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gtk/gdk/gdkframeclockidle.c
Alexander Larsson a27fed47e0 frame-clock: Ensure we're always monotonic 
A call to frame gdk_frame_clock_get_frame_time() outside of the paint
cycle could report an un-error-corrected frame time, and later a
corrected value could be earlier than the previously reported value.

We now always store the latest reported time so we can ensure
monotonicity.
2020-05-28 17:44:51 +02:00

698 lines
23 KiB
C
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/* GDK - The GIMP Drawing Kit
* Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
/*
* Modified by the GTK+ Team and others 1997-2010. See the AUTHORS
* file for a list of people on the GTK+ Team. See the ChangeLog
* files for a list of changes. These files are distributed with
* GTK+ at ftp://ftp.gtk.org/pub/gtk/.
*/
#include "config.h"
#include "gdkframeclockidleprivate.h"
#include "gdkinternals.h"
#include "gdkframeclockprivate.h"
#include "gdk.h"
#include "gdkprofilerprivate.h"
#ifdef G_OS_WIN32
#include <windows.h>
#endif
#define FRAME_INTERVAL 16667 /* microseconds */
struct _GdkFrameClockIdlePrivate
{
gint64 frame_time; /* The exact time we last ran the clock cycle, or 0 if never */
gint64 smoothed_frame_time_base; /* A grid-aligned version of frame_time (grid size == refresh period), never more than half a grid from frame_time */
gint64 smoothed_frame_time_period; /* The grid size that smoothed_frame_time_base is aligned to */
gint64 smoothed_frame_time_reported; /* Ensures we are always monotonic */
gint64 min_next_frame_time; /* We're not synced to vblank, so wait at least until this before next cycle to avoid busy looping */
gint64 sleep_serial;
gint64 freeze_time;
guint flush_idle_id;
guint paint_idle_id;
guint freeze_count;
guint updating_count;
GdkFrameClockPhase requested;
GdkFrameClockPhase phase;
guint in_paint_idle : 1;
#ifdef G_OS_WIN32
guint begin_period : 1;
#endif
};
static gboolean gdk_frame_clock_flush_idle (void *data);
static gboolean gdk_frame_clock_paint_idle (void *data);
G_DEFINE_TYPE_WITH_PRIVATE (GdkFrameClockIdle, gdk_frame_clock_idle, GDK_TYPE_FRAME_CLOCK)
static gint64 sleep_serial;
static gint64 sleep_source_prepare_time;
static GSource *sleep_source;
static gboolean
sleep_source_prepare (GSource *source,
gint *timeout)
{
sleep_source_prepare_time = g_source_get_time (source);
*timeout = -1;
return FALSE;
}
static gboolean
sleep_source_check (GSource *source)
{
if (g_source_get_time (source) != sleep_source_prepare_time)
sleep_serial++;
return FALSE;
}
static gboolean
sleep_source_dispatch (GSource *source,
GSourceFunc callback,
gpointer user_data)
{
return TRUE;
}
static GSourceFuncs sleep_source_funcs = {
sleep_source_prepare,
sleep_source_check,
sleep_source_dispatch,
NULL /* finalize */
};
static gint64
get_sleep_serial (void)
{
if (sleep_source == NULL)
{
sleep_source = g_source_new (&sleep_source_funcs, sizeof (GSource));
g_source_set_priority (sleep_source, G_PRIORITY_HIGH);
g_source_attach (sleep_source, NULL);
g_source_unref (sleep_source);
}
return sleep_serial;
}
static void
gdk_frame_clock_idle_init (GdkFrameClockIdle *frame_clock_idle)
{
GdkFrameClockIdlePrivate *priv;
frame_clock_idle->priv = priv =
gdk_frame_clock_idle_get_instance_private (frame_clock_idle);
priv->freeze_count = 0;
}
static void
gdk_frame_clock_idle_dispose (GObject *object)
{
GdkFrameClockIdlePrivate *priv = GDK_FRAME_CLOCK_IDLE (object)->priv;
if (priv->flush_idle_id != 0)
{
g_source_remove (priv->flush_idle_id);
priv->flush_idle_id = 0;
}
if (priv->paint_idle_id != 0)
{
g_source_remove (priv->paint_idle_id);
priv->paint_idle_id = 0;
}
#ifdef G_OS_WIN32
if (priv->begin_period)
{
timeEndPeriod(1);
priv->begin_period = FALSE;
}
#endif
G_OBJECT_CLASS (gdk_frame_clock_idle_parent_class)->dispose (object);
}
/* Note: This is never called on first frame, so
* smoothed_frame_time_base != 0 and we have a valid frame_interval. */
static gint64
compute_smooth_frame_time (GdkFrameClock *clock,
gint64 new_frame_time,
