[Tree widget]: adjust ChildElementsCache on next

[JonasDov]

Follow up on #1681.
Adding changes from #1678 for ChildElementsCache

[Copilot]

Pull request overview

This PR follows up on prior “next” tree-widget batching work by rewriting ChildElementsCache to use the shared BatchingCache infrastructure and updating tree visibility handlers/helpers to use the new getChildElements/getDescendantsCounts APIs instead of building a full children tree per request.

Changes:

• Replaced ChildElementsCache implementation with a BatchingCache-based, 20ms-batched cache keyed by (modelId, parentElementId/categoryId, childCategoryIds).
• Updated models/categories/classifications visibility handlers and helpers to fetch descendant category IDs via getDescendantsCounts and then fetch descendants via getChildElements.
• Added a comprehensive ChildElementsCache test suite and adjusted test mocks to reflect the new API surface.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
packages/itwin/tree-widget/src/tree-widget-react/components/trees/models-tree/internal/visibility/ModelsTreeVisibilityHelper.ts	Switch grouped-element visibility changes to the new descendant-counts + child-elements flow.
packages/itwin/tree-widget/src/tree-widget-react/components/trees/models-tree/internal/visibility/ModelsTreeVisibilityHandler.ts	Replace getChildElementsTree usage with getDescendantsCounts + getChildElements batching path.
packages/itwin/tree-widget/src/tree-widget-react/components/trees/common/internal/caches/ChildElementsCache.ts	Rewrite cache to extend BatchingCache and query descendants grouped by child category.
packages/itwin/tree-widget/src/tree-widget-react/components/trees/common/internal/caches/BaseIdsCache.ts	Remove tree-based child APIs and re-export getChildElements; broaden getElementsCount args.
packages/itwin/tree-widget/src/tree-widget-react/components/trees/classifications-tree/internal/visibility/ClassificationsTreeVisibilityHandler.ts	Update element visibility change logic to new cache APIs.
packages/itwin/tree-widget/src/tree-widget-react/components/trees/categories-tree/internal/visibility/CategoriesTreeVisibilityHelper.ts	Update category visibility changes to fetch descendants via new cache APIs.
packages/itwin/tree-widget/src/tree-widget-react/components/trees/categories-tree/internal/visibility/CategoriesTreeVisibilityHandler.ts	Update search-target element visibility logic to new cache APIs.
packages/itwin/tree-widget/src/test/trees/models-tree/Utils.ts	Adjust fake ids-cache mock surface for new methods (needs further fix for new getElementsCount calls).
packages/itwin/tree-widget/src/test/trees/common/internal/ChildElementsCache.test.ts	New test suite covering batching, caching, and query behavior for ChildElementsCache.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[github-actions]

