React Update

React DOM 中 React 是如何更新的

class 是如何更新到的

在 React 中更新是通过调用 setState 来完成的,并且不保证是同步函数,研究一下.

React 部分

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function Component(props, context, updater) {
this.props = props;
this.context = context;
// If a component has string refs, we will assign a different object later.
this.refs = emptyObject;
// We initialize the default updater but the real one gets injected by the
// renderer.
this.updater = updater || ReactNoopUpdateQueue;
}

Component.prototype.setState = function (partialState, callback) {
invariant(
typeof partialState === "object" ||
typeof partialState === "function" ||
partialState == null,
"setState(...): takes an object of state variables to update or a " +
"function which returns an object of state variables."
);
this.updater.enqueueSetState(this, partialState, callback, "setState");
};

在 React 中并为指定实际的 updater 对象, 而 React 本身并不提供这部分代码逻辑,通过搜索

可以在 React-DOM 中发现, 这一步是在初始化 Fiber 链表的时候对 class 进行实例化.

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function constructClassInstance(workInProgress: Fiber, ctor: any, props: any) {
// 省略代码
const instance = new ctor(props, context);
const state = (workInProgress.memoizedState =
instance.state !== null && instance.state !== undefined
? instance.state
: null);
adoptClassInstance(workInProgress, instance);
// 省略代码
}
function adoptClassInstance(workInProgress: Fiber, instance: any): void {
instance.updater = classComponentUpdater;
workInProgress.stateNode = instance;
// The instance needs access to the fiber so that it can schedule updates
// 实例需要能获得 fiber 对象才能进行更新
// setInstance 给实例添加了一个属性.值是当前 Fiber 对象的引用
setInstance(instance, workInProgress);
if (__DEV__) {
instance._reactInternalInstance = fakeInternalInstance;
}
}

classComponentUpdater

模块位于 react-reconciler 模块内,此模块负责 React 的更新调度

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const classComponentUpdater = {
isMounted, // 这个已经弃用了,用来表示当前组件是否卸载,应该是 class 以前的时代的 API
// this.setState
enqueueSetState(inst, payload, callback) {
const fiber = getInstance(inst);
const currentTime = requestCurrentTimeForUpdate();
const suspenseConfig = requestCurrentSuspenseConfig();
const expirationTime = computeExpirationForFiber(
currentTime,
fiber,
suspenseConfig,
);

const update = createUpdate(expirationTime, suspenseConfig);

update.payload = payload;
if (callback !== undefined && callback !== null) {
if (__DEV__) {
warnOnInvalidCallback(callback, 'setState');
}
update.callback = callback;
}

enqueueUpdate(fiber, update);
scheduleUpdateOnFiber(fiber, expirationTime);

if (__DEV__) {
if (enableDebugTracing) {
if (fiber.mode & DebugTracingMode) {
const label = priorityLevelToLabel(
((update.priority: any): ReactPriorityLevel),
);
const name = getComponentName(fiber.type) || 'Unknown';
logStateUpdateScheduled(name, label, payload);
}
}
}
},

// 通过搜索发在在几个固定生命周期中调用
enqueueReplaceState(inst, payload, callback) {
const fiber = getInstance(inst);
const currentTime = requestCurrentTimeForUpdate();
const suspenseConfig = requestCurrentSuspenseConfig();
const expirationTime = computeExpirationForFiber(
currentTime,
fiber,
suspenseConfig,
);

const update = createUpdate(expirationTime, suspenseConfig);
update.tag = ReplaceState;
update.payload = payload;

if (callback !== undefined && callback !== null) {
if (__DEV__) {
warnOnInvalidCallback(callback, 'replaceState');
}
update.callback = callback;
}

enqueueUpdate(fiber, update);
scheduleUpdateOnFiber(fiber, expirationTime);

if (__DEV__) {
if (enableDebugTracing) {
if (fiber.mode & DebugTracingMode) {
const label = priorityLevelToLabel(
((update.priority: any): ReactPriorityLevel),
);
const name = getComponentName(fiber.type) || 'Unknown';
logStateUpdateScheduled(name, label, payload);
}
}
}
},

