Module item-queue

item-queue

An item processing queue using Promise.

Features

incrementally add items
concurrent processing
pause and resume processing
automatic watch timer for long pending items
per item timeout with an AbortSignal

Usage

Simple Example:

import { ItemQueue } from "item-queue";

async function test() {
  let total = 0;

  const queue = new ItemQueue<number>({
    // processItem can be an async or sync function
    async processItem(delay) {
      await new Promise((resolve) => setTimeout(resolve, delay));
      total = total + delay;
    },
    itemQ: [10, 20, 30, 40, 50, 60, 70, 80, 90],
    concurrency: 2,
  });

  const waiting = queue.start().wait();
  queue.addItem(75); // add one item while queue in progress
  queue.addItems([55, 45, 35]); // can add multiple items also
  await waiting;

  console.log("result:", total);
}

Timeout

Set timeout to fail any item that takes longer than that many milliseconds.

const queue = new ItemQueue<string>({
  timeout: 5000,
  async processItem(url, _id, signal) {
    const res = await fetch(url, { signal });
    return res.text();
  },
});

A timed out item fails with an ETIMEDOUT error, and its slot goes to the next item. A result that arrives after the timeout is ignored. The queue can't cancel the work, so processItem gets an AbortSignal that is aborted on timeout. Pass it on or check it to stop the work. The signal is only passed when timeout is set.