class DrupalQueue

class DrupalQueue {

  /**
   * Returns the queue object for a given name.
   *
   * The following variables can be set by variable_set or $conf overrides:
   * - queue_class_$name: the class to be used for the queue $name.
   * - queue_default_class: the class to use when queue_class_$name is not
   *   defined. Defaults to SystemQueue, a reliable backend using SQL.
   * - queue_default_reliable_class: the class to use when queue_class_$name is
   *   not defined and the queue_default_class is not reliable. Defaults to
   *   SystemQueue.
   *
   * @param $name
   *   Arbitrary string. The name of the queue to work with.
   * @param $reliable
   *   TRUE if the ordering of items and guaranteeing every item executes at
   *   least once is important, FALSE if scalability is the main concern.
   *
   * @return
   *   The queue object for a given name.
   */
  public static function get($name, $reliable = FALSE) {
    static $queues;
    if (!isset($queues[$name])) {
      $class = variable_get('queue_class_' . $name, NULL);
      if (!$class) {
        $class = variable_get('queue_default_class', 'SystemQueue');
      }
      $object = new $class($name);
      if ($reliable && !$object instanceof DrupalReliableQueueInterface) {
        $class = variable_get('queue_default_reliable_class', 'SystemQueue');
        $object = new $class($name);
      }
      $queues[$name] = $object;
    }
    return $queues[$name];
  }

}