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compositor: Make sure _NET_WM_FRAME_DRAWN timestamp has the right scope

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The timestamp sent with _NET_WM_FRAME_DRAWN should be in "high
resolution X server timestamps", meaning they should have the same scope
as the built in X11 32 bit unsigned integer timestamps, i.e. overflow at
the same time.

This was not done correctly when mutter had determined the X server used
the monotonic clock, where it'd just forward the monotonic clock,
confusing any client using _NET_WM_FRAME_DRAWN and friends.

Fix this by 1) splitting the timestamp conversiot into an X11 case and a
display server case, where the display server case simply clamps the
monotonic clock, as it is assumed Xwayland is always usign the monotonic
clock, and 2) if we're a X11 compositing manager, if the X server is
using the monotonic clock, apply the same semantics as the display
server case and always just clamp, or if not, calculate the offset every
10 seconds, and offset the monotonic clock timestamp with the calculated
X server timestamp offset.

This fixes an issue that would occur if mutter (or rather GNOME Shell)
would have been started before a X11 timestamp overflow, after the
overflow happened. In this case, GTK3 clients would get unclamped
timestamps, and get very confused, resulting in frames queued several
weeks into the future.

https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1494
This commit is contained in:
Jonas Ådahl 2020-07-08 16:53:14 +02:00 committed by Georges Basile Stavracas Neto
parent 53c4ebee82
commit bf6dde87f8
6 changed files with 121 additions and 42 deletions
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6
clutter/clutter/clutter-private.h
View file

@ -298,6 +298,12 @@ ns2us (int64_t ns)
return us (ns / 1000);
}
static inline int64_t
s2us (int64_t s)
{
return ms2us (s * 1000);
}
G_END_DECLS
#endif /* __CLUTTER_PRIVATE_H__ */

23
src/compositor/compositor-private.h
View file

@ -5,6 +5,7 @@
#include <X11/extensions/Xfixes.h>
#include "clutter/clutter-mutter.h"
#include "clutter/clutter.h"
#include "compositor/meta-plugin-manager.h"
#include "compositor/meta-window-actor-private.h"
@ -29,6 +30,8 @@ struct _MetaCompositorClass
ClutterStageView *stage_view);
void (* remove_window) (MetaCompositor *compositor,
MetaWindow *window);
int64_t (* monotonic_to_high_res_xserver_time) (MetaCompositor *compositor,
int64_t time_us);
};
gboolean meta_compositor_do_manage (MetaCompositor *compositor,
@ -49,8 +52,8 @@ void meta_end_modal_for_plugin (MetaCompositor *compositor,
MetaPluginManager * meta_compositor_get_plugin_manager (MetaCompositor *compositor);
gint64 meta_compositor_monotonic_time_to_server_time (MetaDisplay *display,
gint64 monotonic_time);
int64_t meta_compositor_monotonic_to_high_res_xserver_time (MetaCompositor *compositor,
int64_t monotonic_time_us);
void meta_compositor_flash_window (MetaCompositor *compositor,
MetaWindow *window);
@ -77,4 +80,20 @@ gboolean meta_compositor_is_switching_workspace (MetaCompositor *compositor);
MetaLaters * meta_compositor_get_laters (MetaCompositor *compositor);
/*
* This function takes a 64 bit time stamp from the monotonic clock, and clamps
* it to the scope of the X server clock, without losing the granularity.
*/
static inline int64_t
meta_translate_to_high_res_xserver_time (int64_t time_us)
{
int64_t us;
int64_t ms;
us = time_us % 1000;
ms = time_us / 1000;
return ms2us (ms & 0xffffffff) + us;
}
#endif /* META_COMPOSITOR_PRIVATE_H */

