class BatchMemory

class BatchMemory extends Memory {
    
    /**
     * Overrides \Drupal\Core\Queue\Memory::claimItem().
     *
     * Unlike \Drupal\Core\Queue\Memory::claimItem(), this method provides a
     * default lease time of 0 (no expiration) instead of 30. This allows the item
     * to be claimed repeatedly until it is deleted.
     */
    public function claimItem($lease_time = 0) {
        if (!empty($this->queue)) {
            reset($this->queue);
            return current($this->queue);
        }
        return FALSE;
    }
    
    /**
     * Retrieves all remaining items in the queue.
     *
     * This is specific to Batch API and is not part of the
     * \Drupal\Core\Queue\QueueInterface.
     *
     * @return array
     *   An array of queue items.
     */
    public function getAllItems() {
        $result = [];
        foreach ($this->queue as $item) {
            $result[] = $item->data;
        }
        return $result;
    }

}