1 files changed, 49 insertions, 0 deletions
diff --git a/app/workers/issue_placement_worker.rb b/app/workers/issue_placement_worker.rb
new file mode 100644
index 00000000000..a8d59e9125c
--- /dev/null
+++ b/app/workers/issue_placement_worker.rb
@@ -0,0 +1,49 @@
+# frozen_string_literal: true
+
+class IssuePlacementWorker
+  include ApplicationWorker
+
+  idempotent!
+  feature_category :issue_tracking
+  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
+
+    # 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)
+      .where(relative_position: nil)
+      .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(nil).rebalance_if_needed(to_place.max_by(&:relative_position))
+    IssuePlacementWorker.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)
+    IssueRebalancingWorker.perform_async(nil, project_id.presence || issue.project_id)
+  end
+  # rubocop: enable CodeReuse/ActiveRecord
+
+  def find_issue(issue_id, project_id)
+    return Issue.id_in(issue_id).first if issue_id
+
+    project = Project.id_in(project_id).first
+    return unless project
+
+    project.issues.first
+  end
+end