// this.forceUpdate 强制更新
enqueueForceUpdate(inst, callback) {
const fiber = getInstance(inst);
const currentTime = requestCurrentTimeForUpdate();
const suspenseConfig = requestCurrentSuspenseConfig();
const expirationTime = computeExpirationForFiber(
currentTime,
fiber,
suspenseConfig,
);

const update = createUpdate(expirationTime, suspenseConfig);
update.tag = ForceUpdate;

if (callback !== undefined && callback !== null) {
if (__DEV__) {
warnOnInvalidCallback(callback, 'forceUpdate');
}
update.callback = callback;
}

enqueueUpdate(fiber, update);
scheduleUpdateOnFiber(fiber, expirationTime);

if (__DEV__) {
if (enableDebugTracing) {
if (fiber.mode & DebugTracingMode) {
const label = priorityLevelToLabel(
((update.priority: any): ReactPriorityLevel),
);
const name = getComponentName(fiber.type) || 'Unknown';
logForceUpdateScheduled(name, label);
}
}
}
},
};

enqueueSetState

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{
// 可以从上面看到 函数参数传递了四个参数最后一个参数是字符串 setState
// 第一个参数是实例, 第二个是要被合并的对象或者函数,第三个就是回调函数可选
enqueueSetState(inst, payload, callback) {
//上面说到了 classComponentUpdater 被添加到实例的时候会给实例添加当前的fiber对象作为实例属性
const fiber = getInstance(inst);


// 计算一些时间
const currentTime = requestCurrentTimeForUpdate();
const suspenseConfig = requestCurrentSuspenseConfig();
const expirationTime = computeExpirationForFiber(
currentTime,
fiber,
suspenseConfig,
);


// 构建 update 形式如下
/*
update = {
expirationTime: expirationTime,
suspenseConfig: suspenseConfig,
tag: UpdateState,
payload: null,
callback: null,
next: null
};
*/
const update = createUpdate(expirationTime, suspenseConfig);

// 将返回的 state Object or function 赋值供后续调用
update.payload = payload;
if (callback !== undefined && callback !== null) {
// 这里是个开发判断, 判断如果存在callback 那么函数内部判断是不是一个函数或者 null, 如果都不是那么就报错提示用户正确使用方法
if (__DEV__) {
warnOnInvalidCallback(callback, 'setState');
}
update.callback = callback;
}
// enqueueUpdate
// 这个函数会读取 Fiber 对象上的 updateQueue 对象,判断 updateQueue.shared.padding 是否已经存在等待 上方生成的 update对象
// 如果存在那么 会将next 指针指向这个新增的,如果不存在那么就赋值为这个新增的 update , 形式是一个单向链表
// update.next -> newUpdate.next -> 如此的一个链表形式的对象.
// Fiber.updateQueue.padding = update

enqueueUpdate(fiber, update);
// 安排更新
scheduleUpdateOnFiber(fiber, expirationTime);

if (__DEV__) {
if (enableDebugTracing) {
if (fiber.mode & DebugTracingMode) {
const label = priorityLevelToLabel(
((update.priority: any): ReactPriorityLevel),
);
const name = getComponentName(fiber.type) || 'Unknown';
logStateUpdateScheduled(name, label, payload);
}
}
}
},

}

scheduleUpdateOnFiber

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export function scheduleUpdateOnFiber(
fiber: Fiber,
expirationTime: ExpirationTime
) {
// 这里会检查 nestedUpdateCount 的值是否大于阈值(50),如果大于就报错超过最大深度, 而nestedUpdateCount这个值
// 会在 commitRootImpl 函数内 有条件更新
checkForNestedUpdates();
// 判断是否在 render 阶段进行更新,
warnAboutRenderPhaseUpdatesInDEV(fiber);
// 更新过期时间,并从当前节点返回根节点
const root = markUpdateTimeFromFiberToRoot(fiber, expirationTime);
if (root === null) {
warnAboutUpdateOnUnmountedFiberInDEV(fiber);
return;
}

// TODO: computeExpirationForFiber also reads the priority. Pass the
// priority as an argument to that function and this one.
// 获得优先级, 立即更新优先级最高, 然后是用户要求更新, 然后是普通更新等等, 调用setState属于用户要求更新
const priorityLevel = getCurrentPriorityLevel();

if (expirationTime === Sync) {
if (
// Check if we're inside unbatchedUpdates
(executionContext & LegacyUnbatchedContext) !== NoContext &&
// Check if we're not already rendering
(executionContext & (RenderContext | CommitContext)) === NoContext
) {
// Register pending interactions on the root to avoid losing traced interaction data.
schedulePendingInteractions(root, expirationTime);

