Fix crash if sharecontext is requested before initailization

Scene2D can sometimes receive the render initialization event before the
qt3d renderer has been initialized. This causes crash because the
sharecontext hasn't been set yet. Add safeguard against this.

Task-number: QT3DS-904
Change-Id: Ib50a60ed89c12ac54c9165266466d9804affe77c
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/render/backend/renderer_p.h b/src/render/backend/renderer_p.h
index b18b78a7c..dc9f778dd 100644
--- a/src/render/backend/renderer_p.h
+++ b/src/render/backend/renderer_p.h
@@ -308,6 +308,7 @@ private:
     QAtomicInt m_lastFrameCorrect;
     QOpenGLContext *m_glContext;
     QOpenGLContext *m_shareContext;
+    mutable QMutex m_shareContextMutex;
     PickBoundingVolumeJobPtr m_pickBoundingVolumeJob;
 
     qint64 m_time;