PMA\libraries\Util::cacheGet PHP Method

    public static function cacheGet($var, $callback = null)
    {
        if (self::cacheExists($var)) {
            return $_SESSION['cache']['server_' . $GLOBALS['server']][$var];
        } else {
            if ($callback) {
                $val = $callback();
                self::cacheSet($var, $val);
                return $val;
            }
            return null;
        }
    }

 /**
  * Checks if this database server is running on Amazon RDS.
  *
  * @return boolean
  */
 public function isAmazonRds()
 {
     if (Util::cacheExists('is_amazon_rds')) {
         return Util::cacheGet('is_amazon_rds');
     }
     $sql = 'SELECT @@basedir';
     $result = $this->fetchResult($sql);
     $rds = $result[0] == '/rdsdbbin/mysql/';
     Util::cacheSet('is_amazon_rds', $rds);
     return $rds;
 }