promise-wip-throttler v0.2.1

promise-wip-throttler

Set a WIP(work in progress) limit for your promises.

npm install promise-wip-throttler

Example use cases

• Make sure to not overload an external service.
• Limit the number of concurrent memory heavy and/or CPU intensive tasks.

Usage

The following example creates a throttler that will only allow 2 heavyOperations to run concurrently. The third one will not be started until one of the first two resolves.

import { createThrottler } from 'promise-wip-throttler';

const throttler = createThrottler(2);

throttler(() => heavyOperation());
throttler(() => heavyOperation());
throttler(() => heavyOperation());
throttler(() => heavyOperation());
throttler(() => heavyOperation());
throttler(() => heavyOperation());
throttler(() => heavyOperation());

Decorator

The throttler is also available as a higher order function that can wraps the target function. The throttled function returns a promise that will resolve once the function has finished executing.

import { throttled } from 'promise-wip-throttler';


function mySlowFunction() {
 // Heavy lifting, retuns a promise
}

const myThrottledSlowFunction = throttled(1)(mySlowFunction);

// Will only run one at a time
myThrottledSlowFunction().then(() => { console.log('I\'m done'); });
myThrottledSlowFunction().then(() => { console.log('I\'m done'); });
myThrottledSlowFunction().then(() => { console.log('I\'m done'); });
myThrottledSlowFunction().then(() => { console.log('I\'m done'); });
myThrottledSlowFunction().then(() => { console.log('I\'m done'); });
myThrottledSlowFunction().then(() => { console.log('I\'m done'); });

License

MIT

Copyright Daniel Lundin 2017