In a game with a render thread and a game logic thread the game logic thread needs to update the scene graph used by the render thread. I've read about ideas such as a queue of updates.

Can someone describe to a newbie at scene graphs what kind of interface the scene graph exports. Presumably it would be rather complicated. So then how does a queue of updates get implemented in C++ in a way that can handle the complexity of the interface of the scene graph while also being type safe and efficient. Again I'm a newbie at scene graphs and C++.