git filter-branch --filter-notes/--post-rewrite?

git filter-branch --filter-notes/--post-rewrite?

[Hallvard B Furuseth]

Is there a git version where filter-branch can copy notes, or with a
post-rewrite hook?  I found an old discussion of that on WWW, but
nothing seems to have come of that yet.  Currently I remove the 'rm
-rf "$tempdir"' in git-filter-branch.sh so the info is available
for a separate script.

-- 
Hallvard

Re: git filter-branch --filter-notes/--post-rewrite?

[Johan Herland]

On Thursday 17 March 2011, Hallvard B Furuseth wrote:
> Is there a git version where filter-branch can copy notes, or with a
> post-rewrite hook?  I found an old discussion of that on WWW, but
> nothing seems to have come of that yet.  Currently I remove the 'rm
> -rf "$tempdir"' in git-filter-branch.sh so the info is available
> for a separate script.

No, AFAIK notes copying (or post-rewrite hook) has not yet been implemented 
in filter-branch. However, it shouldn't be very difficult to add support for 
this:

Looking at git-rebase.sh (where it _is_ implemented), it seems to be a 
matter of feeding "old_sha1 new_sha1" pairs into a "rewritten" file, and 
then passing that file to the stdin of "git notes copy --for-rewrite=filter-
branch" (followed by passing the same file to the "post-rewrite" hook).


Have fun! :)

...Johan

-- 
Johan Herland, <johan@herland.net>
www.herland.net

Re: git filter-branch --filter-notes/--post-rewrite?

[Thomas Rast]

Johan Herland wrote:
> On Thursday 17 March 2011, Hallvard B Furuseth wrote:
> > Is there a git version where filter-branch can copy notes, or with a
> > post-rewrite hook?  I found an old discussion of that on WWW, but
> > nothing seems to have come of that yet.  Currently I remove the 'rm
> > -rf "$tempdir"' in git-filter-branch.sh so the info is available
> > for a separate script.
> 
> No, AFAIK notes copying (or post-rewrite hook) has not yet been implemented 
> in filter-branch. However, it shouldn't be very difficult to add support for 
> this:
> 
> Looking at git-rebase.sh (where it _is_ implemented), it seems to be a 
> matter of feeding "old_sha1 new_sha1" pairs into a "rewritten" file, and 
> then passing that file to the stdin of "git notes copy --for-rewrite=filter-
> branch" (followed by passing the same file to the "post-rewrite" hook).

I had a patch for this back when post-rewrite was invented,

  http://thread.gmane.org/gmane.comp.version-control.git/139919/focus=139917

but Hannes replied that it should grow a real notes filter, and while
I dropped it there, I tend to agree with him.  Feel free to pick it up
again.

-- 
Thomas Rast
trast@{inf,student}.ethz.ch

Re: git filter-branch --filter-notes/--post-rewrite?

[Hallvard B Furuseth]

Thomas Rast writes:
>Johan Herland wrote:
>
>> Looking at git-rebase.sh (where it _is_ implemented), it seems to be a 
>> matter of feeding "old_sha1 new_sha1" pairs into a "rewritten" file, and 
>> then passing that file to the stdin of "git notes copy --for-rewrite=filter-
>> branch" (followed by passing the same file to the "post-rewrite" hook).

That appends to the notes history instead of replacing it, which seems
broken to me.  So I'm doing fast-export <notes> | edit; fast-import.

> I had a patch for this back when post-rewrite was invented,
> 
>   http://thread.gmane.org/gmane.comp.version-control.git/139919/focus=139917
> 
> but Hannes replied that it should grow a real notes filter, and while
> I dropped it there, I tend to agree with him.  Feel free to pick it up
> again.

A notes filter would be nice, but I don't understand why there's no
post-rewrite hook or option to let us get at the rewrite info before
it is deleted.  For one thing a notes filter might not do just what is
intended (as above), but one might want the mapping info for other
things too.  E.g. just to save it in case there are mailings floating
around which refer to old commit IDs.


In any case, thanks for the answers.  I guess I can live with copying
the git-filter-branch script when needed, it's not as if I run that
every day.

-- 
Hallvard

Re: git filter-branch --filter-notes/--post-rewrite?

[Johan Herland]

On Sunday 20 March 2011, Hallvard B Furuseth wrote:
> Thomas Rast writes:
> >Johan Herland wrote:
> >> Looking at git-rebase.sh (where it _is_ implemented), it seems to be a
> >> matter of feeding "old_sha1 new_sha1" pairs into a "rewritten" file,
> >> and then passing that file to the stdin of "git notes copy
> >> --for-rewrite=filter- branch" (followed by passing the same file to
> >> the "post-rewrite" hook).
> 
> That appends to the notes history instead of replacing it, which seems
> broken to me.  So I'm doing fast-export <notes> | edit; fast-import.

Yeah, Rewriting the notes history along with the "real" history requires a 
bit more work. In reality, though, if the notes history is not interesting 
in itself, you can first do the notes rewrite I describe above, next prune 
the notes tree ("git notes prune") to remove the old notes from the notes 
tree, then finally drop the entire notes history except the last commit 
(using grafts + filter-branch, or using commit-tree to simply wrapping the 
notes tree object in a new parent-less notes commit).

> > I had a patch for this back when post-rewrite was invented,
> > 
> >   http://thread.gmane.org/gmane.comp.version-control.git/139919/focus=1
> >   39917
> > 
> > but Hannes replied that it should grow a real notes filter, and while
> > I dropped it there, I tend to agree with him.  Feel free to pick it up
> > again.
> 
> A notes filter would be nice, but I don't understand why there's no
> post-rewrite hook or option to let us get at the rewrite info before
> it is deleted.  For one thing a notes filter might not do just what is
> intended (as above), but one might want the mapping info for other
> things too.  E.g. just to save it in case there are mailings floating
> around which refer to old commit IDs.

We should probably apply Thomas' post-rewrite patch in any case. It gives 
the post-rewrite hook access to both the old and new commit IDs, so should 
have all the info you need to do whatever you want with the repo.

Note that after filter-branch is done, you should still be able to access 
the old objects (by using the old commit IDs directly), at least until the 
next "git gc".

> In any case, thanks for the answers.  I guess I can live with copying
> the git-filter-branch script when needed, it's not as if I run that
> every day.

Yeah, using filter-branch on an everyday basis would sound like a 
fundamental workflow problem. ;)


Have fun! :)

...Johan

-- 
Johan Herland, <johan@herland.net>
www.herland.net