gboolean new_frame_time_is_regular,
gint64 smoothed_frame_time_base,
gint64 frame_interval)
{
GdkFrameClockIdlePrivate *priv = GDK_FRAME_CLOCK_IDLE (clock)->priv;
int frames_passed;
gint64 new_smoothed_time;
gint64 current_error;
gint64 correction_magnitude;
/* Consecutive frame, assume it is an integer number of frames later, so round to nearest such */
/* NOTE: This is >= 0, because smoothed_frame_time_base is < frame_interval/2 from old_frame_time
* and new_frame_time >= old_frame_time. */
frames_passed = (new_frame_time - smoothed_frame_time_base + frame_interval / 2) / frame_interval;
/* We use an approximately whole number of frames in the future from
* last smoothed frame time. This way we avoid minor jitter in the
* frame times making the animation speed uneven, but still animate
* evenly in case of whole frame skips. */
new_smoothed_time = smoothed_frame_time_base + frames_passed * frame_interval;
/* However, sometimes the smoothed time is too much off from the
* real time. For example, if the first frame clock cycle happened
* not due to a frame rendering but an input event, then
* new_frame_time could happen to be near the middle between two
* frames. If that happens and we then start regularly animating at
* the refresh_rate, then the jitter in the real time may cause us
* to randomly sometimes round up, and sometimes down.
*
* To combat this we converge the smooth time towards the real time
* in a way that is slow when they are near and fast when they are
* far from each other.
*
* This is done by using the square of the error as the correction
* magnitude. I.e. if the error is 0.5 frame, we correct by
* 0.5*0.5=0.25 frame, if the error is 0.25 we correct by 0.125, if
* the error is 0.1, frame we correct by 0.01 frame, etc.
*
* The actual computation is:
* (current_error/frame_interval)*(current_error/frame_interval)*frame_interval
* But this can be simplified as below.
*
* Note: We only do this correction if we're regularly animating (no
* or low frame skip). If the last frame was a long time ago, or if
* we're not doing this in the frame cycle this call was likely
* triggered by an input event and new_frame_time is essentially
* random and not tied to the presentation time.
*/
if (new_frame_time_is_regular)
{
current_error = new_smoothed_time - new_frame_time;
correction_magnitude = current_error * current_error / frame_interval; /* Note, this is always > 0 due to the square */
if (current_error > 0)
new_smoothed_time -= correction_magnitude;
else
new_smoothed_time += correction_magnitude;
}
/* Ensure we're always monotonic */
if (new_smoothed_time <= priv->smoothed_frame_time_reported)
new_smoothed_time = priv->smoothed_frame_time_reported;
return new_smoothed_time;
}
static gint64
gdk_frame_clock_idle_get_frame_time (GdkFrameClock *clock)
{
GdkFrameClockIdlePrivate *priv = GDK_FRAME_CLOCK_IDLE (clock)->priv;
gint64 now;
gint64 new_smoothed_time;
/* can't change frame time during a paint */
if (priv->phase != GDK_FRAME_CLOCK_PHASE_NONE &&
priv->phase != GDK_FRAME_CLOCK_PHASE_FLUSH_EVENTS)
return priv->smoothed_frame_time_base;
/* Outside a paint, pick something smoothed close to now */
now = g_get_monotonic_time ();
/* First time frame, just return something */
if (priv->smoothed_frame_time_base == 0)
{
priv->smoothed_frame_time_reported = now;
return now;
}
/* Since time is monotonic this is <= what we will pick for the next cycle, but
more likely than not it will be equal if we're doing a constant animation. */
new_smoothed_time = compute_smooth_frame_time (clock, now, FALSE,
priv->smoothed_frame_time_base,
priv->smoothed_frame_time_period);
priv->smoothed_frame_time_reported = new_smoothed_time;
return new_smoothed_time;
}
#define RUN_FLUSH_IDLE(priv) \
((priv)->freeze_count == 0 && \
((priv)->requested & GDK_FRAME_CLOCK_PHASE_FLUSH_EVENTS) != 0)
/* The reason why we track updating_count separately here and don't
* just add GDK_FRAME_CLOCK_PHASE_UPDATE into ->request on every frame
* is so that we can avoid doing one more frame when an animation
* is cancelled.
