Use EventPriority to track update priority (facebook#21082)

Instead of LanePriority. Internally, EventPriority is just a lane, so
this skips an extra conversion. Since EventPriority is a "public" (to
the host config) type, I was also able to remove some deep imports
of the Lane module.

This gets us most of the way to deleting the LanePriority entirely.

packages/react-dom/src/__tests__/ReactDOMServerPartialHydration-test.internal.js

@@ -17,11 +17,7 @@ let ReactFeatureFlags;
 let Suspense;
 let SuspenseList;
 let act;
-
-// Copied from ReactFiberLanes. Don't do this!
-// This is hard coded directly to avoid needing to import, and
-// we'll remove this as we replace runWithPriority with React APIs.
-export const IdleLanePriority = 2;
+let IdleEventPriority;
 
 function dispatchMouseEvent(to, from) {
   if (!to) {
@@ -89,6 +85,8 @@ describe('ReactDOMServerPartialHydration', () => {
     Scheduler = require('scheduler');
     Suspense = React.Suspense;
     SuspenseList = React.SuspenseList;
+
+    IdleEventPriority = require('react-reconciler/constants').IdleEventPriority;
   });
 
   // Note: This is based on a similar component we use in www. We can delete
@@ -628,7 +626,7 @@ describe('ReactDOMServerPartialHydration', () => {
     expect(span.textContent).toBe('Hello');
 
     // Schedule an update at idle priority
-    ReactDOM.unstable_runWithPriority(IdleLanePriority, () => {
+    ReactDOM.unstable_runWithPriority(IdleEventPriority, () => {
       root.render(<App text="Hi" className="hi" />);
     });
 

packages/react-dom/src/__tests__/ReactDOMServerSelectiveHydration-test.internal.js

@@ -19,10 +19,7 @@ let Scheduler;
 let Suspense;
 let act;
 
-// Copied from ReactFiberLanes. Don't do this!
-// This is hard coded directly to avoid needing to import, and
-// we'll remove this as we replace runWithPriority with React APIs.
-export const IdleLanePriority = 2;
+let IdleEventPriority;
 
 function dispatchMouseHoverEvent(to, from) {
   if (!to) {
@@ -101,7 +98,7 @@ function dispatchClickEvent(target) {
 // and there's no native DOM event that maps to idle priority, so this is a
 // temporary workaround. Need something like ReactDOM.unstable_IdleUpdates.
 function TODO_scheduleIdleDOMSchedulerTask(fn) {
-  ReactDOM.unstable_runWithPriority(IdleLanePriority, () => {
+  ReactDOM.unstable_runWithPriority(IdleEventPriority, () => {
     const prevEvent = window.event;
     window.event = {type: 'message'};
     try {
@@ -125,6 +122,8 @@ describe('ReactDOMServerSelectiveHydration', () => {
     act = ReactTestUtils.unstable_concurrentAct;
     Scheduler = require('scheduler');
     Suspense = React.Suspense;
+
+    IdleEventPriority = require('react-reconciler/constants').IdleEventPriority;
   });
 
   // @gate experimental

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

@@ -35,9 +35,11 @@ import {
   attemptDiscreteHydration,
   attemptContinuousHydration,
   attemptHydrationAtCurrentPriority,
-  runWithPriority,
-  getCurrentUpdateLanePriority,
 } from 'react-reconciler/src/ReactFiberReconciler';
+import {
+  runWithPriority,
+  getCurrentUpdatePriority,
+} from 'react-reconciler/src/ReactEventPriorities';
 import {createPortal as createPortalImpl} from 'react-reconciler/src/ReactPortal';
 import {canUseDOM} from 'shared/ExecutionEnvironment';
 import ReactVersion from 'shared/ReactVersion';
@@ -74,7 +76,7 @@ setAttemptSynchronousHydration(attemptSynchronousHydration);
 setAttemptDiscreteHydration(attemptDiscreteHydration);
 setAttemptContinuousHydration(attemptContinuousHydration);
 setAttemptHydrationAtCurrentPriority(attemptHydrationAtCurrentPriority);
-setGetCurrentUpdatePriority(getCurrentUpdateLanePriority);
+setGetCurrentUpdatePriority(getCurrentUpdatePriority);
 setAttemptHydrationAtPriority(runWithPriority);
 
 let didWarnAboutUnstableCreatePortal = false;

packages/react-dom/src/events/ReactDOMEventListener.js

@@ -44,16 +44,6 @@ import {
   discreteUpdates,
 } from './ReactDOMUpdateBatching';
 
