Re: [PATCH v3 1/3] QIOChannel: Add io_async_writev & io_async_flush callbacks

[Peter Xu]

On Fri, Sep 24, 2021 at 06:16:04PM +0100, Daniel P. Berrangé wrote:
> > +ssize_t qio_channel_async_writev(QIOChannel *ioc,
> > +                                 const struct iovec *iov,
> > +                                 size_t niov,
> > +                                 int *fds,
> > +                                 size_t nfds,
> > +                                 Error **errp);
> 
> This is missing any flags. We need something like
> 
>    QIO_CHANNEL_WRITE_FLAG_ZEROCOPY
> 
> passed in an 'unsigned int flags' parameter. This in
> turn makes me question whether we should have the
> common helpers at all, as the api is going to be
> different for sync vs async.
> 
> The QIOChannelFeature enum probably ought to be
> extended with QIO_CHANNEL_FEATURE_WRITE_ZEROCOPY with
> support for probing whether that's supported or not.

I'm also wondering whether we could just drop the fds/nfds as per my knowledge
SCM_RIGHT is the only user, at the meantime I don't see why an async interface
would pass in any fd anyways..  Thanks,

-- 
Peter Xu