Ports Repocopy

[Rene Ladan]

On Mon, Mar 01, 2021 at 11:56:18PM +0000, Brooks Davis wrote:
> On Mon, Feb 22, 2021 at 09:10:32PM +0000, Rene Ladan wrote:
> > On Mon, Feb 22, 2021 at 02:46:40PM -0600, Brandon Bergren wrote:
> > > On Mon, Feb 22, 2021, at 1:45 PM, Cy Schubert wrote:
> > > > When ports switches to GIT, given that there is no GIT equivalent to svn 
> > > > copy will repocopy become a thing of the past? Will we live with this or 
> > > > will there be some kind of procedure ports committers must follow to 
> > > > approximate a repocopy?
> > > > 
> > > 
> > > Renames and copies in git are inferred, not tracked.
> > > 
> > > About all you can do to make following stuff easier across a copy is to cp -a and immediately commit, before making any changes, so that it shows up in the index with identical file hashes as what it was copied from.
> > > 
> > > Following a file's history across a copy is dependent on the settings the person looking at the history is using.
> > > 
> > > It is not enabled by default because it is an extremely expensive operation -- it is O(n^2) where n is the number of files in the tree, plus even then it only works if the original file was modified in the same commit. Otherwise you have to use --find-copies-harder which is an even more expensive option.
> > > 
> > > If the commit was done by committing an unmodified version first, you can theoretically use `git log --follow -C100% --find-copies-harder <filename>` which should probably be able to do its work without having to compute similarities on all of the objects. But if you have many files with the same contents, I don't really know what the log will look like past that point. I *think* it will just randomly mix history. I haven't tested it though.
> > > 
> > > I suppose writing a tool that adds metadata about the copy to a git note or something would be the best way to track this stuff...
> > 
> > Hm, or just write something at the bottom of the commit message, like
> > cherry-pick -x does? I remmber that emaste suggested something like this
> > in the last git working group meeting.
> 
> For simple cases like copying one port or resurrecting one port, I think
> the easiest thing to do is to cause the new copy to exist in one commit
> (but don't hook it up) and then update it.  E.g., 
> 
> resurrection:
> git revert --no-commit <hash of commit removing port>
> <remove the change to any Makefiles>
> git revert --continue (or whatever the equivalent is)
> <update the port and hook it to the build>
> git add + git commit
> 
> copying:
> git cp cat/port cat/portng
Alas, there is no "git cp", only "git mv". Or did you mean a plain "cp"?

> git commit cat/portng
> <update the port and hook it to the build>
> git add + git commit
> 
> This gives git the best chance to infer the right history by ensuring
> identical files are copied.  I think the copying case will work better
> than resurrection from a tooling perspective.  Resurrection will likely go
> best if ports are deleted in independent commits rather than in one big
> one during expiration.
> 
Hm, the git version of rmport still creates one big commit when removing
multiple ports, but I can probably change that to individual commits (and
one push at the end).

René