Backport v2’s retain implementation to v1 - #596
Open
charliermarsh wants to merge 3 commits into
Open
Conversation
This file contains hidden or 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
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
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Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be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.
Summary
This PR applies the existing v2 compaction approach to v1's
retain: leave the initial retained prefix in place, then move each survivor into the next hole instead of swapping it with a discarded element. Removed elements are dropped during the scan, and a guard restores the untouched tail if the predicate or a destructor panics.I benchmarked this on Linux (x86), and retaining half the input took 40-60% less time for small integer vectors, 16-21% less time for 4,096 integers, and 24-38% less for 4,096 larger elements.
I included some native benchmarks but removed in a follow-up commit; you can see them in the PR history.