Running code during application shutdown

I am currently rewriting a project from java to rust due to memory usage concerns. It is a music player which requires storing some state on disk. The state is auto-saved periodically but should always be saved when the application shuts down. In the Java world I used to rely heavily on an event system, where it is very easy to store a Runnable for an indefinite amount of time and call it when needed. I have attempted to do something similar to that in rust using Future but am struggling to unb...