redesign caching of application settings

1 files changed, 35 insertions, 19 deletions

diff --git a/lib/gitlab/current_settings.rb b/lib/gitlab/current_settings.rb
index 9e14b35b0f8..48735fd197d 100644
--- a/lib/gitlab/current_settings.rb
+++ b/lib/gitlab/current_settings.rb
@@ -8,39 +8,55 @@ module Gitlab
       end
     end
 
-    def ensure_application_settings!
-      return fake_application_settings unless connect_to_db?
+    delegate :sidekiq_throttling_enabled?, to: :current_application_settings
 
-      unless ENV['IN_MEMORY_APPLICATION_SETTINGS'] == 'true'
-        begin
-          settings = ::ApplicationSetting.current
-        # In case Redis isn't running or the Redis UNIX socket file is not available
-        rescue ::Redis::BaseError, ::Errno::ENOENT
-          settings = ::ApplicationSetting.last
-        end
+    def fake_application_settings
+      OpenStruct.new(::ApplicationSetting.defaults)
+    end
 
-        settings ||= ::ApplicationSetting.create_from_defaults
+    private
+
+    def ensure_application_settings!
+      unless ENV['IN_MEMORY_APPLICATION_SETTINGS'] == 'true'
+        settings = retrieve_settings_from_database?
       end
 
       settings || in_memory_application_settings
     end
 
-    delegate :sidekiq_throttling_enabled?, to: :current_application_settings
+    def retrieve_settings_from_database?
+      settings = retrieve_settings_from_database_cache?
+      return settings if settings.present?
+
+      return fake_application_settings unless connect_to_db?
+
+      begin
+        db_settings = ::ApplicationSetting.current
+        # In case Redis isn't running or the Redis UNIX socket file is not available
+      rescue ::Redis::BaseError, ::Errno::ENOENT
+        db_settings = ::ApplicationSetting.last
+      end
+      db_settings || ::ApplicationSetting.create_from_defaults
+    end
+
+    def retrieve_settings_from_database_cache?
+      begin
+        settings = ApplicationSetting.cached
+      rescue ::Redis::BaseError, ::Errno::ENOENT
+        # In case Redis isn't running or the Redis UNIX socket file is not available
+        settings = nil
+      end
+      settings
+    end
 
     def in_memory_application_settings
       @in_memory_application_settings ||= ::ApplicationSetting.new(::ApplicationSetting.defaults)
-    # In case migrations the application_settings table is not created yet,
-    # we fallback to a simple OpenStruct
     rescue ActiveRecord::StatementInvalid, ActiveRecord::UnknownAttributeError
+      # In case migrations the application_settings table is not created yet,
+      # we fallback to a simple OpenStruct
       fake_application_settings
     end
 
-    def fake_application_settings
-      OpenStruct.new(::ApplicationSetting.defaults)
-    end
-
-    private
-
     def connect_to_db?
       # When the DBMS is not available, an exception (e.g. PG::ConnectionBad) is raised
       active_db_connection = ActiveRecord::Base.connection.active? rescue false