Make opaque EventPriority type a Lane internally (#21065)

Instead of LanePriority, we can use a Lane and skip the extra
conversion. Eventually I want to get rid of LanePriority completely.

Author: acdlite

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

@@ -8,13 +8,9 @@
  */
 
 import type {AnyNativeEvent} from '../events/PluginModuleType';
-import type {
-  FiberRoot,
-  ReactPriorityLevel,
-} from 'react-reconciler/src/ReactInternalTypes';
+import type {FiberRoot} from 'react-reconciler/src/ReactInternalTypes';
 import type {Container, SuspenseInstance} from '../client/ReactDOMHostConfig';
 import type {DOMEventName} from '../events/DOMEventNames';
-import type {LanePriority} from 'react-reconciler/src/ReactFiberLane.new';
 
 import {
   isReplayableDiscreteEvent,
@@ -74,6 +70,8 @@ import {
   IdleEventPriority,
 } 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;
@@ -87,25 +85,6 @@ const getCurrentPriorityLevel = enableNewReconciler
   ? getCurrentPriorityLevel_new
   : getCurrentPriorityLevel_old;
 
-function schedulerPriorityToLanePriority(
-  schedulerPriorityLevel: ReactPriorityLevel,
-): LanePriority {
-  switch (schedulerPriorityLevel) {
-    case ImmediateSchedulerPriority:
-      return DiscreteEventPriority;
-    case UserBlockingSchedulerPriority:
-      return ContinuousEventPriority;
-    case NormalSchedulerPriority:
-    case LowSchedulerPriority:
-      // TODO: Handle LowSchedulerPriority, somehow. Maybe the same lane as hydration.
-      return DefaultEventPriority;
-    case IdleSchedulerPriority:
-      return IdleEventPriority;
-    default:
-      return DefaultEventPriority;
-  }
-}
-
 // TODO: can we stop exporting these?
 export let _enabled = true;
 
@@ -431,7 +410,20 @@ export function getEventPriority(domEventName: DOMEventName): * {
       // Eventually this mechanism will be replaced by a check
       // of the current priority on the native scheduler.
       const schedulerPriority = getCurrentPriorityLevel();
-      return schedulerPriorityToLanePriority(schedulerPriority);
+      switch (schedulerPriority) {
+        case ImmediateSchedulerPriority:
+          return DiscreteEventPriority;
+        case UserBlockingSchedulerPriority:
+          return ContinuousEventPriority;
+        case NormalSchedulerPriority:
+        case LowSchedulerPriority:
+          // TODO: Handle LowSchedulerPriority, somehow. Maybe the same lane as hydration.
+          return DefaultEventPriority;
+        case IdleSchedulerPriority:
+          return IdleEventPriority;
+        default:
+          return DefaultEventPriority;
+      }
     }
     default:
       return DefaultEventPriority;

packages/react-noop-renderer/src/createReactNoop.js

@@ -23,6 +23,7 @@ import * as Scheduler from 'scheduler/unstable_mock';
 import {REACT_FRAGMENT_TYPE, REACT_ELEMENT_TYPE} from 'shared/ReactSymbols';
 import {
   DefaultEventPriority,
+  IdleEventPriority,
   ConcurrentRoot,
   LegacyRoot,
 } from 'react-reconciler/constants';
@@ -909,7 +910,7 @@ function createReactNoop(reconciler: Function, useMutation: boolean) {
 
     idleUpdates<T>(fn: () => T): T {
       const prevEventPriority = currentEventPriority;
-      currentEventPriority = NoopRenderer.IdleEventPriority;
+      currentEventPriority = IdleEventPriority;
       try {
         fn();
       } finally {

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

@@ -8,8 +8,8 @@
  */
 
 export {
-  SyncLanePriority as DiscreteEventPriority,
-  InputContinuousLanePriority as ContinuousEventPriority,
-  DefaultLanePriority as DefaultEventPriority,
-  IdleLanePriority as IdleEventPriority,
+  SyncLane as DiscreteEventPriority,
+  InputContinuousLane as ContinuousEventPriority,
+  DefaultLane as DefaultEventPriority,
+  IdleLane as IdleEventPriority,
 } from './ReactFiberLane.new';