Tree-Widget Next benchmark

Benchmark suite	Current: 95acaba	Previous: 36f8841	Deviation	Status
models tree 50k 3D elements search > get search paths	1266 ms	914 ms	38.51%	🚨
models tree 50k 3D elements search > get search paths (P95 of main thread blocks)	59 ms	49 ms	20.41%	〰️
models tree 50k 3D elements search > load hierarchy from search paths	110859 ms	96550 ms	14.82%	🚨
models tree 50k 3D elements search > load hierarchy from search paths (P95 of main thread blocks)	38 ms	32 ms	18.75%	〰️
models tree 50k categories > collect nodes	2883 ms	2360 ms	22.16%	🚨
models tree 50k categories > collect nodes (P95 of main thread blocks)	144 ms	83 ms	73.49%	🚨
models tree 50k categories > validate initial visibility	2508 ms	2058 ms	21.87%	🚨
models tree 50k categories > validate initial visibility (P95 of main thread blocks)	0 ms	0 ms	0%	🟰
models tree 50k categories > change visibility	76 ms	67 ms	13.43%	〰️
models tree 50k categories > change visibility (P95 of main thread blocks)	66 ms	57 ms	15.79%	〰️
models tree 50k categories > validate changed visibility	4662 ms	3903 ms	19.45%	🚨
models tree 50k categories > validate changed visibility (P95 of main thread blocks)	25 ms	0 ms	2500%	〰️
models tree 50k 3D elements > collect nodes	44424 ms	37646 ms	18.00%	🚨
models tree 50k 3D elements > collect nodes (P95 of main thread blocks)	70 ms	45 ms	55.56%	〰️
models tree 50k 3D elements > validate initial visibility	2574 ms	2081 ms	23.69%	🚨
models tree 50k 3D elements > validate initial visibility (P95 of main thread blocks)	28 ms	0 ms	2800%	〰️
models tree 50k 3D elements > change model visibility	24 ms	17 ms	41.18%	〰️
models tree 50k 3D elements > change model visibility (P95 of main thread blocks)	0 ms	0 ms	0%	🟰
models tree 50k 3D elements > validate changed model visibility	2469 ms	2103 ms	17.40%	🚨
models tree 50k 3D elements > validate changed model visibility (P95 of main thread blocks)	0 ms	0 ms	0%	🟰
models tree 50k 3D elements > change category node visibility	522 ms	421 ms	23.99%	🚨
models tree 50k 3D elements > change category node visibility (P95 of main thread blocks)	63 ms	52 ms	21.15%	〰️
models tree 50k 3D elements > validate changed category visibility	2463 ms	2065 ms	19.27%	🚨
models tree 50k 3D elements > validate changed category visibility (P95 of main thread blocks)	0 ms	0 ms	0%	🟰
models tree 50k 3D elements > validate per-model category override	2455 ms	2054 ms	19.52%	🚨
models tree 50k 3D elements > validate per-model category override (P95 of main thread blocks)	0 ms	0 ms	0%	🟰
models tree 50k 3D elements > change element visibility	54 ms	10 ms	440.00%	〰️
models tree 50k 3D elements > change element visibility (P95 of main thread blocks)	0 ms	0 ms	0%	🟰
models tree 50k 3D elements > validate changed element visibility	3207 ms	2566 ms	24.98%	🚨
models tree 50k 3D elements > validate changed element visibility (P95 of main thread blocks)	68 ms	47 ms	44.68%	〰️
models tree 50k 3D child elements with different categories > collect nodes	44772 ms	37804 ms	18.43%	🚨
models tree 50k 3D child elements with different categories > collect nodes (P95 of main thread blocks)	70 ms	42 ms	66.67%	〰️
models tree 50k 3D child elements with different categories > validate initial visibility	2456 ms	2121 ms	15.79%	🚨
models tree 50k 3D child elements with different categories > validate initial visibility (P95 of main thread blocks)	0 ms	22 ms	-100%	〰️
models tree 50k 3D child elements with different categories > change visibility	45 ms	11 ms	309.09%	〰️
models tree 50k 3D child elements with different categories > change visibility (P95 of main thread blocks)	0 ms	0 ms	0%	🟰
models tree 50k 3D child elements with different categories > validate changed visibility	3273 ms	2570 ms	27.35%	🚨
models tree 50k 3D child elements with different categories > validate changed visibility (P95 of main thread blocks)	63 ms	50 ms	26%	〰️
categories tree 50k subCategories search > get search paths	1829 ms	1402 ms	30.46%	🚨
categories tree 50k subCategories search > get search paths (P95 of main thread blocks)	42 ms	31 ms	35.48%	〰️
categories tree 50k subCategories search > load hierarchy from search paths	5357 ms	4186 ms	27.97%	🚨
categories tree 50k subCategories search > load hierarchy from search paths (P95 of main thread blocks)	49 ms	32 ms	53.13%	〰️
categories tree 50k subCategories > collect nodes	5918 ms	4575 ms	29.36%	🚨
categories tree 50k subCategories > collect nodes (P95 of main thread blocks)	47 ms	34 ms	38.24%	〰️
categories tree 50k subCategories > validate initial visibility	1665 ms	1431 ms	16.35%	🚨
categories tree 50k subCategories > validate initial visibility (P95 of main thread blocks)	21 ms	0 ms	2100%	〰️
categories tree 50k subCategories > change visibility	340 ms	326 ms	4.29%	〰️
categories tree 50k subCategories > change visibility (P95 of main thread blocks)	24 ms	0 ms	2400%	〰️
categories tree 50k subCategories > validate changed visibility	1581 ms	1370 ms	15.40%	🚨
categories tree 50k subCategories > validate changed visibility (P95 of main thread blocks)	26 ms	21 ms	23.81%	〰️
categories tree 50k categories > collect nodes	2472 ms	1973 ms	25.29%	🚨
categories tree 50k categories > collect nodes (P95 of main thread blocks)	116 ms	102 ms	13.73%	〰️
categories tree 50k categories > validate initial visibility	7206 ms	6173 ms	16.73%	🚨
categories tree 50k categories > validate initial visibility (P95 of main thread blocks)	85 ms	70 ms	21.43%	〰️
categories tree 50k categories > change visibility	669 ms	617 ms	8.43%	〰️
categories tree 50k categories > change visibility (P95 of main thread blocks)	49 ms	35 ms	40%	〰️
categories tree 50k categories > validate changed visibility	7168 ms	6106 ms	17.39%	🚨
categories tree 50k categories > validate changed visibility (P95 of main thread blocks)	31 ms	30 ms	3.33%	〰️
classifications tree 50k classifications search > get search paths	2225 ms	1635 ms	36.09%	🚨
classifications tree 50k classifications search > get search paths (P95 of main thread blocks)	133 ms	96 ms	38.54%	〰️
classifications tree 50k classifications search > load hierarchy from search paths	67728 ms	58273 ms	16.23%	🚨
classifications tree 50k classifications search > load hierarchy from search paths (P95 of main thread blocks)	0 ms	0 ms	0%	🟰
classifications tree 50k classifications > collect nodes	36596 ms	29155 ms	25.52%	🚨
classifications tree 50k classifications > collect nodes (P95 of main thread blocks)	86 ms	59 ms	45.76%	〰️
classifications tree 50k classifications > validate initial visibility	4652 ms	3833 ms	21.37%	🚨
classifications tree 50k classifications > validate initial visibility (P95 of main thread blocks)	49 ms	65 ms	-24.62%	〰️
classifications tree 50k classifications > change visibility	29 ms	25 ms	16%	〰️
classifications tree 50k classifications > change visibility (P95 of main thread blocks)	0 ms	0 ms	0%	🟰
classifications tree 50k classifications > validate changed visibility	4858 ms	4011 ms	21.12%	🚨
classifications tree 50k classifications > validate changed visibility (P95 of main thread blocks)	65 ms	54 ms	20.37%	〰️

This comment was automatically generated by workflow using github-action-benchmark.