import { AsyncAction } from './AsyncAction';
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import { Subscription } from '../Subscription';
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import { AsyncScheduler } from './AsyncScheduler';
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import { SchedulerAction } from '../types';
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import { TimerHandle } from './timerHandle';
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export class VirtualTimeScheduler extends AsyncScheduler {
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/** @deprecated Not used in VirtualTimeScheduler directly. Will be removed in v8. */
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static frameTimeFactor = 10;
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/**
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* The current frame for the state of the virtual scheduler instance. The difference
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* between two "frames" is synonymous with the passage of "virtual time units". So if
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* you record `scheduler.frame` to be `1`, then later, observe `scheduler.frame` to be at `11`,
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* that means `10` virtual time units have passed.
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*/
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public frame: number = 0;
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/**
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* Used internally to examine the current virtual action index being processed.
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* @deprecated Internal implementation detail, do not use directly. Will be made internal in v8.
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*/
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public index: number = -1;
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/**
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* This creates an instance of a `VirtualTimeScheduler`. Experts only. The signature of
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* this constructor is likely to change in the long run.
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*
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* @param schedulerActionCtor The type of Action to initialize when initializing actions during scheduling.
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* @param maxFrames The maximum number of frames to process before stopping. Used to prevent endless flush cycles.
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*/
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constructor(schedulerActionCtor: typeof AsyncAction = VirtualAction as any, public maxFrames: number = Infinity) {
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super(schedulerActionCtor, () => this.frame);
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}
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/**
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* Prompt the Scheduler to execute all of its queued actions, therefore
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* clearing its queue.
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* @return {void}
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*/
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public flush(): void {
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const { actions, maxFrames } = this;
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let error: any;
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let action: AsyncAction<any> | undefined;
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while ((action = actions[0]) && action.delay <= maxFrames) {
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actions.shift();
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this.frame = action.delay;
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if ((error = action.execute(action.state, action.delay))) {
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break;
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}
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}
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if (error) {
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while ((action = actions.shift())) {
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action.unsubscribe();
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}
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throw error;
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}
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}
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}
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export class VirtualAction<T> extends AsyncAction<T> {
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protected active: boolean = true;
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constructor(
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protected scheduler: VirtualTimeScheduler,
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protected work: (this: SchedulerAction<T>, state?: T) => void,
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protected index: number = (scheduler.index += 1)
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) {
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super(scheduler, work);
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this.index = scheduler.index = index;
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}
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public schedule(state?: T, delay: number = 0): Subscription {
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if (Number.isFinite(delay)) {
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if (!this.id) {
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return super.schedule(state, delay);
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}
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this.active = false;
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// If an action is rescheduled, we save allocations by mutating its state,
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// pushing it to the end of the scheduler queue, and recycling the action.
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// But since the VirtualTimeScheduler is used for testing, VirtualActions
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// must be immutable so they can be inspected later.
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const action = new VirtualAction(this.scheduler, this.work);
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this.add(action);
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return action.schedule(state, delay);
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} else {
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// If someone schedules something with Infinity, it'll never happen. So we
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// don't even schedule it.
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return Subscription.EMPTY;
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}
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}
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protected requestAsyncId(scheduler: VirtualTimeScheduler, id?: any, delay: number = 0): TimerHandle {
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this.delay = scheduler.frame + delay;
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const { actions } = scheduler;
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actions.push(this);
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(actions as Array<VirtualAction<T>>).sort(VirtualAction.sortActions);
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return 1;
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}
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protected recycleAsyncId(scheduler: VirtualTimeScheduler, id?: any, delay: number = 0): TimerHandle | undefined {
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return undefined;
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}
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protected _execute(state: T, delay: number): any {
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if (this.active === true) {
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return super._execute(state, delay);
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}
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}
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private static sortActions<T>(a: VirtualAction<T>, b: VirtualAction<T>) {
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if (a.delay === b.delay) {
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if (a.index === b.index) {
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return 0;
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} else if (a.index > b.index) {
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return 1;
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} else {
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return -1;
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}
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} else if (a.delay > b.delay) {
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return 1;
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} else {
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return -1;
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}
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}
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}
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