Split actionview log subscriber Start events

Previously one subscriber was used for both the "Rendering" (before) and
"Rendered" (after) events. With the previous change to AS::Subscriber
these need to be split.

Co-authored-by: Adam Hess <[email protected]>

Author: jhawthorn

actionview/lib/action_view/log_subscriber.rb

@@ -50,28 +50,58 @@ def render_collection(event)
       end
     end
 
-    def start(name, id, payload)
-      log_rendering_start(payload, name)
+    module Utils # :nodoc:
+      def logger
+        ActionView::Base.logger
+      end
 
-      super
-    end
+    private
+      def from_rails_root(string)
+        string = string.sub(rails_root, "")
+        string.sub!(VIEWS_PATTERN, "")
+        string
+      end
 
-    def logger
-      ActionView::Base.logger
+      def rails_root # :doc:
+        @root ||= "#{Rails.root}/"
+      end
     end
 
-  private
-    EMPTY = ""
-    def from_rails_root(string) # :doc:
-      string = string.sub(rails_root, EMPTY)
-      string.sub!(VIEWS_PATTERN, EMPTY)
-      string
+    include Utils
+
+    class Start # :nodoc:
+      include Utils
+
+      def start(name, id, payload)
+        return unless logger
+        logger.debug do
+          qualifier =
+            if name == "render_template.action_view"
+              ""
+            elsif name == "render_layout.action_view"
+              "layout "
+            end
+
+          return unless qualifier
+
+          message = +"  Rendering #{qualifier}#{from_rails_root(payload[:identifier])}"
+          message << " within #{from_rails_root(payload[:layout])}" if payload[:layout]
+          message
+        end
+      end
+
+      def finish(name, id, payload)
+      end
     end
 
-    def rails_root # :doc:
-      @root ||= "#{Rails.root}/"
+    def self.attach_to(*)
+      ActiveSupport::Notifications.subscribe("render_template.action_view", ActionView::LogSubscriber::Start.new)
+      ActiveSupport::Notifications.subscribe("render_layout.action_view", ActionView::LogSubscriber::Start.new)
+
+      super
     end
 
+  private
     def render_count(payload) # :doc:
       if payload[:cache_hits]
         "[#{payload[:cache_hits]} / #{payload[:count]} cache hits]"
@@ -88,23 +118,6 @@ def cache_message(payload) # :doc:
         "[cache miss]"
       end
     end
-
-    def log_rendering_start(payload, name)
-      debug do
-        qualifier =
-          if name == "render_template.action_view"
-            ""
-          elsif name == "render_layout.action_view"
-            "layout "
-          end
-
-        return unless qualifier
-
-        message = +"  Rendering #{qualifier}#{from_rails_root(payload[:identifier])}"
-        message << " within #{from_rails_root(payload[:layout])}" if payload[:layout]
-        message
-      end
-    end
   end
 end