x11: Decouple sync alarms from window XIDs

Store the alarms in a different hashtable, and look up the MetaSyncCounter
right away. It so far avoids the MetaWindow middle man, but will also be
simpler when each window can possibly have more than one active alarms.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2175>

src/x11/events.c

@@ -1314,15 +1314,17 @@ handle_other_xevent (MetaX11Display *x11_display,
   if (META_X11_DISPLAY_HAS_XSYNC (x11_display) &&
       event->type == (x11_display->xsync_event_base + XSyncAlarmNotify))
     {
-      MetaWindow *alarm_window = meta_x11_display_lookup_sync_alarm (x11_display,
+      MetaSyncCounter *sync_counter;
+
+      sync_counter = meta_x11_display_lookup_sync_alarm (x11_display,
                                                          ((XSyncAlarmNotifyEvent*)event)->alarm);
 
-      if (alarm_window != NULL)
+      if (sync_counter != NULL)
         {
           XSyncValue value = ((XSyncAlarmNotifyEvent*)event)->counter_value;
           gint64 new_counter_value;
           new_counter_value = XSyncValueLow32 (value) + ((gint64)XSyncValueHigh32 (value) << 32);
-          meta_window_x11_update_sync_request_counter (alarm_window, new_counter_value);
+          meta_sync_counter_update (sync_counter, new_counter_value);
           bypass_gtk = TRUE; /* GTK doesn't want to see this really */
         }
       else if (x11_display->alarm_filters)

src/x11/meta-sync-counter.c

@@ -152,7 +152,7 @@ meta_sync_counter_create_sync_alarm (MetaSyncCounter *sync_counter)
     {
       meta_x11_display_register_sync_alarm (x11_display,
                                             &sync_counter->sync_request_alarm,
-                                            window);
+                                            sync_counter);
     }
   else
     {

src/x11/meta-x11-display-private.h

@@ -37,6 +37,7 @@
 #include "meta-startup-notification-x11.h"
 #include "meta-x11-stack-private.h"
 #include "ui/ui.h"
+#include "x11/meta-sync-counter.h"
 
 typedef struct _MetaGroupPropHooks  MetaGroupPropHooks;
 typedef struct _MetaWindowPropHooks MetaWindowPropHooks;
@@ -109,6 +110,7 @@ struct _MetaX11Display
   Window composite_overlay_window;
 
   GHashTable *xids;
+  GHashTable *alarms;
 
   gboolean has_xinerama_indices;
 
@@ -211,11 +213,13 @@ void        meta_x11_display_register_x_window   (MetaX11Display *x11_display,
 void        meta_x11_display_unregister_x_window (MetaX11Display *x11_display,
                                                   Window          xwindow);
 
-MetaWindow *meta_x11_display_lookup_sync_alarm     (MetaX11Display *x11_display,
+MetaSyncCounter * meta_x11_display_lookup_sync_alarm (MetaX11Display *x11_display,
                                                       XSyncAlarm      alarm);
+
 void        meta_x11_display_register_sync_alarm (MetaX11Display  *x11_display,
                                                   XSyncAlarm      *alarmp,
-                                                    MetaWindow     *window);
+                                                  MetaSyncCounter *sync_counter);
+
 void        meta_x11_display_unregister_sync_alarm (MetaX11Display *x11_display,
                                                     XSyncAlarm      alarm);
 

src/x11/meta-x11-display.c

@@ -217,6 +217,8 @@ meta_x11_display_dispose (GObject *object)
       x11_display->xids = NULL;
     }
 
+  g_clear_pointer (&x11_display->alarms, g_hash_table_unref);
+
   if (x11_display->xroot != None)
     {
       unset_wm_check_hint (x11_display);
@@ -1311,6 +1313,8 @@ meta_x11_display_new (MetaDisplay  *display,
 
   x11_display->xids = g_hash_table_new (meta_unsigned_long_hash,
                                         meta_unsigned_long_equal);
+  x11_display->alarms = g_hash_table_new (meta_unsigned_long_hash,
+                                          meta_unsigned_long_equal);
 
   x11_display->groups_by_leader = NULL;
   x11_display->composite_overlay_window = None;
@@ -1700,36 +1704,30 @@ meta_x11_display_unregister_x_window (MetaX11Display *x11_display,
   g_hash_table_remove (x11_display->xids, &xwindow);
 }
 
-
+MetaSyncCounter *
-/* We store sync alarms in the window ID hash table, because they are
- * just more types of XIDs in the same global space, but we have
- * typesafe functions to register/unregister for readability.
- */
-
-MetaWindow *
 meta_x11_display_lookup_sync_alarm (MetaX11Display *x11_display,
                                     XSyncAlarm      alarm)
 {
-  return g_hash_table_lookup (x11_display->xids, &alarm);
+  return g_hash_table_lookup (x11_display->alarms, &alarm);
 }
 
 void
 meta_x11_display_register_sync_alarm (MetaX11Display  *x11_display,
                                       XSyncAlarm      *alarmp,
-                                      MetaWindow     *window)
+                                      MetaSyncCounter *sync_counter)
 {
-  g_return_if_fail (g_hash_table_lookup (x11_display->xids, alarmp) == NULL);
+  g_return_if_fail (g_hash_table_lookup (x11_display->alarms, alarmp) == NULL);
 
-  g_hash_table_insert (x11_display->xids, alarmp, window);
+  g_hash_table_insert (x11_display->alarms, alarmp, sync_counter);
 }
 
 void
 meta_x11_display_unregister_sync_alarm (MetaX11Display *x11_display,
                                         XSyncAlarm      alarm)
 {
-  g_return_if_fail (g_hash_table_lookup (x11_display->xids, &alarm) != NULL);
+  g_return_if_fail (g_hash_table_lookup (x11_display->alarms, &alarm) != NULL);
 
-  g_hash_table_remove (x11_display->xids, &alarm);
+  g_hash_table_remove (x11_display->alarms, &alarm);
 }
 
 MetaX11AlarmFilter *

src/x11/window-x11.c

@@ -4123,16 +4123,6 @@ meta_window_x11_destroy_sync_request_alarm (MetaWindow *window)
   meta_sync_counter_destroy_sync_alarm (&priv->sync_counter);
 }
 
-void
-meta_window_x11_update_sync_request_counter (MetaWindow *window,
-                                             gint64      new_counter_value)
-{
-  MetaWindowX11 *window_x11 = META_WINDOW_X11 (window);
-  MetaWindowX11Private *priv = meta_window_x11_get_instance_private (window_x11);
-
-  meta_sync_counter_update (&priv->sync_counter, new_counter_value);
-}
-
 Window
 meta_window_x11_get_toplevel_xwindow (MetaWindow *window)
 {

src/x11/window-x11.h

@@ -62,8 +62,6 @@ void meta_window_x11_set_allowed_actions_hint    (MetaWindow *window);
 
 void meta_window_x11_create_sync_request_alarm   (MetaWindow *window);
 void meta_window_x11_destroy_sync_request_alarm  (MetaWindow *window);
-void meta_window_x11_update_sync_request_counter (MetaWindow *window,
-                                                  gint64      new_counter_value);
 
 void meta_window_x11_update_input_region         (MetaWindow *window);
 void meta_window_x11_update_shape_region         (MetaWindow *window);