Fix infinite loop if unmemoized val passed to uDV

The current implementation of useDeferredValue will spawn a new render any time the input value is different from the previous one. So if you pass an unmemoized value (like an inline object), it will never stop spawning new renders. The fix is to only defer during an urgent render. If we're already inside a transition, retry, offscreen, or other non-urgen render, then we can use the latest value.
facebook · Apr 11, 2022 · 422d102 · 422d102
1 parent 0568c0f
commit 422d102
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Showing 3 changed files with 348 additions and 64 deletions.
diff --git a/packages/react-reconciler/src/ReactFiberHooks.new.js b/packages/react-reconciler/src/ReactFiberHooks.new.js
@@ -47,6 +47,8 @@ import {
   NoLanes,
   isSubsetOfLanes,
   includesBlockingLane,
+  includesOnlyNonUrgentLanes,
+  claimNextTransitionLane,
   mergeLanes,
   removeLanes,
   intersectLanes,
@@ -1929,45 +1931,73 @@ function updateMemo<T>(
 }
 
 function mountDeferredValue<T>(value: T): T {
-  const [prevValue, setValue] = mountState(value);
-  mountEffect(() => {
-    const prevTransition = ReactCurrentBatchConfig.transition;
-    ReactCurrentBatchConfig.transition = {};
-    try {
-      setValue(value);
-    } finally {
-      ReactCurrentBatchConfig.transition = prevTransition;
-    }
-  }, [value]);
-  return prevValue;
+  const hook = mountWorkInProgressHook();
+  hook.memoizedState = value;
+  return value;
 }
 
 function updateDeferredValue<T>(value: T): T {
-  const [prevValue, setValue] = updateState(value);
-  updateEffect(() => {
-    const prevTransition = ReactCurrentBatchConfig.transition;
-    ReactCurrentBatchConfig.transition = {};
-    try {
-      setValue(value);
-    } finally {
-      ReactCurrentBatchConfig.transition = prevTransition;
-    }
-  }, [value]);
-  return prevValue;
+  const hook = updateWorkInProgressHook();
+  const resolvedCurrentHook: Hook = (currentHook: any);
+  const prevValue: T = resolvedCurrentHook.memoizedState;
+  return updateDeferredValueImpl(hook, prevValue, value);
 }
 
 function rerenderDeferredValue<T>(value: T): T {
-  const [prevValue, setValue] = rerenderState(value);
-  updateEffect(() => {
-    const prevTransition = ReactCurrentBatchConfig.transition;
-    ReactCurrentBatchConfig.transition = {};
-    try {
-      setValue(value);
-    } finally {
-      ReactCurrentBatchConfig.transition = prevTransition;
+  const hook = updateWorkInProgressHook();
+  if (currentHook === null) {
+    // This is a rerender during a mount.
+    hook.memoizedState = value;
+    return value;
+  } else {
+    // This is a rerender during an update.
+    const prevValue: T = currentHook.memoizedState;
+    return updateDeferredValueImpl(hook, prevValue, value);
+  }
+}
+
+function updateDeferredValueImpl<T>(hook: Hook, prevValue: T, value: T): T {
+  const shouldDeferValue = !includesOnlyNonUrgentLanes(renderLanes);
+  if (shouldDeferValue) {
+    // This is an urgent update. If the value has changed, keep using the
+    // previous value and spawn a deferred render to update it later.
+
+    if (!is(value, prevValue)) {
+      // Schedule a deferred render
+      const deferredLane = claimNextTransitionLane();
+      currentlyRenderingFiber.lanes = mergeLanes(
+        currentlyRenderingFiber.lanes,
+        deferredLane,
+      );
+      markSkippedUpdateLanes(deferredLane);
+
+      // Set this to true to indicate that the rendered value is inconsistent
+      // from the latest value. The name "baseState" doesn't really match how we
+      // use it because we're reusing a state hook field instead of creating a
+      // new one.
+      hook.baseState = true;
     }
-  }, [value]);
-  return prevValue;
+
+    // Reuse the previous value
+    return prevValue;
+  } else {
+    // This is not an urgent update, so we can use the latest value regardless
+    // of what it is. No need to defer it.
+
+    // However, if we're currently inside a spawned render, then we need to mark
+    // this as an update to prevent the fiber from bailing out.
+    //
+    // `baseState` is true when the current value is different from the rendered
+    // value. The name doesn't really match how we use it because we're reusing
+    // a state hook field instead of creating a new one.
+    if (hook.baseState) {
+      // Flip this back to false.
+      hook.baseState = false;
+      markWorkInProgressReceivedUpdate();
+    }
+
+    return value;
+  }
 }
 
