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| 'use strict';
| const pTry = require('p-try');
|
| const pLimit = concurrency => {
| if (!((Number.isInteger(concurrency) || concurrency === Infinity) && concurrency > 0)) {
| return Promise.reject(new TypeError('Expected `concurrency` to be a number from 1 and up'));
| }
|
| const queue = [];
| let activeCount = 0;
|
| const next = () => {
| activeCount--;
|
| if (queue.length > 0) {
| queue.shift()();
| }
| };
|
| const run = (fn, resolve, ...args) => {
| activeCount++;
|
| const result = pTry(fn, ...args);
|
| resolve(result);
|
| result.then(next, next);
| };
|
| const enqueue = (fn, resolve, ...args) => {
| if (activeCount < concurrency) {
| run(fn, resolve, ...args);
| } else {
| queue.push(run.bind(null, fn, resolve, ...args));
| }
| };
|
| const generator = (fn, ...args) => new Promise(resolve => enqueue(fn, resolve, ...args));
| Object.defineProperties(generator, {
| activeCount: {
| get: () => activeCount
| },
| pendingCount: {
| get: () => queue.length
| },
| clearQueue: {
| value: () => {
| queue.length = 0;
| }
| }
| });
|
| return generator;
| };
|
| module.exports = pLimit;
| module.exports.default = pLimit;
|
|
