this post was submitted on 03 Apr 2024
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It not always goes and not always forward. I think you need metric time(TAI) instread.
UTC always goes forward regardless of the timezone and local time. That is why you should use it. To take my EPG situation above, I stored program start / end times in UTC so they would render properly even if DST kicked in or not during the middle of the program.
Ok, this is more unix time quirk that can't handle 24:00:00 and skipping 23:59:59.
But not unix time.
If your program finishes in less than one seond it might report negative time.
I didn't say Unix time, I said UTC. And no it won't report negative time, not unless somehow the system clock was modified while it was running..
Which is how most systems handle leap seconds.
Leap seconds still make time go forwards, not backwards. NTP clients would also resolve small time discrepancies while still advancing forwards prior to the next time sync.
Leap seconds can make time go both ways, but adding them makes time stop/go back because 24:00:00 cannot be represented as 1/86400 part of day N instead of day N+1 on major OSes. And they were only added so far.
It doesn't work like that. UTC goes forward always. Leap seconds are scheduled and known in advance. NTP time services will just smear time advancement a little to account for an additional second. Time never has to go backwards. This is how Google does it.
This is how Google does it in their datacenters, but not major OSes by default