*/
#define RUN_PAINT_IDLE(priv) \
((priv)->freeze_count == 0 && \
(((priv)->requested & ~GDK_FRAME_CLOCK_PHASE_FLUSH_EVENTS) != 0 || \
(priv)->updating_count > 0))
static void
maybe_start_idle (GdkFrameClockIdle *clock_idle)
{
GdkFrameClockIdlePrivate *priv = clock_idle->priv;
if (RUN_FLUSH_IDLE (priv) || RUN_PAINT_IDLE (priv))
{
guint min_interval = 0;
if (priv->min_next_frame_time != 0)
{
gint64 now = g_get_monotonic_time ();
gint64 min_interval_us = MAX (priv->min_next_frame_time, now) - now;
min_interval = (min_interval_us + 500) / 1000;
}
if (priv->flush_idle_id == 0 && RUN_FLUSH_IDLE (priv))
{
priv->flush_idle_id = g_timeout_add_full (GDK_PRIORITY_EVENTS + 1,
min_interval,
gdk_frame_clock_flush_idle,
g_object_ref (clock_idle),
(GDestroyNotify) g_object_unref);
g_source_set_name_by_id (priv->flush_idle_id, "[gtk] gdk_frame_clock_flush_idle");
}
if (!priv->in_paint_idle &&
priv->paint_idle_id == 0 && RUN_PAINT_IDLE (priv))
{
priv->paint_idle_id = g_timeout_add_full (GDK_PRIORITY_REDRAW,
min_interval,
gdk_frame_clock_paint_idle,
g_object_ref (clock_idle),
(GDestroyNotify) g_object_unref);
g_source_set_name_by_id (priv->paint_idle_id, "[gtk] gdk_frame_clock_paint_idle");
}
}
}
static void
maybe_stop_idle (GdkFrameClockIdle *clock_idle)
{
GdkFrameClockIdlePrivate *priv = clock_idle->priv;
if (priv->flush_idle_id != 0 && !RUN_FLUSH_IDLE (priv))
{
g_source_remove (priv->flush_idle_id);
priv->flush_idle_id = 0;
}
if (priv->paint_idle_id != 0 && !RUN_PAINT_IDLE (priv))
{
g_source_remove (priv->paint_idle_id);
priv->paint_idle_id = 0;
}
}
static gint64
compute_min_next_frame_time (GdkFrameClockIdle *clock_idle,
gint64 last_frame_time)
{
gint64 presentation_time;
gint64 refresh_interval;
gdk_frame_clock_get_refresh_info (GDK_FRAME_CLOCK (clock_idle),
last_frame_time,
&refresh_interval, &presentation_time);
if (presentation_time == 0)
return last_frame_time + refresh_interval;
else
return presentation_time + refresh_interval / 2;
}
static gboolean
gdk_frame_clock_flush_idle (void *data)
{
GdkFrameClock *clock = GDK_FRAME_CLOCK (data);
GdkFrameClockIdle *clock_idle = GDK_FRAME_CLOCK_IDLE (clock);
GdkFrameClockIdlePrivate *priv = clock_idle->priv;
priv->flush_idle_id = 0;
if (priv->phase != GDK_FRAME_CLOCK_PHASE_NONE)
return FALSE;
priv->phase = GDK_FRAME_CLOCK_PHASE_FLUSH_EVENTS;
priv->requested &= ~GDK_FRAME_CLOCK_PHASE_FLUSH_EVENTS;
_gdk_frame_clock_emit_flush_events (clock);
if ((priv->requested & ~GDK_FRAME_CLOCK_PHASE_FLUSH_EVENTS) != 0 ||
