use std::time::Duration;
use std::time::Instant;
pub trait Clock: Send + Sync {
fn now(&self) -> Instant;
fn elapsed(&self, start: Instant) -> Duration {
self.now().duration_since(start)
}
fn elapsed_ms(&self, start: Instant) -> u64 {
self.elapsed(start).as_millis() as u64
}
}