VirtualizedList up-to-date state: Thread props to _createViewToken()

NickGerleman · facebook-github-bot · commit a53512fda4d6 · 2022-08-02T01:30:21.000-07:00
Summary: This diff is part of an overall stack, meant to fix incorrect usage of `setState()` in `VirtualizedList`, which triggers new invariant checks added in `VirtualizedList_EXPERIMENTAL`. See the stack summary below for more information on the broader change. ## Diff Summary `_createViewToken()` is called during state changes. Use explicit props passed in. ## Stack Summary `VirtualizedList`'s component state is a set of cells to render. This state is set via the `setState()` class component API. The main "tick" function `VirtualizedList._updateCellsToRender()` calculates this new state using a combination of the current component state, and instance-local state like maps, measurement caches, etc. From: https://reactjs.org/docs/state-and-lifecycle.html#state-updates-may-be-asynchronous --- > React may batch multiple setState() calls into a single update for performance. Because this.props and this.state may be updated asynchronously, you should not rely on their values for calculating the next state. For example, this code may fail to update the counter: ``` // Wrong this.setState({ counter: this.state.counter + this.props.increment, }); ``` > To fix it, use a second form of setState() that accepts a function rather than an object. That function will receive the previous state as the first argument, and the props at the time the update is applied as the second argument: ``` // Correct this.setState((state, props) => ({ counter: state.counter + props.increment })); ``` --- `_updateCellsToRender()` transitively calls many functions which will read directly from `this.props` or `this.state` instead of the value passed by the state updater. This intermittently fires invariant violations, when there is a mismatch. This diff migrates all usages of `props` and `state` during state update to the values provied in `setState()`. To prevent future mismatch, and to provide better clarity on when it is safe to use `this.props`, `this.state`, I overrode `setState` to fire an invariant violation if it is accessed when it is unsafe to: {F756963772} Changelog: [Internal][Fixed] - Thread props to _createViewToken() Reviewed By: genkikondo Differential Revision: D38294339 fbshipit-source-id: dc215e267f126a3789742c14c35479f509822710
diff --git a/Libraries/Lists/ViewabilityHelper.js b/Libraries/Lists/ViewabilityHelper.js
@@ -189,7 +189,11 @@ class ViewabilityHelper {
       offset: number,
       ...
     },
-    createViewToken: (index: number, isViewable: boolean) => ViewToken,
+    createViewToken: (
+      index: number,
+      isViewable: boolean,
+      props: FrameMetricProps,
+    ) => ViewToken,
     onViewableItemsChanged: ({
       viewableItems: Array<ViewToken>,
       changed: Array<ViewToken>,
@@ -236,6 +240,7 @@ class ViewabilityHelper {
          * see the error delete this comment and run Flow. */
         this._timers.delete(handle);
         this._onUpdateSync(
+          props,
           viewableIndices,
           onViewableItemsChanged,
           createViewToken,
@@ -247,6 +252,7 @@ class ViewabilityHelper {
       this._timers.add(handle);
     } else {
       this._onUpdateSync(
+        props,
         viewableIndices,
         onViewableItemsChanged,
         createViewToken,
@@ -269,13 +275,18 @@ class ViewabilityHelper {
   }
 
   _onUpdateSync(
+    props: FrameMetricProps,
     viewableIndicesToCheck: Array<number>,
     onViewableItemsChanged: ({
       changed: Array<ViewToken>,
       viewableItems: Array<ViewToken>,
       ...
     }) => void,
-    createViewToken: (index: number, isViewable: boolean) => ViewToken,
+    createViewToken: (
+      index: number,
+      isViewable: boolean,
+      props: FrameMetricProps,
+    ) => ViewToken,
   ) {
     // Filter out indices that have gone out of view since this call was scheduled.
     viewableIndicesToCheck = viewableIndicesToCheck.filter(ii =>
@@ -284,7 +295,7 @@ class ViewabilityHelper {
     const prevItems = this._viewableItems;
     const nextItems = new Map(
       viewableIndicesToCheck.map(ii => {
-        const viewable = createViewToken(ii, true);
+        const viewable = createViewToken(ii, true, props);
         return [viewable.key, viewable];
       }),
     );
diff --git a/Libraries/Lists/VirtualizedList_EXPERIMENTAL.js b/Libraries/Lists/VirtualizedList_EXPERIMENTAL.js
@@ -1754,13 +1754,17 @@ class VirtualizedList extends React.PureComponent<Props, State> {
     });
   };
 
-  _createViewToken = (index: number, isViewable: boolean) => {
-    const {data, getItem} = this.props;
+  _createViewToken = (
+    index: number,
+    isViewable: boolean,
+    props: FrameMetricProps,
+  ) => {
+    const {data, getItem} = props;
     const item = getItem(data, index);
     return {
       index,
       item,
-      key: this._keyExtractor(item, index, this.props),
+      key: this._keyExtractor(item, index, props),
       isViewable,
     };
   };
