3 files changed, 154 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
diff --git a/app/workers/issues/rebalancing_worker.rb b/app/workers/issues/rebalancing_worker.rb
new file mode 100644
index 00000000000..466617d9fa1
--- /dev/null
+++ b/app/workers/issues/rebalancing_worker.rb
@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+module Issues
+  class RebalancingWorker
+    include ApplicationWorker
+
+    data_consistency :always
+
+    sidekiq_options retry: 3
+
+    idempotent!
+    urgency :low
+    feature_category :team_planning
+    deduplicate :until_executed, including_scheduled: true
+
+    def perform(ignore = nil, project_id = nil, root_namespace_id = nil)
+      # we need to have exactly one of the project_id and root_namespace_id params be non-nil
+      raise ArgumentError, "Expected only one of the params project_id: #{project_id} and root_namespace_id: #{root_namespace_id}" if project_id && root_namespace_id
+      return if project_id.nil? && root_namespace_id.nil?
+
+      # pull the projects collection to be rebalanced either the project if namespace is not a group(i.e. user namesapce)
+      # or the root namespace, this also makes the worker backward compatible with previous version where a project_id was
+      # passed as the param
+      projects_to_rebalance = projects_collection(project_id, root_namespace_id)
+
+      # something might have happened with the namespace between scheduling the worker and actually running it,
+      # maybe it was removed.
+      if projects_to_rebalance.blank?
+        Gitlab::ErrorTracking.log_exception(
+          ArgumentError.new("Projects to be rebalanced not found for arguments: project_id #{project_id}, root_namespace_id: #{root_namespace_id}"),
+          { project_id: project_id, root_namespace_id: root_namespace_id })
+
+        return
+      end
+
+      Issues::RelativePositionRebalancingService.new(projects_to_rebalance).execute
+    rescue Issues::RelativePositionRebalancingService::TooManyConcurrentRebalances => e
+      Gitlab::ErrorTracking.log_exception(e, root_namespace_id: root_namespace_id, project_id: project_id)
+    end
+
+    private
+
+    def projects_collection(project_id, root_namespace_id)
+      # we can have either project_id(older version) or project_id if project is part of a user namespace and not a group
+      # or root_namespace_id(newer version) never both.
+      return Project.id_in([project_id]) if project_id
+
+      Namespace.find_by_id(root_namespace_id)&.all_projects
+    end
+  end
+end
diff --git a/app/workers/issues/reschedule_stuck_issue_rebalances_worker.rb b/app/workers/issues/reschedule_stuck_issue_rebalances_worker.rb
new file mode 100644
index 00000000000..d1759589cc0
--- /dev/null
+++ b/app/workers/issues/reschedule_stuck_issue_rebalances_worker.rb
@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+module Issues
+  class RescheduleStuckIssueRebalancesWorker
+    include ApplicationWorker
+    include CronjobQueue
+
+    data_consistency :sticky
+
+    idempotent!
+    urgency :low
+    feature_category :team_planning
+    deduplicate :until_executed, including_scheduled: true
+
+    def perform
+      namespace_ids, project_ids = ::Gitlab::Issues::Rebalancing::State.fetch_rebalancing_groups_and_projects
+
+      return if namespace_ids.blank? && project_ids.blank?
+
+      namespaces = Namespace.id_in(namespace_ids)
+      projects = Project.id_in(project_ids)
+
+      IssueRebalancingWorker.bulk_perform_async_with_contexts(
+        namespaces,
+        arguments_proc: -> (namespace) { [nil, nil, namespace.id] },
+        context_proc: -> (namespace) { { namespace: namespace } }
+      )
+
+      IssueRebalancingWorker.bulk_perform_async_with_contexts(
+        projects,
+        arguments_proc: -> (project) { [nil, project.id, nil] },
+        context_proc: -> (project) { { project: project } }
+      )
+    end
+  end
+end