[mutter/wip/carlosg/xwayland-on-demand: 129/143] core: Prepare MetaStackTracker for X11 display being closed

[Carlos Garnacho <carlosg src gnome org>]

commit 41e4b4b9e8e9cb6ef7e6bc49c240ad3a4eaf6623
Author: Carlos Garnacho <carlosg gnome org>
Date:   Fri May 24 20:04:09 2019 +0200

    core: Prepare MetaStackTracker for X11 display being closed
    
    If the display is closed prematurely, go through all windows that
    look X11-y and remove them for future calculations. This is not
    strictly needed as Xwayland should shut down orderly (thus no client
    windows be there), but doesn't hurt to prepare in advance for the
    cases where it might not be the case.

 src/core/stack-tracker.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)
---
diff --git a/src/core/stack-tracker.c b/src/core/stack-tracker.c
index ee8bf011f..f7f240b86 100644
--- a/src/core/stack-tracker.c
+++ b/src/core/stack-tracker.c
@@ -508,6 +508,42 @@ query_xserver_stack (MetaDisplay      *display,
   XFree (children);
 }
 
+static void
+drop_x11_windows (MetaDisplay      *display,
+                  MetaStackTracker *tracker)
+{
+  GArray *new_stack;
+  GList *l;
+  int i;
+
+  tracker->xserver_serial = 0;
+
+  new_stack = g_array_new (FALSE, FALSE, sizeof (guint64));
+
+  for (i = 0; i < tracker->verified_stack->len; i++)
+    {
+      guint64 window = g_array_index (tracker->verified_stack, guint64, i);
+
+      if (!META_STACK_ID_IS_X11 (window))
+        g_array_append_val (new_stack, window);
+    }
+
+  g_array_unref (tracker->verified_stack);
+  tracker->verified_stack = new_stack;
+  l = tracker->unverified_predictions->head;
+
+  while (l)
+    {
+      MetaStackOp *op = l->data;
+      GList *next = l->next;
+
+      if (META_STACK_ID_IS_X11 (op->any.window))
+        g_queue_remove (tracker->unverified_predictions, op);
+
+      l = next;
+    }
+}
+
 MetaStackTracker *
 meta_stack_tracker_new (MetaDisplay *display)
 {
@@ -523,6 +559,10 @@ meta_stack_tracker_new (MetaDisplay *display)
                     "x11-display-opened",
                     G_CALLBACK (query_xserver_stack),
                     tracker);
+  g_signal_connect (display,
+                    "x11-display-closing",
+                    G_CALLBACK (drop_x11_windows),
+                    tracker);
 
   meta_stack_tracker_dump (tracker);
 
@@ -546,6 +586,9 @@ meta_stack_tracker_free (MetaStackTracker *tracker)
   g_signal_handlers_disconnect_by_func (tracker->display,
                                         (gpointer)query_xserver_stack,
                                         tracker);
+  g_signal_handlers_disconnect_by_func (tracker->display,
+                                        drop_x11_windows,
+                                        tracker);
 
   g_free (tracker);
 }