Re: [Qemu-devel] [PATCH 2/8] io: introduce a network socket listener API

["Daniel P. Berrange" <berrange@redhat.com>]

On Fri, Aug 11, 2017 at 01:39:43PM +0100, Dr. David Alan Gilbert wrote:
> * Daniel P. Berrange (berrange@redhat.com) wrote:
> > On Fri, Aug 11, 2017 at 01:26:00PM +0100, Dr. David Alan Gilbert wrote:
> > > * Daniel P. Berrange (berrange@redhat.com) wrote:
> > > > The existing QIOChannelSocket class provides the ability to
> > > > listen on a single socket at a time. This patch introduces
> > > > a QIONetListener class that provides a higher level API
> > > > concept around listening for network services, allowing
> > > > for listening on multiple sockets.
> > > 
> > > What protects against a connection on more than one of the sockets?
> > 
> > That's not the responsibility of this module. If a backend only
> > wants to allow a single client at a time, it has to unregister
> > the new client callback and re-register when it is ready to
> > accept a new client. This aspect is no different to the existing
> > case of multiple clients connecting to a single listener socket.
> 
> OK, and we guarantee that we never call accept() twice because we
> make sure we do that unregister before we get back to the main loop?

Yes, and even if 2 clients arrive at exactly the same time, and thus
both sockets show G_IO_IN on the same iteration of the main loop,
we check whether the new client callback is NULL, and so will just
drop the 2nd client.


Regards,
Daniel
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