Ooh, I wonder whether Apple made the classic mistake of using a wall clock timer when they should have used a monotonic (local) clock timer.

edit: having personally gone through this kind of mess, the correct solution is to use strict typing to make sure you keep track of the difference between times and durations and the difference between different clock types. Don’t use plain integers and also don’t try to fudge it the way that Go’s standard library solution does. The modern C++ library is actually pretty good, although you need to use very recent versions of the standard for full functionality.