Adds Rollback functionality to HashedStorage migration

We are adding sidekiq workers and service classes to allow to rollback
a hashed storage migration. There are some refactoring involved as well
as part of the code can be reused by both the migration and the rollback
logic.

2 files changed, 43 insertions, 0 deletions

diff --git a/app/workers/all_queues.yml b/app/workers/all_queues.yml
index 337f39b2091..82351c1334f 100644
--- a/app/workers/all_queues.yml
+++ b/app/workers/all_queues.yml
@@ -127,6 +127,7 @@
 - project_destroy
 - project_export
 - project_migrate_hashed_storage
+- project_rollback_hashed_storage
 - project_service
 - propagate_service_template
 - reactive_caching
diff --git a/app/workers/project_rollback_hashed_storage_worker.rb b/app/workers/project_rollback_hashed_storage_worker.rb
new file mode 100644
index 00000000000..38faffd2bfa
--- /dev/null
+++ b/app/workers/project_rollback_hashed_storage_worker.rb
@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+class ProjectRollbackHashedStorageWorker
+  include ApplicationWorker
+
+  LEASE_TIMEOUT = 30.seconds.to_i
+
+  # rubocop: disable CodeReuse/ActiveRecord
+  def perform(project_id, old_disk_path = nil)
+    uuid = lease_for(project_id).try_obtain
+
+    if uuid
+      project = Project.find_by(id: project_id)
+      return if project.nil? || project.pending_delete?
+
+      old_disk_path ||= project.disk_path
+
+      ::Projects::HashedStorage::RollbackService.new(project, old_disk_path, logger: logger).execute
+    else
+      return false
+    end
+
+  ensure
+    cancel_lease_for(project_id, uuid) if uuid
+  end
+  # rubocop: enable CodeReuse/ActiveRecord
+
+  def lease_for(project_id)
+    Gitlab::ExclusiveLease.new(lease_key(project_id), timeout: LEASE_TIMEOUT)
+  end
+
+  private
+
+  def lease_key(project_id)
+    # we share the same lease key for both migration and rollback so they don't run simultaneously
+    "#{ProjectMigrateHashedStorageWorker::LEASE_KEY_SEGMENT}:#{project_id}"
+  end
+
+  def cancel_lease_for(project_id, uuid)
+    Gitlab::ExclusiveLease.cancel(lease_key(project_id), uuid)
+  end
+end