Convert state providers to use use-context-selector

This user-land library improves performance by removing unnecessary
re-renders to components which use global contexts. By selecting the
state that the components use from the contexts, they'll limit their
re-rendering to only when that state changes.

See reactjs/rfcs#119 for more relevant
information about the performance issues with the context API.

Author: samholmes

jestSetup.js

@@ -233,3 +233,30 @@ jest.mock('react-native-reanimated', () => require('react-native-reanimated/mock
 for (const log in global.console) {
   global.console[log] = jest.fn()
 }
+
+jest.mock('use-context-selector', () => {
+  const contextValues = new Map()
+  return {
+    createContext: defaultValue => {
+      // Create new provider
+      const Provider = (props, context) => {
+        contextValues.set(Provider, props.value)
+        return props.children
+      }
+      // Get the value for the provider:
+      const currentValue = contextValues.get(Provider)
+      // Set it's default value:
+      contextValues.set(Provider, currentValue ?? defaultValue)
+      // Return provider
+      return {
+        Provider: Provider,
+        displayName: 'test'
+      }
+    },
+    useContextSelector: (context, selector) => {
+      const currentValue = contextValues.get(context.Provider)
+      const selected = selector(currentValue)
+      return selected
+    }
+  }
+})

package.json

@@ -206,10 +206,12 @@
     "redux-thunk": "^2.3.0",
     "rn-id-blurview": "^1.2.1",
     "rn-qr-generator": "^1.3.1",
+    "scheduler": "^0.23.0",
     "sha.js": "^2.4.11",
     "sprintf-js": "^1.1.1",
     "url": "^0.11.0",
     "url-parse": "^1.5.2",
+    "use-context-selector": "^1.4.1",
     "yaob": "^0.3.12",
     "yavent": "^0.1.3"
   },

src/components/common/SceneWrapper.tsx

@@ -120,7 +120,7 @@ export function SceneWrapper(props: SceneWrapperProps): JSX.Element {
   const activeUsername = useSelector(state => state.core.account.username)
   const isLightAccount = accountId != null && activeUsername == null
 
-  const { footerHeight = 0 } = useSceneFooterState()
+  const footerHeight = useSceneFooterState(({ footerHeight = 0 }) => footerHeight)
 
   const navigation = useNavigation<NavigationBase>()
   const theme = useTheme()
@@ -138,15 +138,15 @@ export function SceneWrapper(props: SceneWrapperProps): JSX.Element {
     [frame.height, frame.width]
   )
 
-  const notificationHeight = theme.rem(4)
-  const headerBarHeight = getDefaultHeaderHeight(frame, false, 0)
-
   // If the scene has scroll, this will be required for tabs and/or header animation
   const handleScroll = useSceneScrollHandler(scroll && (hasTabs || hasHeader))
 
-  const { renderFooter } = useSceneFooterRenderState()
+  const renderFooter = useSceneFooterRenderState(({ renderFooter }) => renderFooter)
 
   const renderScene = (keyboardAnimation: Animated.Value | undefined, trackerValue: number): JSX.Element => {
+    const notificationHeight = theme.rem(4)
+    const headerBarHeight = getDefaultHeaderHeight(frame, false, 0)
+
     // If function children, the caller handles the insets and overscroll
     const isFuncChildren = typeof children === 'function'
 

src/components/navigation/HeaderBackground.tsx

@@ -13,7 +13,7 @@ import { BlurBackground } from '../ui4/BlurBackground'
 export const HeaderBackground = (props: any) => {
   const theme = useTheme()
 
