[rfc] bzr-colo into core

[John Arbash Meinel]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 03/25/2011 02:10 AM, Martin Pool wrote:
...

>> I wish bzr can hardlink packs and indices while cloning repo locally.
>> Actually we're at the better position here than hg: packs and indices are
>> immutable, only pack-names should be different when you commit new stuff and
>> clones diverge. Packing repo in one clone should not affect other clones I
>> think, but maybe it's important to break links before moving old packs into
>> obsolete area. And it should work on the Windows too (although Martin gz
>> metioned some issues there).
> 
>> Can we?
> 
> We could do that.  I thought there was a bug for this already, but I
> can't see one, so I filed <http://pad.lv/742183>.
> 
> Martin
> 

What did you think about my repository-reference idea (similar to
BranchReference which we already have). There are reasons in hg that you
don't want to share a repository (it always wants to collapse heads).
There is very rarely a reason where you might want to hardlink a
repository, but not actually share it in bzr.

It would actually be a way to get rid of shared repositories between
colo workspaces, because this workspace could say "and I'm storing my
data over here with the other one".

Anyway, it feels like it fits better with the existing bzr model, but I
understand that it *is* a new concept, and is not backwards compatible.

Just hard-linking is actually pretty difficult technically, because we
default to creating a new repository and then using the stream api to
pull in content. None of which is very amenable to simply hard-linking
the files on disk.

*Today* you can do "cp -rl", because files that bzr changes are pretty
much never changed in-place. The dirstate file being the only exception
to the general rule. (I pretty sure even config files change with
'rename-over-top'.)

John
=:->
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.10 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/

iEYEARECAAYFAk2MPcEACgkQJdeBCYSNAAM82ACfUJArpmcBoP7sfg7PMRzcdN7+
KBsAnRXpdSEQQyqPhv/W46wWH8v0TKrC
=yP0z
-----END PGP SIGNATURE-----