bevformer源码

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mob64ca14173efa 2024-11-28 07:19:35

文章标签 bevformer源码 react.js javascript 前端初始化 文章分类 计算机视觉人工智能

react三种启动模式

legacy

// LegacyRoot
ReactDOM.render(<App />, document.getElementById('root'), dom => {}); // 支持callback回调, 参数是一个dom对象

Blocking模式

仅提供了 concurrent 模式的小部分功能, 作为迁移到 concurrent 模式的第一个步骤.

// BolckingRoot
// 1. 创建ReactDOMRoot对象
const reactDOMBolckingRoot = ReactDOM.createBlockingRoot(
  document.getElementById('root'),
);
// 2. 调用render
reactDOMBolckingRoot.render(<App />); // 不支持回调

Concurrent模式

这个模式开启了所有的新功能

// ConcurrentRoot
// 1. 创建ReactDOMRoot对象
const reactDOMRoot = ReactDOM.createRoot(document.getElementById('root'));
// 2. 调用render
reactDOMRoot.render(<App />); // 不支持回调

bevformer源码_初始化

legacy启动

ReactDOM.render后续调用legacyRenderSubtreeIntoContainer

legacyRenderSubtreeIntoContainer

function legacyRenderSubtreeIntoContainer(
  parentComponent: ?React$Component<any, any>,
  children: ReactNodeList,
  container: Container,
  forceHydrate: boolean,
  callback: ?Function,
) {
  let root: RootType = (container._reactRootContainer: any);
  let fiberRoot;
  if (!root) {
    // 初次调用, root还未初始化, 会进入此分支
    //1. 创建ReactDOMRoot对象, 初始化react应用环境
    root = container._reactRootContainer = legacyCreateRootFromDOMContainer(
      container,
      forceHydrate,
    );
    //获取fiberRoot
    fiberRoot = root._internalRoot;
    if (typeof callback === 'function') {
      const originalCallback = callback;
      callback = function() {
        // instance最终指向children生成的dom节点(入参: 如<App/>)
        const instance = getPublicRootInstance(fiberRoot);
        originalCallback.call(instance);
      };
    }
    // 2. 调用unbatchedUpdates更新容器
    unbatchedUpdates(() => {
      updateContainer(children, fiberRoot, parentComponent, callback);
    });
    // root已经初始化, 二次调用render会进入
  } else {
    // 1. 获取ReactDOMRoot对象
    fiberRoot = root._internalRoot;
    if (typeof callback === 'function') {
      const originalCallback = callback;
      callback = function() {
        const instance = getPublicRootInstance(fiberRoot);
        originalCallback.call(instance);
      };
    }
    // 2. 调用更新
    updateContainer(children, fiberRoot, parentComponent, callback);
  }
  return getPublicRootInstance(fiberRoot);
}

legacyCreateRootFromDOMContainer

function legacyCreateRootFromDOMContainer(
  container: Container,
  forceHydrate: boolean,
): RootType {
  const shouldHydrate =
    forceHydrate || shouldHydrateDueToLegacyHeuristic(container);
  //实际调用createLegacyRoot
  return createLegacyRoot(
    container,
    shouldHydrate
      ? {
          hydrate: true,
        }
      : undefined,
  );
}

export function createLegacyRoot(
  container: Container,
  options?: RootOptions,
): RootType {
  return new ReactDOMBlockingRoot(container, LegacyRoot, options); // 注意这里的LegacyRoot是固定的, 并不是外界传入的
}

创建ReactDOMBlockingRoot实例(在 Concurrent 模式和 Blocking 模式中也是), 初始化 react 应用环境
然后后续调用updateContainer进行更新.

Concurrent 模式和 Blocking 模式

分别调用ReactDOM.createRoot和ReactDOM.createBlockingRoot创建ReactDOMRoot和ReactDOMBlockingRoot实例
然后调用ReactDOMRoot和ReactDOMBlockingRoot实例的render方法

export function createRoot(
  container: Container,
  options?: RootOptions,
): RootType {
  return new ReactDOMRoot(container, options);
}

export function createBlockingRoot(
  container: Container,
  options?: RootOptions,
): RootType {
  return new ReactDOMBlockingRoot(container, BlockingRoot, options); // 注意第2个参数BlockingRoot是固定写死的
}

ReactDOMRoot和ReactDOMBlockingRoot对象

function ReactDOMRoot(container: Container, options: void | RootOptions) {
  // 创建一个fiberRoot对象, 并将其挂载到this._internalRoot之上
  this._internalRoot = createRootImpl(container, ConcurrentRoot, options);
}

