I am no expert in this area but I will attempt expand a bit on Mr Davis' answer. If I were you I would start looking at http://library.gnome.org/devel/glib/stable/glib-The-Main-Event-Loop.html. Also download the sources and dig though glib/gmain.c.
The
short answer is that the main loop does not use threads at all. At
least not that I could detect by looking through the glib sources. I am
not clear on how GDK integrates with the main loop. I guess it is
possible that it uses separate threads but I would be surprised if that
were the case.
The core of the (GLIB) main loop is the poll()
function (or something that looks like it). See the man paged for more
on poll(). In glib/gmain.c there are two custom implementations of
poll(). Both are called g_poll(). If the OS you are on does not provide
a system implementation of poll() then one of the other two are used.
If you are on a WIN32 platform the first one is used, otherwise the
second one is used. The second simply simulates what poll() does using
select(). The WIN32 one is rather complicated and tries to process the
content of the Window message pump as well as waiting for "EVENTS"
using WaitForMultipleObjects(). On unix systems the core of the main
loop relies on the fact that file descriptors could represent more than
just regular disk files. Unfortunately Windows does not work that way.
A
cursory glance at the gdk code makes me think it relies on the glib
main loop for input processing. If you look at gdk/x11/gdkevents-x11.c
the _gdk_events_init() function seems to get a file descriptor that is
assigns to a GdkDisplaySource (derived from GSource?) which is attached
to the default main loop using g_source_attach(). So it seems that at
least on X11 no additional threads are needed to get input events. I
noticed that there are also gdk/win32, gdk/quartz, gdk/linux-fb and
gdk/direct-fb directories. Who knows if any of them rely on threads to
capture user input. I would be surprised if that were the case for
win32 and quartz since the underlying OS likely takes care of that for
us.
Hope that helps. Again, I am no expert. If I misspoke I am sure someone will correct me. :)
Peter Long
----- Original Message ----
From: 刘志波 <boerliu gmail com>
To: paul linuxaudiosystems com
Cc: gtk-list gnome org
Sent: Friday, December 7, 2007 1:27:10 PM
Subject: Re: Is GTK+-(GDK) implemented by Multi-thread method?
Thanks a lot!
2007/12/8, Paul Davis <paul linuxaudiosystems com>:
On Sat, 2007-12-08 at 02:09 +0800, 刘志波 wrote:
> Hi forks,
> I want to know whether the GTK+- Library is implemented by
> Multi-thread method for itself. You know, it has been driven by event
> mechanism. How does GTK's main loop catch user events like key events,
> mouse motion,etc when other flows alway hold the CPU resource? I know,
> maybe the GTK lib can use the signal to receive all of the hardware
> events. I just want to know the GTK wheter uses the Multi-thread
> mechanism to program itself!
no.
