llvm dev - Jan 2011 - [LLVMdev] Official git mirroring of llvm, clang, lldb, test-suite, etc.?

Óscar Fuentes <ofv at wanadoo.es> writes:
> Are you saying that git-svn is slow at pulling changes? It is quite okay
> in my experience, unless you pull once every other month. But I can't
> relate that to your original assertion quoted above.
I can't use git-svn to pull because we use svn on our end.  One can't do
this:

(Upstream) svn <--> git-svn <--> git <--> git-svn <-->
svn (Downstream)

because the revisions in the two svn repositories don't have anything to
do with each other.
> What I recall from previous discussions is that you are interested on
> having local feature branches shared among your coworkers. That's
doable
> with git-svn with some constraints.
Actually, I am mostly interesed in git because it makes merging in
upstream code dead simple.  Right now I've implemented a couple of
downright scary scripts to hack a ditributed SCM module on top of
Subversion.  It's really about as far away from "fun" as one can
get.

It would be even better if LLVM had a git mirror that could push changes
to svn as well but let's do things one step at a time.  :)

                          -Dave

greened at obbligato.org (David A. Greene) writes:
> I can't use git-svn to pull because we use svn on our end.  One
can't do
> this:
>
> (Upstream) svn <--> git-svn <--> git <--> git-svn
<--> svn (Downstream)
>
> because the revisions in the two svn repositories don't have anything
to
> do with each other.
That's what you deserve, for using svn at your side ;-)

But if you want to transfer revisions from LLVM's svn to your svn repo,
maybe you can do that:

(Upstream) svn <--> git-svn <--> svn (Downstream)

You would use two git-svn branches on the git repo, one for each svn
repo, and merge revisions among the two. I'm not user if that's
possible, though. Another option is to use two git-svn repos:

(Upstream) svn <--> git-svn <--> git-svn <--> svn (Downstream)
> Actually, I am mostly interesed in git because it makes merging in
> upstream code dead simple.  Right now I've implemented a couple of
> downright scary scripts to hack a ditributed SCM module on top of
> Subversion.  It's really about as far away from "fun" as one
can get.
>
> It would be even better if LLVM had a git mirror that could push changes
> to svn as well but let's do things one step at a time.  :)
The difficult part is not on LLVM's using svn, the problem is on you
using svn.

And for a git mirror that pushes changes to the LLVM svn repo, that's
*way* more tricky than it seems.

Óscar Fuentes <ofv at wanadoo.es> writes:
> greened at obbligato.org (David A. Greene) writes:
>
>> I can't use git-svn to pull because we use svn on our end.  One
can't do
>> this:
>>
>> (Upstream) svn <--> git-svn <--> git <--> git-svn
<--> svn (Downstream)
>>
>> because the revisions in the two svn repositories don't have
anything to
>> do with each other.
> But if you want to transfer revisions from LLVM's svn to your svn repo,
> maybe you can do that:
>
> (Upstream) svn <--> git-svn <--> svn (Downstream)
>
> You would use two git-svn branches on the git repo, one for each svn
> repo, and merge revisions among the two. I'm not user if that's
> possible, though. Another option is to use two git-svn repos:
>
> (Upstream) svn <--> git-svn <--> git-svn <--> svn
(Downstream)
I asked about both to the git guys.  They said it isn't supported.
Double-ended git-svn just won't work, period.  You can't do it because a
git branch is still tied to the revision numbering of the first git-svn
gateway created.  Git branches still must relate to each other, they
can't run independently or one wouldn't get any merging benefit.
>> It would be even better if LLVM had a git mirror that could push
changes
>> to svn as well but let's do things one step at a time.  :)
>
> The difficult part is not on LLVM's using svn, the problem is on you
> using svn.
Umm...that's more than a bit off-putting, thanks.  If it's a problem to
use svn (and it IS a problem), then it's a problem on BOTH ends.  That
is in fact why people are asking about it.  Remember, it ain't just me.
I didn't even bring up this current thread.

And to be clear, the root of the problem _is_ LLVM's using svn because
it doesn't allow the kind of distributed development natural to an open
source project.  If one is not supposed to use svn (the official blessed
LLVM SCM) on "our side," pray tell, what _are_ we supposed to use?
> And for a git mirror that pushes changes to the LLVM svn repo, that's
> *way* more tricky than it seems.
I suspect for exactly the same reasons git-svn isn't tenable in general.
svn is just bad business all around.

                         -Dave