Use Kahn's algorithm for CRDT toposort #5
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 existing implementation is O(n^2) in the number of nodes. That's fine for drawings, but it takes minutes to process big text documents because the reMarkable creates a node for each word. This patch implements [Kahn's algorithm](https://en.wikipedia.org/wiki/Topological_sorting#Kahn's_algorithm). That would ordinarily be O(n), but to maintain deterministic ordering for concurrent edits (as the current algorithm does), we use a heap instead of a set, making the runtime O(n log n). My text-heavy notebook now processes in about a second instead of minutes.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
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Outdated suggestions cannot be applied.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.
The existing implementation is O(n^2) in the number of nodes. That's fine for drawings, but it takes minutes to process big text documents because the reMarkable creates a node for each word.
This patch implements Kahn's algorithm. That would ordinarily be O(n), but to maintain deterministic ordering for concurrent edits (as the current algorithm does), we use a heap instead of a set, making the runtime O(n log n).
My text-heavy notebook now processes in about a second instead of minutes.
Original PR here: ricklupton#49