Fix QWinEventNotifier for auto-reset events

Auto-reset events are automatically reset to non-signaled when we get
notified about the signaled state. This implies that we cannot check the
event state again in activateEventNotifiers. Instead, store the signaled
state in a QAtomicInt and test and decrement that.

This amends commit 85403d0a.

Task-number: QTBUG-63555
Change-Id: I0adee3d2929783f98d91060f9106c8b5266d72fa
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>

1 files changed, 2 insertions, 1 deletions

diff --git a/src/corelib/kernel/qeventdispatcher_win.cpp b/src/corelib/kernel/qeventdispatcher_win.cpp
index 569fbc2796..bbd442d570 100644
--- a/src/corelib/kernel/qeventdispatcher_win.cpp
+++ b/src/corelib/kernel/qeventdispatcher_win.cpp
@@ -942,7 +942,8 @@ void QEventDispatcherWin32::activateEventNotifiers()
     for (int i = d->winEventNotifierList.count(); --i >= 0;) {
         QWinEventNotifier *notifier = d->winEventNotifierList.at(i);
         QWinEventNotifierPrivate *nd = QWinEventNotifierPrivate::get(notifier);
-        if (WaitForSingleObject(nd->handleToEvent, 0) == WAIT_OBJECT_0) {
+        if (nd->signaledCount.load() != 0) {
+            --nd->signaledCount;
             nd->unregisterWaitObject();
             d->activateEventNotifier(notifier);
         }