public function addWatch($path, $cb, $flags = null)
    {
        $path = realpath($path);
        if (!isset($this->files[$path])) {
            $this->files[$path] = [];
            if ($this->inotify) {
                $this->descriptors[inotify_add_watch($this->inotify, $path, $flags ?: IN_MODIFY)] = $path;
            }
        }
        $this->files[$path][] = $cb;
        Timer::setTimeout('fileWatcher');
        return true;
    }