Remove ProjectActivityCacheObserver

app/models/event.rb

@@ -41,6 +41,9 @@ class Event < ActiveRecord::Base
   # For Hash only
   serialize :data
 
+  # Callbacks
+  after_create :reset_project_activity
+
   # Scopes
   scope :recent, -> { order("created_at DESC") }
   scope :code_push, -> { where(action: PUSHED) }
@@ -303,4 +306,10 @@ class Event < ActiveRecord::Base
       target.respond_to? :title
     end
   end
+
+  def reset_project_activity
+    if project
+      project.update_column(:last_activity_at, event.created_at)
+    end
+  end
 end

app/observers/project_activity_cache_observer.rb

-class ProjectActivityCacheObserver < BaseObserver
-  observe :event
-
-  def after_create(event)
-    event.project.update_column(:last_activity_at, event.created_at) if event.project
-  end
-end
-

config/application.rb

@@ -19,8 +19,7 @@ module Gitlab
     # config.plugins = [ :exception_notification, :ssl_requirement, :all ]
 
     # Activate observers that should always be running.
-    config.active_record.observers = :project_activity_cache_observer,
-                                     :note_observer,
+    config.active_record.observers = :note_observer,
                                      :project_observer,
                                      :system_hook_observer,
                                      :user_observer,