time.Sleep can block VERY long time, when drift the clock backwards

in this scenario, NextID() could block very long time.
1. in a high load: `(sf.sequence + 1) & maskSequence == 0`
2. in the same time, system clock drift backwards, say 8 hours

this will block the function for 8 hour.

can we use some kind of Monotonic time or add a new function with timeout-control to avoid this?
