• arc
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    2 months ago

    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.

    • uis
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      2 months ago

      Ok, this is more unix time quirk that can’t handle 24:00:00 and skipping 23:59:59.

      UTC always goes forward regardless of the timezone and local time

      But not unix time.

      I stored program start / end times in UTC

      If your program finishes in less than one seond it might report negative time.

      • arc
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        2 months ago

        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…

        • uis
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          2 months ago

          not unless somehow the system clock was modified while it was running…

          Which is how most systems handle leap seconds.

          • arc
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            2 months ago

            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.

            • uis
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              2 months ago

              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.

              • arc
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                2 months ago

                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.

                • uis
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                  2 months ago

                  This is how Google does it in their datacenters, but not major OSes by default