// This is a legacy edge case. The initial mount of a ReactDOM.render-ed
// root inside of batchedUpdates should be synchronous, but layout updates
// should be deferred until the end of the batch.
performSyncWorkOnRoot(root);
} else {
// 这里来安排一个回调事件供调度器安排
ensureRootIsScheduled(root);
schedulePendingInteractions(root, expirationTime);
// 如果以下判断成立那么这次的 setState 将是同步的否则是异步的
if (executionContext === NoContext) {
// Flush the synchronous work now, unless we're already working or inside
// a batch. This is intentionally inside scheduleUpdateOnFiber instead of
// scheduleCallbackForFiber to preserve the ability to schedule a callback
// without immediately flushing it. We only do this for user-initiated
// updates, to preserve historical behavior of legacy mode.
// 立即进行同步工作, 除非我们已经在工作中,或者在批量处理中, 这是有意放在 scheduleUpdateOnFiber 中的,
// 而不是 scheduleCallbackForFiber 以保留在不理解刷新回调的情况下安排调度的能力,只针对用户更新
flushSyncCallbackQueue();
}
}
} else {
// Schedule a discrete update but only if it's not Sync.
// 调度不相关的更新,但是值在非同步下
if (
(executionContext & DiscreteEventContext) !== NoContext &&
// Only updates at user-blocking priority or greater are considered
// discrete, even inside a discrete event.
// 只有用户堵塞由下级更高的更新才被认为是布线管的, 即使在不相关事件内也是如此
(priorityLevel === UserBlockingPriority ||
priorityLevel === ImmediatePriority)
) {
// This is the result of a discrete event. Track the lowest priority
// discrete update per root so we can flush them early, if needed.
// 这是不相关事件的结果, 追中根上的不相关的低优先级更新,这样就可以尽早的flush 他们, 如果需要
if (rootsWithPendingDiscreteUpdates === null) {
rootsWithPendingDiscreteUpdates = new Map([[root, expirationTime]]);
} else {
const lastDiscreteTime = rootsWithPendingDiscreteUpdates.get(root);
if (
lastDiscreteTime === undefined ||
lastDiscreteTime > expirationTime
) {
rootsWithPendingDiscreteUpdates.set(root, expirationTime);
}
}
}
// Schedule other updates after in case the callback is sync.
// 安排其他更新防止同步回调
ensureRootIsScheduled(root);
schedulePendingInteractions(root, expirationTime);
}
}

ensureRootIsScheduled

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// Use this function to schedule a task for a root. There's only one task per
// root; if a task was already scheduled, we'll check to make sure the
// expiration time of the existing task is the same as the expiration time of
// the next level that the root has work on. This function is called on every
// update, and right before exiting a task.
// 使用这个函数从 root 上安排任务, 每个 root 只有一个任务, 如果一个任务已经被安排,
// 我们将检查以确保现有的任务的过期时间,与root要处理的下一层任务的过期时间相同,
// 这个函数调用每个 update. 在完成任务之前.
function ensureRootIsScheduled(root: FiberRoot) {
//从 root 上获取最后超时时间
const lastExpiredTime = root.lastExpiredTime;
if (lastExpiredTime !== NoWork) {
// Special case: Expired work should flush synchronously.
// 特殊条件下: 过期的任务应该被同步处理
root.callbackExpirationTime = Sync;
root.callbackPriority_old = ImmediatePriority;

root.callbackNode = scheduleSyncCallback(
performSyncWorkOnRoot.bind(null, root)
);
return;
}

const expirationTime = getNextRootExpirationTimeToWorkOn(root);
const existingCallbackNode = root.callbackNode;
if (expirationTime === NoWork) {
// There's nothing to work on.
// 没有什么工作
if (existingCallbackNode !== null) {
root.callbackNode = null;
root.callbackExpirationTime = NoWork;
root.callbackPriority_old = NoPriority;
}
return;
}