priv->updating_count > 0)
priv->phase = GDK_FRAME_CLOCK_PHASE_BEFORE_PAINT;
else
priv->phase = GDK_FRAME_CLOCK_PHASE_NONE;
return FALSE;
}
static gboolean
gdk_frame_clock_paint_idle (void *data)
{
GdkFrameClock *clock = GDK_FRAME_CLOCK (data);
GdkFrameClockIdle *clock_idle = GDK_FRAME_CLOCK_IDLE (clock);
GdkFrameClockIdlePrivate *priv = clock_idle->priv;
gboolean skip_to_resume_events;
GdkFrameTimings *timings = NULL;
gint64 before = g_get_monotonic_time ();
priv->paint_idle_id = 0;
priv->in_paint_idle = TRUE;
priv->min_next_frame_time = 0;
skip_to_resume_events =
(priv->requested & ~(GDK_FRAME_CLOCK_PHASE_FLUSH_EVENTS | GDK_FRAME_CLOCK_PHASE_RESUME_EVENTS)) == 0 &&
priv->updating_count == 0;
if (priv->phase > GDK_FRAME_CLOCK_PHASE_BEFORE_PAINT)
{
timings = gdk_frame_clock_get_current_timings (clock);
}
if (!skip_to_resume_events)
{
switch (priv->phase)
{
case GDK_FRAME_CLOCK_PHASE_FLUSH_EVENTS:
break;
case GDK_FRAME_CLOCK_PHASE_NONE:
case GDK_FRAME_CLOCK_PHASE_BEFORE_PAINT:
if (priv->freeze_count == 0)
{
gint64 frame_interval = FRAME_INTERVAL;
GdkFrameTimings *prev_timings = gdk_frame_clock_get_current_timings (clock);
gint64 old_frame_time = priv->frame_time;
if (prev_timings && prev_timings->refresh_interval)
frame_interval = prev_timings->refresh_interval;
priv->frame_time = g_get_monotonic_time ();
if (priv->smoothed_frame_time_base == 0)
{
/* First frame */
priv->smoothed_frame_time_base = priv->frame_time;
priv->smoothed_frame_time_period = frame_interval;
}
else
{
/* For long delays, cycle was probably caused by input event rather than animation */
gboolean is_regular = priv->frame_time - old_frame_time < 4 * FRAME_INTERVAL;
priv->smoothed_frame_time_base =
compute_smooth_frame_time (clock, priv->frame_time,
is_regular,
priv->smoothed_frame_time_base,
priv->smoothed_frame_time_period);
priv->smoothed_frame_time_period = frame_interval;
}
priv->smoothed_frame_time_reported = priv->smoothed_frame_time_base;
_gdk_frame_clock_begin_frame (clock);
/* Note "current" is different now so timings != prev_timings */
timings = gdk_frame_clock_get_current_timings (clock);
timings->frame_time = priv->frame_time;
timings->smoothed_frame_time = priv->smoothed_frame_time_base;
timings->slept_before = priv->sleep_serial != get_sleep_serial ();
priv->phase = GDK_FRAME_CLOCK_PHASE_BEFORE_PAINT;
/* We always emit ::before-paint and ::after-paint if
* any of the intermediate phases are requested and
* they don't get repeated if you freeze/thaw while
* in them.
