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Async function optimiser
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| const EventEmitter = require('events'); | |
| class Optimizer extends EventEmitter { | |
| // state | |
| #inprogress = {}; | |
| constructor(fn, maxConcurrentCall = 10) { | |
| super(); | |
| this.setMaxListeners(maxConcurrentCall); | |
| return (tag) => { | |
| return async (...args) => { | |
| return new Promise((resolve, reject) => { | |
| this.once(tag, (err, result) => { | |
| if (err) reject(err); | |
| else resolve(result) | |
| }); | |
| if (!this.#inprogress[tag]) { | |
| this.#inprogress[tag] = true; | |
| fn(...args) | |
| .then((result) => { | |
| this.emit(tag, null, result); | |
| }) | |
| .catch((err) => { | |
| this.emit(tag, err, null); | |
| }) | |
| .finally(() => { | |
| this.#inprogress[tag] = false; | |
| }); | |
| } | |
| }); | |
| } | |
| } | |
| } | |
| } |
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| async function getRandomInOneSecond() { | |
| return new Promise((resolve) => { | |
| setTimeout(function (){ | |
| resolve(Math.random()); | |
| }, 1000); | |
| }) | |
| } | |
| async function test() { | |
| const getRandomInOneSecondFor = new Optimizer(getRandomInOneSecond); | |
| Promise.all([ | |
| getRandomInOneSecondFor('LuckyDraw A')(), | |
| getRandomInOneSecondFor('LuckyDraw B')(), | |
| getRandomInOneSecondFor('LuckyDraw A')(), | |
| getRandomInOneSecondFor('LuckyDraw A')(), | |
| getRandomInOneSecondFor('LuckyDraw B')(), | |
| ]).then((results) => { | |
| console.log(results); | |
| }); | |
| } | |
| test().catch(console.error); |
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