Files
react/packages/shared/forks/ReactFeatureFlags.test-renderer.js
T
Sebastian Markbåge 9f2eebd807 [Fiber/Fizz] Support AsyncIterable as Children and AsyncGenerator Client Components (#28868)
Stacked on #28849, #28854, #28853. Behind a flag.

If you're following along from the side-lines. This is probably not what
you think it is.

It's NOT a way to get updates to a component over time. The
AsyncIterable works like an Iterable already works in React which is how
an Array works. I.e. it's a list of children - not the value of a child
over time.

It also doesn't actually render one component at a time. The way it
works is more like awaiting the entire list to become an array and then
it shows up. Before that it suspends the parent.

To actually get these to display one at a time, you have to opt-in with
`<SuspenseList>` to describe how they should appear. That's really the
interesting part and that not implemented yet.

Additionally, since these are effectively Async Functions and uncached
promises, they're not actually fully "supported" on the client yet for
the same reason rendering plain Promises and Async Functions aren't.
They warn. It's only really useful when paired with RSC that produces
instrumented versions of these. Ideally we'd published instrumented
helpers to help with map/filter style operations that yield new
instrumented AsyncIterables.

The way the implementation works basically just relies on unwrapThenable
and otherwise works like a plain Iterator.

There is one quirk with these that are different than just promises. We
ask for a new iterator each time we rerender. This means that upon retry
we kick off another iteration which itself might kick off new requests
that block iterating further. To solve this and make it actually
efficient enough to use on the client we'd need to stash something like
a buffer of the previous iteration and maybe iterator on the iterable so
that we can continue where we left off or synchronously iterate if we've
seen it before. Similar to our `.value` convention on Promises.

In Fizz, I had to do a special case because when we render an iterator
child we don't actually rerender the parent again like we do in Fiber.
However, it's more efficient to just continue on where we left off by
reusing the entries from the thenable state from before in that case.
2024-04-22 13:25:05 -04:00

103 lines
4.1 KiB
JavaScript

/**
* Copyright (c) Meta Platforms, Inc. and affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*
* @flow
*/
import typeof * as FeatureFlagsType from 'shared/ReactFeatureFlags';
import typeof * as ExportsType from './ReactFeatureFlags.test-renderer';
export const debugRenderPhaseSideEffectsForStrictMode = false;
export const enableDebugTracing = false;
export const enableAsyncDebugInfo = false;
export const enableSchedulingProfiler = false;
export const enableProfilerTimer = __PROFILE__;
export const enableProfilerCommitHooks = __PROFILE__;
export const enableProfilerNestedUpdatePhase = __PROFILE__;
export const enableUpdaterTracking = false;
export const enableCache = true;
export const enableLegacyCache = __EXPERIMENTAL__;
export const enableFetchInstrumentation = true;
export const enableBinaryFlight = true;
export const enableFlightReadableStream = true;
export const enableAsyncIterableChildren = false;
export const enableTaint = true;
export const enablePostpone = false;
export const disableCommentsAsDOMContainers = true;
export const disableInputAttributeSyncing = false;
export const disableIEWorkarounds = true;
export const enableScopeAPI = false;
export const enableCreateEventHandleAPI = false;
export const enableSuspenseCallback = false;
export const enableTrustedTypesIntegration = false;
export const disableTextareaChildren = false;
export const enableSuspenseAvoidThisFallback = false;
export const enableSuspenseAvoidThisFallbackFizz = false;
export const enableCPUSuspense = false;
export const enableUseMemoCacheHook = true;
export const enableNoCloningMemoCache = false;
export const enableUseEffectEventHook = false;
export const favorSafetyOverHydrationPerf = true;
export const enableComponentStackLocations = true;
export const enableLegacyFBSupport = false;
export const enableFilterEmptyStringAttributesDOM = true;
export const enableGetInspectorDataForInstanceInProduction = false;
export const enableRetryLaneExpiration = false;
export const retryLaneExpirationMs = 5000;
export const syncLaneExpirationMs = 250;
export const transitionLaneExpirationMs = 5000;
export const disableSchedulerTimeoutInWorkLoop = false;
export const enableLazyContextPropagation = false;
export const enableLegacyHidden = false;
export const forceConcurrentByDefaultForTesting = false;
export const enableUnifiedSyncLane = __EXPERIMENTAL__;
export const allowConcurrentByDefault = false;
export const consoleManagedByDevToolsDuringStrictMode = false;
export const enableTransitionTracing = false;
export const useModernStrictMode = false;
export const enableDO_NOT_USE_disableStrictPassiveEffect = false;
export const enableFizzExternalRuntime = true;
export const enableDeferRootSchedulingToMicrotask = true;
export const enableAsyncActions = true;
export const alwaysThrottleRetries = true;
export const passChildrenWhenCloningPersistedNodes = false;
export const enableUseDeferredValueInitialArg = __EXPERIMENTAL__;
export const disableClientCache = true;
export const enableServerComponentKeys = true;
export const enableServerComponentLogs = true;
export const enableInfiniteRenderLoopDetection = false;
export const enableEarlyReturnForPropDiffing = false;
export const renameElementSymbol = true;
// TODO: This must be in sync with the main ReactFeatureFlags file because
// the Test Renderer's value must be the same as the one used by the
// react package.
//
// We really need to get rid of this whole module. Any test renderer specific
// flags should be handled by the Fiber config.
// const __NEXT_MAJOR__ = __EXPERIMENTAL__;
export const enableRefAsProp = true;
export const disableStringRefs = true;
export const disableLegacyMode = true;
export const disableLegacyContext = true;
export const disableDOMTestUtils = true;
export const enableRenderableContext = true;
export const enableReactTestRendererWarning = true;
export const disableDefaultPropsExceptForClasses = true;
// Flow magic to verify the exports of this file match the original version.
((((null: any): ExportsType): FeatureFlagsType): ExportsType);