Add Gitlab::Utils::StrongMemoize

2 files changed, 36 insertions, 3 deletions

diff --git a/lib/api/api_guard.rb b/lib/api/api_guard.rb
index b9c7d443f6c..c1c0d344917 100644
--- a/lib/api/api_guard.rb
+++ b/lib/api/api_guard.rb
@@ -42,6 +42,8 @@ module API
 
     # Helper Methods for Grape Endpoint
     module HelperMethods
+      include Gitlab::Utils::StrongMemoize
+
       def find_current_user!
         user = find_user_from_access_token || find_user_from_warden
         return unless user
@@ -52,9 +54,9 @@ module API
       end
 
       def access_token
-        return @access_token if defined?(@access_token)
-
-        @access_token = find_oauth_access_token || find_personal_access_token
+        strong_memoize(:access_token) do
+          find_oauth_access_token || find_personal_access_token
+        end
       end
 
       def validate_access_token!(scopes: [])
diff --git a/lib/gitlab/utils/strong_memoize.rb b/lib/gitlab/utils/strong_memoize.rb
new file mode 100644
index 00000000000..a2ac9285b56
--- /dev/null
+++ b/lib/gitlab/utils/strong_memoize.rb
@@ -0,0 +1,31 @@
+module Gitlab
+  module Utils
+    module StrongMemoize
+      # Instead of writing patterns like this:
+      #
+      #     def trigger_from_token
+      #       return @trigger if defined?(@trigger)
+      #
+      #       @trigger = Ci::Trigger.find_by_token(params[:token].to_s)
+      #     end
+      #
+      # We could write it like:
+      #
+      #     def trigger_from_token
+      #       strong_memoize(:trigger) do
+      #         Ci::Trigger.find_by_token(params[:token].to_s)
+      #       end
+      #     end
+      #
+      def strong_memoize(name)
+        ivar_name = "@#{name}"
+
+        if instance_variable_defined?(ivar_name)
+          instance_variable_get(ivar_name)
+        else
+          instance_variable_set(ivar_name, yield)
+        end
+      end
+    end
+  end
+end