Collaborative Text Editing with Eg-walker: Better, Faster, Smaller

TL;DR

Eg-walker is a novel collaborative text editing algorithm that significantly improves memory efficiency and merging speed over existing CRDTs and OT algorithms, enabling more scalable peer-to-peer collaboration.

Contribution

The paper introduces Eg-walker, a new text collaboration algorithm that overcomes the memory and speed limitations of current CRDTs and OT methods.

Findings

Consumes an order of magnitude less memory than existing CRDTs

Loads documents from disk orders of magnitude faster

Merges long-running branches much faster than OT algorithms

Abstract

Collaborative text editing algorithms allow several users to concurrently modify a text file, and automatically merge concurrent edits into a consistent state. Existing algorithms fall in two categories: Operational Transformation (OT) algorithms are slow to merge files that have diverged substantially due to offline editing; CRDTs are slow to load and consume a lot of memory. We introduce Eg-walker, a collaboration algorithm for text that avoids these weaknesses. Compared to existing CRDTs, it consumes an order of magnitude less memory in the steady state, and loading a document from disk is orders of magnitude faster. Compared to OT, merging long-running branches is orders of magnitude faster. In the worst case, the merging performance of Eg-walker is comparable with existing CRDT algorithms. Eg-walker can be used everywhere CRDTs are used, including peer-to-peer systems without a central server. By offering performance that is competitive with centralised algorithms, our result paves the way towards the widespread adoption of peer-to-peer collaboration software.