Perfomance updating Project activity sort

app/models/project.rb

@@ -29,7 +29,7 @@ class Project < ActiveRecord::Base
 
   attr_accessible :name, :path, :description, :default_branch, :issues_tracker,
     :issues_enabled, :wall_enabled, :merge_requests_enabled, :snippets_enabled, :issues_tracker_id,
-    :wiki_enabled, :public, :import_url, as: [:default, :admin]
+    :wiki_enabled, :public, :import_url, :last_activity_at, as: [:default, :admin]
 
   attr_accessible :namespace_id, :creator_id, as: :admin
 
@@ -92,12 +92,12 @@ class Project < ActiveRecord::Base
   scope :in_team, ->(team) { where("id IN (:ids)", ids: team.projects.map(&:id)) }
   scope :in_namespace, ->(namespace) { where(namespace_id: namespace.id) }
   scope :in_group_namespace, -> { joins(:group) }
-  scope :sorted_by_activity, -> { order("(SELECT max(events.created_at) FROM events WHERE events.project_id = projects.id) DESC") }
+  scope :sorted_by_activity, -> { order("last_activity_at DESC") }
   scope :personal, ->(user) { where(namespace_id: user.namespace_id) }
   scope :joined, ->(user) { where("namespace_id != ?", user.namespace_id) }
   scope :public_only, -> { where(public: true) }
 
-  enumerize :issues_tracker, :in => (Gitlab.config.issues_tracker.keys).append(:gitlab), :default => :gitlab
+  enumerize :issues_tracker, in: (Gitlab.config.issues_tracker.keys).append(:gitlab), default: :gitlab
 
   class << self
     def abandoned
@@ -157,8 +157,7 @@ class Project < ActiveRecord::Base
     unless creator.can_create_project?
       errors[:limit_reached] << ("Your own projects limit is #{creator.projects_limit}! Please contact administrator to increase it")
     end
-  rescue => ex
-    errors[:base] << ex.message
+  rescue
     errors[:base] << ("Can't check your ability to create project")
   end
 
@@ -191,7 +190,7 @@ class Project < ActiveRecord::Base
   end
 
   def last_activity_date
-    last_event.try(:created_at) || updated_at
+    last_activity_at
   end
 
   def project_id

app/observers/project_activity_cache_observer.rb

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

config/application.rb

@@ -24,6 +24,7 @@ module Gitlab
 
     # Activate observers that should always be running.
     config.active_record.observers = :activity_observer,
+                                     :project_activity_cache_observer,
                                      :issue_observer,
                                      :key_observer,
                                      :merge_request_observer,

db/migrate/20130403003950_add_last_activity_column_into_project.rb

+class AddLastActivityColumnIntoProject < ActiveRecord::Migration
+  def up
+    add_column :projects, :last_activity_at, :datetime
+    add_index :projects, :last_activity_at
+
+    Project.find_each do |project|
+      project.update_attribute(:last_activity_at, project.last_activity_date)
+    end
+  end
+
+  def down
+    remove_index :projects, :last_activity_at
+    remove_column :projects, :last_activity_at
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20130325173941) do
+ActiveRecord::Schema.define(:version => 20130403003950) do
 
   create_table "events", :force => true do |t|
     t.string   "target_type"
@@ -156,9 +156,11 @@ ActiveRecord::Schema.define(:version => 20130325173941) do
     t.string   "issues_tracker",         :default => "gitlab", :null => false
     t.string   "issues_tracker_id"
     t.boolean  "snippets_enabled",       :default => true,     :null => false
+    t.datetime "last_activity_at"
   end
 
   add_index "projects", ["creator_id"], :name => "index_projects_on_owner_id"
+  add_index "projects", ["last_activity_at"], :name => "index_projects_on_last_activity_at"
   add_index "projects", ["namespace_id"], :name => "index_projects_on_namespace_id"
 
   create_table "protected_branches", :force => true do |t|