Add unstable_concurrentUpdatesByDefault

packages/react-dom/src/__tests__/ReactDOMRoot-test.js

@@ -13,6 +13,7 @@ let React = require('react');
 let ReactDOM = require('react-dom');
 let ReactDOMServer = require('react-dom/server');
 let Scheduler = require('scheduler');
+let act;
 
 describe('ReactDOMRoot', () => {
   let container;
@@ -24,6 +25,7 @@ describe('ReactDOMRoot', () => {
     ReactDOM = require('react-dom');
     ReactDOMServer = require('react-dom/server');
     Scheduler = require('scheduler');
+    act = require('react-dom/test-utils').unstable_concurrentAct;
   });
 
   if (!__EXPERIMENTAL__) {
@@ -316,4 +318,37 @@ describe('ReactDOMRoot', () => {
       {withoutStack: true},
     );
   });
+
+  // @gate experimental
+  it('opts-in to concurrent default updates', async () => {
+    const root = ReactDOM.unstable_createRoot(container, {
+      unstable_concurrentUpdatesByDefault: true,
+    });
+
+    function Foo({value}) {
+      Scheduler.unstable_yieldValue(value);
+      return <div>{value}</div>;
+    }
+
+    await act(async () => {
+      root.render(<Foo value="a" />);
+    });
+
+    expect(container.textContent).toEqual('a');
+
+    await act(async () => {
+      root.render(<Foo value="b" />);
+
+      expect(Scheduler).toHaveYielded(['a']);
+      expect(container.textContent).toEqual('a');
+
+      expect(Scheduler).toFlushAndYieldThrough(['b']);
+      if (gate(flags => flags.allowConcurrentByDefault)) {
+        expect(container.textContent).toEqual('a');
+      } else {
+        expect(container.textContent).toEqual('b');
+      }
+    });
+    expect(container.textContent).toEqual('b');
+  });
 });

packages/react-dom/src/client/ReactDOMRoot.js

@@ -28,6 +28,7 @@ export type RootOptions = {
     ...
   },
   unstable_strictModeLevel?: number,
+  unstable_concurrentUpdatesByDefault?: boolean,
   ...
 };
 
@@ -52,6 +53,7 @@ import {
 } from 'react-reconciler/src/ReactFiberReconciler';
 import invariant from 'shared/invariant';
 import {ConcurrentRoot, LegacyRoot} from 'react-reconciler/src/ReactRootTags';
+import {allowConcurrentByDefault} from 'shared/ReactFeatureFlags';
 
 function ReactDOMRoot(container: Container, options: void | RootOptions) {
   this._internalRoot = createRootImpl(container, ConcurrentRoot, options);
@@ -126,12 +128,21 @@ function createRootImpl(
       ? options.unstable_strictModeLevel
       : null;
 
+  let concurrentUpdatesByDefaultOverride = null;
+  if (allowConcurrentByDefault) {
+    concurrentUpdatesByDefaultOverride =
+      options != null && options.unstable_concurrentUpdatesByDefault != null
+        ? options.unstable_concurrentUpdatesByDefault
+        : null;
+  }
+
   const root = createContainer(
     container,
     tag,
     hydrate,
     hydrationCallbacks,
     strictModeLevelOverride,
+    concurrentUpdatesByDefaultOverride,
   );
   markContainerAsRoot(root.current, container);
 

packages/react-native-renderer/src/ReactFabric.js

@@ -207,7 +207,7 @@ function render(
   if (!root) {
     // TODO (bvaughn): If we decide to keep the wrapper component,
     // We could create a wrapper for containerTag as well to reduce special casing.
-    root = createContainer(containerTag, LegacyRoot, false, null, null);
+    root = createContainer(containerTag, LegacyRoot, false, null, null, null);
     roots.set(containerTag, root);
   }
   updateContainer(element, root, null, callback);