-import {
-  InputContinuousLanePriority as InputContinuousLanePriority_old,
-  getCurrentUpdateLanePriority as getCurrentUpdateLanePriority_old,
-  setCurrentUpdateLanePriority as setCurrentUpdateLanePriority_old,
-} from 'react-reconciler/src/ReactFiberLane.old';
-import {
-  InputContinuousLanePriority as InputContinuousLanePriority_new,
-  getCurrentUpdateLanePriority as getCurrentUpdateLanePriority_new,
-  setCurrentUpdateLanePriority as setCurrentUpdateLanePriority_new,
-} from 'react-reconciler/src/ReactFiberLane.new';
 import {getCurrentPriorityLevel as getCurrentPriorityLevel_old} from 'react-reconciler/src/SchedulerWithReactIntegration.old';
 import {
   getCurrentPriorityLevel as getCurrentPriorityLevel_new,
@@ -68,19 +58,10 @@ import {
   ContinuousEventPriority,
   DefaultEventPriority,
   IdleEventPriority,
+  getCurrentUpdatePriority,
+  setCurrentUpdatePriority,
 } from 'react-reconciler/src/ReactEventPriorities';
 
-// TODO: These should use the opaque EventPriority type instead of LanePriority.
-// Then internally we can use a Lane.
-const InputContinuousLanePriority = enableNewReconciler
-  ? InputContinuousLanePriority_new
-  : InputContinuousLanePriority_old;
-const getCurrentUpdateLanePriority = enableNewReconciler
-  ? getCurrentUpdateLanePriority_new
-  : getCurrentUpdateLanePriority_old;
-const setCurrentUpdateLanePriority = enableNewReconciler
-  ? setCurrentUpdateLanePriority_new
-  : setCurrentUpdateLanePriority_old;
 const getCurrentPriorityLevel = enableNewReconciler
   ? getCurrentPriorityLevel_new
   : getCurrentPriorityLevel_old;
@@ -167,12 +148,12 @@ function dispatchContinuousEvent(
   container,
   nativeEvent,
 ) {
-  const previousPriority = getCurrentUpdateLanePriority();
+  const previousPriority = getCurrentUpdatePriority();
   try {
-    setCurrentUpdateLanePriority(InputContinuousLanePriority);
+    setCurrentUpdatePriority(ContinuousEventPriority);
     dispatchEvent(domEventName, eventSystemFlags, container, nativeEvent);
   } finally {
-    setCurrentUpdateLanePriority(previousPriority);
+    setCurrentUpdatePriority(previousPriority);
   }
 }
 

packages/react-dom/src/events/ReactDOMEventReplaying.js

@@ -12,7 +12,7 @@ import type {Container, SuspenseInstance} from '../client/ReactDOMHostConfig';
 import type {DOMEventName} from '../events/DOMEventNames';
 import type {EventSystemFlags} from './EventSystemFlags';
 import type {FiberRoot} from 'react-reconciler/src/ReactInternalTypes';
-import type {LanePriority} from 'react-reconciler/src/ReactFiberLane.old';
+import type {EventPriority} from 'react-reconciler/src/ReactEventPriorities';
 
 import {enableSelectiveHydration} from 'shared/ReactFeatureFlags';
 import {
@@ -30,6 +30,7 @@ import {
   getClosestInstanceFromNode,
 } from '../client/ReactDOMComponentTree';
 import {HostRoot, SuspenseComponent} from 'react-reconciler/src/ReactWorkTags';
+import {isHigherEventPriority} from 'react-reconciler/src/ReactEventPriorities';
 
 let attemptSynchronousHydration: (fiber: Object) => void;
 
@@ -57,16 +58,16 @@ export function setAttemptHydrationAtCurrentPriority(
   attemptHydrationAtCurrentPriority = fn;
 }
 
-let getCurrentUpdatePriority: () => LanePriority;
+let getCurrentUpdatePriority: () => EventPriority;
 
