From bdd2dacf2d8668b3a1f59db3c6cc859f95868eb2 Mon Sep 17 00:00:00 2001

From: Georges Basile Stavracas Neto <gbsneto@gnome.org>

Date: Thu, 27 May 2021 19:55:04 -0300

Subject: [PATCH 19/40] Client: Don't always recreate frame callbacks

The main QWaylandWindow method that is executed when handling updates is

QWaylandWindow::handleUpdate(). This method always, unconditionally queues

a frame callback, regardless of whether any other one is already queued.

On some circumstances, e.g. when a window is hidden or completely obscured

by other windows, it stops receiving frame callbacks from the compositor.

However, QWaylandWindow would continue to request for them, which eventually

fills up the Wayland socket, and causes the application to crash.

This can be avoided by checking if the platform window is already waiting

for a frame callback, before queueing another one.

In QWaylandWindow::handleUpdate(), check if mWaitingForFrameCallback is true

before queueing frame callbacks, and early return if that's the case.

The XDG-shell test needed to be updated for this: The mock compositor is

not responding to any frame callbacks, so the window will be unexposed,

no longer get paint events and therefore not trigger any commit. This

worked by accident before because we were issuing updates quickly enough

to reset the timer before it had a chance to unexpose the window. The

easiest fix is just to disable the dependency on frame callbacks in

this test, since that is clearly not what it's testing.

Task-number: QTBUG-81504

Change-Id: Ieacb05c7d5a5fcf662243d9177ebcc308cb9ca84

Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

Reviewed-by: Georges Basile Stavracas Neto <gbsneto@gnome.org>

Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>

(cherry picked from commit cbc74ba6d7186457d8d07183272e952dee5f34f9)

---

 src/client/qwaylandwindow.cpp               | 4 ++++

 tests/auto/client/xdgshell/tst_xdgshell.cpp | 2 ++

 2 files changed, 6 insertions(+)

diff --git a/src/client/qwaylandwindow.cpp b/src/client/qwaylandwindow.cpp

index bd70f4af..85307875 100644

--- a/src/client/qwaylandwindow.cpp

+++ b/src/client/qwaylandwindow.cpp

@@ -1170,6 +1170,10 @@ void QWaylandWindow::requestUpdate()

 void QWaylandWindow::handleUpdate()

 {

     qCDebug(lcWaylandBackingstore) << "handleUpdate" << QThread::currentThread();

+

+    if (mWaitingForFrameCallback)

+        return;

+

     // TODO: Should sync subsurfaces avoid requesting frame callbacks?

     QReadLocker lock(&mSurfaceLock);

     if (!mSurface)

diff --git a/tests/auto/client/xdgshell/tst_xdgshell.cpp b/tests/auto/client/xdgshell/tst_xdgshell.cpp

index 2fdd0a7c..e2593314 100644

--- a/tests/auto/client/xdgshell/tst_xdgshell.cpp

+++ b/tests/auto/client/xdgshell/tst_xdgshell.cpp

@@ -138,6 +138,7 @@ void tst_xdgshell::configureSize()

 void tst_xdgshell::configureStates()

 {

+    QVERIFY(qputenv("QT_WAYLAND_FRAME_CALLBACK_TIMEOUT", "0"));

     QRasterWindow window;

     window.resize(64, 48);

     window.show();

@@ -186,6 +187,7 @@ void tst_xdgshell::configureStates()

     QCOMPARE(window.windowStates(), Qt::WindowNoState);

     QCOMPARE(window.frameGeometry().size(), windowedSize);

 //    QCOMPARE(window.frameGeometry().topLeft(), QPoint()); // TODO: this doesn't currently work when window decorations are enabled

+    QVERIFY(qunsetenv("QT_WAYLAND_FRAME_CALLBACK_TIMEOUT"));

 }

 void tst_xdgshell::popup()

-- 

2.35.1