Re: Add sleep builtin

[L A Walsh]

On 8/25/2018 3:16 PM, Bob Proulx wrote:
> Greg Wooledge wrote:
>   
> > If true, that would actually violate POSIX.
> > You might be remembering it wrong.
Naw...just the marginalia that Bob mentions...
> I also remember that at one time the Unix sleep was implemented by
> polling a second granularity clock register.  If one was not lucky
> then polling just before the second turned, and then just after, would
> cause sleep to exit because the second had changed.  A 1 second sleep
> was 0-1 seconds. 
>
> And certainly any using the fractional second extension is past any
> need to worry about the problem.  Because any such system with the
> problem would only handle to a granularity of integer seconds anyway.
>   
---
   I'd hope such would be the case, but as soon as I'd expect such
sane behavior, I'd run into a more simplistic implementation that
met the letter if not intent of some requirement...so such things
tend to stick in my head as possible, though not very useful
implementations.

   I certainly would not take the ever-changing POSIX spec as
a guide to what actually exists or is implemented in the field.
POSIX moved away from their original mission statement of being
"descriptive" to one that is "prescriptive" a long time ago,
with "prescriptive" being based on the wants and desires of
its current membership with little or no regard for usability
or compatibility.