System.Time.Clock Design Issues
ketil+haskell at ii.uib.no
Thu Feb 3 12:06:11 EST 2005
"Bayley, Alistair" <Alistair_Bayley at ldn.invesco.com> writes:
> - UTC/POSIX/CalenderTime are isomorphic, and represent some
> idealised notion of time where leap seconds don't exist i.e. a day
> always has duration 23:59:59.
I don't think this is correct. In UTC, extra leap seconds are denoted
23:59:60 and the missing ones have :59:58 as the last second. Posix's
seconds are thus not isomorphic to UTC.
> - Most (all?) system clocks return UTC. They may slow down around leap
> seconds to support this - is this behaviour only seen on systems with NTP?
I think so.
> - It's not possible to simply get the number of actual ticks since some
> epoch; the OS time function may slow down for leap seconds and we can't
> avoid this.
Unless you move the epoch, which is basically what POSIX does.
If I haven't seen further, it is by standing in the footprints of giants
More information about the Libraries