packages/react-native-renderer/src/ReactNativeRenderer.js

@@ -203,7 +203,7 @@ function render(
   if (!root) {
     // TODO (bvaughn): If we decide to keep the wrapper component,
     // We could create a wrapper for containerTag as well to reduce special casing.
-    root = createContainer(containerTag, LegacyRoot, false, null, null);
+    root = createContainer(containerTag, LegacyRoot, false, null, null, null);
     roots.set(containerTag, root);
   }
   updateContainer(element, root, null, callback);

packages/react-reconciler/src/ReactFiber.new.js

@@ -24,6 +24,8 @@ import {
   enableStrictEffects,
   enableProfilerTimer,
   enableScopeAPI,
+  enableSyncDefaultUpdates,
+  allowConcurrentByDefault,
 } from 'shared/ReactFeatureFlags';
 import {NoFlags, Placement, StaticMask} from './ReactFiberFlags';
 import {ConcurrentRoot} from './ReactRootTags';
@@ -68,6 +70,7 @@ import {
   ProfileMode,
   StrictLegacyMode,
   StrictEffectsMode,
+  ConcurrentUpdatesByDefaultMode,
 } from './ReactTypeOfMode';
 import {
   REACT_FORWARD_REF_TYPE,
@@ -420,6 +423,7 @@ export function resetWorkInProgress(workInProgress: Fiber, renderLanes: Lanes) {
 export function createHostRootFiber(
   tag: RootTag,
   strictModeLevelOverride: null | number,
+  concurrentUpdatesByDefaultOverride: null | boolean,
 ): Fiber {
   let mode;
   if (tag === ConcurrentRoot) {
@@ -440,6 +444,15 @@ export function createHostRootFiber(
         mode |= StrictLegacyMode;
       }
     }
+    if (
+      // We only use this flag for our repo tests to check both behaviors.
+      // TODO: Flip this flag and rename it something like "forceConcurrentByDefaultForTesting"
+      !enableSyncDefaultUpdates ||
+      // Only for internal experiments.
+      (allowConcurrentByDefault && concurrentUpdatesByDefaultOverride)
+    ) {
+      mode |= ConcurrentUpdatesByDefaultMode;
+    }
   } else {
     mode = NoMode;
   }

packages/react-reconciler/src/ReactFiber.old.js

@@ -24,6 +24,8 @@ import {
   enableStrictEffects,
   enableProfilerTimer,
   enableScopeAPI,
+  enableSyncDefaultUpdates,
+  allowConcurrentByDefault,
 } from 'shared/ReactFeatureFlags';
 import {NoFlags, Placement, StaticMask} from './ReactFiberFlags';
 import {ConcurrentRoot} from './ReactRootTags';
@@ -68,6 +70,7 @@ import {
   ProfileMode,
   StrictLegacyMode,
   StrictEffectsMode,
+  ConcurrentUpdatesByDefaultMode,
 } from './ReactTypeOfMode';
 import {
   REACT_FORWARD_REF_TYPE,
@@ -420,6 +423,7 @@ export function resetWorkInProgress(workInProgress: Fiber, renderLanes: Lanes) {
 export function createHostRootFiber(
   tag: RootTag,
   strictModeLevelOverride: null | number,
+  concurrentUpdatesByDefaultOverride: null | boolean,
 ): Fiber {
   let mode;
   if (tag === ConcurrentRoot) {
@@ -440,6 +444,15 @@ export function createHostRootFiber(
         mode |= StrictLegacyMode;
       }
     }
+    if (
+      // We only use this flag for our repo tests to check both behaviors.
+      // TODO: Flip this flag and rename it something like "forceConcurrentByDefaultForTesting"
+      !enableSyncDefaultUpdates ||
+      // Only for internal experiments.
+      (allowConcurrentByDefault && concurrentUpdatesByDefaultOverride)
+    ) {
+      mode |= ConcurrentUpdatesByDefaultMode;
+    }
   } else {
     mode = NoMode;
   }

packages/react-reconciler/src/ReactFiberLane.new.js

@@ -39,9 +39,10 @@ import {
   enableCache,
   enableSchedulingProfiler,
   enableUpdaterTracking,
-  enableSyncDefaultUpdates,
+  allowConcurrentByDefault,
 } from 'shared/ReactFeatureFlags';
 import {isDevToolsPresent} from './ReactFiberDevToolsHook.new';
+import {ConcurrentUpdatesByDefaultMode, NoMode} from './ReactTypeOfMode';
 
 export const SyncLanePriority: LanePriority = 12;
 