 function startTransition(setPending, callback, options) {

diff --git a/packages/react-reconciler/src/ReactFiberHooks.old.js b/packages/react-reconciler/src/ReactFiberHooks.old.js
@@ -47,6 +47,8 @@ import {
   NoLanes,
   isSubsetOfLanes,
   includesBlockingLane,
+  includesOnlyNonUrgentLanes,
+  claimNextTransitionLane,
   mergeLanes,
   removeLanes,
   intersectLanes,
@@ -1929,45 +1931,73 @@ function updateMemo<T>(
 }
 
 function mountDeferredValue<T>(value: T): T {
-  const [prevValue, setValue] = mountState(value);
-  mountEffect(() => {
-    const prevTransition = ReactCurrentBatchConfig.transition;
-    ReactCurrentBatchConfig.transition = {};
-    try {
-      setValue(value);
-    } finally {
-      ReactCurrentBatchConfig.transition = prevTransition;
-    }
-  }, [value]);
-  return prevValue;
+  const hook = mountWorkInProgressHook();
+  hook.memoizedState = value;
+  return value;
 }
 
 function updateDeferredValue<T>(value: T): T {
-  const [prevValue, setValue] = updateState(value);
-  updateEffect(() => {
-    const prevTransition = ReactCurrentBatchConfig.transition;
-    ReactCurrentBatchConfig.transition = {};
-    try {
-      setValue(value);
-    } finally {
-      ReactCurrentBatchConfig.transition = prevTransition;
-    }
-  }, [value]);
-  return prevValue;
+  const hook = updateWorkInProgressHook();
+  const resolvedCurrentHook: Hook = (currentHook: any);
+  const prevValue: T = resolvedCurrentHook.memoizedState;
+  return updateDeferredValueImpl(hook, prevValue, value);
 }
 
 function rerenderDeferredValue<T>(value: T): T {
-  const [prevValue, setValue] = rerenderState(value);
-  updateEffect(() => {
-    const prevTransition = ReactCurrentBatchConfig.transition;
-    ReactCurrentBatchConfig.transition = {};
-    try {
-      setValue(value);
-    } finally {
-      ReactCurrentBatchConfig.transition = prevTransition;
+  const hook = updateWorkInProgressHook();
+  if (currentHook === null) {
+    // This is a rerender during a mount.
+    hook.memoizedState = value;
+    return value;
+  } else {
+    // This is a rerender during an update.
+    const prevValue: T = currentHook.memoizedState;
+    return updateDeferredValueImpl(hook, prevValue, value);
+  }
+}
+
+function updateDeferredValueImpl<T>(hook: Hook, prevValue: T, value: T): T {
+  const shouldDeferValue = !includesOnlyNonUrgentLanes(renderLanes);
+  if (shouldDeferValue) {
+    // This is an urgent update. If the value has changed, keep using the
+    // previous value and spawn a deferred render to update it later.
+
+    if (!is(value, prevValue)) {
+      // Schedule a deferred render
+      const deferredLane = claimNextTransitionLane();
+      currentlyRenderingFiber.lanes = mergeLanes(
+        currentlyRenderingFiber.lanes,
+        deferredLane,
+      );
+      markSkippedUpdateLanes(deferredLane);
+
+      // Set this to true to indicate that the rendered value is inconsistent
+      // from the latest value. The name "baseState" doesn't really match how we
+      // use it because we're reusing a state hook field instead of creating a
+      // new one.
+      hook.baseState = true;
     }
-  }, [value]);
-  return prevValue;
+
+    // Reuse the previous value
+    return prevValue;
+  } else {
+    // This is not an urgent update, so we can use the latest value regardless
+    // of what it is. No need to defer it.
+
+    // However, if we're currently inside a spawned render, then we need to mark
+    // this as an update to prevent the fiber from bailing out.
+    //
+    // `baseState` is true when the current value is different from the rendered
+    // value. The name doesn't really match how we use it because we're reusing
+    // a state hook field instead of creating a new one.
+    if (hook.baseState) {
+      // Flip this back to false.
+      hook.baseState = false;
+      markWorkInProgressReceivedUpdate();
+    }
+
+    return value;
+  }
 }
 
 function startTransition(setPending, callback, options) {