Adopt Brent's algorithm for cycle detection #809
Merged
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
The previous cycle detection algorithm (a naive check against the largest possible tail list) is simple and gets the job done, but has the potential to take a very long time on disks with many blocks. Brent's algorithm, on the other hand, takes at most 2x the number of blocks in the tail list. Originally naive cycle detection was chosen over Floyd's algorithm to avoid the extra complexity of managing two desynced traversals for every traversal of the tail list, but Brent's algorithm is very well suited for our use case, requiring only we keep track of an additional mdir pointer on the stack as we traverse.
geky
changed the title
Merged
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Outdated suggestions cannot be applied.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.
See #746
I accidentally merged the previous PR into the wrong branch. It doesn't look like GitHub has an option to reopen a merged PR, so creating a new PR to merge this in with CI correctly.