[Ekiga-devel-list] Unthreading ekiga : a strategy

[Julien Puydt <jpuydt free fr>]

Hi,

first, let me spell out that the goal isn't to get rid of threads
entirely : that would be very stupid! No, the goal is to make all
graphical operations happen in a single thread, so we aren't hit by
forgotten _thread_enter/_thread_leave in our code, or thread-unsafety in
libraries we depend on (accessibility comes to mind).

The current code in the network code looks like this :
OnFooHappens (...)
{
 /* declaration of good variables */
 /* declaration of gui variables */

 /* good code */
 /* gui code */
 /* good code */
}

The first step is certainly to separate GUI code from good code like this :

OnFooHappensGUI (...)
{
  /* declaration of gui variables */

  /* gui code */
}

OnFooHappens (...)
{
 /* declaration of good variables */

 /* good code */
 OnFooHappensGUI (...);
 /* good code */
}

The second step is then to re-implement the GUI functions to push
treatment in the main thread :
OnFooHappensGUISafe (...)
{
  /* declaration of gui variables */

  /* gui code */

  /* free nice structure */
}

OnFoHappensGUI (...)
{
  /* allocate a nice structure */
  /* populate with the needed data */
  /* push to the main thread */
}

There are several ways the push can be done :
- the most simple way is to g_idle_add the function to call (this is the
trick I use in my LDAP code) ;
- the most complete way is �a-GstBus, where we have a GSource whichs
watches a GQueue (or GAsyncQueue) and executes code from there (there we
can probably just take the GstBus code since 1. it's been well-tested
2. it's LGPL or GPL).

Snark

PS: this is reported here :
http://bugzilla.gnome.org/show_bug.cgi?id=353533