// TODO: If this is an update, we already read the current time. Pass the
// time as an argument.
// TODO: 如果这是一个 update, 我们已经读取当前时间, 通过参数传递这个时间
const currentTime = requestCurrentTimeForUpdate();
const priorityLevel = inferPriorityFromExpirationTime(
currentTime,
expirationTime
);

// If there's an existing render task, confirm it has the correct priority and
// expiration time. Otherwise, we'll cancel it and schedule a new one.
if (existingCallbackNode !== null) {
const existingCallbackPriority = root.callbackPriority_old;
const existingCallbackExpirationTime = root.callbackExpirationTime;
if (
// Callback must have the exact same expiration time.
existingCallbackExpirationTime === expirationTime &&
// Callback must have greater or equal priority.
existingCallbackPriority >= priorityLevel
) {
// Existing callback is sufficient.
return;
}
// Need to schedule a new task.
// TODO: Instead of scheduling a new task, we should be able to change the
// priority of the existing one.
cancelCallback(existingCallbackNode);
}

root.callbackExpirationTime = expirationTime;
root.callbackPriority_old = priorityLevel;

let callbackNode;
if (expirationTime === Sync) {
// Sync React callbacks are scheduled on a special internal queue
// 同步 React 回调 被 安排在一个特殊的队列里面
//scheduleSyncCallback 函数会将 performSyncWorkOnRoot 放在一个队列里面,这个函数会在到期之前被 flushSyncCallbackQueue 调用
// performSyncWorkOnRoot 函数是不经过调度器的同步任务入口点
callbackNode = scheduleSyncCallback(performSyncWorkOnRoot.bind(null, root));
} else if (disableSchedulerTimeoutBasedOnReactExpirationTime) {
callbackNode = scheduleCallback(
priorityLevel,
performConcurrentWorkOnRoot.bind(null, root)
);
} else {
callbackNode = scheduleCallback(
priorityLevel,
performConcurrentWorkOnRoot.bind(null, root),
// Compute a task timeout based on the expiration time. This also affects
// ordering because tasks are processed in timeout order.
{ timeout: expirationTimeToMs(expirationTime) - now() }
);
}

root.callbackNode = callbackNode;
}

所以 setState 构造一个 update 对象给当前 fiber 对象, 最后由 flushSyncCallbackQueue 函数去更新.
关于同步异步的问题, react 通过 判断当前上下文的值 executionContext 的值,如果是 0 那么说明不在 react 中,那么就是同步更新的.
否则就是异步的

enqueueForceUpdate

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{
enqueueForceUpdate(inst, callback) {
//...
const update = createUpdate(expirationTime, suspenseConfig);
// 可以看到差别就是这个
/**
export const UpdateState = 0;
export const ReplaceState = 1;
export const ForceUpdate = 2;
export const CaptureUpdate = 3;
*/
update.tag = ForceUpdate;
//...
enqueueUpdate(fiber, update);
scheduleUpdateOnFiber(fiber, expirationTime);
//...
},
}

flushSyncCallbackQueue

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export function flushSyncCallbackQueue() {
// immediateQueueCallbackNode 会在 scheduleSyncCallback 被赋值

/**
函数返回了类似这样的一个对象
newTask = {
id: taskIdCounter++, // 自增数字
callback,// callback 这里传入的是 flushSyncCallbackQueueImpl
priorityLevel, // 任务等级
startTime, // 会通过函数获得一个时间
expirationTime, // 根据优先级获得一个超时时间,最高优先级超时时间是 -1
sortIndex: -1,
}
*/
if (immediateQueueCallbackNode !== null) {
const node = immediateQueueCallbackNode;
immediateQueueCallbackNode = null;
Scheduler_cancelCallback(node); // 可以从下面看到这里取消掉了task 的callback
}
flushSyncCallbackQueueImpl();
}
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function Scheduler_cancelCallback(task) {
if (enableProfiling) {
if (task.isQueued) {
const currentTime = getCurrentTime();
markTaskCanceled(task, currentTime);
task.isQueued = false;
}
}

