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  • License MIT

Queue promises into pool limiting concurrency

Package Exports

  • promise-pool-ext
  • promise-pool-ext/lib/index.js

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (promise-pool-ext) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

promise-pool-ext

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Queue promises into pool limiting concurrency

Install

Install with npm:

$ npm install --save promise-pool-ext

Usage

Pool

import { Pool } from 'promise-pool-ext';

const pool = Pool({ concurrency: 10 });

// queue array of functions, returns Promise < array of function results >
pool([
  () => new Promise((resolve) => { /* do async logic here */ }),
  async () => { /* do async logic here */ }
]);

// queue function, returns Promise < function result >
pool(async () => { /* do async logic here */ });

See tests for more examples

PoolManager

import { PoolManager } from 'promise-pool-ext';

const manager = PoolManager({
  check1: {
    if: () => false, // when not true returned, promise is not resolved and undefined is returned
    fn: () => { /* return async logic */ }
  },
  check2: {
    requires: ['check1'],
    fn: ({ check1 }) => {
      if (check1) { /* return async logic */ }
    }
  },
  data: {
    requires: ['check1', 'check2'],
    fn: ({ check1, check2 }) => {
      if (check1 && check2) { /* return async logic */ }
    }
  }
}, { concurrency: 10 });

// returns Promise < data.fn result >
manager.get('data');

See tests for more examples

Parameters

concurrency: Integer

How many promises can resolve in parallel.

timeout: Integer = undefined

Maximum amount of time in ms that a promise can take to resolve before a failure is returned.

If 0 or undefined is passes, no timeout is enforced.

Errors

When a promise is rejected or an error is thrown, the returned promise is rejected once all promises in batch have completed execution.

Why

As an example, when making a lot of external requests one can hit limits of the external API or the node runtime itself. This library makes it easy to limit the amount of parallel executions.