39
src/compositor/compositor.c
View file

@ -1458,7 +1458,7 @@ meta_compositor_flash_window (MetaCompositor *compositor,
}
/**
* meta_compositor_monotonic_time_to_server_time:
* meta_compositor_monotonic_to_high_res_xserver_time:
* @display: a #MetaDisplay
* @monotonic_time: time in the units of g_get_monotonic_time()
*
@ -1471,40 +1471,13 @@ meta_compositor_flash_window (MetaCompositor *compositor,
* a time representation with high accuracy. If there is not a common
* time source, then the time synchronization will be less accurate.
*/
gint64
meta_compositor_monotonic_time_to_server_time (MetaDisplay *display,
gint64 monotonic_time)
int64_t
meta_compositor_monotonic_to_high_res_xserver_time (MetaCompositor *compositor,
int64_t monotonic_time_us)
{
MetaCompositor *compositor = display->compositor;
MetaCompositorPrivate *priv =
meta_compositor_get_instance_private (compositor);
MetaCompositorClass *klass = META_COMPOSITOR_GET_CLASS (compositor);
if (priv->server_time_query_time == 0 ||
(!priv->server_time_is_monotonic_time &&
monotonic_time > priv->server_time_query_time + 10*1000*1000)) /* 10 seconds */
{
guint32 server_time = meta_display_get_current_time_roundtrip (display);
gint64 server_time_usec = (gint64)server_time * 1000;
gint64 current_monotonic_time = g_get_monotonic_time ();
priv->server_time_query_time = current_monotonic_time;
/* If the server time is within a second of the monotonic time,
* we assume that they are identical. This seems like a big margin,
* but we want to be as robust as possible even if the system
* is under load and our processing of the server response is
* delayed.
*/
if (server_time_usec > current_monotonic_time - 1000*1000 &&
server_time_usec < current_monotonic_time + 1000*1000)
priv->server_time_is_monotonic_time = TRUE;
priv->server_time_offset = server_time_usec - current_monotonic_time;
}
if (priv->server_time_is_monotonic_time)
return monotonic_time;
else
return monotonic_time + priv->server_time_offset;
return klass->monotonic_to_high_res_xserver_time (compositor, monotonic_time_us);
}
void

9
src/compositor/meta-compositor-server.c
View file

@ -36,6 +36,13 @@ meta_compositor_server_unmanage (MetaCompositor *compositor)
{
}
static int64_t
meta_compositor_server_monotonic_to_high_res_xserver_time (MetaCompositor *compositor,
int64_t monotonic_time_us)
{
return meta_translate_to_high_res_xserver_time (monotonic_time_us);
}
MetaCompositorServer *
meta_compositor_server_new (MetaDisplay *display,
MetaBackend *backend)
@ -58,4 +65,6 @@ meta_compositor_server_class_init (MetaCompositorServerClass *klass)
compositor_class->manage = meta_compositor_server_manage;
compositor_class->unmanage = meta_compositor_server_unmanage;
compositor_class->monotonic_to_high_res_xserver_time =
meta_compositor_server_monotonic_to_high_res_xserver_time;
}

