Async timers built on [SystemTime].
[tokio::time::Sleep] operates on Instants,
which are inconvenient when one wants to schedule timers according to wall-clock time.
Implemented using [libc::timerfd_create] et al.
Async timers built on [SystemTime].
[tokio::time::Sleep] operates on Instants,
which are inconvenient when one wants to schedule timers according to wall-clock time.
Implemented using [libc::timerfd_create] et al.