-  const { scrollState } = useSceneScrollContext()
+  const scrollState = useSceneScrollContext(state => state.scrollState)
 
   return (
     <HeaderBackgroundContainerView scrollY={scrollState.scrollY}>

src/components/notification/NotificationView.tsx

@@ -33,7 +33,8 @@ const NotificationViewComponent = (props: Props) => {
   const isBackupWarningShown = account.id != null && account.username == null
 
   const { bottom: insetBottom } = useSafeAreaInsets()
-  const { footerOpenRatio, footerHeight = 0 } = useSceneFooterState()
+  const footerOpenRatio = useSceneFooterState(state => state.footerOpenRatio)
+  const footerHeight = useSceneFooterState(state => state.footerHeight ?? 0)
 
   const [autoDetectTokenCards, setAutoDetectTokenCards] = React.useState<React.JSX.Element[]>([])
 

src/components/themed/MenuTabs.tsx

@@ -70,8 +70,9 @@ export const MenuTabs = (props: BottomTabBarProps) => {
 
   const { bottom: insetBottom } = useSafeAreaInsets()
 
-  const { footerOpenRatio, resetFooterRatio } = useSceneFooterState()
-  const { renderFooter } = useSceneFooterRenderState()
+  const footerOpenRatio = useSceneFooterState(state => state.footerOpenRatio)
+  const resetFooterRatio = useSceneFooterState(state => state.resetFooterRatio)
+  const renderFooter = useSceneFooterRenderState(state => state.renderFooter)
 
   const { height: keyboardHeight, progress: keyboardProgress } = useReanimatedKeyboardAnimation()
   const menuTabHeightAndInsetBottomTermForShiftY = useDerivedValue(() => keyboardProgress.value * (insetBottom + MAX_TAB_BAR_HEIGHT), [insetBottom])

src/components/themed/SceneFooterWrapper.tsx

@@ -20,7 +20,7 @@ export interface SceneFooterProps {
 export const SceneFooterWrapper = (props: SceneFooterProps) => {
   const { children, noBackgroundBlur = false, sceneWrapperInfo } = props
   const { hasTabs = true, isKeyboardOpen = false } = sceneWrapperInfo ?? {}
-  const { footerOpenRatio } = useSceneFooterState()
+  const footerOpenRatio = useSceneFooterState(state => state.footerOpenRatio)
 
   const handleFooterLayout = useLayoutHeightInFooter()
   const safeAreaInsets = useSafeAreaInsets()

src/components/themed/SearchFooter.tsx

@@ -27,7 +27,8 @@ export const SearchFooter = (props: SearchFooterProps) => {
 
   const textInputRef = React.useRef<SimpleTextInputRef>(null)
 
-  const { footerOpenRatio, setKeepOpen } = useSceneFooterState()
+  const footerOpenRatio = useSceneFooterState(state => state.footerOpenRatio)
+  const setKeepOpen = useSceneFooterState(state => state.setKeepOpen)
 
   const handleSearchChangeText = useHandler((text: string) => {
     onChangeText(text)

src/state/SceneFooterState.tsx

@@ -80,7 +80,7 @@ export const [SceneFooterRenderProvider, useSceneFooterRenderState] = createStat
  * @param deps the dependencies for the render function to trigger re-renders
  */
 export const useSceneFooterRender = (renderFn: FooterRender = defaultFooterRender, deps: DependencyList) => {
-  const { setRenderFooter } = useSceneFooterRenderState()
+  const setRenderFooter = useSceneFooterRenderState(state => state.setRenderFooter)
 
   // The callback will allow us to trigger a re-render when the deps change
   // eslint-disable-next-line react-hooks/exhaustive-deps
@@ -127,11 +127,15 @@ export const useSceneFooterRender = (renderFn: FooterRender = defaultFooterRende
  * thrashing for the footer state shared values.
  */
 export const FooterAccordionEventService = () => {
-  const { scrollState } = useSceneScrollContext()
+  const scrollState = useSceneScrollContext(state => state.scrollState)
   const { scrollBeginEvent, scrollEndEvent, scrollMomentumBeginEvent, scrollMomentumEndEvent, scrollY } = scrollState
 
   const scrollYStart = useSharedValue<number | undefined>(undefined)
-  const { footerOpenRatio, footerOpenRatioStart, keepOpen, footerHeight = 1, snapTo } = useSceneFooterState()
+  const footerOpenRatio = useSceneFooterState(state => state.footerOpenRatio)
+  const footerOpenRatioStart = useSceneFooterState(state => state.footerOpenRatioStart)
+  const keepOpen = useSceneFooterState(state => state.keepOpen)
+  const footerHeight = useSceneFooterState(state => state.footerHeight ?? 1)
+  const snapTo = useSceneFooterState(state => state.snapTo)
 
