/**
  * Extra Time handling: add or remove time on delivery executions
  * 
  * @throws \common_Exception
  */
 public function extraTime()
 {
     $deliveryExecution = $this->getRequestParameter('execution');
     $extraTime = floatval($this->getRequestParameter('time'));
     if (!is_array($deliveryExecution)) {
         $deliveryExecution = array($deliveryExecution);
     }
     try {
         $reported = DeliveryHelper::setExtraTime($deliveryExecution, $extraTime);
         $notReported = array_diff($deliveryExecution, $reported);
         $this->returnJson(array('success' => !count($notReported), 'processed' => $reported, 'unprocessed' => $notReported));
     } catch (ServiceNotFoundException $e) {
         \common_Logger::w('No delivery service defined for proctoring');
         $this->returnError('Proctoring interface not available');
     }
 }