c.f. https://inside.pixiv.blog/sue445/7729

z_backup_repository_monkey_patch.rake

# 巨大なリポジトリのバックアップを作ろうとするとBackup::Repositoryでエラーになるのでコネクションを明示的に取得するためのモンキーパッチ
# (lib/tasks/gitlab/backup.rake よりも後にloadされてほしいのでわざとz_を付与)
# https://gitlab.com/gitlab-org/gitlab-ce/blob/v12.2.4/lib/backup/repository.rb
# FIXME: gitlab-ceにMRを投げてマージされたら削除したい

task :backup_repository_monkey_patch do
  module BackupRepositoryMonkeyPatch
    MAX_RETRY_COUNT = 1

    def backup_custom_hooks(project)
      FileUtils.mkdir_p(project_backup_path(project))

      custom_hooks_path = custom_hooks_tar(project)

      # monkey patched
      with_reconnect_and_retry do
        Gitlab::GitalyClient::RepositoryService.new(project.repository)
          .backup_custom_hooks(custom_hooks_path)
      end
    end

    def display_repo_path(project)
      with_reconnect_and_retry do
        super project
      end
    end

    def with_reconnect_and_retry
      ActiveRecord::Base.connection_pool.with_connection do |conn|
        yield
      rescue ActiveRecord::StatementInvalid => e
        case e.cause
        when PG::UnableToSend, PG::ConnectionBad
          retry_count ||= 0
          retry_count += 1

          raise if retry_count > MAX_RETRY_COUNT

          progress.puts "[WARNING] Error occurred #{e}. So reconnect and retry (#{retry_count}/#{MAX_RETRY_COUNT})".color(:orange)
          conn.reconnect!
          retry
        else
          raise
        end
      end
    end
  end

  require "backup/repository"

  Backup::Repository.prepend BackupRepositoryMonkeyPatch
end

# gitlab:backup:repo:create の実行直前にBackup::Repositoryにモンキーパッチを仕込む
Rake::Task["gitlab:backup:repo:create"].enhance([:backup_repository_monkey_patch])