-export function setGetCurrentUpdatePriority(fn: () => LanePriority) {
+export function setGetCurrentUpdatePriority(fn: () => EventPriority) {
   getCurrentUpdatePriority = fn;
 }
 
-let attemptHydrationAtPriority: <T>(priority: LanePriority, fn: () => T) => T;
+let attemptHydrationAtPriority: <T>(priority: EventPriority, fn: () => T) => T;
 
 export function setAttemptHydrationAtPriority(
-  fn: <T>(priority: LanePriority, fn: () => T) => T,
+  fn: <T>(priority: EventPriority, fn: () => T) => T,
 ) {
   attemptHydrationAtPriority = fn;
 }
@@ -109,7 +110,7 @@ const queuedPointerCaptures: Map<number, QueuedReplayableEvent> = new Map();
 type QueuedHydrationTarget = {|
   blockedOn: null | Container | SuspenseInstance,
   target: Node,
-  lanePriority: LanePriority,
+  priority: EventPriority,
 |};
 const queuedExplicitHydrationTargets: Array<QueuedHydrationTarget> = [];
 
@@ -390,7 +391,7 @@ function attemptExplicitHydrationTarget(
           // We're blocked on hydrating this boundary.
           // Increase its priority.
           queuedTarget.blockedOn = instance;
-          attemptHydrationAtPriority(queuedTarget.lanePriority, () => {
+          attemptHydrationAtPriority(queuedTarget.priority, () => {
             attemptHydrationAtCurrentPriority(nearestMounted);
           });
 
@@ -412,16 +413,23 @@ function attemptExplicitHydrationTarget(
 
 export function queueExplicitHydrationTarget(target: Node): void {
   if (enableSelectiveHydration) {
-    const updateLanePriority = getCurrentUpdatePriority();
+    // TODO: This will read the priority if it's dispatched by the React
+    // event system but not native events. Should read window.event.type, like
+    // we do for updates (getCurrentEventPriority).
+    const updatePriority = getCurrentUpdatePriority();
     const queuedTarget: QueuedHydrationTarget = {
       blockedOn: null,
       target: target,
-      lanePriority: updateLanePriority,
+      priority: updatePriority,
     };
     let i = 0;
     for (; i < queuedExplicitHydrationTargets.length; i++) {
+      // Stop once we hit the first target with lower priority than
       if (
-        updateLanePriority <= queuedExplicitHydrationTargets[i].lanePriority
+        !isHigherEventPriority(
+          updatePriority,
+          queuedExplicitHydrationTargets[i].priority,
+        )
       ) {
         break;
       }

packages/react-reconciler/src/ReactEventPriorities.js

@@ -14,24 +14,61 @@ import {
   ContinuousEventPriority as ContinuousEventPriority_old,
   DefaultEventPriority as DefaultEventPriority_old,
   IdleEventPriority as IdleEventPriority_old,
+  getCurrentUpdatePriority as getCurrentUpdatePriority_old,
+  setCurrentUpdatePriority as setCurrentUpdatePriority_old,
+  runWithPriority as runWithPriority_old,
+  isHigherEventPriority as isHigherEventPriority_old,
 } from './ReactEventPriorities.old';
 
 import {
   DiscreteEventPriority as DiscreteEventPriority_new,
   ContinuousEventPriority as ContinuousEventPriority_new,
   DefaultEventPriority as DefaultEventPriority_new,
   IdleEventPriority as IdleEventPriority_new,
+  getCurrentUpdatePriority as getCurrentUpdatePriority_new,
+  setCurrentUpdatePriority as setCurrentUpdatePriority_new,
+  runWithPriority as runWithPriority_new,
+  isHigherEventPriority as isHigherEventPriority_new,
 } from './ReactEventPriorities.new';
 
