Recalculate CI extra minutes when monthly minutes defaults to nil

This fixes a bug that skipped recalculating CI extra minutes
where namespaces.shared_runners_minutes_limit was `nil`.

ee/app/models/ee/namespace.rb

@@ -36,13 +36,6 @@ module EE
       scope :include_gitlab_subscription, -> { includes(:gitlab_subscription) }
       scope :join_gitlab_subscription, -> { joins("LEFT OUTER JOIN gitlab_subscriptions ON gitlab_subscriptions.namespace_id=namespaces.id") }
 
-      scope :requiring_ci_extra_minutes_recalculation, -> do
-        joins(:namespace_statistics)
-          .where('namespaces.shared_runners_minutes_limit > 0')
-          .where('namespaces.extra_shared_runners_minutes_limit > 0')
-          .where('namespace_statistics.shared_runners_seconds > (namespaces.shared_runners_minutes_limit * 60)')
-      end
-
       scope :with_feature_available_in_plan, -> (feature) do
         plans = plans_with_feature(feature)
         matcher = ::Plan.where(name: plans)

ee/app/services/ci/minutes/batch_reset_service.rb

@@ -39,14 +39,44 @@ module Ci
         @errors << { count: namespaces.size, first_id: namespaces.first.id, last_id: namespaces.last.id }
       end
 
+      # This service is responsible for the logic that recalculates the extra shared runners
+      # minutes including how to deal with the cases where shared_runners_minutes_limit is `nil`.
+      # We prefer to keep the queries here rather than scatter them across classes.
+      # rubocop: disable CodeReuse/ActiveRecord
       def recalculate_extra_shared_runners_minutes_limits!(namespaces)
         namespaces
-          .requiring_ci_extra_minutes_recalculation
-          .update_all("extra_shared_runners_minutes_limit = #{extra_minutes_left_sql} FROM namespace_statistics")
+          .joins(:namespace_statistics)
+          .where(namespaces_arel[:extra_shared_runners_minutes_limit].gt(0))
+          .where(actual_shared_runners_minutes_limit.gt(0))
+          .where(namespaces_statistics_arel[:shared_runners_seconds].gt(actual_shared_runners_minutes_limit * 60))
+          .update_all("extra_shared_runners_minutes_limit = #{extra_minutes_left.to_sql} FROM namespace_statistics")
       end
+      # rubocop: enable CodeReuse/ActiveRecord
 
-      def extra_minutes_left_sql
-        "GREATEST((namespaces.shared_runners_minutes_limit + namespaces.extra_shared_runners_minutes_limit) - ROUND(namespace_statistics.shared_runners_seconds / 60.0), 0)"
+      def extra_minutes_left
+        shared_minutes_limit = actual_shared_runners_minutes_limit + namespaces_arel[:extra_shared_runners_minutes_limit]
+        used_minutes = arel_function("round", [namespaces_statistics_arel[:shared_runners_seconds] / Arel::Nodes::SqlLiteral.new('60.0')])
+
+        arel_function("greatest", [shared_minutes_limit - used_minutes, 0])
+      end
+
+      def actual_shared_runners_minutes_limit
+        namespaces_arel.coalesce(
+          namespaces_arel[:shared_runners_minutes_limit],
+          [::Gitlab::CurrentSettings.shared_runners_minutes.presence, 0].compact
+        )
+      end
+
+      def namespaces_arel
+        Namespace.arel_table
+      end
+
+      def namespaces_statistics_arel
+        NamespaceStatistics.arel_table
+      end
+
+      def arel_function(name, attrs)
+        Arel::Nodes::NamedFunction.new(name, attrs)
       end
 
       def reset_shared_runners_seconds!(namespaces)

ee/changelogs/unreleased/fix-ci-extra-minutes-recalculation.yml

+---
+title: Recalculate CI extra minutes when monthly minutes default to nil
+merge_request: 36046
+author:
+type: fixed