From d6e7ebcb26f83e4c4d7bbc44d7c94162f88dabef Mon Sep 17 00:00:00 2001
From: Philipp Knechtges <philipp-dev@knechtges.com>
Date: Thu, 19 Jan 2012 11:38:04 +0100
Subject: [PATCH] kwin: fixing high cpu usage bugs

In some unfortunate situations it is possible that a window is deleted
before it is marked ready_for_painting=true. The last point is
especially troublesome for effects that reference the deleted window.

Many thanks to Elias Probst for all the testing.

CCBUG: 290025
CCBUG: 288948
REVIEW: 103733
---
 deleted.cpp | 9 +++++++++
 deleted.h   | 3 ++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/deleted.cpp b/deleted.cpp
index f46515923a..e166bf1039 100644
--- a/deleted.cpp
+++ b/deleted.cpp
@@ -66,6 +66,15 @@ void Deleted::copyToDeleted(Toplevel* c)
 {
     assert(dynamic_cast< Deleted* >(c) == NULL);
     Toplevel::copyToDeleted(c);
+    // In some cases the window has been deleted before the sync request which marks
+    // the window ready for painting has finished. This is especially troublesome
+    // when effects reference the deleted window and the unreferencing is part of
+    // the rendering pass (e.g. Effect::postPaintScreen/postPaintWindow), which will
+    // never be executed because we remove it every time from the stacking list in
+    // Workspace::performCompositing.
+    if (!c->readyForPainting()) {
+        QTimer::singleShot(0, this, SLOT(discard()));
+    }
     desk = c->desktop();
     activityList = c->activities();
     contentsRect = QRect(c->clientPos(), c->clientSize());
diff --git a/deleted.h b/deleted.h
index 1f98aaf9de..81012973e6 100644
--- a/deleted.h
+++ b/deleted.h
@@ -35,7 +35,6 @@ public:
     // used by effects to keep the window around for e.g. fadeout effects when it's destroyed
     void refWindow();
     void unrefWindow(bool delay = false);
-    void discard(allowed_t);
     virtual int desktop() const;
     virtual QStringList activities() const;
     virtual QPoint clientPos() const;
@@ -58,6 +57,8 @@ public:
     }
     void layoutDecorationRects(QRect &left, QRect &top, QRect &right, QRect &bottom) const;
     QRect decorationRect() const;
+public slots:
+    void discard(allowed_t = Allowed);
 protected:
     virtual void debug(QDebug& stream) const;
     virtual bool shouldUnredirect() const;