Reduce base-path ".." removal in merge_path to a linear pass - #242
Merged
Conversation
The RFC2396 5.2 6a step used Array#index/slice! in a loop, making URI.join / URI#merge O(n^2) in the number of base-path segments, so a 640KB base of repeated "a/../" took several seconds. Rewrite it as a single left-to-right pass while preserving the exact previous output, including the leading-".." case where the whole base path is dropped. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be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.
URI.joinandURI#mergedegrade quadratically as the base path grows. Joining against a base built from repeateda/../takes several seconds once it reaches a few hundred thousand segments, because the RFC2396 Section 5.2 6a step scans withArray#indexand deletes withslice!inside a loop.I replaced that loop with a single left-to-right pass over the base path, matching the linear stack already used for the relative path. The output is unchanged for every input, including the case where a leading
..discards the whole base path rather than being kept as the relative side would.I verified this by diffing the new pass against the old implementation over exhaustive segment combinations and hundreds of thousands of random deep inputs, both on
merge_pathdirectly and end to end throughURI.join. Every result was identical.