qt5: Fix timer leak in qtwayland to avoid animations being sluggish

With long-running qt applications which have fluid animations
in wayland environment, the animation becomes obviously sluggish
because massive amount of memcpy() is called through a constructor
being placed in a loop in QTimerInfoList::timerInsert() function.
This is caused by a timer-index leak bug of qtwayland, which is
already reported to the qt project as following ticket.

https://bugreports.qt.io/browse/QTBUG-79838

Unfortunately QTBUG-79838 is still open because maintenance of
non-commercial version of qt5 is already stopped. However, we've
confirmed that the patch attached to that ticket works fine
except for that part of it is no longer needed due to the deletion
of the code. So let's apply only effective part of it.

Bug-AGL: SPEC-3991

Signed-off-by: Hiroyuki Ishii <ishii.hiroyuki002@jp.panasonic.com>
Change-Id: Ib148b81aabb98e8df10c1414cdbfe26f7ddf09a6
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/26466
Tested-by: Jenkins Job builder account
ci-image-build: Jenkins Job builder account
ci-image-boot-test: Jenkins Job builder account
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/26759
Reviewed-by: Scott Murray <scott.murray@konsulko.com>
Reviewed-by: Naoto YAMAGUCHI <naoto.yamaguchi@aisin.co.jp>

3 files changed, 49 insertions, 0 deletions

diff --git a/meta-agl-core/dynamic-layers/meta-qt5/recipes-qt/qt5/qtwayland/0001-Fix-timer-leak-and-a-potential-race.patch b/meta-agl-core/dynamic-layers/meta-qt5/recipes-qt/qt5/qtwayland/0001-Fix-timer-leak-and-a-potential-race.patch
new file mode 100644
index 000000000..642eabc4b
--- /dev/null
+++ b/meta-agl-core/dynamic-layers/meta-qt5/recipes-qt/qt5/qtwayland/0001-Fix-timer-leak-and-a-potential-race.patch
@@ -0,0 +1,42 @@
+From f4d3297e6705cc524729d629bf94db11841dbb24 Mon Sep 17 00:00:00 2001
+From: Simon Yuan <simon.yuan@navico.com>
+Date: Thu, 7 Nov 2019 09:22:37 +1300
+Subject: [PATCH] Fix timer leak and a potential race
+
+The callback timer is now killed immediately before starting a new timer, this
+makes sure there is always a single active callback timer. It's unclear why
+killing the timer in a separate lambda doesn't always kill the timer in time,
+the hypothesis is that if killing the timer comes after starting a new one, then
+the previous timer is now left dangling. Whatever the reason is, it makes even
+more sense to kill the timer in the same lamda and immediately before starting a
+new timer anyway.
+---
+ src/client/qwaylandwindow.cpp | 11 +++++------
+ 1 file changed, 5 insertions(+), 6 deletions(-)
+
+diff --git a/src/client/qwaylandwindow.cpp b/src/client/qwaylandwindow.cpp
+index 0df99d9f..93b46bf1 100644
+--- a/src/client/qwaylandwindow.cpp
++++ b/src/client/qwaylandwindow.cpp
+@@ -1136,13 +1136,12 @@ void QWaylandWindow::handleUpdate()
+     mWaitingForFrameCallback = true;
+     mWaitingForUpdate = false;
+ 
+-    // Stop current frame timer if any, can't use killTimer directly, see comment above.
+-    int fcbId = mFrameCallbackTimerId.fetchAndStoreOrdered(-1);
+-    if (fcbId != -1)
+-        QMetaObject::invokeMethod(this, [this, fcbId] { killTimer(fcbId); }, Qt::QueuedConnection);
+-
+     // Start a timer for handling the case when the compositor stops sending frame callbacks.
+-    QMetaObject::invokeMethod(this, [this] { // Again; can't do it directly
++    // Can't use killTimer directly, see comment above.
++    QMetaObject::invokeMethod(this, [this] {
++        int fcbId = mFrameCallbackTimerId.fetchAndStoreOrdered(-1);
++        if (fcbId != -1)
++            killTimer(fcbId);
+         if (mWaitingForFrameCallback)
+             mFrameCallbackTimerId = startTimer(100);
+     }, Qt::QueuedConnection);
+-- 
+2.25.1
+
diff --git a/meta-agl-core/dynamic-layers/meta-qt5/recipes-qt/qt5/qtwayland_%.bbappend b/meta-agl-core/dynamic-layers/meta-qt5/recipes-qt/qt5/qtwayland_%.bbappend
new file mode 100644
index 000000000..aa55c3a0c
--- /dev/null
+++ b/meta-agl-core/dynamic-layers/meta-qt5/recipes-qt/qt5/qtwayland_%.bbappend
@@ -0,0 +1 @@
+require ${@bb.utils.contains('AGL_FEATURES', 'aglcore', 'qtwayland_aglcore.inc', '', d)}
diff --git a/meta-agl-core/dynamic-layers/meta-qt5/recipes-qt/qt5/qtwayland_aglcore.inc b/meta-agl-core/dynamic-layers/meta-qt5/recipes-qt/qt5/qtwayland_aglcore.inc
new file mode 100644
index 000000000..ef5d0c7b5
--- /dev/null
+++ b/meta-agl-core/dynamic-layers/meta-qt5/recipes-qt/qt5/qtwayland_aglcore.inc
@@ -0,0 +1,6 @@
+FILESEXTRAPATHS_prepend := "${THISDIR}/qtwayland:"
+
+# Patch reported in https://bugreports.qt.io/browse/QTBUG-79838, not upstreamed
+SRC_URI += " \
+           file://0001-Fix-timer-leak-and-a-potential-race.patch \
+           "