Apply all folds in one update

andreimokrousov commented

2026-06-22 18:20:23 +02:00

Contributor

This PR deals with one problem - transactions with a large number of foldEffects are very slow (For example, folding all foldable ranges of 10MB json (~130K ranges) takes about 10-15s on my machine; in contrast, unfolding them all takes only 1-2s)

I believe that the root of the problem is updating ranges one-by-one in this line folded.update({add: [widget.range(e.value.from, e.value.to)]}), because every call re-creates RangeBuilder and iterates through every existing fold, effectively making such transaction quadratic by foldEffect count.

In this PR I group all ranges that should be folded, and apply them all at once.
This reduces the time from 10-15s to <1s in my case.

Please take a look at this patch and kindly tell if it can be merged. Thanks!

This PR deals with one problem - transactions with a large number of `foldEffect`s are very slow (For example, folding all foldable ranges of 10MB json (~130K ranges) takes about 10-15s on my machine; in contrast, unfolding them all takes only 1-2s) I believe that the root of the problem is updating ranges one-by-one in this line `folded.update({add: [widget.range(e.value.from, e.value.to)]})`, because every call re-creates RangeBuilder and iterates through every existing fold, effectively making such transaction quadratic by foldEffect count. In this PR I group all ranges that should be folded, and apply them all at once. This reduces the time from 10-15s to <1s in my case. Please take a look at this patch and kindly tell if it can be merged. Thanks!

andreimokrousov added 1 commit

2026-06-22 18:20:24 +02:00

apply all folds in one update 1e7db6fd57

andreimokrousov changed title from ~~WIP: apply all folds in one update~~ to apply all folds in one update

2026-06-22 18:21:23 +02:00

andreimokrousov changed title from ~~apply all folds in one update~~ to Apply all folds in one update

2026-06-22 18:21:44 +02:00

andreimokrousov requested review from marijn

2026-06-22 18:21:57 +02:00

marijn commented

2026-06-22 18:41:34 +02:00

Owner

Oh right, yes, that would be quadratic. Having that many folds come in at the same time wasn't something I considered. The patch looks good, but could you make sure the indentation of the if at the bottom uses two instead of four spaces?

👍 1

andreimokrousov added 1 commit

2026-06-22 19:31:39 +02:00

fixup! apply all folds in one update 60f2354903

andreimokrousov commented

2026-06-22 19:44:21 +02:00

Author

Contributor

Oops, vscode formatter glitched.
I fixed it, thanks!

Oops, vscode formatter glitched. I fixed it, thanks!

marijn merged commit 487593a321 into main

2026-06-22 21:39:38 +02:00