// Null out the callback to indicate the task has been canceled. (Can't
// remove from the queue because you can't remove arbitrary nodes from an
// array based heap, only the first one.)
task.callback = null;
}

flushSyncCallbackQueueImpl

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function flushSyncCallbackQueueImpl() {
// 判断当前没有在 flush 同步队列以及队列不为空
if (!isFlushingSyncQueue && syncQueue !== null) {
// Prevent re-entrancy.
// 对flag进行赋值,防止重复进行
isFlushingSyncQueue = true;
let i = 0;
try {
const isSync = true;
const queue = syncQueue;
// 这里开始运行队列任务
runWithPriority(ImmediatePriority, () => {
for (; i < queue.length; i++) {
let callback = queue[i];
do {
// callback 会被转到 performSyncWorkOnRoot 函数这里调用 workLoopSync 进行整个流程 初次渲染流程在上一篇 ReactDOM中有
//这里主要看一下 如何 diff code
callback = callback(isSync);
} while (callback !== null);
}
});
syncQueue = null;
} catch (error) {
// If something throws, leave the remaining callbacks on the queue.
if (syncQueue !== null) {
syncQueue = syncQueue.slice(i + 1);
}
// Resume flushing in the next tick
Scheduler_scheduleCallback(
Scheduler_ImmediatePriority,
flushSyncCallbackQueue
);
throw error;
} finally {
isFlushingSyncQueue = false;
}
}
}

workLoopConcurrent 开始调用 performUnitOfWork 来遍历链表, performUnitOfWork 开始调用 beginWork 开始处理每个节点

后面主要看如何比对新旧节点找出差异进行更新.

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function performUnitOfWork(unitOfWork) {
// 两棵树是交替进行的,这里取 alternate 作为 current
var current = unitOfWork.alternate;
var next;
if ((unitOfWork.mode & ProfileMode) !== NoMode) {
startProfilerTimer(unitOfWork);
next = beginWork$1(current, unitOfWork, renderExpirationTime$1);
//...
}

//...
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function beginWork(
current: Fiber | null,
workInProgress: Fiber,
renderLanes: Lanes
): Fiber | null {
//...
if (current !== null) {
// 非第一次渲染 current 就不等 null 了

// 新旧 props
const oldProps = current.memoizedProps;
const newProps = workInProgress.pendingProps;

if (
oldProps !== newProps ||
hasLegacyContextChanged() ||
// Force a re-render if the implementation changed due to hot reload:
(__DEV__ ? workInProgress.type !== current.type : false)
) {
// If props or context changed, mark the fiber as having performed work.
// This may be unset if the props are determined to be equal later (memo).
// 如果 props 或者 context 变化了, 将标记这个 fiber 完成了工作
didReceiveUpdate = true;
} else if (!includesSomeLane(renderLanes, updateLanes)) {
//...
} else {
// 初次渲染 因为 alternate === null 所以current ===null 走 这里的逻辑
}

