If you don't provide (real) time as an input to the program, then non-determinism of time does not affect determinism of the program. At least, in theory. It's definitely a long way from there to practice.
That's true -- but "the program" is also any code using yours as a middle-step, which is the case of a network service is a huge number of people. So anything that requires total program control rather than subroutine enforced safety is a nonstarter.
The timing may occur outside of your control, and then statistical profiling used. If the timing of a reponse to a network request has a time component that depends on shared load, then you have a side-channel.
The timing may occur outside of your control, and then statistical profiling used. If the timing of a reponse to a network request has a time component that depends on shared load, then you have a side-channel.