[Gnu-arch-users] Re: advanced usage advice: the prism technique

[Miles Bader]

Pau Aliagas <address@hidden> writes:
> > I can't understand this, what's this revision library, and what does it
> > mean perpetually up-to-date? if the scripts above are painfully slow
> > without this, then I guess I need this too?
> 
> Revision libraries are untarred versions, optimized via hardlinks to
> unchanged files of previous revision, of projects up to a patch level. 
> They are highly optimized in space use, so ot's like convnient having them 
> instead of reapplying a large number of patches.

But note that things don't get particularly slow until it has to apply
like 50 patches in a row or something.  So you don't really need
everything in a revision library, just `occasional' versions.

These are some changes I suggested in a bug-report about `tla library-add':

   By the way, my thought was to add two more options to library-add:

   * an `--every=N' option, which would add a separate library entry for
     every patch-P, where (P % N) == 0 between the requested revision and
     the highest existing revisions

   * an `--until' option which would say basically `just add some revisions
     and stop at the requested revision, but it's not necessary to actually
     add the requested revision'

   * allow specifying a version instead of a revision, in which case it
     uses the last revision in the version, and make the argument default
     to the latest revision in the current tree (if you're in a tree)

   The old behavior of library add could be had with just `tla library-add
   --every=1 REV', and a useful thing for your cron-job/hook to do might be
   `tla library-add --every=10 --until VERSION', which would make sure the
   library space was populated automatically by every 10th revision (the
   --until makes it do this nicely regardless of the revision number
   actually used).

I think this would make it easier to get a nice balance of
space-usage/update-speed (having a rev-lib for _every_ version is, I've
found actually fairly wasteful -- simply all the directories needed to
hold the hard-links end up taking up quite a bit of space for a large
tree).

-Miles
-- 
Quidquid latine dictum sit, altum viditur.