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| 1 | +/* |
| 2 | + * Adapted from https://github.com/rxaviers/async-pool/blob/1.x/lib/es6.js |
| 3 | + * |
| 4 | + * Copyright (c) 2017 Rafael Xavier de Souza http://rafael.xavier.blog.br |
| 5 | + * |
| 6 | + * Permission is hereby granted, free of charge, to any person |
| 7 | + * obtaining a copy of this software and associated documentation |
| 8 | + * files (the "Software"), to deal in the Software without |
| 9 | + * restriction, including without limitation the rights to use, |
| 10 | + * copy, modify, merge, publish, distribute, sublicense, and/or sell |
| 11 | + * copies of the Software, and to permit persons to whom the |
| 12 | + * Software is furnished to do so, subject to the following |
| 13 | + * conditions: |
| 14 | + * |
| 15 | + * The above copyright notice and this permission notice shall be |
| 16 | + * included in all copies or substantial portions of the Software. |
| 17 | + * |
| 18 | + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
| 19 | + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES |
| 20 | + * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND |
| 21 | + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT |
| 22 | + * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, |
| 23 | + * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
| 24 | + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR |
| 25 | + * OTHER DEALINGS IN THE SOFTWARE. |
| 26 | + */ |
| 27 | + |
| 28 | +/** Executes the given async function over the iterable, up to a determined number of promises in parallel. */ |
| 29 | +export function asyncPool<T, R>(poolLimit: number, iterable: T[], iteratorFn: (item: T, iterable: T[]) => Promise<R>) { |
| 30 | + let i = 0; |
| 31 | + const ret: Promise<R>[] = []; |
| 32 | + const executing: Set<Promise<R>> = new Set(); |
| 33 | + const enqueue = (): Promise<any> => { |
| 34 | + if (i === iterable.length) { |
| 35 | + return Promise.resolve(); |
| 36 | + } |
| 37 | + const item = iterable[i++]; |
| 38 | + const p = Promise.resolve().then(() => iteratorFn(item, iterable)); |
| 39 | + ret.push(p); |
| 40 | + executing.add(p); |
| 41 | + const clean = () => executing.delete(p); |
| 42 | + p.then(clean).catch(clean); |
| 43 | + let r: Promise<any> = Promise.resolve(); |
| 44 | + if (executing.size >= poolLimit) { |
| 45 | + r = Promise.race(executing); |
| 46 | + } |
| 47 | + return r.then(() => enqueue()); |
| 48 | + }; |
| 49 | + return enqueue().then(() => Promise.all(ret)); |
| 50 | +} |
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