Symfony\Component\HttpKernel\Kernel::writeCacheFile PHP Method

    protected function writeCacheFile($file, $content)
    {
        $tmpFile = tempnam(dirname($file), basename($file));
        if (false !== @file_put_contents($tmpFile, $content) && @rename($tmpFile, $file)) {
            chmod($file, 0644);

            return;
        }

        throw new \RuntimeException(sprintf('Failed to write cache file "%s".', $file));
    }