PersistentDatabaseLockBackend.php

<?php

namespace Drupal\Core\Lock;

use Drupal\Core\Database\Connection;

/**
 * Defines the persistent database lock backend. This backend is global for this
 * Drupal installation.
 *
 * @ingroup lock
 */
class PersistentDatabaseLockBackend extends DatabaseLockBackend {
    
    /**
     * Constructs a new PersistentDatabaseLockBackend.
     *
     * @param \Drupal\Core\Database\Connection $database
     *   The database connection.
     */
    public function __construct(Connection $database) {
        // Do not call the parent constructor to avoid registering a shutdown
        // function that releases all the locks at the end of a request.
        $this->database = $database;
        // Set the lockId to a fixed string to make the lock ID the same across
        // multiple requests. The lock ID is used as a page token to relate all the
        // locks set during a request to each other.
        // @see \Drupal\Core\Lock\LockBackendInterface::getLockId()
        $this->lockId = 'persistent';
    }

}