QtQml: When clearing the type loader, also clear any pending events

The events typically hold references to the data blobs they want to
notify about. Those will prevent such blobs from getting cleaned up.
Since we are explicitly asked to clear everything, we should also clear
those.

Change-Id: I476b071d78555a561396181128f2e915df13aeee
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

2 files changed, 18 insertions, 0 deletions

diff --git a/src/qml/qml/ftw/qqmlthread.cpp b/src/qml/qml/ftw/qqmlthread.cpp
index 8589402bff..2aa8a57050 100644
--- a/src/qml/qml/ftw/qqmlthread.cpp
+++ b/src/qml/qml/ftw/qqmlthread.cpp
@@ -399,5 +399,22 @@ void QQmlThread::waitForNextMessage()
     d->m_mainThreadWaiting = false;
 }
 
+/*!
+    \internal
+    \note This method must be called in the main thread
+    \warning This method requires that the lock is held!
+
+    Clear all pending events, for either thread.
+*/
+void QQmlThread::discardMessages()
+{
+    Q_ASSERT(!isThisThread());
+    if (Message *mainSync = std::exchange(d->mainSync, nullptr))
+        delete mainSync;
+    while (!d->mainList.isEmpty())
+        delete d->mainList.takeFirst();
+    while (!d->threadList.isEmpty())
+        delete d->threadList.takeFirst();
+}
 
 QT_END_NAMESPACE
diff --git a/src/qml/qml/ftw/qqmlthread_p.h b/src/qml/qml/ftw/qqmlthread_p.h
index 4af94036b5..35f586f7e7 100644
--- a/src/qml/qml/ftw/qqmlthread_p.h
+++ b/src/qml/qml/ftw/qqmlthread_p.h
@@ -64,6 +64,7 @@ public:
     void postMethodToMain(Method &&method, Args &&...args);
 
     void waitForNextMessage();
+    void discardMessages();
 
 private:
     friend class QQmlThreadPrivate;