1 files changed, 67 insertions, 0 deletions

diff --git a/app/workers/issues/placement_worker.rb b/app/workers/issues/placement_worker.rb
new file mode 100644
index 00000000000..ec29a754128
--- /dev/null
+++ b/app/workers/issues/placement_worker.rb
@@ -0,0 +1,67 @@
+# frozen_string_literal: true
+
+module Issues
+  class PlacementWorker
+    include ApplicationWorker
+
+    data_consistency :always
+
+    sidekiq_options retry: 3
+
+    idempotent!
+    deduplicate :until_executed, including_scheduled: true
+    feature_category :team_planning
+    urgency :high
+    worker_resource_boundary :cpu
+    weight 2
+
+    # Move at most the most recent 100 issues
+    QUERY_LIMIT = 100
+
+    # rubocop: disable CodeReuse/ActiveRecord
+    def perform(issue_id, project_id = nil)
+      issue = find_issue(issue_id, project_id)
+      return unless issue
+
+      # Temporary disable moving null elements because of performance problems
+      # For more information check https://gitlab.com/gitlab-com/gl-infra/production/-/issues/4321
+      return if issue.blocked_for_repositioning?
+
+      # Move the oldest 100 unpositioned items to the end.
+      # This is to deal with out-of-order execution of the worker,
+      # while preserving creation order.
+      to_place = Issue
+                 .relative_positioning_query_base(issue)
+                 .with_null_relative_position
+                 .order({ created_at: :asc }, { id: :asc })
+                 .limit(QUERY_LIMIT + 1)
+                 .to_a
+
+      leftover = to_place.pop if to_place.count > QUERY_LIMIT
+
+      Issue.move_nulls_to_end(to_place)
+      Issues::BaseService.new(project: nil).rebalance_if_needed(to_place.max_by(&:relative_position))
+      Issues::PlacementWorker.perform_async(nil, leftover.project_id) if leftover.present?
+    rescue RelativePositioning::NoSpaceLeft => e
+      Gitlab::ErrorTracking.log_exception(e, issue_id: issue_id, project_id: project_id)
+      Issues::RebalancingWorker.perform_async(nil, *root_namespace_id_to_rebalance(issue, project_id))
+    end
+
+    def find_issue(issue_id, project_id)
+      return Issue.id_in(issue_id).take if issue_id
+
+      project = Project.id_in(project_id).take
+      return unless project
+
+      project.issues.take
+    end
+    # rubocop: enable CodeReuse/ActiveRecord
+
+    private
+
+    def root_namespace_id_to_rebalance(issue, project_id)
+      project_id = project_id.presence || issue.project_id
+      Project.find(project_id)&.self_or_root_group_ids
+    end
+  end
+end