workInProgress.lanes = NoLanes;
// 匹配标签处理
switch (workInProgress.tag) {
case IndeterminateComponent: {
return mountIndeterminateComponent(
current,
workInProgress,
workInProgress.type,
renderLanes,
);
}
case LazyComponent: {
const elementType = workInProgress.elementType;
return mountLazyComponent(
current,
workInProgress,
elementType,
updateLanes,
renderLanes,
);
}
case FunctionComponent: {
const Component = workInProgress.type;
const unresolvedProps = workInProgress.pendingProps;
const resolvedProps =
workInProgress.elementType === Component
? unresolvedProps
: resolveDefaultProps(Component, unresolvedProps);
return updateFunctionComponent(
current,
workInProgress,
Component,
resolvedProps,
renderLanes,
);
}
case ClassComponent: {
const Component = workInProgress.type;
const unresolvedProps = workInProgress.pendingProps;
const resolvedProps =
workInProgress.elementType === Component
? unresolvedProps
: resolveDefaultProps(Component, unresolvedProps);
return updateClassComponent(
current,
workInProgress,
Component,
resolvedProps,
renderLanes,
);
}
case HostRoot:
return updateHostRoot(current, workInProgress, renderLanes);
case HostComponent:
return updateHostComponent(current, workInProgress, renderLanes);
case HostText:
return updateHostText(current, workInProgress);
case SuspenseComponent:
return updateSuspenseComponent(current, workInProgress, renderLanes);
case HostPortal:
return updatePortalComponent(current, workInProgress, renderLanes);
case ForwardRef: {
const type = workInProgress.type;
const unresolvedProps = workInProgress.pendingProps;
const resolvedProps =
workInProgress.elementType === type
? unresolvedProps
: resolveDefaultProps(type, unresolvedProps);
return updateForwardRef(
current,
workInProgress,
type,
resolvedProps,
renderLanes,
);
}
case Fragment:
return updateFragment(current, workInProgress, renderLanes);
case Mode:
return updateMode(current, workInProgress, renderLanes);
case Profiler:
return updateProfiler(current, workInProgress, renderLanes);
case ContextProvider:
return updateContextProvider(current, workInProgress, renderLanes);
case ContextConsumer:
return updateContextConsumer(current, workInProgress, renderLanes);
case MemoComponent: {
const type = workInProgress.type;
const unresolvedProps = workInProgress.pendingProps;
// Resolve outer props first, then resolve inner props.
let resolvedProps = resolveDefaultProps(type, unresolvedProps);
if (__DEV__) {
if (workInProgress.type !== workInProgress.elementType) {
const outerPropTypes = type.propTypes;
if (outerPropTypes) {
checkPropTypes(
outerPropTypes,
resolvedProps, // Resolved for outer only
'prop',
getComponentName(type),
);
}
}
}
resolvedProps = resolveDefaultProps(type.type, resolvedProps);
return updateMemoComponent(
current,
workInProgress,
type,
resolvedProps,
updateLanes,
renderLanes,
);
}
case SimpleMemoComponent: {
return updateSimpleMemoComponent(
current,
workInProgress,
workInProgress.type,
workInProgress.pendingProps,
updateLanes,
renderLanes,
);
}
case IncompleteClassComponent: {
const Component = workInProgress.type;
const unresolvedProps = workInProgress.pendingProps;
const resolvedProps =
workInProgress.elementType === Component
? unresolvedProps
: resolveDefaultProps(Component, unresolvedProps);
return mountIncompleteClassComponent(
current,
workInProgress,
Component,
resolvedProps,
renderLanes,
);
}
case SuspenseListComponent: {
return updateSuspenseListComponent(current, workInProgress, renderLanes);
}
case FundamentalComponent: {
if (enableFundamentalAPI) {
return updateFundamentalComponent(current, workInProgress, renderLanes);
}
break;
}
case ScopeComponent: {
if (enableScopeAPI) {
return updateScopeComponent(current, workInProgress, renderLanes);
}
break;
}
case Block: {
if (enableBlocksAPI) {
const block = workInProgress.type;
const props = workInProgress.pendingProps;
return updateBlock(current, workInProgress, block, props, renderLanes);
}
break;
}
case OffscreenComponent: {
return updateOffscreenComponent(current, workInProgress, renderLanes);
}
case LegacyHiddenComponent: {
return updateLegacyHiddenComponent(current, workInProgress, renderLanes);
}
}
}

下面就是实际更新当前值了

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function commitWork(current: Fiber | null, finishedWork: Fiber): void {
if (!supportsMutation) {
switch (finishedWork.tag) {
case FunctionComponent:
case ForwardRef:
case MemoComponent:
case SimpleMemoComponent:
case Block: {
// Layout effects are destroyed during the mutation phase so that all
// destroy functions for all fibers are called before any create functions.
// This prevents sibling component effects from interfering with each other,
// e.g. a destroy function in one component should never override a ref set
// by a create function in another component during the same commit.
if (
enableProfilerTimer &&
enableProfilerCommitHooks &&
finishedWork.mode & ProfileMode
) {
try {
startLayoutEffectTimer();
commitHookEffectListUnmount(
HookLayout | HookHasEffect,
finishedWork,
);
} finally {
recordLayoutEffectDuration(finishedWork);
}
} else {
commitHookEffectListUnmount(HookLayout | HookHasEffect, finishedWork);
}
return;
}
case Profiler: {
return;
}
case SuspenseComponent: {
commitSuspenseComponent(finishedWork);
attachSuspenseRetryListeners(finishedWork);
return;
}
case SuspenseListComponent: {
attachSuspenseRetryListeners(finishedWork);
return;
}
case HostRoot: {
if (supportsHydration) {
const root: FiberRoot = finishedWork.stateNode;
if (root.hydrate) {
// We've just hydrated. No need to hydrate again.
root.hydrate = false;
commitHydratedContainer(root.containerInfo);
}
}
break;
}
}