//也是legacy模式最后返回的实例
function ReactDOMBlockingRoot(
  container: Container,
  tag: RootTag,
  options: void | RootOptions,
) {
  // 创建一个fiberRoot对象, 并将其挂载到this._internalRoot之上
  this._internalRoot = createRootImpl(container, tag, options);
}

ReactDOMRoot.prototype.render = ReactDOMBlockingRoot.prototype.render = function(
  children: ReactNodeList,
): void {
  const root = this._internalRoot;
  // 执行更新
  updateContainer(children, root, null, null);
};

ReactDOMRoot.prototype.unmount = ReactDOMBlockingRoot.prototype.unmount = function(): void {
  const root = this._internalRoot;
  const container = root.containerInfo;
  // 执行卸载更新
  updateContainer(null, root, null, () => {
    unmarkContainerAsRoot(container);
  });
};

createRootImpl

function createRootImpl(
  container: Container,
  tag: RootTag,
  options: void | RootOptions,
) {
  // ... 省略部分源码(有关hydrate服务端渲染等, 暂时用不上)
  // 1. 创建fiberRoot
  const root = createContainer(container, tag, hydrate, hydrationCallbacks); // 注意RootTag的传递
  // 2. 标记dom对象, 把dom和fiber对象关联起来
  markContainerAsRoot(root.current, container);
  // ...省略部分无关代码
  return root;
}

createContainer

export function createContainer(
  containerInfo: Container,
  tag: RootTag,
  hydrate: boolean,
  hydrationCallbacks: null | SuspenseHydrationCallbacks,
): OpaqueRoot {
  // 创建fiberRoot对象
  return createFiberRoot(containerInfo, tag, hydrate, hydrationCallbacks); // 注意RootTag的传递
}

createFiberRoot

创建fiberRoot
创建RootFiber，且fiber.tag = HostRootFiber

export function createFiberRoot(
  containerInfo: any,
  tag: RootTag,
  hydrate: boolean,
  hydrationCallbacks: null | SuspenseHydrationCallbacks,
): FiberRoot {
  // 创建fiberRoot对象, 注意RootTag的传递
  const root: FiberRoot = (new FiberRootNode(containerInfo, tag, hydrate): any);

  // 1. 这里创建了`react`应用的首个`fiber`对象, 称为`HostRootFiber`
  const uninitializedFiber = createHostRootFiber(tag);
  // fiberRoot的current指向了rootFiber
  root.current = uninitializedFiber;
  //rootFiber的stateNode保存root实例
  uninitializedFiber.stateNode = root;
  // 2. 初始化HostRootFiber的updateQueue
  initializeUpdateQueue(uninitializedFiber);

  return root;
}

createHostRootFiber

其中fiber.mode属性, 会与 3 种RootTag(ConcurrentRoot,BlockingRoot,LegacyRoot)关联起来
fiber树中节点的mode都会和HostRootFiber.mode一致(新建的 fiber 节点, 其 mode 来源于父节点)
mode决定了以后整个 fiber 树构建过程

export function createHostRootFiber(tag: RootTag): Fiber {
  let mode;
  if (tag === ConcurrentRoot) {
    mode = ConcurrentMode | BlockingMode | StrictMode;
  } else if (tag === BlockingRoot) {
    mode = BlockingMode | StrictMode;
  } else {
    mode = NoMode;
  }
  return createFiber(HostRoot, null, null, mode); // 注意这里设置的mode属性是由RootTag决定的
}

legacy模式下

bevformer源码_react.js_02

concurrent模式下

bevformer源码_初始化_03

blocking模式下

bevformer源码_前端_04

调用更新
legacy中

unbatchedUpdates(() => {
  updateContainer(children, fiberRoot, parentComponent, callback);
});

concurrent和blocking中

ReactDOMRoot.prototype.render = ReactDOMBlockingRoot.prototype.render = function(
  children: ReactNodeList,
): void {
  const root = this._internalRoot;
  // 执行更新
  updateContainer(children, root, null, null);
};

updateContainer

export function updateContainer(
  element: ReactNodeList,
  container: OpaqueRoot,//fiberRoot
  parentComponent: ?React$Component<any, any>,
  callback: ?Function,
): Lane {
  //即fiberRoot.current,指向了rootFiber
  const current = container.current;
  
  // 1. 获取当前时间戳, 计算本次更新的优先级
  const eventTime = requestEventTime();
  const lane = requestUpdateLane(current);

  // 2. 设置fiber.updateQueue
  const update = createUpdate(eventTime, lane);
  update.payload = { element };
  callback = callback === undefined ? null : callback;
  if (callback !== null) {
    update.callback = callback;
  }
  enqueueUpdate(current, update);

  // 3. 进入reconcier运作流程中的`输入`环节，即通过scheduler注册调度任务
  scheduleUpdateOnFiber(current, lane, eventTime);
  return lane;
}