[mutter/wip/carlosg/xwayland-on-demand: 1/10] core: Prepare MetaStackTracker for X11 display being closed

[Carlos Garnacho <carlosg src gnome org>]

commit de8a600e454151ccb4f67ec3a6ab4e39344adbe2
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 | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
---
diff --git a/src/core/stack-tracker.c b/src/core/stack-tracker.c
index ee8bf011f..765223cef 100644
--- a/src/core/stack-tracker.c
+++ b/src/core/stack-tracker.c
@@ -508,6 +508,41 @@ 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;
+
+  for (l = tracker->unverified_predictions->head; l; l = l->next)
+    {
+      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 +558,10 @@ 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 +585,9 @@ 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);
 }