*/
priv->requested &= ~GDK_FRAME_CLOCK_PHASE_BEFORE_PAINT;
_gdk_frame_clock_emit_before_paint (clock);
priv->phase = GDK_FRAME_CLOCK_PHASE_UPDATE;
}
G_GNUC_FALLTHROUGH;
case GDK_FRAME_CLOCK_PHASE_UPDATE:
if (priv->freeze_count == 0)
{
if ((priv->requested & GDK_FRAME_CLOCK_PHASE_UPDATE) != 0 ||
priv->updating_count > 0)
{
priv->requested &= ~GDK_FRAME_CLOCK_PHASE_UPDATE;
_gdk_frame_clock_emit_update (clock);
}
}
G_GNUC_FALLTHROUGH;
case GDK_FRAME_CLOCK_PHASE_LAYOUT:
if (priv->freeze_count == 0)
{
int iter;
#ifdef G_ENABLE_DEBUG
if (GDK_DEBUG_CHECK (FRAMES))
{
if (priv->phase != GDK_FRAME_CLOCK_PHASE_LAYOUT &&
(priv->requested & GDK_FRAME_CLOCK_PHASE_LAYOUT))
timings->layout_start_time = g_get_monotonic_time ();
}
#endif
priv->phase = GDK_FRAME_CLOCK_PHASE_LAYOUT;
/* We loop in the layout phase, because we don't want to progress
* into the paint phase with invalid size allocations. This may
* happen in some situation like races between user window
* resizes and natural size changes.
*/
iter = 0;
while ((priv->requested & GDK_FRAME_CLOCK_PHASE_LAYOUT) &&
priv->freeze_count == 0 && iter++ < 4)
{
priv->requested &= ~GDK_FRAME_CLOCK_PHASE_LAYOUT;
_gdk_frame_clock_emit_layout (clock);
}
if (iter == 5)
g_warning ("gdk-frame-clock: layout continuously requested, giving up after 4 tries");
}
G_GNUC_FALLTHROUGH;
case GDK_FRAME_CLOCK_PHASE_PAINT:
if (priv->freeze_count == 0)
{
#ifdef G_ENABLE_DEBUG
if (GDK_DEBUG_CHECK (FRAMES))
{
if (priv->phase != GDK_FRAME_CLOCK_PHASE_PAINT &&
(priv->requested & GDK_FRAME_CLOCK_PHASE_PAINT))
timings->paint_start_time = g_get_monotonic_time ();
}
#endif
priv->phase = GDK_FRAME_CLOCK_PHASE_PAINT;
if (priv->requested & GDK_FRAME_CLOCK_PHASE_PAINT)
{
priv->requested &= ~GDK_FRAME_CLOCK_PHASE_PAINT;
_gdk_frame_clock_emit_paint (clock);
}
}
G_GNUC_FALLTHROUGH;
case GDK_FRAME_CLOCK_PHASE_AFTER_PAINT:
if (priv->freeze_count == 0)
{
priv->requested &= ~GDK_FRAME_CLOCK_PHASE_AFTER_PAINT;
_gdk_frame_clock_emit_after_paint (clock);
/* the ::after-paint phase doesn't get repeated on freeze/thaw,
*/
priv->phase = GDK_FRAME_CLOCK_PHASE_NONE;
}
#ifdef G_ENABLE_DEBUG
if (GDK_DEBUG_CHECK (FRAMES))
timings->frame_end_time = g_get_monotonic_time ();
#endif /* G_ENABLE_DEBUG */
G_GNUC_FALLTHROUGH;
case GDK_FRAME_CLOCK_PHASE_RESUME_EVENTS:
default:
;
}
}
if (priv->requested & GDK_FRAME_CLOCK_PHASE_RESUME_EVENTS)
{
priv->requested &= ~GDK_FRAME_CLOCK_PHASE_RESUME_EVENTS;
_gdk_frame_clock_emit_resume_events (clock);
}
if (priv->freeze_count == 0)
priv->phase = GDK_FRAME_CLOCK_PHASE_NONE;
priv->in_paint_idle = FALSE;
/* If there is throttling in the backend layer, then we'll do another
* update as soon as the backend unthrottles (if there is work to do),
* otherwise we need to figure when the next frame should be.
