Is there a way to check the (gpu/state machine?) status on openVG?

Currently the only way I have to synchronize is vgFinish which will stall the CPU and it cannot by used by my application. I need a mechanism to poll the state without blocking, such:

rslt = vgIsFinish();

Or getting a callback when finished... if it is done I can swap buffers and render the next frame other wise I can check later.

Thanks in advance.