Kismet Hasanaj
58 lines
1.8 KiB
JavaScript
58 lines
1.8 KiB
JavaScript
/*
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This is a simple promise queue that allows you to limit the number of concurrent promises
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that are running at any given time. It's used to limit the number of concurrent
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prefetch requests that are being made to the server but could be used for other
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things as well.
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*/ export class PromiseQueue {
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#maxConcurrency;
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#runningCount;
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#queue;
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constructor(maxConcurrency = 5){
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this.#maxConcurrency = maxConcurrency;
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this.#runningCount = 0;
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this.#queue = [];
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}
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enqueue(promiseFn) {
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let taskResolve;
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let taskReject;
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const taskPromise = new Promise((resolve, reject)=>{
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taskResolve = resolve;
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taskReject = reject;
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});
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const task = async ()=>{
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try {
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this.#runningCount++;
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const result = await promiseFn();
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taskResolve(result);
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} catch (error) {
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taskReject(error);
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} finally{
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this.#runningCount--;
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this.#processNext();
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}
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};
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const enqueueResult = {
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promiseFn: taskPromise,
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task
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};
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// wonder if we should take a LIFO approach here
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this.#queue.push(enqueueResult);
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this.#processNext();
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return taskPromise;
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}
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bump(promiseFn) {
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const index = this.#queue.findIndex((item)=>item.promiseFn === promiseFn);
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if (index > -1) {
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const bumpedItem = this.#queue.splice(index, 1)[0];
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this.#queue.unshift(bumpedItem);
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this.#processNext(true);
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}
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}
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#processNext(forced = false) {
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if ((this.#runningCount < this.#maxConcurrency || forced) && this.#queue.length > 0) {
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this.#queue.shift()?.task();
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}
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}
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}
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//# sourceMappingURL=promise-queue.js.map
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