The `last_presentation_time` is usually a little in the past (although
sometimes in the future depending on the driver). When it's over 2ms
(`sync_delay`) in the past that would trigger the while loop to count up so
that the next `update_time` is in the future.
The problem with that is for common values of `last_presentation_time`
which are only a few milliseconds ago, incrementing `update_time` by
`refresh_interval` also means counting past the next physical frame that
we haven't rendered yet. And so mutter would skip that frame.
**Example**
Given:
```
last_presentation_time = now - 3ms
sync_delay = 2ms
refresh_interval = 16ms
next_presentation_time = last_presentation_time + refresh_interval
= now + 13ms
-3ms now +13ms +29ms +45ms
----|--+------------|---------------|---------------|----
: :
last_presentation_time next_presentation_time
```
Old algorithm:
```
update_time = last_presentation_time + sync_delay
= now - 1ms
while (update_time < now)
(now - 1ms < now)
update_time = now - 1ms + 16ms
update_time = now + 15ms
next_presentation_time = now + 13ms
available_render_time = next_presentation_time - max(now, update_time)
= (now + 13ms) - (now + 15ms)
= -2ms so the next frame will be skipped.
-3ms now +13ms +29ms +45ms
----|--+------------|-+-------------|---------------|----
: : :
: : update_time (too late)
: :
last_presentation_time next_presentation_time (a missed frame)
```
New algorithm:
```
min_render_time_allowed = refresh_interval / 2
= 8ms
max_render_time_allowed = refresh_interval - sync_delay
= 14ms
target_presentation_time = last_presentation_time + refresh_interval
= now - 3ms + 16ms
= now + 13ms
while (target_presentation_time - min_render_time_allowed < now)
(now + 13ms - 8ms < now)
(5ms < 0ms)
# loop is never entered
update_time = target_presentation_time - max_render_time_allowed
= now + 13ms - 14ms
= now - 1ms
next_presentation_time = now + 13ms
available_render_time = next_presentation_time - max(now, update_time)
= (now + 13ms) - now
= 13ms which is plenty of render time.
-3ms now +13ms +29ms +45ms
----|-++------------|---------------|---------------|----
: : :
: update_time :
: :
last_presentation_time next_presentation_time
```
The reason nobody noticed these missed frames very often was because
mutter has some accidental workarounds built-in:
* Prior to 3.32, the offending code was only reachable in Xorg sessions.
It was never reached in Wayland sessions because it hadn't been
implemented yet (till e9e4b2b72).
* Even though Wayland support is now implemented the native backend
provides a `last_presentation_time` much faster than Xorg sessions
(being in the same process) and so is less likely to spuriously enter
the while loop to miss a frame.
* For Xorg sessions we are accidentally triple buffering (#334). This
is a good way to avoid the missed frames, but is also an accident.
* `sync_delay` is presently just high enough (2ms by coincidence is very
close to common values of `now - last_presentation_time`) to push the
`update_time` into the future in some cases, which avoids entering the
while loop. This is why the same missed frames problem was also noticed
when experimenting with `sync_delay = 0`.
v2: adjust variable names and code style.
Fixes: https://bugzilla.gnome.org/show_bug.cgi?id=789186
and most of https://gitlab.gnome.org/GNOME/mutter/issues/571https://gitlab.gnome.org/GNOME/mutter/merge_requests/520
Linux glibc supports a malloc implementation that is allows to be tunable using
environment variables, to check allocation issues.
When MALLOC_CHECK_ is set to 3, a diagnostic message is printed on stderr and
the program is aborted.
Setting the MALLOC_PERTURB_ environment variable causes the malloc functions in
to return memory which has been wiped and initialized with the byte value of the
environment variable.
So use this features when running tests in order to catch better memory errors.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/578
We only call _clutter_input_device_update with devices that are not
Keyboard devices. Also passing a Keyboard device to a function whose
primary purpose is picking should be considered a bug in the caller.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/547
We're bailing out of clutter_stage_cogl_add_redraw_clip() early without
doing anything if we're ignoring redraw clips, so no need to call it if
we already know that will be the case.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/547
This function was added for historic reasons, before that we had GSlist's
free_full function.
Since this can be now easily implemented with a function call and an explicit
GDestroyFunc, while no known dependency uses it let's move to use
g_slist_free_func instead.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/57
GList's used in legacy code were free'd using a g_slist_foreach + g_slist_free,
while we can just use g_slist_free_full as per GLib 2.28.
