SERVER-44047 added an AtomicWord* parameter to several Interruptible wait functions, expressed as an AtomicWord<Microseconds::rep>*. This provides no type safety about the Duration it represents. There's no difference in the type system between Microseconds::rep, Milliseconds::rep, or plain int64_t. Another parameter to these functions is a Milliseconds duration, so it's easy to get confused. We should be able to directly accept an atomically-updated Duration, or come up with a typesafe proxy that can synchronously update a Duration.