44 lines
1.1 KiB
TypeScript
44 lines
1.1 KiB
TypeScript
/**
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* Allow promises to be queued up and executed in order.
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*/
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export class PromiseQueue {
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private queue: any[] = [];
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private locked: boolean = false;
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/** Add new promise to queue */
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add(p: () => Promise<any>, delay?: number) {
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this._add(p, false, delay);
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}
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/** Add new promise to the from of the queue */
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addToBeginning(p: () => Promise<any>, delay?: number) {
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this._add(p, true, delay);
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}
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/** Clear the queue and reset state. */
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clearQueue() {
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this.queue = [];
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}
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private delay = (ms: number) => () => new Promise(resolve => setTimeout(resolve, ms));
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_add = (p: () => Promise<any>, beginning: boolean = false, delay?: number) => {
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const newPromise = delay ? [p, this.delay(delay)] : [p];
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beginning ? this.queue.unshift(newPromise) : this.queue.push(newPromise);
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if (!this.locked) {
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this.next();
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}
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};
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private next() {
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this.locked = true;
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const p = this.queue.shift();
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const finished = () => {
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this.queue.length > 0 ? this.next() : (this.locked = false);
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};
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Promise.all(p.map((v: any) => v()))
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.then(finished)
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.catch(finished);
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}
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}
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