*/
if (priv->freeze_count == 0)
{
priv->min_next_frame_time = compute_min_next_frame_time (clock_idle,
priv->frame_time);
maybe_start_idle (clock_idle);
}
if (priv->freeze_count == 0)
priv->sleep_serial = get_sleep_serial ();
if (GDK_PROFILER_IS_RUNNING)
gdk_profiler_end_mark (before, "frameclock cycle", NULL);
return FALSE;
}
static void
gdk_frame_clock_idle_request_phase (GdkFrameClock *clock,
GdkFrameClockPhase phase)
{
GdkFrameClockIdle *clock_idle = GDK_FRAME_CLOCK_IDLE (clock);
GdkFrameClockIdlePrivate *priv = clock_idle->priv;
priv->requested |= phase;
maybe_start_idle (clock_idle);
}
static void
gdk_frame_clock_idle_begin_updating (GdkFrameClock *clock)
{
GdkFrameClockIdle *clock_idle = GDK_FRAME_CLOCK_IDLE (clock);
GdkFrameClockIdlePrivate *priv = clock_idle->priv;
#ifdef G_OS_WIN32
/* We need a higher resolution timer while doing animations */
if (priv->updating_count == 0 && !priv->begin_period)
{
timeBeginPeriod(1);
priv->begin_period = TRUE;
}
#endif
priv->updating_count++;
maybe_start_idle (clock_idle);
}
static void
gdk_frame_clock_idle_end_updating (GdkFrameClock *clock)
{
GdkFrameClockIdle *clock_idle = GDK_FRAME_CLOCK_IDLE (clock);
GdkFrameClockIdlePrivate *priv = clock_idle->priv;
g_return_if_fail (priv->updating_count > 0);
priv->updating_count--;
maybe_stop_idle (clock_idle);
#ifdef G_OS_WIN32
if (priv->updating_count == 0 && priv->begin_period)
{
timeEndPeriod(1);
priv->begin_period = FALSE;
}
#endif
}
static void
gdk_frame_clock_idle_freeze (GdkFrameClock *clock)
{
GdkFrameClockIdle *clock_idle = GDK_FRAME_CLOCK_IDLE (clock);
GdkFrameClockIdlePrivate *priv = clock_idle->priv;
if (priv->freeze_count == 0)
{
if (GDK_PROFILER_IS_RUNNING)
priv->freeze_time = g_get_monotonic_time ();
}
priv->freeze_count++;
maybe_stop_idle (clock_idle);
}
static void
gdk_frame_clock_idle_thaw (GdkFrameClock *clock)
{
GdkFrameClockIdle *clock_idle = GDK_FRAME_CLOCK_IDLE (clock);
GdkFrameClockIdlePrivate *priv = clock_idle->priv;
g_return_if_fail (priv->freeze_count > 0);
priv->freeze_count--;
if (priv->freeze_count == 0)
{
maybe_start_idle (clock_idle);
/* If nothing is requested so we didn't start an idle, we need
* to skip to the end of the state chain, since the idle won't
* run and do it for us.
*/
if (priv->paint_idle_id == 0)
priv->phase = GDK_FRAME_CLOCK_PHASE_NONE;
priv->sleep_serial = get_sleep_serial ();
if (GDK_PROFILER_IS_RUNNING)
{
if (priv->freeze_time != 0)
{
gdk_profiler_end_mark (priv->freeze_time,
"frameclock frozen", NULL);
priv->freeze_time = 0;
}
}
}
}
static void
gdk_frame_clock_idle_class_init (GdkFrameClockIdleClass *klass)
{
GObjectClass *gobject_class = (GObjectClass*) klass;
GdkFrameClockClass *frame_clock_class = (GdkFrameClockClass *)klass;
gobject_class->dispose = gdk_frame_clock_idle_dispose;
frame_clock_class->get_frame_time = gdk_frame_clock_idle_get_frame_time;
frame_clock_class->request_phase = gdk_frame_clock_idle_request_phase;
frame_clock_class->begin_updating = gdk_frame_clock_idle_begin_updating;
frame_clock_class->end_updating = gdk_frame_clock_idle_end_updating;
frame_clock_class->freeze = gdk_frame_clock_idle_freeze;
frame_clock_class->thaw = gdk_frame_clock_idle_thaw;
}
GdkFrameClock *
_gdk_frame_clock_idle_new (void)
{
GdkFrameClockIdle *clock;
clock = g_object_new (GDK_TYPE_FRAME_CLOCK_IDLE, NULL);
return GDK_FRAME_CLOCK (clock);
}
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