(PHP 5 >= 5.2.0, PHP 7, PECL swoole >= 1.9.0)
Swoole\Async::write — Write data to a file stream asynchronously.
$filename
   , string $content
   [, integer $offset
   [, callable $callback
  ]] ) : void
filenameThe filename being written.
contentThe content writing to the file.
offsetThe offset.
callback