queue-promise
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A simple, dependency-free library for concurrent promise-based queues. Comes with with concurrency and timeout control.
queue-promise is a small, dependency-free library for promise-based queues. It will execute enqueued tasks concurrently at a given speed. When a task is being resolved or rejected, an event is emitted.
$ npm install queue-promise
import Queue from "queue-promise";
const queue = new Queue({
concurrent: 1,
interval: 2000,
start: true
});
queue.on("start", () => /* … */);
queue.on("stop", () => /* … */);
queue.on("end", () => /* … */);
queue.on("resolve", data => console.log(data));
queue.on("reject", error => console.error(error));
queue.enqueue(asyncTaskA); // resolved/rejected after 0ms
queue.enqueue(asyncTaskB); // resolved/rejected after 2000ms
queue.enqueue(asyncTaskC); // resolved/rejected after 4000ms
queue.enqueue(asyncTaskD); // resolved/rejected after 6000ms
new Queue(options)Create a new Queue instance.
| Option | Default | Description |
|---|---|---|
concurrent | 5 | How many tasks should be executed in parallel |
interval | 500 | How often should new tasks be executed (in ms) |
start | true | Whether it should automatically execute new tasks as soon as they are added |
.enqueue(tasks)/.add(tasks)Adds a new task to the queue. A task should be an async function (ES2017) or return a Promise. Throws an error if the provided task is not a valid function.
Example:
async function getRepos(user) {
return await github.getRepos(user);
}
queue.enqueue(() => {
return getRepos("userA");
});
queue.enqueue(async () => {
await getRepos("userB");
});
// …equivalent to:
queue.enqueue([() => getRepos("userA"), () => getRepos("userB")]);
.dequeue()Executes n concurrent (based od options.concurrent) promises from the queue. Uses global Promises. Is called automatically if options.start is set to true. Emits resolve and reject events.
Example:
queue.enqueue(() => getRepos("userA"));
queue.enqueue(() => getRepos("userB"));
// If "concurrent" is set to 1, only one promise is executed on dequeue:
const userA = await queue.dequeue();
const userB = await queue.dequeue();
// If "concurrent" is set to 2, two promises are executed concurrently:
const [userA, userB] = await queue.dequeue();
Note:
.dequeue() function throttles (is executed at most once per every options.interval milliseconds).
.on(event, callback)Sets a callback for an event. You can set callback for those events: start, stop, resolve, reject, dequeue, end.
Example:
queue.on("dequeue", () => …);
queue.on("resolve", data => …);
queue.on("reject", error => …);
queue.on("start", () => …);
queue.on("stop", () => …);
queue.on("end", () => …);
Note:
dequeue, resolve and reject events are emitted per task. This means that even if concurrent is set to 2, 2 events will be emitted.
.start()Starts the queue – it will automatically dequeue tasks periodically. Emits start event.
queue.enqueue(() => getRepos("userA"));
queue.enqueue(() => getRepos("userB"));
queue.enqueue(() => getRepos("userC"));
queue.enqueue(() => getRepos("userD"));
queue.start();
// No need to call `dequeue` – you can just listen for events:
queue.on("resolve", data => …);
queue.on("reject", error => …);
.stop()Forces the queue to stop. New tasks will not be executed automatically even if options.start was set to true. Emits stop event.
.clear()Removes all tasks from the queue.
.startedWhether the queue is running.
.stoppedWhether the queue has been forced to stop by calling Queue.stop.
.isEmptyWhether the queue is empty, i.e. there's no tasks.
$ npm test
2.1.0 (2020-07-01)
All notable changes to this project will be documented in this file. See standard-version for commit guidelines.
FAQs
A simple, dependency-free library for concurrent promise-based queues. Comes with with concurrency and timeout control.
The npm package queue-promise receives a total of 9,273 weekly downloads. As such, queue-promise popularity was classified as popular.
We found that queue-promise demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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