bug#22493: 25.1.50; open-gnutls-stream doesn't respect :nowait, so the connections are synchronous

[Eli Zaretskii <eliz@gnu.org>]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: 22493@debbugs.gnu.org
> Date: Fri, 05 Feb 2016 13:36:06 +1100
> 
> >> No matter how we call gnutls_boot, it will currently hang Emacs while
> >> it's transferring all those certificates back and forth.
> >
> > That last sentence is exactly the point I was trying to make all
> > along: we have to wait for this, therefore any time savings from
> > running gnutls_boot in the background are minor or even non-existent.
> > So I question the need for complicating the heck out of the underlying
> > code, for no practical gain.
> 
> I describe the call chain, and why it's necessary to have the
> gnutls_boot called from the C layer.  If you see anything wrong with the
> logic I described, please let me know.
> 
> And as I've said repeatedly, gnutls_boot is only synchronous now as a
> quirk of our implementation, and making it async is the next step I am
> going to take.  But it's a separate issue, and will be dealt with once
> the first round of changes are in.

If by "making it async" you mean to test for it in the idle loop, that
is not really async, and _that_ is _my_ point, which I've expressed
repeatedly already.  Waiting in the idle loop is still waiting, as far
as the main thread is concerned.

> > Why shouldn't we assume that the problem you saw in erc is the tip of
> > an iceberg, and the other places are happy exceptions?  Who knows how
> > many other packages are out there that are like erc?
> 
> That's why :async 'dns.

As I wrote elsewhere, this is not enough.