g_idle_add and thread safety

[Gabriele Greco <gabrielegreco tin it>]

I know GTK APIs are not thread safe, I've an app with a thread doing a 
massive job that wants to update the gui status every few cycles, to do 
so I remembered an old post speaking about g_idle_add.

The question I have and which I didn't find answers both googling, both 
looking at the sources is if g_idle_add can be called without any extra 
mutex/lock from another thread.

- I have to use gdk_threads_init() mechanism?
- I have to use gdk_threads_enter/leave() around gtk_main() and around 
the g_idle_add call?
- If so, if I use the gdk_threads_idle_add() facility I can avoid all 
the locks or I have to lock around gtk_main anyway? (the example doesn't 
clarify this)

Ideally my code should be something like:

static progress_datas;

gint myfunc(vod *unused)
{
        gtk_label_set_text(blablabla, progress_data);

        return FALSE; // call only once
}

work_thread() {
        while(1) {
                loops++;
[... do the real work ...]
                if ((loops % 1000) == 0) {
                        update_progress_datas();
                        g_idle_add(myfunc, NULL);
                }
        }
}

int main()
{
[..gui init and thread start]
        gtk_main()
}