absolute_time

https://github.com/bwbuchanan/absolute_time

This gem provides a monotonically increasing timer to permit safe measurement of time intervals. Using Time.now for measuring intervals is not reliable (and sometimes unsafe) because the system clock may be stepped forwards or backwards between the two measurements, or may be running slower or faster than real time in order to effect clock synchronization with UTC. The module uses OS-specific functions such as mach_absolute_time() and clock_gettime() to access the system tick counter. The time values returned by this module cannot be interpreted as real time clock values; they are only useful for comparison with another time value from this module.