Re: Split commit graphs and commit-graph read

From: Bryan Turner <bturner@atlassian.com>
Date: Nov 12, 2019, 00:28 UTC
Message-ID: <CAGyf7-EqQdvg4fQcZJv6BpqZ9hPDx72KBiLp1Xe3Ur7NrSMBeA@mail.gmail.com>
In-Reply-To: <87f16645-6af4-9703-1d0d-eb64728d2849@gmail.com>

On Sun, Nov 10, 2019 at 5:19 PM Derrick Stolee <stolee@gmail.com> wrote:

Show 28 quoted lines

>
> > But git commit-graph read isn't:
> > .../objects$ git commit-graph read
> > fatal: Could not open commit-graph
> > '/path/to/repository/objects/info/commit-graph': No such file or
> > directory
> >
> > Running some tests with commands like git for-each-ref and git
> > rev-list shows that the "split" commit graph is being used (setting
> > core.commitGraph=false makes commands noticeably slower), so
> > functionally all seems well. But should git commit-graph read be
> > handling this better?
>
> Unfortunately, you're running into an issue because I designed the
> "read" subcommand poorly (and also forgot to update it for
> incremental commit-graph files). The biggest issue is that "read"
> is not really meant for end-users. It really should have been built
> as a test-tool. This point was corrected when I got around to writing
> the multi-pack-index since it uses "test-tool read-midx" instead of
> add.
>
> To fix this issue, I would probably go about it by removing the "read"
> subcommand and creating a "test-tool read-commit-graph" for the tests
> that need that output.
>
> If others on-list think that the better thing to do is to update the
> "read" subcommand to provide the same output, but iterate over each
> layer of an incremental commit-graph, then I can do that work instead.

I was only running "git commit-graph read" as another way of verifying that everything looked good (to Git, that is). I'd already run "git commit-graph verify" and just found the discrepancy in their behavior surprising/interesting. For what it's worth, I personally don't see anything amiss with removing the "read" subcommand if that's simpler than updating it to handle incremental graphs. (Put differently, it's not a command I'd ever have Bitbucket Server run, or that I'm likely to try and run going forward. In this case I just completed some commit graph-related changes to Bitbucket Server and was looking for every possible avenue I could pursue to try and ensure what I did was producing the "correct" output after my changes got deployed to our internal dogfooding server.)

Thanks for taking the time to look into it and clarify the behavior! I really appreciate it.

Best regards, Bryan Turner

>
> Thanks,
> -Stolee