@@ -318,11 +319,12 @@ export function getNextLanes(root: FiberRoot, wipLanes: Lanes): Lanes {
   }
 
   if (
-    // TODO: Check for root override, once that lands
-    enableSyncDefaultUpdates &&
-    (nextLanes & InputContinuousLane) !== NoLanes
+    allowConcurrentByDefault &&
+    (root.current.mode & ConcurrentUpdatesByDefaultMode) !== NoMode
   ) {
-    // When updates are sync by default, we entangle continous priority updates
+    // Do nothing, use the lanes as they were assigned.
+  } else if ((nextLanes & InputContinuousLane) !== NoLanes) {
+    // When updates are sync by default, we entangle continuous priority updates
     // and default updates, so they render in the same batch. The only reason
     // they use separate lanes is because continuous updates should interrupt
     // transitions, but default updates should not.
@@ -527,17 +529,21 @@ export function shouldTimeSlice(root: FiberRoot, lanes: Lanes) {
     // finish rendering without yielding execution.
     return false;
   }
-  if (enableSyncDefaultUpdates) {
-    const SyncDefaultLanes =
-      InputContinuousHydrationLane |
-      InputContinuousLane |
-      DefaultHydrationLane |
-      DefaultLane;
-    // TODO: Check for root override, once that lands
-    return (lanes & SyncDefaultLanes) === NoLanes;
-  } else {
+
+  if (
+    allowConcurrentByDefault &&
+    (root.current.mode & ConcurrentUpdatesByDefaultMode) !== NoMode
+  ) {
+    // Concurrent updates by default always use time slicing.
     return true;
   }
+
+  const SyncDefaultLanes =
+    InputContinuousHydrationLane |
+    InputContinuousLane |
+    DefaultHydrationLane |
+    DefaultLane;
+  return (lanes & SyncDefaultLanes) === NoLanes;
 }
 
 export function isTransitionLane(lane: Lane) {

packages/react-reconciler/src/ReactFiberLane.old.js

@@ -39,9 +39,10 @@ import {
   enableCache,
   enableSchedulingProfiler,
   enableUpdaterTracking,
-  enableSyncDefaultUpdates,
+  allowConcurrentByDefault,
 } from 'shared/ReactFeatureFlags';
 import {isDevToolsPresent} from './ReactFiberDevToolsHook.old';
+import {ConcurrentUpdatesByDefaultMode, NoMode} from './ReactTypeOfMode';
 
 export const SyncLanePriority: LanePriority = 12;
 
@@ -318,11 +319,12 @@ export function getNextLanes(root: FiberRoot, wipLanes: Lanes): Lanes {
   }
 
   if (
-    // TODO: Check for root override, once that lands
-    enableSyncDefaultUpdates &&
-    (nextLanes & InputContinuousLane) !== NoLanes
+    allowConcurrentByDefault &&
+    (root.current.mode & ConcurrentUpdatesByDefaultMode) !== NoMode
   ) {
-    // When updates are sync by default, we entangle continous priority updates
+    // Do nothing, use the lanes as they were assigned.
+  } else if ((nextLanes & InputContinuousLane) !== NoLanes) {
+    // When updates are sync by default, we entangle continuous priority updates
     // and default updates, so they render in the same batch. The only reason
     // they use separate lanes is because continuous updates should interrupt
     // transitions, but default updates should not.
@@ -527,17 +529,21 @@ export function shouldTimeSlice(root: FiberRoot, lanes: Lanes) {
     // finish rendering without yielding execution.
     return false;
   }
-  if (enableSyncDefaultUpdates) {
-    const SyncDefaultLanes =
-      InputContinuousHydrationLane |
-      InputContinuousLane |
-      DefaultHydrationLane |
-      DefaultLane;
-    // TODO: Check for root override, once that lands
-    return (lanes & SyncDefaultLanes) === NoLanes;
-  } else {
+
+  if (
+    allowConcurrentByDefault &&
+    (root.current.mode & ConcurrentUpdatesByDefaultMode) !== NoMode
+  ) {
+    // Concurrent updates by default always use time slicing.
     return true;
   }
+
+  const SyncDefaultLanes =
+    InputContinuousHydrationLane |
+    InputContinuousLane |
+    DefaultHydrationLane |
+    DefaultLane;
+  return (lanes & SyncDefaultLanes) === NoLanes;
 }
 