-export const DiscreteEventPriority = enableNewReconciler
-  ? DiscreteEventPriority_new
-  : DiscreteEventPriority_old;
-export const ContinuousEventPriority = enableNewReconciler
-  ? ContinuousEventPriority_new
-  : ContinuousEventPriority_old;
-export const DefaultEventPriority = enableNewReconciler
-  ? DefaultEventPriority_new
-  : DefaultEventPriority_old;
-export const IdleEventPriority = enableNewReconciler
-  ? IdleEventPriority_new
-  : IdleEventPriority_old;
+export opaque type EventPriority = number;
+
+export const DiscreteEventPriority: EventPriority = enableNewReconciler
+  ? (DiscreteEventPriority_new: any)
+  : (DiscreteEventPriority_old: any);
+export const ContinuousEventPriority: EventPriority = enableNewReconciler
+  ? (ContinuousEventPriority_new: any)
+  : (ContinuousEventPriority_old: any);
+export const DefaultEventPriority: EventPriority = enableNewReconciler
+  ? (DefaultEventPriority_new: any)
+  : (DefaultEventPriority_old: any);
+export const IdleEventPriority: EventPriority = enableNewReconciler
+  ? (IdleEventPriority_new: any)
+  : (IdleEventPriority_old: any);
+
+export function runWithPriority<T>(priority: EventPriority, fn: () => T): T {
+  return enableNewReconciler
+    ? runWithPriority_new((priority: any), fn)
+    : runWithPriority_old((priority: any), fn);
+}
+
+export function getCurrentUpdatePriority(): EventPriority {
+  return enableNewReconciler
+    ? (getCurrentUpdatePriority_new(): any)
+    : (getCurrentUpdatePriority_old(): any);
+}
+
+export function setCurrentUpdatePriority(priority: EventPriority) {
+  return enableNewReconciler
+    ? setCurrentUpdatePriority_new((priority: any))
+    : setCurrentUpdatePriority_old((priority: any));
+}
+
+export function isHigherEventPriority(
+  a: EventPriority,
+  b: EventPriority,
+): boolean {
+  return enableNewReconciler
+    ? isHigherEventPriority_new((a: any), (b: any))
+    : isHigherEventPriority_old((a: any), (b: any));
+}

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

@@ -7,9 +7,76 @@
  * @flow
  */
 
-export {
-  SyncLane as DiscreteEventPriority,
-  InputContinuousLane as ContinuousEventPriority,
-  DefaultLane as DefaultEventPriority,
-  IdleLane as IdleEventPriority,
+import type {Lane, Lanes} from './ReactFiberLane.new';
+
+import {
+  NoLane,
+  SyncLane,
+  InputContinuousLane,
+  DefaultLane,
+  IdleLane,
+  getHighestPriorityLane,
+  includesNonIdleWork,
 } from './ReactFiberLane.new';
+
+export opaque type EventPriority = Lane;
+
+export const DiscreteEventPriority: EventPriority = SyncLane;
+export const ContinuousEventPriority: EventPriority = InputContinuousLane;
+export const DefaultEventPriority: EventPriority = DefaultLane;
+export const IdleEventPriority: EventPriority = IdleLane;
+
+let currentUpdatePriority: EventPriority = NoLane;
+
+export function getCurrentUpdatePriority(): EventPriority {
+  return currentUpdatePriority;
+}
+
+export function setCurrentUpdatePriority(newPriority: EventPriority) {
+  currentUpdatePriority = newPriority;
+}
+
+export function runWithPriority<T>(priority: EventPriority, fn: () => T): T {
+  const previousPriority = currentUpdatePriority;
+  try {
+    currentUpdatePriority = priority;
+    return fn();
+  } finally {
+    currentUpdatePriority = previousPriority;
+  }
+}
+
+export function higherEventPriority(
+  a: EventPriority,
+  b: EventPriority,
+): EventPriority {
+  return a !== 0 && a < b ? a : b;
+}
+
+export function lowerEventPriority(
+  a: EventPriority,
+  b: EventPriority,
+): EventPriority {
+  return a === 0 || a > b ? a : b;
+}
+
+export function isHigherEventPriority(
+  a: EventPriority,
+  b: EventPriority,
+): boolean {
+  return a !== 0 && a < b;
+}
+
+export function lanesToEventPriority(lanes: Lanes): EventPriority {
+  const lane = getHighestPriorityLane(lanes);
+  if (!isHigherEventPriority(DiscreteEventPriority, lane)) {
+    return DiscreteEventPriority;
+  }
+  if (!isHigherEventPriority(ContinuousEventPriority, lane)) {
+    return ContinuousEventPriority;
+  }
+  if (includesNonIdleWork(lane)) {
+    return DefaultEventPriority;
+  }
+  return IdleEventPriority;
+}