[Vala] Signals not being called back

[Michael Starkweather <mpstark gmail com>]

Hello!

I'm having issues getting signals to callback in my Vala application and
I'm kind of at a loss. I'm fairly confident that this is a setup issue
relating to Gtk.Appplication.run() and Gtk.main() but I cannot be sure.
Here's my basic setup:

main () creates and runs a Gtk.Application which creates a Gtk.Window
(MainWindow) containing basic buttons and a search entry. The signals
related to these widgets work just fine and will merrily call back.
However, I have a Gtk.TreeView with a Gtk.TreeStore that is contained
within a class called ApplicationProcessModel which inherits from
GLib.Object -- these are all created in the MainWindow constructor. The
ApplicationProcessModel is supposed to update the Gtk.TreeStore with
information relating to running applications and processes. To do this, I'm
using libbamf-3.0 which has a number of signals relating to when an
application or window is launched and a custom /proc/ parser which I am
writing. In ApplicationProcessModel's constructor, I do a connect() to the
signals from libbamf just fine and the compiler doesn't complain at all,
however, the callbacks never run. I actually get a list of running
applications from libbamf and it works just fine.

Now, initially, my thought was that I didn't understand how libbamf's
signals worked and I was just doing it wrong. So I looked at Plank's
(another Vala application using libbamf) source code and it was doing
nearly the same thing that I was doing, and it was obviously working. So I
tried a couple other signals and callbacks that I knew worked. None of them
worked from within ApplicationProcessModel. Then, in desperation to get
anything to callback, I went ahead and tried putting a Glib.Timeout that
would trigger a callback every second in the ApplicationProcessModel. You
can imagine my surprise when, not only is the callback from the Timeout
called properly, suddenly my libbamf signal handlers are called, and not
just when the timer triggers, but whenever a window is created or closed
(like is the intended behavior of the signals). Now, this is great, because
it now kind of works -- but I have no idea what exactly putting in the
Timeout did to make it work! Moving the Timeout to MainWindow from
ApplicationProcessModel causes the fix to not work.

I suspect that there is some setup that I'm missing that creating a Timeout
does, perhaps related to how the signal is checked and dispatched from the
main loop in Gtk.Application.run() or Gtk.main(). I've tried moving to a
simpler setup without Gtk.Application with MainWindow created by main()
with calls to Gtk.init() at the beginning and Gtk.main() at the end, but
that didn't actually change any behavior at all, it still doesn't work
normally and works with the Timeout. I'm sure that I'm just missing out on
some vital piece of information regarding callbacks. I can provide code if
that is needed.


Any ideas?

Michael P. Starkweather