Implement Partial Hydration for Activity #32863
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I pushed the Partial Hydration and Selection Hydration tests which I converted from the Suspense form to equivalent-ish Activity forms. So this should have pretty solid coverage now. |
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rickhanlonii
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Apr 22, 2025
… SSR Then we handle this fully in the Activity wrapper. That's what determines whether the offscreen content is SSR:ed or not. This also optimizes by avoiding an emit commit pass that used to hydrate the hidden Activity and then client renders the hidden content.
This is ported from the Suspense version with applicable changes.
but only with the alwaysThrottleRetries flag.
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Stacked on #32862 and #32842. This means that Activity boundaries now act as boundaries which can have their effects mounted independently. Just like Suspense boundaries, we hydrate the outer content first and then start hydrating the content in an Offscreen lane. Flowing props or interacting with the content increases the priority just like Suspense boundaries. This skips emitting even the comments for `<Activity mode="hidden">` so we don't hydrate those. Instead those are deferred to a later client render. The implementation are just forked copies of the SuspenseComponent branches and then carefully going through each line and tweaking it. The main interesting bit is that, unlike Suspense, Activity boundaries don't have fallbacks so all those branches where you might commit a suspended tree disappears. Instead, if something suspends while hydration, we can just leave the dehydrated content in place. However, if something does suspend during client rendering then it should bubble up to the parent. Therefore, we have to be careful to only pushSuspenseHandler when hydrating. That's really the main difference. This just uses the existing basic Activity tests but I've started work on port all of the applicable Suspense tests in SelectiveHydration-test and PartialHydration-test to Activity versions. DiffTrain build for [3ef31d1](3ef31d1)
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Stacked on #32862 and #32842. This means that Activity boundaries now act as boundaries which can have their effects mounted independently. Just like Suspense boundaries, we hydrate the outer content first and then start hydrating the content in an Offscreen lane. Flowing props or interacting with the content increases the priority just like Suspense boundaries. This skips emitting even the comments for `<Activity mode="hidden">` so we don't hydrate those. Instead those are deferred to a later client render. The implementation are just forked copies of the SuspenseComponent branches and then carefully going through each line and tweaking it. The main interesting bit is that, unlike Suspense, Activity boundaries don't have fallbacks so all those branches where you might commit a suspended tree disappears. Instead, if something suspends while hydration, we can just leave the dehydrated content in place. However, if something does suspend during client rendering then it should bubble up to the parent. Therefore, we have to be careful to only pushSuspenseHandler when hydrating. That's really the main difference. This just uses the existing basic Activity tests but I've started work on port all of the applicable Suspense tests in SelectiveHydration-test and PartialHydration-test to Activity versions. DiffTrain build for [3ef31d1](3ef31d1)
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Stacked on facebook#32862 and facebook#32842. This means that Activity boundaries now act as boundaries which can have their effects mounted independently. Just like Suspense boundaries, we hydrate the outer content first and then start hydrating the content in an Offscreen lane. Flowing props or interacting with the content increases the priority just like Suspense boundaries. This skips emitting even the comments for `<Activity mode="hidden">` so we don't hydrate those. Instead those are deferred to a later client render. The implementation are just forked copies of the SuspenseComponent branches and then carefully going through each line and tweaking it. The main interesting bit is that, unlike Suspense, Activity boundaries don't have fallbacks so all those branches where you might commit a suspended tree disappears. Instead, if something suspends while hydration, we can just leave the dehydrated content in place. However, if something does suspend during client rendering then it should bubble up to the parent. Therefore, we have to be careful to only pushSuspenseHandler when hydrating. That's really the main difference. This just uses the existing basic Activity tests but I've started work on port all of the applicable Suspense tests in SelectiveHydration-test and PartialHydration-test to Activity versions. DiffTrain build for [3ef31d1](facebook@3ef31d1)
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Stacked on facebook#32862 and facebook#32842. This means that Activity boundaries now act as boundaries which can have their effects mounted independently. Just like Suspense boundaries, we hydrate the outer content first and then start hydrating the content in an Offscreen lane. Flowing props or interacting with the content increases the priority just like Suspense boundaries. This skips emitting even the comments for `<Activity mode="hidden">` so we don't hydrate those. Instead those are deferred to a later client render. The implementation are just forked copies of the SuspenseComponent branches and then carefully going through each line and tweaking it. The main interesting bit is that, unlike Suspense, Activity boundaries don't have fallbacks so all those branches where you might commit a suspended tree disappears. Instead, if something suspends while hydration, we can just leave the dehydrated content in place. However, if something does suspend during client rendering then it should bubble up to the parent. Therefore, we have to be careful to only pushSuspenseHandler when hydrating. That's really the main difference. This just uses the existing basic Activity tests but I've started work on port all of the applicable Suspense tests in SelectiveHydration-test and PartialHydration-test to Activity versions. DiffTrain build for [3ef31d1](facebook@3ef31d1)
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Stacked on #32862 and #32842.
This means that Activity boundaries now act as boundaries which can have their effects mounted independently. Just like Suspense boundaries, we hydrate the outer content first and then start hydrating the content in an Offscreen lane. Flowing props or interacting with the content increases the priority just like Suspense boundaries.
This skips emitting even the comments for
<Activity mode="hidden">so we don't hydrate those. Instead those are deferred to a later client render.The implementation are just forked copies of the SuspenseComponent branches and then carefully going through each line and tweaking it.
The main interesting bit is that, unlike Suspense, Activity boundaries don't have fallbacks so all those branches where you might commit a suspended tree disappears. Instead, if something suspends while hydration, we can just leave the dehydrated content in place. However, if something does suspend during client rendering then it should bubble up to the parent. Therefore, we have to be careful to only pushSuspenseHandler when hydrating. That's really the main difference.
This just uses the existing basic Activity tests but I've started work on port all of the applicable Suspense tests in SelectiveHydration-test and PartialHydration-test to Activity versions.