Bug 247943

Description of problem:  Nautilus leaks memory when changing background images.
 Each time I switch images, the memory goes up, and stays up.  (If I change the
sizing of an image, it spikes briefly.)  According to massif, the memory at
issue is the pixbuf image storage allocated in gdk_pixbuf_new.

Version-Release number of selected component (if applicable):
nautilus-2.18.3-1.fc7
eel2-2.18.0.1-5.fc7
gnome-desktop-2.18.3-1.fc7

How reproducible: Always

Steps to Reproduce:
1. Right click on desktop
2. Choose "Change desktop background"
3. switch to different images (particularly big ones)

Observe nautilus memory usage using top or valgrind --tool=massif.
  
Actual results: Memory leak.

Expected results: Background image memory freed once the image isn't the
background anymore.

Additional info:
I'm filing this in Red Hat's bugzilla rather than GNOME's because this appears
to be a bug in gnome-bg.c, which is part of the gnome-desktop package only
because of gnome-desktop-2.18.0-gnome-bg.patch .  (It looks like it might be a
backport from a newer version of GNOME, given the "Since: 2.20" that appears in
it, but I'm not sure where in GNOME it comes from, and thus, where to file a
bug.  And, astonishingly to me, http://svn.gnome.org/viewcvs/ has no way to
search for a file.)

What seems to be happening is the following:
 * When the user changes the background image, nautilus and eel essentially
re-use an existing GnomeBG object, via the following stack:

#1  0x00cef3ea in gnome_bg_set_uri (bg=0x90bb470, 
    uri=0x9164838
"file:///home/dbaron/Pictures/2003-08-29-8-Oslo-Akershus-Panorama-1.jpg") at
gnome-bg.c:233
#2  0x059dbd27 in eel_background_reload_image (
    background=<value optimized out>) at eel-background.c:536
#3  0x059dc958 in eel_background_set_image_uri_helper (background=0x8f9bec8, 
    image_uri=0x90a96d0
"file:///home/dbaron/Pictures/2003-08-29-8-Oslo-Akershus-Panorama-1.jpg",
emit_setting_change=1, emit_appearance_change=1)
    at eel-background.c:573
#4  0x080fa41e in initialize_background_from_settings (file=0x8ecea08, 
    background=0x8f9bec8) at nautilus-directory-background.c:486
#5  0x080faaa8 in call_settings_changed (background=0x8f9bec8)
    at nautilus-directory-background.c:294
#6  0x00c54bf6 in g_timeout_dispatch (source=0x919db78, callback=0, 
    user_data=0x8f9bec8) at gmain.c:3422
...

gnome_bg_set_uri calls clear_cache to free some of the objects associated with
the previous image, but it doesn't clear file_cache.  file_cache owns a
reference to the pixbuf, transferred to it when get_as_pixbuf calls
file_cache_add_pixbuf.  Thus the reference in the GnomeBG's file_cache is not
freed when transitioning between background images.

I'll admit that it looks, from the code, that this *might* be intentional that
the file_cache lasts across uri changes (although I'm not sure why it would be
desirable).

If it's not intended, then the correct fix would seem to be making clear_cache
free the items in file_cache.

If it is intended, however, then there are two fixes needed:
 * gnome_bg_finalize needs to free the items in file_cache
 * the callers in eel / nautilus need to be given some other way to free the pixbuf.