 export function isTransitionLane(lane: Lane) {

packages/react-reconciler/src/ReactFiberReconciler.new.js

@@ -249,13 +249,15 @@ export function createContainer(
   hydrate: boolean,
   hydrationCallbacks: null | SuspenseHydrationCallbacks,
   strictModeLevelOverride: null | number,
+  concurrentUpdatesByDefaultOverride: null | boolean,
 ): OpaqueRoot {
   return createFiberRoot(
     containerInfo,
     tag,
     hydrate,
     hydrationCallbacks,
     strictModeLevelOverride,
+    concurrentUpdatesByDefaultOverride,
   );
 }
 

packages/react-reconciler/src/ReactFiberReconciler.old.js

@@ -249,13 +249,15 @@ export function createContainer(
   hydrate: boolean,
   hydrationCallbacks: null | SuspenseHydrationCallbacks,
   strictModeLevelOverride: null | number,
+  concurrentUpdatesByDefaultOverride: null | boolean,
 ): OpaqueRoot {
   return createFiberRoot(
     containerInfo,
     tag,
     hydrate,
     hydrationCallbacks,
     strictModeLevelOverride,
+    concurrentUpdatesByDefaultOverride,
   );
 }
 

packages/react-reconciler/src/ReactFiberRoot.new.js

@@ -99,6 +99,7 @@ export function createFiberRoot(
   hydrate: boolean,
   hydrationCallbacks: null | SuspenseHydrationCallbacks,
   strictModeLevelOverride: null | number,
+  concurrentUpdatesByDefaultOverride: null | boolean,
 ): FiberRoot {
   const root: FiberRoot = (new FiberRootNode(containerInfo, tag, hydrate): any);
   if (enableSuspenseCallback) {
@@ -107,7 +108,11 @@ export function createFiberRoot(
 
   // Cyclic construction. This cheats the type system right now because
   // stateNode is any.
-  const uninitializedFiber = createHostRootFiber(tag, strictModeLevelOverride);
+  const uninitializedFiber = createHostRootFiber(
+    tag,
+    strictModeLevelOverride,
+    concurrentUpdatesByDefaultOverride,
+  );
   root.current = uninitializedFiber;
   uninitializedFiber.stateNode = root;
 

packages/react-reconciler/src/ReactFiberRoot.old.js

@@ -99,6 +99,7 @@ export function createFiberRoot(
   hydrate: boolean,
   hydrationCallbacks: null | SuspenseHydrationCallbacks,
   strictModeLevelOverride: null | number,
+  concurrentUpdatesByDefaultOverride: null | boolean,
 ): FiberRoot {
   const root: FiberRoot = (new FiberRootNode(containerInfo, tag, hydrate): any);
   if (enableSuspenseCallback) {
@@ -107,7 +108,11 @@ export function createFiberRoot(
 
   // Cyclic construction. This cheats the type system right now because
   // stateNode is any.
-  const uninitializedFiber = createHostRootFiber(tag, strictModeLevelOverride);
+  const uninitializedFiber = createHostRootFiber(
+    tag,
+    strictModeLevelOverride,
+    concurrentUpdatesByDefaultOverride,
+  );
   root.current = uninitializedFiber;
   uninitializedFiber.stateNode = root;