[PATCH 01/10] server: allow polling for no events in set_fd_events

[Mike Kaplinskiy]

On Tue, Apr 6, 2010 at 2:03 PM, Alexandre Julliard <julliard at winehq.org> wrote:
> Mike Kaplinskiy <mike.kaplinskiy at gmail.com> writes:
>
>> Would allowing adding the fd to the poll loop after it has been
>> removed be more sane? Otherwise we have to resort to ugly things like
>> sock_try_event (which only half work).
>
> I don't think that makes sense either. The error condition is not going
> to go away so you can no longer poll on it anyway, you really need to
> close the socket and create a new one.
>
> --
> Alexandre Julliard
> julliard at winehq.org
>

That's only true in the case of a full close; if you do
shutdown(,SD_SEND) on the remote end, we will get POLLIN/0 recv, but
if we decide to do a send after that and the connection gets broken
(either the remote fully closes the socket or we get connection
reset), we will receive a POLLHUP/POLLERR with a different error code,
which is what windows reports. The problem is that there are two
halves of the connection to hang up (when both have hangup we get a
POLLHUP, otherwise just a POLLIN/0 recv). (data from
http://www.greenend.org.uk/rjk/2001/06/poll.html )

But I see your point that perhaps it doesn't belong in the main loop
when one of the halves gets closed. I guess we can keep sock_try_event
around but only use it when the socket has been removed from the main
loop. I'll also add detection of half-closed connection and drop that
event if the other half hasn't hung up yet. Sadly looks like MacOS
will be left out of that detection since it reports POLLIN|POLLHUP for
everything.

Does that sound good?

Mike.