Re: [PATCH] Shallow clone: low level machinery.

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Feb 1, 2006, 14:33 UTC
Message-ID: <Pine.LNX.4.63.0602011528030.28923@wbgn013.biozentrum.uni-wuerzburg.de>
In-Reply-To: <7vzmlcz28x.fsf@assigned-by-dhcp.cox.net>

Hi,

On Tue, 31 Jan 2006, Junio C Hamano wrote:

Show 7 quoted lines

> Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
> 
> > Worse, you cannot pull from older servers into shallow repos.
> 
> "have X" means different thing if you do not have matching
> grafts information, so I suspect that is fundamentally
> unsolvable.

If the shallow-capable client could realize that the server is not shallow-capable *and* the local repo is shallow, and refuse to operate (unless called with "-f", in which case the result may or may not be a broken repo, which has to be fixed up manually by copying over ORIG_HEAD to HEAD).

Of course, the client has to know that the local repo is shallow, which it 
must not determine by looking at the grafts file.

Show 7 quoted lines

> I am not sure you can convince "git-rev-list ^A" to mean "not at
> A but things before that is still interesting", especially when
> you give many other heads to start traversing from, but if you
> can, then you can do things at rev-list command line parameter
> level without doing the "exchange and use the same grafts"
> trickery.  That _might_ be easier to implement but I do not see
> an obvious correctness guarantee in the approach.

If you introduce a different "have X" -- like "have-no-parent X" -- and teach git-rev-list that "~A" means "traverse the tree of A, but not A's parents", you'd basically have everything you need, right?

> Implementation bugs aside, it is obvious the things _would_ work 
> correctly with "exchange and use the same grafts" approach.

Yes, I agree. But again, the local repo has to know which grafts were introduced by making the repo shallow.

Ciao, Dscho