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

@@ -8,8 +8,8 @@
  */
 
 export {
-  SyncLanePriority as DiscreteEventPriority,
-  InputContinuousLanePriority as ContinuousEventPriority,
-  DefaultLanePriority as DefaultEventPriority,
-  IdleLanePriority as IdleEventPriority,
+  SyncLane as DiscreteEventPriority,
+  InputContinuousLane as ContinuousEventPriority,
+  DefaultLane as DefaultEventPriority,
+  IdleLane as IdleEventPriority,
 } from './ReactFiberLane.old';

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

@@ -118,7 +118,7 @@ export const SelectiveHydrationLane: Lane = /*          */ 0b0001000000000000000
 const NonIdleLanes = /*                                 */ 0b0001111111111111111111111111111;
 
 export const IdleHydrationLane: Lane = /*               */ 0b0010000000000000000000000000000;
-const IdleLane: Lanes = /*                              */ 0b0100000000000000000000000000000;
+export const IdleLane: Lanes = /*                       */ 0b0100000000000000000000000000000;
 
 export const OffscreenLane: Lane = /*                   */ 0b1000000000000000000000000000000;
 

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

@@ -118,7 +118,7 @@ export const SelectiveHydrationLane: Lane = /*          */ 0b0001000000000000000
 const NonIdleLanes = /*                                 */ 0b0001111111111111111111111111111;
 
 export const IdleHydrationLane: Lane = /*               */ 0b0010000000000000000000000000000;
-const IdleLane: Lanes = /*                              */ 0b0100000000000000000000000000000;
+export const IdleLane: Lanes = /*                       */ 0b0100000000000000000000000000000;
 
 export const OffscreenLane: Lane = /*                   */ 0b1000000000000000000000000000000;
 

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

@@ -93,16 +93,6 @@ import {
 } from './ReactFiberHotReloading.new';
 import {markRenderScheduled} from './SchedulingProfiler';
 
-// Ideally host configs would import these constants from the reconciler
-// entry point, but we can't do this because of a circular dependency.
-// They are used by third-party renderers so they need to stay up to date.
-export {
-  SyncLanePriority as DiscreteEventPriority,
-  InputContinuousLanePriority as ContinuousEventPriority,
-  DefaultLanePriority as DefaultEventPriority,
-  IdleLanePriority as IdleEventPriority,
-} from './ReactFiberLane.new';
-
 export {registerMutableSourceForHydration} from './ReactMutableSource.new';
 export {createPortal} from './ReactPortal';
 export {

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

@@ -93,16 +93,6 @@ import {
 } from './ReactFiberHotReloading.old';
 import {markRenderScheduled} from './SchedulingProfiler';
 
-// Ideally host configs would import these constants from the reconciler
-// entry point, but we can't do this because of a circular dependency.
-// They are used by third-party renderers so they need to stay up to date.
-export {
-  SyncLanePriority as DiscreteEventPriority,
-  InputContinuousLanePriority as ContinuousEventPriority,
-  DefaultLanePriority as DefaultEventPriority,
-  IdleLanePriority as IdleEventPriority,
-} from './ReactFiberLane.old';
-
 export {registerMutableSourceForHydration} from './ReactMutableSource.old';
 export {createPortal} from './ReactPortal';
 export {

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

@@ -436,8 +436,11 @@ export function requestUpdateLane(fiber: Fiber): Lane {
 
   // This update originated outside React. Ask the host environement for an
   // appropriate priority, based on the type of event.
-  const eventLanePriority = getCurrentEventPriority();
-  return findUpdateLane(eventLanePriority);
+  //
+  // The opaque type returned by the host config is internally a lane, so we can
+  // use that directly.
+  const eventLane = getCurrentEventPriority();
+  return eventLane;
 }
 
 function requestRetryLane(fiber: Fiber) {

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

@@ -436,8 +436,11 @@ export function requestUpdateLane(fiber: Fiber): Lane {
 
   // This update originated outside React. Ask the host environement for an
   // appropriate priority, based on the type of event.
-  const eventLanePriority = getCurrentEventPriority();
-  return findUpdateLane(eventLanePriority);
+  //
+  // The opaque type returned by the host config is internally a lane, so we can
+  // use that directly.
+  const eventLane = getCurrentEventPriority();
+  return eventLane;
 }
 
 function requestRetryLane(fiber: Fiber) {