FileStorageInterface.php

<?php

namespace Drupal\file;

use Drupal\Core\Entity\ContentEntityStorageInterface;

/**
 * Defines an interface for file entity storage classes.
 */
interface FileStorageInterface extends ContentEntityStorageInterface {
    
    /**
     * Determines total disk space used by a single user or the whole filesystem.
     *
     * @param int $uid
     *   Optional. A user id, specifying NULL returns the total space used by all
     *   non-temporary files.
     * @param int $status
     *   (Optional) The file status to consider. The default is to only
     *   consider files in status FileInterface::STATUS_PERMANENT.
     *
     * @return int
     *   An integer containing the number of bytes used.
     */
    public function spaceUsed($uid = NULL, $status = FileInterface::STATUS_PERMANENT);

}