65
src/compositor/meta-compositor-x11.c
View file

@ -45,6 +45,10 @@ struct _MetaCompositorX11
gboolean have_x11_sync_object;
MetaWindow *unredirected_window;
gboolean xserver_uses_monotonic_clock;
int64_t xserver_time_query_time_us;
int64_t xserver_time_offset_us;
};
G_DEFINE_TYPE (MetaCompositorX11, meta_compositor_x11, META_TYPE_COMPOSITOR)
@ -102,6 +106,32 @@ meta_compositor_x11_process_xevent (MetaCompositorX11 *compositor_x11,
meta_x11_handle_event (xevent);
}
static void
determine_server_clock_source (MetaCompositorX11 *compositor_x11)
{
MetaCompositor *compositor = META_COMPOSITOR (compositor_x11);
MetaDisplay *display = meta_compositor_get_display (compositor);
MetaX11Display *x11_display = display->x11_display;
uint32_t server_time_ms;
int64_t server_time_us;
int64_t translated_monotonic_now_us;
server_time_ms = meta_x11_display_get_current_time_roundtrip (x11_display);
server_time_us = ms2us (server_time_ms);
translated_monotonic_now_us =
meta_translate_to_high_res_xserver_time (g_get_monotonic_time ());
/* If the server time offset is within a second of the monotonic time, we
* assume that they are identical. This seems like a big margin, but we want
* to be as robust as possible even if the system is under load and our
* processing of the server response is delayed.
*/
if (ABS (server_time_us - translated_monotonic_now_us) < s2us (1))
compositor_x11->xserver_uses_monotonic_clock = TRUE;
else
compositor_x11->xserver_uses_monotonic_clock = FALSE;
}
static gboolean
meta_compositor_x11_manage (MetaCompositor *compositor,
GError **error)
@ -135,6 +165,8 @@ meta_compositor_x11_manage (MetaCompositor *compositor,
return FALSE;
}
determine_server_clock_source (compositor_x11);
meta_x11_display_set_cm_selection (display->x11_display);
compositor_x11->output = display->x11_display->composite_overlay_window;
@ -376,6 +408,37 @@ meta_compositor_x11_remove_window (MetaCompositor *compositor,
parent_class->remove_window (compositor, window);
}
static int64_t
meta_compositor_x11_monotonic_to_high_res_xserver_time (MetaCompositor *compositor,
int64_t monotonic_time_us)
{
MetaCompositorX11 *compositor_x11 = META_COMPOSITOR_X11 (compositor);
int64_t now_us;
if (compositor_x11->xserver_uses_monotonic_clock)
return meta_translate_to_high_res_xserver_time (monotonic_time_us);
now_us = g_get_monotonic_time ();
if (compositor_x11->xserver_time_query_time_us == 0 ||
now_us > (compositor_x11->xserver_time_query_time_us + s2us (10)))
{
MetaDisplay *display = meta_compositor_get_display (compositor);
MetaX11Display *x11_display = display->x11_display;
uint32_t xserver_time_ms;
int64_t xserver_time_us;
compositor_x11->xserver_time_query_time_us = now_us;
xserver_time_ms =
meta_x11_display_get_current_time_roundtrip (x11_display);
xserver_time_us = ms2us (xserver_time_ms);
compositor_x11->xserver_time_offset_us = xserver_time_us - now_us;
}
return monotonic_time_us + compositor_x11->xserver_time_offset_us;
}
Window
meta_compositor_x11_get_output_xwindow (MetaCompositorX11 *compositor_x11)
{
@ -443,4 +506,6 @@ meta_compositor_x11_class_init (MetaCompositorX11Class *klass)
compositor_class->before_paint = meta_compositor_x11_before_paint;
compositor_class->after_paint = meta_compositor_x11_after_paint;
compositor_class->remove_window = meta_compositor_x11_remove_window;
compositor_class->monotonic_to_high_res_xserver_time =
meta_compositor_x11_monotonic_to_high_res_xserver_time;
}

21
src/compositor/meta-window-actor-x11.c
View file

@ -163,12 +163,14 @@ do_send_frame_drawn (MetaWindowActorX11 *actor_x11,
meta_window_actor_get_meta_window (META_WINDOW_ACTOR (actor_x11));
MetaDisplay *display = meta_window_get_display (window);
Display *xdisplay = meta_x11_display_get_xdisplay (display->x11_display);
int64_t now_us;
XClientMessageEvent ev = { 0, };
now_us = g_get_monotonic_time ();
frame->frame_drawn_time =
meta_compositor_monotonic_time_to_server_time (display,
g_get_monotonic_time ());
meta_compositor_monotonic_to_high_res_xserver_time (display->compositor,
now_us);
actor_x11->frame_drawn_time = frame->frame_drawn_time;
ev.type = ClientMessage;
@ -208,9 +210,12 @@ do_send_frame_timings (MetaWindowActorX11 *actor_x11,
if (presentation_time != 0)
{
int64_t presentation_time_server =
meta_compositor_monotonic_time_to_server_time (display,
presentation_time);
MetaCompositor *compositor = display->compositor;
int64_t presentation_time_server;
presentation_time_server =
meta_compositor_monotonic_to_high_res_xserver_time (compositor,
presentation_time);
int64_t presentation_time_offset = presentation_time_server - frame->frame_drawn_time;
if (presentation_time_offset == 0)
presentation_time_offset = 1;
@ -283,6 +288,7 @@ queue_send_frame_messages_timeout (MetaWindowActorX11 *actor_x11)
meta_window_actor_get_meta_window (META_WINDOW_ACTOR (actor_x11));
MetaDisplay *display = meta_window_get_display (window);
MetaLogicalMonitor *logical_monitor;
int64_t now_us;
int64_t current_time;
float refresh_rate;
int interval, offset;
@ -307,9 +313,10 @@ queue_send_frame_messages_timeout (MetaWindowActorX11 *actor_x11)
refresh_rate = 60.0f;
}
now_us = g_get_monotonic_time ();
current_time =
meta_compositor_monotonic_time_to_server_time (display,
g_get_monotonic_time ());
meta_compositor_monotonic_to_high_res_xserver_time (display->compositor,
now_us);
interval = (int) (1000000 / refresh_rate) * 6;
offset = MAX (0, actor_x11->frame_drawn_time + interval - current_time) / 1000;