Stacked Git Internals Discussion

[NonLogicalDev]

@jpgrayson I was looking into Stacked Git's Stack Implementation in relation to #163, and found myself a little confused about the
reasons behind the patches directory on the stacks/<branch> branch.

What are those files used for? I found the logic to write them:

• https://github.com/stacked-git/stgit/blob/master/stgit/lib/log.py#L265

But could not find where if it is ever actually read back. It seems they largely have the same information as the commit objects.

Bottom: $(git rev-parse "$PATCH_OID^1^{tree}")
Top: $(git rev-parse "$PATCH_OID^{tree}")
Author/Date: $(git cat-file -p $PATCH_OID | grep author)

Are those files still used?

After experimenting with a shell script that fixes up the topmost commit it seems like patches get regenerated anyway, even if incorrectly updated by the script:

https://gist.github.com/NonLogicalDev/bd110dc0a9c1519f6d79a4138b3c80de

[jpgrayson]

You are correct that those per-patch metadata files are not parsed/used by StGit directly.

Their purpose is to provide rich patch logging. This is a fairly deeply buried feature--you would only encounter the content of these patch metadata files when running stg log --diff <patchname>.

This feature has been there since before I became involved in the project. I've preserved this feature over the ages, but I've only occasionally found its utility useful. I may not appreciate the workflows or use cases where this is really helpful.

it seems like patches get regenerated anyway, even if incorrectly updated by the script

Are you referring to the patch refs? I.e. refs/patches/<branch>/<patchname>? An issue StGit has to deal with is that patch refs are redundantly found both in refs/patches/<branch> and in refs/stacks/<branch>:stack.json. The problem is that there is opportunity either via StGit bugs or the user doing manual ref updates for patch refs in refs/patches/<branch> to be out-of-sync with stack.json. The way StGit resolves this is to treat stack.json as canon and synchronize refs/patches/<branch> whenever a Stack object is initialized; i.e. resynchronize everytime stg is run.

Alternatively, if you are referring to the patch metadata files in refs/stacks/<branch>:patches/, yes, that tree is regenerated whenever any change is made to the patch series.