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Re: [Scheme-reports] current-posix-second is a disastrous mistake
Taylor R Campbell scripsit:
> The proposal claims that `there is about a 1 in 10^-8 probability that
> a computation of elapsed time made by calling this procedure twice
> will be off by 1.' This langauge suggests that there is some random
> chance involved here. But there isn't: leap seconds aren't drawn
> uniformly at random from time. Instead, in a network of POSIX agents
> with reasonably accurate and well-synchronized clocks, every agent
> will observe an erratic clock simultaneously, once every few years.
I have removed this paragraph.
The real point of the 10^-8 is that an interval clock cannot keep the
difference between Posix and UTC time unless it is at least that
accurate, which is very improbable.
> Programs dealing with timing, rather than with calendars, don't care
> about leap seconds. Giving them a clock corrupted by subtracting the
> number of leap seconds either breaks natural assumptions badly or
> requires extra work to cover up the corruption. Either way, it wastes
> operator and programmer time, costs program complexity, and adds code
> paths that are hit dangerously seldom, only once every few years.
I have now added `current-jiffy` for elapsed time.
John Cowan http://www.ccil.org/~cowan cowan@x
Would your name perchance be surname Puppet, given name Sock?
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