Measure all Rack middlewares

Author: alexisbernard

CHANGELOG.md

@@ -5,6 +5,7 @@
 
 * Compress data before sending
 * Start measuring requests from Rails::Engine#call
+* Measure all Rack middlewares
 * [local profiler] Integrate Rails' new ActiveSupport::Editor feature
 * [local profiler] Toggle low impact sections visibility
 * [local profiler] Fix Safari's incompatible date format bug

lib/rorvswild/plugin/rack.rb

@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+module RorVsWild
+  module Plugin
+    class Rack
+      def self.setup(agent)
+        return if @installed
+        return if !defined?(ActiveSupport::Notifications.subscribe)
+        ActiveSupport::Notifications.subscribe("process_middleware.action_dispatch", new)
+        @installed = true
+      end
+
+      def start(name, id, payload)
+        section = RorVsWild::Section.start
+        section.kind = "rack"
+        if location = source_location(payload[:middleware])
+          section.file = location[0]
+          section.line = location[1]
+          section.commands << payload[:middleware]
+        else
+          section.file = payload[:middleware]
+        end
+      end
+
+      def finish(name, id, payload)
+        RorVsWild::Section.stop
+      end
+
+      private
+
+      def source_location(middleware_name)
+        middleware = Kernel.const_get(middleware_name)
+        middleware.instance_method(:call).source_location
+      rescue NameError
+      end
+    end
+  end
+end

test/plugin/rack_test.rb

@@ -0,0 +1,30 @@
+require File.expand_path("#{File.dirname(__FILE__)}/../helper")
+
+class RorVsWild::Plugin::RackTest < Minitest::Test
+  include RorVsWild::AgentHelper
+
+  FAKE_MIDDLEWARE_LINE = __LINE__ + 2
+  class FakeMiddleware
+    def call(env)
+    end
+  end
+
+  def test_process_middleware_callback
+    agent.measure_block("test") do
+      ActiveSupport::Notifications.instrument("process_middleware.action_dispatch", {middleware: "RorVsWild::Plugin::RackTest::FakeMiddleware"}) do
+        sleep 0.001
+      end
+    end
+
+    sections = current_user_sections
+    section = sections.find { |s| s.kind == "rack" }
+
+    assert(section)
+    assert_equal("rack", section.kind)
+    assert_equal("RorVsWild::Plugin::RackTest::FakeMiddleware", section.command)
+    assert_equal(1, section.calls)
+    assert_equal(FAKE_MIDDLEWARE_LINE, section.line)
+    assert(section.file.end_with?("rack_test.rb"))
+    assert(section.total_ms >= 1)
+  end
+end