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];
    }

}