[mutter] Remove cache of last stacking order in stack.c

[Owen Taylor <otaylor src gnome org>]

commit 9401196e88503d07c5252f4c904a03ade6c531ea
Author: Owen W. Taylor <otaylor fishsoup net>
Date:   Tue Sep 9 16:03:34 2014 -0400

    Remove cache of last stacking order in stack.c
    
    stack.c kept it's own record of the last stacking it requested, so that
    restacking could be done with minimal moves, but we already have a better
    view of the stacking order with the stack tracker, so use that instead.
    
    This allows eliminating the special case for the first restack.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=736559

 src/core/stack.c |   54 +++++++++++++++++-------------------------------------
 1 files changed, 17 insertions(+), 37 deletions(-)
---
diff --git a/src/core/stack.c b/src/core/stack.c
index f335fe4..a4d2b1c 100644
--- a/src/core/stack.c
+++ b/src/core/stack.c
@@ -76,8 +76,6 @@ meta_stack_new (MetaScreen *screen)
   stack->removed = NULL;
 
   stack->freeze_count = 0;
-  stack->last_all_root_children_stacked = NULL;
-
   stack->n_positions = 0;
 
   stack->need_resort = FALSE;
@@ -87,13 +85,6 @@ meta_stack_new (MetaScreen *screen)
   return stack;
 }
 
-static void
-free_last_all_root_children_stacked_cache (MetaStack *stack)
-{
-  g_array_free (stack->last_all_root_children_stacked, TRUE);
-  stack->last_all_root_children_stacked = NULL;
-}
-
 void
 meta_stack_free (MetaStack *stack)
 {
@@ -103,9 +94,6 @@ meta_stack_free (MetaStack *stack)
   g_list_free (stack->added);
   g_list_free (stack->removed);
 
-  if (stack->last_all_root_children_stacked)
-    free_last_all_root_children_stacked_cache (stack);
-
   g_free (stack);
 }
 
@@ -1237,21 +1225,7 @@ stack_sync_to_xserver (MetaStack *stack)
 
   meta_error_trap_push (stack->screen->display);
 
-  if (stack->last_all_root_children_stacked == NULL)
-    {
-      /* Just impose our stack, we don't know the previous state.
-       * This involves a ton of circulate requests and may flicker.
-       */
-      meta_topic (META_DEBUG_STACK, "Don't know last stack state, restacking everything\n");
-
-      if (all_root_children_stacked->len > 1)
-        {
-          meta_stack_tracker_restack_windows (stack->screen->stack_tracker,
-                                              (guint64 *) all_root_children_stacked->data,
-                                              all_root_children_stacked->len);
-        }
-    }
-  else if (all_root_children_stacked->len > 0)
+  if (all_root_children_stacked->len > 0)
     {
       /* Try to do minimal window moves to get the stack in order */
       /* A point of note: these arrays include frames not client windows,
@@ -1259,10 +1233,14 @@ stack_sync_to_xserver (MetaStack *stack)
        * was saved, then we may have inefficiency, but I don't think things
        * break...
        */
-      const guint64 *old_stack = (guint64 *) stack->last_all_root_children_stacked->data;
+      guint64 *old_stack;
+      int old_len;
+      meta_stack_tracker_get_stack (stack->screen->stack_tracker,
+                                    &old_stack, &old_len);
+
       const guint64 *new_stack = (guint64 *) all_root_children_stacked->data;
-      const int old_len = stack->last_all_root_children_stacked->len;
       const int new_len = all_root_children_stacked->len;
+
       const guint64 *oldp = old_stack;
       const guint64 *newp = new_stack;
       const guint64 *old_end = old_stack + old_len;
@@ -1281,12 +1259,17 @@ stack_sync_to_xserver (MetaStack *stack)
                 last_xwindow = (Window)*newp;
               last_window = *newp;
               ++newp;
+
+              continue;
             }
-          else if (meta_display_lookup_stack_id (stack->screen->display,
-                                                 *oldp) == NULL)
+
+          MetaWindow *old_window = meta_display_lookup_stack_id (stack->screen->display,
+                                                                 *oldp);
+
+          if (old_window == NULL || old_window->override_redirect)
             {
-              /* *oldp is no longer known to us (probably destroyed),
-               * so we can just skip it
+              /* *oldp is not known to us (probably unmanaged), or override_redirect, so
+               * we should skip it.
                */
               ++oldp;
             }
@@ -1396,10 +1379,7 @@ stack_sync_to_xserver (MetaStack *stack)
                    x11_stacked->len);
 
   g_array_free (x11_stacked, TRUE);
-
-  if (stack->last_all_root_children_stacked)
-    free_last_all_root_children_stacked_cache (stack);
-  stack->last_all_root_children_stacked = all_root_children_stacked;
+  g_array_free (all_root_children_stacked, TRUE);
 
   /* That was scary... */
 }