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

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Hi,

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

> 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.
 
> 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