Avoid traversing retained subtrees - #5183
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Port of #5182 to v11. On a successful shouldComponentUpdate/memo bailout, set oldDom via getDomSibling directly in diff()'s bailout block instead of recursively walking the retained child tree through insert(); the existing result branch in diffChildren picks it up. Actual placements still use insert(), which now only handles placement and drops its shouldPlace flag. -20 B gzip / -18 B brotli on preact.mjs
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Size Change: -21 B (-0.13%) Total Size: 15.7 kB 📦 View Changed
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diff() already returns the next host cursor for function components; elements returned their own DOM node, which diffChildren discarded and re-derived via newDom.nextSibling. Return the sibling directly so the function-type check in the hot loop can go. The JSON-injection guard now returns UNDEFINED so an invalid child leaves the cursor untouched instead of clobbering it with NULL.
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coverage: 98.534%. remained the same — perf/v11-retained-subtree-bailout into main |
This reverts commit 6df9a00.
JoviDeCroock
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marvinhagemeister
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Summary
Port of #5182 to v11. On a successful
shouldComponentUpdate/memo bailout, setoldDomviagetDomSibling(oldVNode)directly indiff()'s bailout block instead of recursively walking the retained child tree throughinsert(); the existingresultbranch indiffChildrenpicks it up. Actual placements still useinsert(), which now only handles placement and drops itsshouldPlaceflag (themoveBefore/isMountinghandling is unchanged).A follow-up commit finishes unifying the cursor:
diff()now returns the next sibling cursor for element vnodes too (instead of the element's own DOM node, whichdiffChildrendiscarded and re-derived vianewDom.nextSibling), so the function-type check in the hot loop goes away. The JSON-injection guard returnsUNDEFINEDso an invalid child leaves the cursor untouched.