‘use strict’;
const kDone = Symbol(‘kDone’); const kRun = Symbol(‘kRun’);
/**
* A very simple job queue with adjustable concurrency. Adapted from * https://github.com/STRML/async-limiter */
class Limiter {
/** * Creates a new `Limiter`. * * @param {Number} [concurrency=Infinity] The maximum number of jobs allowed * to run concurrently */ constructor(concurrency) { this[kDone] = () => { this.pending--; this[kRun](); }; this.concurrency = concurrency || Infinity; this.jobs = []; this.pending = 0; } /** * Adds a job to the queue. * * @param {Function} job The job to run * @public */ add(job) { this.jobs.push(job); this[kRun](); } /** * Removes a job from the queue and runs it if possible. * * @private */ [kRun]() { if (this.pending === this.concurrency) return; if (this.jobs.length) { const job = this.jobs.shift(); this.pending++; job(this[kDone]); } }
}
module.exports = Limiter;