Expanded class hierarchy of PersistentDatabaseLockBackend in Zircon Profile 8
- class \Drupal\Core\Lock\LockBackendAbstract implements LockBackendInterface
- class \Drupal\Core\Lock\DatabaseLockBackend
- class \Drupal\Core\Lock\PersistentDatabaseLockBackend
- class \Drupal\memcache\MemcacheLockBackend
- class \Drupal\Core\Lock\DatabaseLockBackend