[LEAPSECS] Java: ThreeTen/JSR-310

Warner Losh imp at bsdimp.com
Fri Jan 28 10:55:34 EST 2011

On 01/28/2011 06:11, Stephen Colebourne wrote:

> On 28 January 2011 05:33, Tom Van Baak<tvb at leapsecond.com> wrote:

>> There are many forms of "SLS"; from those that spread the

>> leap across one second, or two seconds, or 30 seconds or

>> a minute, or an hour, or a day. Spread it across a year (or

>> however long it's been since the last leap second) and you

>> have UT1. And that's just the versions of SLS that use linear

>> ramping. You can imagine nicer ones that take off and end

>> slowly instead of the abrupt quantum rate change as seen

>> in the utc-sls write-up. 1200 might make a better choice if

>> there are 50/60 Hz effects (1000 is not divisible by 60). Or

>> 300. 1024 or a smaller power of 2 is nicer for low cost, low

>> power devices. 1200 has more common prime factors than

>> 1000 which can come in handy in some cases. You get the

>> idea. Lots of ways to do it.

> And thats fine. But since the %age of users that care is

> infinitessimally small, I need one number and no configuration. The

> only well-written document (proto-standard) is UTC-SLS which uses

> 1000.


> Now if this list or others wants to get together and writeup a

> replacement for UTC-SLS in the next few months that it prefers with

> justifications as to why its better and a process for making it a real

> standard, then so be it. Otherwise, UTC-SLS with 1000 will get used

> simply because it exists now. And by virtue of being used in Java it

> would then be a de facto standard.


> @Gerard, The point about making UTC-SLS more certain than one webpage

> is well made.

The larger point is that nobody implements this in the real world.
UTC-SLS is largely just a paper standard that the vast majority of
people completely ignore. It seems unwise to code such a tenuous thing
into the Java standard libraries. Not only does UTC-SLS need to have
better availability of the standard it is based on, it also needs to
actually be implemented by people...


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