Merge pull request #14137 from dasch/better-fragment-cache-instrumentation

Add controller and action name to the fragment caching instrumentation payload

Conflicts:
	actionpack/CHANGELOG.md

actionpack/CHANGELOG.md

@@ -1,3 +1,11 @@
+*   Instrument fragment cache metrics.
+
+    Adds `:controller`: and `:action` keys to the instrumentation payload
+    for the `*_fragment.action_controller` notifications. This allows tracking
+    e.g. the fragment cache hit rates for each controller action.
+
+    *Daniel Schierbeck*
+
 *   Always use the provided port if the protocol is relative.
 
     Fixes #15043.

actionpack/lib/action_controller/caching/fragments.rb

@@ -90,7 +90,13 @@ module ActionController
       end
 
       def instrument_fragment_cache(name, key) # :nodoc:
-        ActiveSupport::Notifications.instrument("#{name}.action_controller", :key => key){ yield }
+        payload = {
+          controller: controller_name,
+          action: action_name,
+          key: key
+        }
+
+        ActiveSupport::Notifications.instrument("#{name}.action_controller", payload) { yield }
       end
     end
   end

actionpack/test/controller/caching_test.rb

@@ -227,6 +227,22 @@ CACHED
       @store.read("views/test.host/functional_caching/inline_fragment_cached/#{template_digest("functional_caching/inline_fragment_cached")}"))
   end
 
+  def test_fragment_cache_instrumentation
+    payload = nil
+
+    subscriber = proc do |*args|
+      event = ActiveSupport::Notifications::Event.new(*args)
+      payload = event.payload
+    end
+
+    ActiveSupport::Notifications.subscribed(subscriber, "read_fragment.action_controller") do
+      get :inline_fragment_cached
+    end
+
+    assert_equal "functional_caching", payload[:controller]
+    assert_equal "inline_fragment_cached", payload[:action]
+  end
+
   def test_html_formatted_fragment_caching
     get :formatted_fragment_cached, :format => "html"
     assert_response :success