/**
  * Executes this action.
  *
  * @param \wcf\form\LoginForm $eventObj    Object firing the event
  * @param string              $className   class name of $eventObj
  * @param string              $eventName   name of the event fired
  * @param array               &$parameters given parameters
  */
 public function execute($eventObj, $className, $eventName, array &$parameters)
 {
     $sql = "SELECT\tuserID\n\t\t\tFROM\t" . UserFollow::getDatabaseTableName() . "\n\t\t\tWHERE\tfollowUserID = ?";
     $statement = WCF::getDB()->prepareStatement($sql);
     $statement->execute(array(WCF::getUser()->userID));
     // collect users
     $userIDs = array();
     while ($row = $statement->fetchArray()) {
         $userIDs[] = $row['userID'];
     }
     // send push notifications
     if ($userIDs) {
         PushHandler::getInstance()->sendDeferredMessage('com.mrk.wcf.loginNotification', $userIDs, array('username' => WCF::getUser()->username));
     }
 }