Subject: Re: standalone library/tool to query commit-graph?

From: Ævar Arnfjörð Bjarmason <[email-masked]>
Date: Thu, 23 May 2019 23:54:22 +0200

On Thu, May 23 2019, Jakub Narebski wrote:

> Derrick Stolee <[email-masked]> writes:
>> On 5/22/2019 2:49 PM, Karl Ostmo wrote:
>
>>> After producing the file ".git/objects/info/commit-graph" with the
>>> command "git commit-graph write", is there a way to answer queries
>>> like "git merge-base --is-ancestor" without having a .git directory?
>>> E.g. is there a library that will operate on the "commit-graph" file
>>> all by itself?
>>
>> You could certainly build such a tool, assuming your merge-base parameters are
>> full-length commit ids. If you try to start at ref names, you'll need the .git
>> directory.
>>
>> I would not expect such a tool to ever exist in the Git codebase. Instead, you
>> would need a new project, say "graph-analyzer --graph=<path> --is-ancestor <id1> <id2>"
>
> It would be nice if such tool could convert commit-graph into other
> commonly used augmented graph storage formats, like GEXF (Graph Exchange
> XML Format), GraphML, GML (Graph Modelling Language), Pajek format or
> Graphviz .dot format.

Wouldn't that make more sense as a hypothetical output format for "log
--graph" rather than something you'd want to emit from the commit-graph?
Presumably you'd want to export in such a format to see the shape of the
repo, and since the commit graph doesn't include any commits outside of
packs you'd miss any loose commits.