Reduce load on DB for license upgrade check

1. Only check if the user is an admin
2. Cache the active user count for an hour

Helps gitlab-com/operations#298

CHANGELOG-EE

 Please view this file on the master branch, on stable branches it's out of date.
 
+v 8.8.3
+  - Reduce load on DB for license upgrade check
+
 v 8.8.2
   - Fix repository mirror updates for new imports stuck in started
 

app/helpers/license_helper.rb

@@ -37,7 +37,7 @@ module LicenseHelper
 
     return unless signed_in
 
-    return unless ((license.notify_admins? || license.warn_upgrade_license_message?) && is_admin) || license.notify_users?
+    return unless (is_admin && (license.notify_admins? || license.warn_upgrade_license_message?)) || license.notify_users?
 
     message = []
 

app/models/license.rb

@@ -92,6 +92,12 @@ class License < ActiveRecord::Base
     self.restrictions[:active_user_count]
   end
 
+  def current_user_count
+    Rails.cache.fetch("current_active_user_count", expires_in: 1.hour) do
+      User.active.count
+    end
+  end
+
   def warn_upgrade_license_message?
     restricted_user_count = user_count
 
@@ -99,9 +105,7 @@ class License < ActiveRecord::Base
 
     return false unless Time.now >= self.starts_at + 3.months
 
-    active_user_count = User.active.count
-
-    restricted_user_count && active_user_count > restricted_user_count
+    restricted_user_count && current_user_count > restricted_user_count
   end
 
   private