Case
+ doctest Prometheus.Metric
+
defmacro __before_compile__(_env) do
quote do
def injected_fun() do
1
end
end
end
test "@metric attributes leads to metric declaration" do
defmodule ModuleWithMetrics do
use Prometheus.Metric
@before_compile Prometheus.MetricTest
@counter name: :test_counter1, labels: [], help: "qwe"
@counter name: :test_counter2, labels: [:tag], help: "qwa"
@gauge name: :test_gauge1, labels: [], help: "qwe"
@gauge name: :test_gauge2, labels: [:tag], help: "qwa"
@boolean name: :test_boolean1, labels: [], help: "qwe"
@boolean name: :test_boolean2, labels: [:tag], help: "qwa"
@summary name: :test_summary1, labels: [], help: "qwe"
@summary name: :test_summary2, labels: [:tag], help: "qwa"
@histogram name: :test_histogram1, labels: [], buckets: [1, 2], help: "qwe"
@histogram name: :test_histogram2, labels: [:tag], buckets: [1, 2], help: "qwa"
@on_load :custom_on_load_fun
def custom_on_load_fun() do
Counter.declare(name: :custom_counter, labels: [], help: "qwe")
:ok
end
end
defmodule ModuleWithoutOnLoad do
use Prometheus.Metric
@counter name: :test_counter3, labels: [], help: "qwe"
end
assert 1 == ModuleWithMetrics.injected_fun()
+
assert false == Counter.declare(name: :custom_counter, labels: [], help: "qwe")
assert false == Counter.declare(name: :test_counter3, labels: [], help: "qwe")
assert false == Counter.declare(name: :test_counter1, labels: [], help: "qwe")
assert false == Counter.declare(name: :test_counter2, labels: [:tag], help: "qwa")
assert false == Gauge.declare(name: :test_gauge1, labels: [], help: "qwe")
assert false == Gauge.declare(name: :test_gauge2, labels: [:tag], help: "qwa")
assert false == Boolean.declare(name: :test_boolean1, labels: [], help: "qwe")
assert false == Boolean.declare(name: :test_boolean2, labels: [:tag], help: "qwa")
assert false == Summary.declare(name: :test_summary1, labels: [], help: "qwe")
assert false == Summary.declare(name: :test_summary2, labels: [:tag], help: "qwa")
assert false == Histogram.declare(name: :test_histogram1, labels: [], buckets: [1, 2], help: "qwe")
assert false == Histogram.declare(name: :test_histogram2, labels: [:tag], buckets: [1, 2], help: "qwa")
end
end

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