Refs #5176.
forEachDecorationAtCell and getDecorationsAtCell previously scanned every
registered decoration on each call. With thousands of search highlights this
becomes O(total decorations) per cell and blocks rendering during viewport
refreshes.
Maintain a Map of buffer line -> decorations that cover that line. Multi-line
decorations are indexed on every line in their span, so mixed single-line and
multi-line workloads stay fast without falling back to a full scan.
Keep the index aligned with buffer mutations:
- Register and unregister decorations in the line buckets on add/dispose.
- On trim, shift line keys synchronously (before marker handlers run).
- On insert/delete, re-index affected decorations in a microtask after marker
line updates are applied.
Inject IBufferService so line listeners follow the active buffer. Add unit
tests for trim, dispose-on-trim, insert, and dense single-line plus multi-line
lookup. Add DecorationService.benchmark.ts to measure sparse hits and
viewport-sized grid scans with 20k decorations.
Co-authored-by: Cursor <cursoragent@cursor.com>
Daniel ImmsandCursor
f484584b70