Signal emission from an object thread

[Emmanuel Pacaud <emmanuel gnome org>]

Hi,

I have an issue related to the use of g_signal_emit called from an 
object thread.

The object has a 'new-buffer' signal. It receives data in a thread it 
owns, and emits this signal from this thread. When the object is 
finalized, it sets a 'stop' gboolean to TRUE, that tells the thread to 
stop. It then joins the thread, then proceed to ressource deallocation.

The problem is g_signal_emit increases the reference count of the 
object. That means if the user unref the object from the main thread 
(thinking he releases the last reference) during the call to 
g_signal_emit, the object is now owned only by the thread. When 
g_signal_emit unref the object, the finalization happens on the object 
thread, which will lead to the thread trying to join itself.

Hence my question: is it possible to emit a signal without increasing 
the reference count of the object ? I'd really like to avoid adding an 
explicit 'stop-the-thread' or 'inhibit-signal' function, to be used 
before g_object_unref.

The code is here:

https://github.com/AravisProject/aravis/blob/7a024607f812d03ff87a906ce7f99a1a3bc13b9f/src/arvstream.c
https://github.com/AravisProject/aravis/blob/7a024607f812d03ff87a906ce7f99a1a3bc13b9f/src/arvuvstream.c

A fix proposal with an explicit inhibit signal function:

https://github.com/AravisProject/aravis/pull/51

Cheers,

        Emmanuel.