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

[Lars Ingebrigtsen <larsi@gnus.org>]

I have now implemented this, but in a slightly different way.  I
introduced a new process slot to say that we shouldn't be writing yet.

However, the Lisp part of the implementation is not very satisfactory.
This is basically it:

  (let ((process (open-network-stream name buffer host service
                                      :nowait nowait)))
    (if nowait
        (progn
          (gnutls-mark-process process t)
          (set-process-sentinel process 'gnutls-async-sentinel)
          process)
      (gnutls-negotiate :process (open-network-stream name buffer host service)
                        :type 'gnutls-x509pki
                        :hostname host))))
...

(defun gnutls-async-sentinel (process change)
  (when (string-match "open" change)
    (gnutls-negotiate :process process
                      :type 'gnutls-x509pki
                      :hostname (car (process-contact process)))
    (gnutls-mark-process process nil)))


The problem here is that this library is now putting a sentinel on the
process.  But any callers that want an asynchronous connection will also
be setting sentinels on the same process, which means that the
connection sentinel will be overwritten.

I've kludged this together in one of the callers (in url-http.el), but
that's too ugly to live.  (It checks for a sentinel and daisy-chains the
previous one.  Eek.)

So that has to be rewritten.  But I'm not sure how...  We, like, have
several layers of possible sentinels here, and...  uhm...

Ideas?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no