Re: Commit graph chains with no corresponding files?

[Derrick Stolee <stolee@gmail.com>]

On 6/29/2020 6:07 PM, Jonathan Tan wrote:
> At $DAYJOB, a few people have reported "warning: unable to find all
> commit-graph files" warnings. Their commit-graph-chain files have a few
> lines, but they only have one commit graph file with very few commits. I
> suspected something happening during fetch, because (as far as I know) a
> fetch may cause an incremental commit graph to be written, but I ran a
> fetch on a large repository myself and didn't run into this problem.
> 
> Has anyone ran into this problem before, and know how to reproduce?

The incremental commit-graph code deletes any commit-graph files
that do not appear in the chain. I believe this is done by comparing
the contents of the ".git/objects/info/commit-graphs/" directory to
the contents of the chain file.

These appear to be case-sensitive, full-path comparisons.

It is _possible_ that something like a case switch or a symlink
could be causing a problem here. That's where I would look on
the affected systems.

Likely the full-path comparison in expire_commit_graphs() should
be dropped in favor of local filename comparisons. A case-
sensitive match is less likely to be important here since Git
is writing the paths itself and should get the proper case back
from the directory listing.

Thanks,
-Stolee