limiter/README.md

Limiter

A promise pool with RPS limiter.

Features:

• TypeScript first
• Limits parrallel promises execution
• Limits RPS (requests per second), evenly distributes the requests over time
• Able to retry
• Simple API
• Simple async/await flow
• Allows to handle errors silently using onError callback
• Works with any runtime (Bun/Deno/Node)

Install

bun add github:nesterow/limiter # or pnpm

Usage

Add tasks

import { Limiter, LimiterRetryError } from "@nesterow/limiter";

const task = ({ url }) => {
  await fetch(url);
  // ... write
};

const limiter = new Limiter({
  limit: 20,
  onError(error) {
    // Logger.error(error)
  },
});

limiter.process(task);
limiter.process(task);
limiter.process(task);

Limit number of requests

import { Limiter } from "@nesterow/limiter";

const task = () => {
  await fetch("https://my.api.xyz");
  // ... write
};

const limiter = new Limiter({
  limit: 10,
});

await limiter.process(...Array.from({ length: 100 }, () => task()));

Limit RPS

import { Limiter } from "@nesterow/limiter";

const execEvery100ms = () => {
  await fetch("https://my.api.xyz");
  // ... write
};

const limiter = new Limiter({
  limit: 20,
  rps: 10,
});

await limiter.process(...Array.from({ length: 100 }, () => execEvery100ms()));

Retry

import { Limiter, LimiterRetryError } from "@nesterow/limiter";

const retry5times = () => {
  await fetch("https://my.api.xyz");
  throw new Error("Connection refused");
  // ... write
};

const limiter = new Limiter({
  limit: 20,
  maxRetry: 5,
});

for (let i = 0; i < 100; i++) {
  try {
    await limiter.process(Array.from({ length: 100 }, () => retry5times()));
  } catch (e) {
    if (e instanceof LimiterRetryError) {
      // Logger.log(e)
    }
  }
}

Handle errors in background

import { Limiter, LimiterRetryError } from "@nesterow/limiter";

const wontStopPooling = () => {
  await fetch("https://my.api.xyz");
  throw new Error("Connection refused");
  // ... write
};

const limiter = new Limiter({
  limit: 20,
  maxRetry: 5,
  onError(error) {
    // Logger.error(error)
  },
});

for (let i = 0; i < 100; i++) {
  await limiter.process(Array.from({ length: 100 }, () => wontStopPooling()));
}