Class TreeNode

src/binder.ts:614–693

* Node in the tree that manages the collective state of shutdowns, so that * terminations and disconnections happen gracefully in-order.

 * terminations and disconnections happen gracefully in-order.
 */
class TreeNode {
  public static targetNodes = new WeakMap<ITarget, TreeNode>();
  public readonly threadData = getDeferred<ThreadData>();

  private _state = TargetState.Running;
  private readonly _children = new Set<TreeNode>();
  private readonly _stateChangeEmitter = new EventEmitter<TargetState>();

  public get state() {
    return this._state;
  }

  public set state(state: TargetState) {
    if (state > this._state) {
      this._state = state;
      this._stateChangeEmitter.fire(state);
    }
  }

  /** Value is only undefined for the root node */
  constructor(public readonly value: ITarget | undefined) {
    if (value) {
      TreeNode.targetNodes.set(value, this);
    }
  }

  /**
   * Adds a new child to the target tree.
   */
  public add(child: TreeNode) {
    this._children.add(child);
  }

  /**
   * Removes a child to the target tree.
   */
  public remove(child: TreeNode) {
    this._children.delete(child);
  }

  /**
   * Returns a promise that resolves when this node has reached at least the
   * given state in the lifecycle.
   */
  public async waitUntil(state: TargetState) {
    if (this._state >= state) {
      return Promise.resolve();
    }

    return new Promise<void>(resolve => {
      const l = this._stateChangeEmitter.event(s => {
        if (s >= state) {
          l.dispose();
          resolve();
        }
      });
    });
  }