Re: [Monotone-devel] date certs on net.venge.monotone

[Markus Wanner]

Hi,

Stephen Leake wrote:
> If there is no global shared clock, then developers working in
> different time zones can easily commit revisions to a shared server
> that have timestamps using local times that appear to be "out of
> order" with respect to each other.

Any sane OS today knows the difference between local time and UTC.
Measurement shows that this is not an issue (except maybe for Xaraya,
which needs further investigation)

> On the other hand, there are such things as global clocks; we use them
> all the time at NASA. If each developer on a team commits to
> configuring their computer such that the functions "local_to_UTC" and
> "UTC_to_local" work properly,

My assumption is that most clocks are close enough to "the" global clock
to be useful for mtns purpose. Looking at the dates in nvm, this
assumption holds true for the vast majority of committed revisions.

> monotone could support an option to use
> UTC times for timestamps.

Monotone currently uses UTC dates for its certs, which might not be
overly user friendly. However, we do not take leap seconds into account
within our own date calculation routines.

> TAI might be a better global time choice,
> since it doesn't do leap seconds, and hence is monotonic.

Conversion between UTC and local time is pretty simple on most systems,
where as UTC to TAI and back is not as common.

IMO the user shouldn't need to care about anything except local time.

Regards

Markus Wanner