/**
* Sends headers and content. This method expects an **exit** upon returning.
* @param object $subject Given to {@link $content}
*/
public function __invoke($subject)
{
// O::file() isn't used because there is a race between it and the Expires header.
static::lock(LOCK_SH);
$this->prepare($subject);
$file = fopen($this->path, 'rb');
flock($file, LOCK_SH);
clearstatcache(true, $this->path);
O::mtime(filemtime($this->path));
O::$headers['Content-Length'] = filesize($this->path);
O::$headers['Cache-Control'] = $this->control . ', max-age=' . $this->ttl;
O::$headers['Expires'] = gmdate('D, d M Y H:i:s T', filemtime($this->path) + $this->ttl);
O::headers();
fpassthru($file);
}
