Re: [Summit topic] The state of getting a reftable backend working in git.git

On Tue, Oct 26, 2021 at 12:16 AM Ævar Arnfjörð Bjarmason
[off-list ref] wrote:

From memory I think the more general concern Philip Oakley was also
expressing (but maybe he'll chime in) could also be addressed by a tool
that just un-reftable-ifies a repository.

I think such a thing would be useful, and I think we don't have that
already. Isn't the files backend or reftable usage now an "init"-time
setting.
..
Maybe there's more complexity I'm not considering than just the *.lock
dance in .git/*, but if not such a tool could also convert freely
between the two backends, so you could try refable out in an existing
checkout.

I added a convert-ref-storage command to the JGit command line client
for exactly this,

$ jgit convert-ref-storage  -h
jgit convert-ref-storage [--format VAL] [--help (-h)] [--ssh [JSCH | APACHE]]

 --format VAL          : Format to convert to (reftable or refdir) (default:
                         reftable)
 --help (-h)           : display this help text (default: true)
 --ssh [JSCH | APACHE] : Selects the built-in ssh library to use, JSch or
                         Apache MINA sshd. (default: JSCH)

See here[1] for implementation. It's not safe for concurrent use with
other git commands, but that's hardly a common use-case.

[1] https://eclipse.googlesource.com/gerrit/jgit/jgit/+/1825a2230c06e7a6cbe23c69b63c3b7ecd2ceac6/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/FileRepository.java#806


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