Merge branch 'master' into backstage/gb/migrate-stages-statuses

* master: (319 commits)
  remove redundant changelog entries
  Merge branch '24570-use-re2-for-user-supplied-regexp-9-3' into 'security-9-3'
  Merge branch '33303-404-for-unauthorized-project' into 'security-9-3'
  Merge branch '33359-pers-snippet-files-location' into 'security-9-3'
  Merge branch 'bvl-remove-appearance-symlink' into 'security-9-3'
  Hide description about protected branches to non-member
  Update CHANGELOG.md for 9.0.11
  Update CHANGELOG.md for 9.1.8
  Update CHANGELOG.md for 8.17.7
  Update CHANGELOG.md for 9.2.8
  Update CHANGELOG.md for 9.3.8
  Respect blockquote line breaks in markdown
  35209 Add wip message to new navigation preference section
  Add github imported projects count to usage data
  Add versions to Prometheus metrics doc
  Add Bulgarian translations of Pipeline Schedules
  Add Esperanto translations of Pipeline Schedules
  Add Traditional Chinese in HongKong translations of Pipeline Schedules
  Add Simplified Chinese translations of Pipeline Schedules
  Resolve "Clarify k8s service keys"
  ...

Conflicts:
	db/schema.rb

1 files changed, 28 insertions, 7 deletions

diff --git a/lib/gitlab/background_migration.rb b/lib/gitlab/background_migration.rb
index d95ecd7b291..b0741b1fba7 100644
--- a/lib/gitlab/background_migration.rb
+++ b/lib/gitlab/background_migration.rb
@@ -1,24 +1,45 @@
 module Gitlab
   module BackgroundMigration
+    def self.queue
+      @queue ||= BackgroundMigrationWorker.sidekiq_options['queue']
+    end
+
     # Begins stealing jobs from the background migrations queue, blocking the
     # caller until all jobs have been completed.
     #
+    # When a migration raises a StandardError is is going to be retries up to
+    # three times, for example, to recover from a deadlock.
+    #
+    # When Exception is being raised, it enqueues the migration again, and
+    # re-raises the exception.
+    #
     # steal_class - The name of the class for which to steal jobs.
     def self.steal(steal_class)
-      queue = Sidekiq::Queue
-        .new(BackgroundMigrationWorker.sidekiq_options['queue'])
+      enqueued = Sidekiq::Queue.new(self.queue)
+      scheduled = Sidekiq::ScheduledSet.new
 
-      queue.each do |job|
-        migration_class, migration_args = job.args
+      [scheduled, enqueued].each do |queue|
+        queue.each do |job|
+          migration_class, migration_args = job.args
 
-        next unless migration_class == steal_class
+          next unless job.queue == self.queue
+          next unless migration_class == steal_class
 
-        perform(migration_class, migration_args)
+          begin
+            perform(migration_class, migration_args, retries: 3) if job.delete
+          rescue Exception # rubocop:disable Lint/RescueException
+            BackgroundMigrationWorker # enqueue this migration again
+              .perform_async(migration_class, migration_args)
 
-        job.delete
+            raise
+          end
+        end
       end
     end
 
+    ##
+    # Performs a background migration.
+    #
     # class_name - The name of the background migration class as defined in the
     #              Gitlab::BackgroundMigration namespace.
     #