So replace code where we were using this legacy codepath.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/576
GList's used in legacy code were free'd using a g_list_foreach + g_list_free,
while we can just use g_list_free_full as per GLib 2.28.
So replace code where we were using this legacy codepath.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/576
This shouldn't happen frequently, but is just a sign that the source is
being replaced by something else. Just keep the warning for other possible
error situations.
Also, plug the potential GError leak.
Closes: https://gitlab.gnome.org/GNOME/mutter/issues/598
Moving an actor with a ClutterDeformEffect applied flickers because
the depth_testing, setting the depth testing test function to
COGL_DEPTH_TEST_FUNCTION_LEQUAL fixes the problem.
Fixes https://gitlab.gnome.org/GNOME/mutter/issues/507
When the pointer is grabbed, we send the crossing events that are
initiated by this pointer only to the actor that has the grab. For
grabbed touch sequences, we always capture and bubble the crossing
events right now.
Fix this and make grabbed pointers and touch sequences behave the same
by sending touch crossing events only to the grab actor.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/422
It's important to cancel click actions when we get a touch cancel event,
otherwise the long press event might get emitted after the compositor
took over the touches because it detected a gesture.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/396
All child classes of `MetaWaylandShellSurface` as well as
`MetaWaylandSurfaceRoleXWayland` should only sync their actor if
their toplevel surface has a window. Currently this check is done
in the actor-surface class, but not all surface classes have a
toplevel window, e.g. dnd-surfaces.
Move the check to the right places.
For subsurfaces this assumes that the subsurface is not the child of
a window-less surface (like, as stated above, e.g. a dnd-surface).
If we want to support subsurfaces of window-less surfaces in the future
we have to extend the check here.
But as this is not a regression, ignore this case for now.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/537
Depending on the type of session, one or the other might be NULL, which
is not meant to be handled by these functions. Check for both DISPLAY
envvars before setting them on the GAppLaunchContext.
Closes: https://gitlab.gnome.org/GNOME/mutter/issues/586
This is 1) relatively likely as not all touchscreens are nice enough to
report a device size that will help us here and 2) Better than nothing if
everything fails anyway, as it will break on multi-monitor and non-default
monitor rotations.
Closes: https://gitlab.gnome.org/GNOME/mutter/issues/581
The check for the focus xwindow is called, but not used. Fix that by
renaming the variable to reflect better what it does and actually using
the return value of the check.
This was the original intention of the author in commit
05899596d1 and got broken in commit
8e7e1eeef5.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/535
If we update the ready time while the source is already in the
to-dispatch list, changing the ready time doesn't have any effect, and
the source will still be dispatched. This could cause incorrect idle
watch firing causing the power management plugin in
gnome-settings-daemon to sometimes turn off monitors due to it believing
the user had been idle for some time, while in fact, they just logged
back in.
Fix this by not actually dispatching the idle timeout if the ready time
is in the future when actually dispatching.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/543
meta_workspace_activate_with_focus is supposed to focus the passed window after
switching the workspace.
However if the passed workspace is already the active one, we just return
without activating the window.
So fix this calling meta_window_activate on the foucs_this window if that is
valid.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/562
Cogl unit tests are just functions inside normal code files that needs to be
dload'ed by the test binary.
So in case unit-tests are enabled, we need to export those symbols.
Since map file can't be overridden, use a configure_file to generate the map
file when tests are enabled, in order to export the needed symbols.
Then goes through the source files to look unit tests checking for their macro
definition and load them with the runner script.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/442
Use find-conform-unit-tests.sh to create a meson list of tests to run.
This allows to run each test as single test with meson and to remove the timeout
for all the tests.
Instead of changing 'run-tests.sh' to take test-names as arguments we can just
generate simple dummy test-files for each test, without having to change the
tooling.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/442
Don't launch the stacking tests in one single shot, to allow better debugging
and being able to launch just one single test using meson test.
Those tests can now be all launched with:
meson test --suite stacking [single-test-name]
https://gitlab.gnome.org/GNOME/mutter/merge_requests/442
This is a simple clipboard manager implementation on top of MetaSelection.
It will inspect the clipboard content for UTF-8 text and image data whenever
any other selection source claims ownership, and claim it for itself
whenever the clipboard goes unowned.
The stored text has a maximum size of 4MB and images 200MB, to prevent the
compositor from allocating indefinite amounts of memory.
This is not quite a X11 clipboard manager, but also works there.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/320
This code takes care of both setting up X11 selection sources whenever
X11 clients claim selection ownership, and claiming selection ownership
on a mutter X11 window whenever other selection sources claim ownership.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/320
