public function destroy($notify = false)
    {
        if ($this->destroyed) {
            return false;
        }
        $this->destroyed = true;
        if ($notify) {
            if ($this->callback) {
                $func = $this->callback;
                $func($this);
            }
        }
        unset($this->conn->cursors[$this->id]);
        return true;
    }