Timer

A monotonic, high performance timer.

Timer.start() is used to initialize the timer and gives the caller an opportunity to check for the existence of a supported clock. Once a supported clock is discovered, it is assumed that it will be available for the duration of the Timer's use.

Monotonicity is ensured by saturating on the most previous sample. This means that while timings reported are monotonic, they're not guaranteed to tick at a steady rate as this is up to the underlying system.