Teak.js

A simple async task queue. Preserve order of async tasks.

Getting Started

To install:

npm i @skapoor8/teak

Features

Queue async tasks from different requests on the server

Use in node.js:

const TaskQueue = require("@skapoor8/teak");

function main() {
  var tq = new TaskQueue();

  var wait = (ms) =>
    new Promise((resolve, reject) => {
      setTimeout(() => resolve(ms), ms);
    });

  console.log("Start time:", new Date());
  tq.enqueue(wait, [1000]).then((res) =>
    console.log(`${res} seconds passed. Current time:`, new Date())
  );
  tq.enqueue(wait, [5000]).then((res) =>
    console.log(`${res} seconds passed. Current time:`, new Date())
  );
  tq.enqueue(wait, [10000]).then((res) => {
    console.log(`${res} seconds passed. Current time:`, new Date());
    tq.enqueue(wait, [1000]).then((res) =>
      console.log(`${res} seconds passed. Current time:`, new Date())
    );
  });
}
main();

Output in console:

Start time: 2021-07-03T21:04:53.536Z
1000 seconds passed. Current time: 2021-07-03T21:04:54.548Z
5000 seconds passed. Current time: 2021-07-03T21:04:59.551Z
10000 seconds passed. Current time: 2021-07-03T21:05:09.552Z
1000 seconds passed. Current time: 2021-07-03T21:05:10.556Z

Motivation

Typically async tasks like the one show above can be performed in order by simply using async-await. This is a little trickier on the server side when tasks may be enqueued in response to a http request, and therefore we cannot use the await keyword or chain callbacks to ensure tasks are performed in order. Teak.js can be used in such situations.

Specifically, I wrote teak.js when I was working on an embedded database, and wanted to queue sequential writes to the same record coming from different requests.

Future Directions

1. Add unit tests
2. Add an ES6 wrapper

API

1. new TaskQueue()

   • returns a task queue

2. TaskQueue.enqueue(f, args)

   • returns a Promise that is resolved when f is called and resolved
   • f is an async function
   • args is an array of arguments expected by f