Force pull from subrepos

Mike Meyer mwm at mired.org
Wed Jul 15 18:17:49 CDT 2009


On Wed, 15 Jul 2009 17:41:20 -0500
Matt Mackall <mpm at selenic.com> wrote:
> Sounds like your build system wants to grab a collection of tips of a
> bunch of repos, which ends up giving you a pretty arbitrary collection
> of csets based on when the build system decided to poll. Such a build
> system is not repeatable, and thus not very interesting to SCM folks.

Pulling the tip isn't all that interesting, but it shows up a
shortcoming of hg (possibly fixed in 1.3?).

With a large enough project, you start wanting to break things up in
ways that don't necessarily match the world. For example, I have one
client that distributes about 50 different linux builds, so things
like the kernel & glibc are common across all of them, but other
things - say some third parties proprietary code - will only be used
in a few builds. Further, they are contractually obligated to restrict
access to some licensed code to people who are working on it, but
pretty much everyone needs access to the kernel. End result - they
need multiple repos in pretty much any SCM system.

In that environment, reproducible builds means you need a way to
specify a revision that all the repos will understand as "the same
snapshot" across all the repos. They're currently using svn (and
previously CVS), both of which allow a date/time string to mean "check
out HEAD as of this time." Whenever someone does a build, we figure
out the appropriate string and save it for future reference.

There doesn't appear to be anything in 1.2.1 that could be used this
way. It's not clear to me that this can even be done in hg. If I push
changes into a repo that predate such a timestamp, can it be
prevented from changing what using such a timestamp (if the feature
existed) checks out?

	  <mike
-- 
Mike Meyer <mwm at mired.org>		http://www.mired.org/consulting.html
Independent Network/Unix/Perforce consultant, email for more information.

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