Inconsistance in snapshots repository

[Craig Burley]

>  > BTW, would it be possible to have a ``moving tag'' called
>  > `egcs_latest_snapshot', updated whenever a snapshot is released?
>This is an excellent idea.  The only trick is to coordinate it with
>the actual "release" of a snapshot.

I'm CVS-unaware, but, generally, is this really guaranteed to provide
a coherent snapshot to anyone, anytime, including if they try using
it while a snapshot is being produced (and the "moving tag" updated)?

That is, is whatever procedure people normally use to obtain a
snapshot via CVS guaranteed to obtain either all the files for
snapshot N *or* all the files for P, but never a mix, if, partway
through said obtaining, snapshot N is "replaced" as the "latest"
with snapshot P?

(E.g. I could think of this moving tag idea as perhaps a symbolic
link to a directory containing a snapshot in a non-CVS universe.
Whenver a new snapshot is made, after its directory is fully
populated and coherent, the symbolic link is simply updated.  That
works fine for simple uses like "cd .../symbolic-link; cp -a * ...",
because cd'ing to a symbolic link really cd's to the directory it
points to, at least in most cases; it's not just an updating of
some environment symbol.  But, in effect, it *might* be if the
target directory is mounted by NFS.  Further, if the procedure is
more complicated, e.g. "cp -a .../symbolic-link/file-a ...; cp
-a .../symbolic-link/file-b ...; cp -a .../symbolic-link/file-c ...",
then a change to the symbolic link *can* affect the procedure
midstream.)

If the answer to the above is not definitely "yes, it's always
guaranteed", then I think it's best to set up whatever means
is appropriate to *designate* a given snapshot as the "latest"
and encourage everyone to use procedures that obtain that
designation only *once* per snapshot-grab.  In essence, copy
that designation to a local temporary variable that is thus
guaranteed to not change while the snapshot is obtained (using
that same temporary variable to specify the stuff being obtained).

        tq vm, (burley)