Expanded class hierarchy of PersistentDatabaseLockBackend in Drupal 9
- class \Drupal\Core\Lock\LockBackendAbstract implements LockBackendInterface
- class \Drupal\Core\Lock\DatabaseLockBackend
- class \Drupal\Core\Lock\PersistentDatabaseLockBackend
- class \Drupal\Core\Lock\DatabaseLockBackend