   // This factor will convert scroll delta into footer open value delta (a 0 to 1 fraction)
   const scrollDeltaToRatioDeltaFactor = 1 / footerHeight
@@ -236,7 +240,7 @@ export const FooterAccordionEventService = () => {
  * @returns layout handler for the component which height you want to measure
  */
 export const useLayoutHeightInFooter = (): ((event: LayoutChangeEvent) => void) => {
-  const { setFooterHeight } = useSceneFooterState()
+  const setFooterHeight = useSceneFooterState(state => state.setFooterHeight)
 
   const [layoutHeight, setLayoutHeight] = useState<number | undefined>(undefined)
 

src/state/SceneScrollState.tsx

@@ -50,7 +50,7 @@ export type SceneScrollHandler = (event: NativeSyntheticEvent<NativeScrollEvent>
  * the hook by the optional `isEnabled` boolean parameter.
  */
 export const useSceneScrollHandler = (isEnabled: boolean = true): SceneScrollHandler => {
-  const { setScrollState } = useSceneScrollContext()
+  const setScrollState = useSceneScrollContext(state => state.setScrollState)
 
   const localScrollState: ScrollState = useScrollState()
   const isFocused = useIsFocused()

src/state/createStateProvider.tsx

@@ -1,25 +1,29 @@
-import React, { useContext } from 'react'
+import React from 'react'
+import { createContext, useContextSelector } from 'use-context-selector'
 
+type Selector<State> = <T>(selector: (state: State) => T) => T
 /**
  * This creates a "state provider" component from a getter function.
  * The function passed is a getter function to return the value for the state
  * provider's context.
  *
- * @param getValue the function to return the context value
- * @returns The context provider component and a useContextValue hook
+ * @param getState the function to return the context value (state)
+ * @returns The context provider component and a useStateSelector hook to select context state
  */
-export function createStateProvider<Value>(getValue: () => Value): [React.FunctionComponent<{ children: React.ReactNode }>, () => Value] {
-  const Context = React.createContext<Value | undefined>(undefined)
+export function createStateProvider<State>(getState: () => State): [React.FunctionComponent<{ children: React.ReactNode }>, Selector<State>] {
+  const Context = createContext<State | undefined>(undefined)
   function WithContext({ children }: { children: React.ReactNode }) {
-    const value = getValue()
+    const value = getState()
     return <Context.Provider value={value}>{children}</Context.Provider>
   }
 
-  function useContextValue() {
-    const context = useContext(Context)
-    if (context == null) throw new Error(`Cannot call useDefinedContext outside of ${Context.displayName}`)
-    return context
+  function useStateSelector<T>(selector: (state: State) => T): T {
+    const state = useContextSelector(Context, state => {
+      if (state == null) throw new Error(`Cannot call useStateSelector outside of ${Context.displayName}`)
+      return selector(state)
+    })
+    return state
   }
 
-  return [WithContext, useContextValue]
+  return [WithContext, useStateSelector]
 }

yarn.lock

@@ -18067,6 +18067,11 @@ url@^0.11.0:
     punycode "1.3.2"
     querystring "0.2.0"
 
+use-context-selector@^1.4.1:
+  version "1.4.1"
+  resolved "https://registry.yarnpkg.com/use-context-selector/-/use-context-selector-1.4.1.tgz#eb96279965846b72915d7f899b8e6ef1d768b0ae"
+  integrity sha512-Io2ArvcRO+6MWIhkdfMFt+WKQX+Vb++W8DS2l03z/Vw/rz3BclKpM0ynr4LYGyU85Eke+Yx5oIhTY++QR0ZDoA==
+
 use-latest-callback@^0.1.5:
   version "0.1.5"
   resolved "https://registry.yarnpkg.com/use-latest-callback/-/use-latest-callback-0.1.5.tgz#a4a836c08fa72f6608730b5b8f4bbd9c57c04f51"