Re: new wifi connection = nntp timeout = Emacs restart?

[David Engster <deng@randomsample.de>]

> Eric Abrahamsen <eric@ericabrahamsen.net> writes:
>
>> Oh I see. I was assuming that adding connection closing to
>> nnimap-keepalive would make the NOOP-prepend mechanism unnecessary.
>> Seems like we'd only need one of the two, so long as whatever it was
>> came with teeth (closing the connection).
>
> nnimap-keepalive-connection-drop doesn't help with the common "I just
> woke my laptop up and now `g' hangs" situation.

Another possiblity: Instead of trying to detect dead connections, let's
try to get notified when networking has changed and react accordingly. I
think this is what those "apps" do on mobiles?

On GNU/Linux my guess is the lowest common denominator nowadays for
doing stuff like this is systemd and DBus?

It's actually surprisingly easy to do this in Emacs if you know what to
fill in:

(require 'dbus)

(defun my-dbus-handler (interface-name values novals)
  (message "Change registered on: %s" interface-name)
  (message "Changed values: %s" (prin1-to-string values))
  (message "Changed without value: %s" (prin1-to-string novals)))

(dbus-register-signal :system
		      "org.freedesktop.systemd1"
		      "/org/freedesktop/systemd1/unit/networking_2eservice"
		      "org.freedesktop.DBus.Properties"		      
		      "PropertiesChanged"
		      'my-dbus-handler)

Now do "systemctl restart networking.service" and watch all these spiffy
messages. This is on Debian 10, I'm hoping it's at least similar on
other systems? You can inspect this stuff with 'busctl', for instance:

busctl tree org.freedesktop.systemd1

busctl introspect org.freedesktop.systemd1 /org/freedesktop/systemd1/unit/networking_2eservice

I have no idea if this is "The Best Way", probably not. Also, I'm not
seeing anything on resuming, but maybe there's another path for that...?
Or maybe I'm not letting my laptop sleep long enough?

-David