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React 深度学习:ReactFiberRoot

packages/react-reconciler/src/ReactFiberRoot.js

类型

export type Batch = {
  _defer: boolean,
  _expirationTime: ExpirationTime,
  _onComplete: () => mixed,
  _next: Batch | null,
};

export type PendingInteractionMap = Map<ExpirationTime, Set<Interaction>>;


type BaseFiberRootProperties = {|
  // Any additional information from the host associated with this root.
  containerInfo: any,
  // Used only by persistent updates.
  pendingChildren: any,
  // The currently active root fiber. This is the mutable root of the tree.
  current: Fiber,

  // The following priority levels are used to distinguish between 1)
  // uncommitted work, 2) uncommitted work that is suspended, and 3) uncommitted
  // work that may be unsuspended. We choose not to track each individual
  // pending level, trading granularity for performance.
  //
  // The earliest and latest priority levels that are suspended from committing.
  earliestSuspendedTime: ExpirationTime,
  latestSuspendedTime: ExpirationTime,
  // The earliest and latest priority levels that are not known to be suspended.
  earliestPendingTime: ExpirationTime,
  latestPendingTime: ExpirationTime,
  // The latest priority level that was pinged by a resolved promise and can
  // be retried.
  latestPingedTime: ExpirationTime,

  pingCache:
    | WeakMap<Thenable, Set<ExpirationTime>>
    | Map<Thenable, Set<ExpirationTime>>
    | null,

  // If an error is thrown, and there are no more updates in the queue, we try
  // rendering from the root one more time, synchronously, before handling
  // the error.
  didError: boolean,

  pendingCommitExpirationTime: ExpirationTime,
  // A finished work-in-progress HostRoot that's ready to be committed.
  finishedWork: Fiber | null,
  // Timeout handle returned by setTimeout. Used to cancel a pending timeout, if
  // it's superseded by a new one.
  timeoutHandle: TimeoutHandle | NoTimeout,
  // Top context object, used by renderSubtreeIntoContainer
  context: Object | null,
  pendingContext: Object | null,
  // Determines if we should attempt to hydrate on the initial mount
  +hydrate: boolean,
  // Remaining expiration time on this root.
  // TODO: Lift this into the renderer
  nextExpirationTimeToWorkOn: ExpirationTime,
  expirationTime: ExpirationTime,
  // List of top-level batches. This list indicates whether a commit should be
  // deferred. Also contains completion callbacks.
  // TODO: Lift this into the renderer
  firstBatch: Batch | null,
  // Linked-list of roots
  nextScheduledRoot: FiberRoot | null,
|};

type ProfilingOnlyFiberRootProperties = {|
  interactionThreadID: number,
  memoizedInteractions: Set<Interaction>,
  pendingInteractionMap: PendingInteractionMap,
|};

// Exported FiberRoot type includes all properties,
// To avoid requiring potentially error-prone :any casts throughout the project.
// Profiling properties are only safe to access in profiling builds (when enableSchedulerTracing is true).
// The types are defined separately within this file to ensure they stay in sync.
// (We don't have to use an inline :any cast when enableSchedulerTracing is disabled.)
export type FiberRoot = {
  ...BaseFiberRootProperties,
  ...ProfilingOnlyFiberRootProperties,
};

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createFiberRoot

export function createFiberRoot(
  containerInfo: any,
  isConcurrent: boolean,
  hydrate: boolean,
): FiberRoot {
  // Cyclic construction. This cheats the type system right now because
  // stateNode is any.
  const uninitializedFiber = createHostRootFiber(isConcurrent);

  let root;
  if (enableSchedulerTracing) {
    root = ({
      current: uninitializedFiber,
      containerInfo: containerInfo,
      pendingChildren: null,

      earliestPendingTime: NoWork,
      latestPendingTime: NoWork,
      earliestSuspendedTime: NoWork,
      latestSuspendedTime: NoWork,
      latestPingedTime: NoWork,

      pingCache: null,

      didError: false,

      pendingCommitExpirationTime: NoWork,
      finishedWork: null,
      timeoutHandle: noTimeout,
      context: null,
      pendingContext: null,
      hydrate,
      nextExpirationTimeToWorkOn: NoWork,
      expirationTime: NoWork,
      firstBatch: null,
      nextScheduledRoot: null,

      interactionThreadID: unstable_getThreadID(),
      memoizedInteractions: new Set(),
      pendingInteractionMap: new Map(),
    }: FiberRoot);
  } else {
    root = ({
      current: uninitializedFiber,
      containerInfo: containerInfo,
      pendingChildren: null,

      pingCache: null,

      earliestPendingTime: NoWork,
      latestPendingTime: NoWork,
      earliestSuspendedTime: NoWork,
      latestSuspendedTime: NoWork,
      latestPingedTime: NoWork,

      didError: false,

      pendingCommitExpirationTime: NoWork,
      finishedWork: null,
      timeoutHandle: noTimeout,
      context: null,
      pendingContext: null,
      hydrate,
      nextExpirationTimeToWorkOn: NoWork,
      expirationTime: NoWork,
      firstBatch: null,
      nextScheduledRoot: null,
    }: BaseFiberRootProperties);
  }

  uninitializedFiber.stateNode = root;

  // The reason for the way the Flow types are structured in this file,
  // Is to avoid needing :any casts everywhere interaction tracing fields are used.
  // Unfortunately that requires an :any cast for non-interaction tracing capable builds.
  // $FlowFixMe Remove this :any cast and replace it with something better.
  return ((root: any): FiberRoot);
}
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