commitContainer(finishedWork);
return;
}

switch (finishedWork.tag) {
case FunctionComponent:
case ForwardRef:
case MemoComponent:
case SimpleMemoComponent:
case Block: {
// Layout effects are destroyed during the mutation phase so that all
// destroy functions for all fibers are called before any create functions.
// This prevents sibling component effects from interfering with each other,
// e.g. a destroy function in one component should never override a ref set
// by a create function in another component during the same commit.
if (
enableProfilerTimer &&
enableProfilerCommitHooks &&
finishedWork.mode & ProfileMode
) {
try {
startLayoutEffectTimer();
commitHookEffectListUnmount(HookLayout | HookHasEffect, finishedWork);
} finally {
recordLayoutEffectDuration(finishedWork);
}
} else {
commitHookEffectListUnmount(HookLayout | HookHasEffect, finishedWork);
}
return;
}
case ClassComponent: {
return;
}
case HostComponent: {
const instance: Instance = finishedWork.stateNode;
if (instance != null) {
// Commit the work prepared earlier.
const newProps = finishedWork.memoizedProps;
// For hydration we reuse the update path but we treat the oldProps
// as the newProps. The updatePayload will contain the real change in
// this case.
const oldProps = current !== null ? current.memoizedProps : newProps;
const type = finishedWork.type;
// TODO: Type the updateQueue to be specific to host components.
const updatePayload: null | UpdatePayload = (finishedWork.updateQueue: any);
finishedWork.updateQueue = null;
if (updatePayload !== null) {
commitUpdate(
instance,
updatePayload,
type,
oldProps,
newProps,
finishedWork,
);
}
if (enableDeprecatedFlareAPI) {
const prevListeners = oldProps.DEPRECATED_flareListeners;
const nextListeners = newProps.DEPRECATED_flareListeners;
if (prevListeners !== nextListeners) {
updateDeprecatedEventListeners(nextListeners, finishedWork, null);
}
}
}
return;
}
case HostText: {
invariant(
finishedWork.stateNode !== null,
'This should have a text node initialized. This error is likely ' +
'caused by a bug in React. Please file an issue.',
);
const textInstance: TextInstance = finishedWork.stateNode;
const newText: string = finishedWork.memoizedProps;
// For hydration we reuse the update path but we treat the oldProps
// as the newProps. The updatePayload will contain the real change in
// this case.
const oldText: string =
current !== null ? current.memoizedProps : newText;
commitTextUpdate(textInstance, oldText, newText);
return;
}
case HostRoot: {
if (supportsHydration) {
const root: FiberRoot = finishedWork.stateNode;
if (root.hydrate) {
// We've just hydrated. No need to hydrate again.
root.hydrate = false;
commitHydratedContainer(root.containerInfo);
}
}
return;
}
case Profiler: {
return;
}
case SuspenseComponent: {
commitSuspenseComponent(finishedWork);
attachSuspenseRetryListeners(finishedWork);
return;
}
case SuspenseListComponent: {
attachSuspenseRetryListeners(finishedWork);
return;
}
case IncompleteClassComponent: {
return;
}
case FundamentalComponent: {
if (enableFundamentalAPI) {
const fundamentalInstance = finishedWork.stateNode;
updateFundamentalComponent(fundamentalInstance);
return;
}
break;
}
case ScopeComponent: {
if (enableScopeAPI) {
const scopeInstance = finishedWork.stateNode;
if (enableDeprecatedFlareAPI) {
const newProps = finishedWork.memoizedProps;
const oldProps = current !== null ? current.memoizedProps : newProps;
const prevListeners = oldProps.DEPRECATED_flareListeners;
const nextListeners = newProps.DEPRECATED_flareListeners;
if (prevListeners !== nextListeners || current === null) {
updateDeprecatedEventListeners(nextListeners, finishedWork, null);
}
}
prepareScopeUpdate(scopeInstance, finishedWork);
return;
}
break;
}
}
invariant(
false,
'This unit of work tag should not have side-effects. This error is ' +
'likely caused by a bug in React. Please file an issue.',
);
}