rebase: skip duplicate divergent commits by default #6302
+123
−13
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
I'm going to introduce more options other than empty, so this struct will hold all of the options related to abandoning rebased commits.
This serves a similar purpose to Git's patch ID mechanism, however it is slightly different in that it only compares commits which have the same change ID as each other (divergent changes), and it does a full comparison of the commits to see if they would have identical trees if rebased onto the same parents. Since most changes aren't divergent, I believe this should have a negligible performance cost in most cases.
I think skipping these commits by default makes sense for `jj rebase`, since usually this will be a helpful behavior for the user. With this behavior, a safe first step when encountering divergent changes would be to rebase one branch on top of the other, since that will abandon any divergent changes that have identical contents to existing commits, leaving behind any non-trivial divergent changes for the user to resolve manually.
yuja
reviewed
Apr 11, 2025
| .range(&ResolvedRevsetExpression::commits(self.new_parents.clone())), | ||
| ) | ||
| .evaluate(self.mut_repo) | ||
| .map_err(|err| BackendError::Other(Box::new(err)))?; |
There was a problem hiding this comment.
Since we're only interested in ancestors of the new parents (which I think are equivalent to the ancestors of the rebase destination), maybe we can abandon divergent commits before starting the rebase process?
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This is a partial fix for #5381 and #2979. It doesn't handle the general case (it only detects duplicate changes between divergent commits with the same change ID), but I think it should handle many useful cases, especially for users with the
change-idheader enabled. I'm looking for feedback about whether this is a good general approach and about the implementation.This serves a similar purpose to Git's patch ID mechanism, however it is slightly different in that it only compares commits which have the same change ID as each other (divergent changes), and it does a full comparison of the commits to see if they would have identical trees if rebased onto the same parents. Since most changes aren't divergent, I believe this should have a negligible performance cost in most cases.
I think skipping these commits by default makes sense for
jj rebase, since usually this will be a helpful behavior for the user. With this behavior, a safe first step when encountering divergent changes would be to rebase one branch on top of the other, since that will abandon any divergent changes that have identical contents to existing commits, leaving behind any non-trivial divergent changes for the user to resolve manually.Checklist
If applicable:
CHANGELOG.md