https://github.com/insidewhy/rxjs-ratelimiter

rxjs lossless rate limiter
https://github.com/insidewhy/rxjs-ratelimiter

angular rate-limiter rate-limiting redux-observable rxjs rxjs6

Last synced: 3 months ago
JSON representation

rxjs lossless rate limiter

• Host: GitHub
• URL: https://github.com/insidewhy/rxjs-ratelimiter
• Owner: insidewhy
• Created: 2017-06-10T11:56:08.000Z (about 8 years ago)
• Default Branch: master
• Last Pushed: 2025-03-24T16:40:57.000Z (3 months ago)
• Last Synced: 2025-03-27T22:36:47.189Z (3 months ago)
• Topics: angular, rate-limiter, rate-limiting, redux-observable, rxjs, rxjs6
• Language: TypeScript
• Homepage:
• Size: 134 KB
• Stars: 17
• Watchers: 1
• Forks: 5
• Open Issues: 13
• Metadata Files:
  • Readme: readme.markdown

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README

        
# rxjs-ratelimiter

[![build status](https://circleci.com/gh/ohjames/rxjs-ratelimiter.png?style=shield)](https://circleci.com/gh/ohjames/rxjs-ratelimiter)

[![Known Vulnerabilities](https://snyk.io/test/github/ohjames/rxjs-ratelimiter/badge.svg)](https://snyk.io/test/github/ohjames/rxjs-ratelimiter)

An rxjs library to facilitate dealing with rate limited resources (say, external REST APIs). Great for use with [@angular/http](https://www.npmjs.com/package/@angular/http).

This library is [fully tested](src/index.spec.ts) using rxjs's [marble testing](https://github.com/ReactiveX/rxjs/blob/master/doc/writing-marble-tests.md) and rxjs's [TestScheduler](http://reactivex.io/rxjs/file/es6/testing/TestScheduler.js.html) to provide virtual time scheduling.

## How to install

```bash

npm install -S rxjs-ratelimiter

```

```bash

yarn add rxjs-ratelimiter

```

## How to use

This example uses angular 2:

```javascript

import { Injectable } from '@angular/core';

import { Http, Response } from '@angular/http';

import RateLimiter from 'rxjs-ratelimiter'

@Injectable()

export class RateLimitedApi {

  // allow at most 6 requests every 1000ms

  private rateLimiter = new RateLimiter(6, 1000)

  constructor(private http: Http) {}

  makeRequest(path: string): Promise {

    return this.rateLimiter.limit(

      this.http.get(`https://my.api/${path}`)

    ).toPromise()

  }

}

```

`rateLimiter.limit` returns an observable that rate limits the subscription to the passed observable. To understand how this works it is important to realise that cold observables create requests lazily (when subscribed to, not when instantiated). In this example the http request happens when the rate limiter passes a subscription through to the observable returned by `this.http.get`, not at the time that `this.http.get` is called.

## Retrying requests

A consequence of the lazy nature of rate limited observable is that resubscriptions by operators chained from them (such as [retry](http://reactivex.io/rxjs/class/es6/Observable.js~Observable.html#instance-method-retry)) will also be subject to rate limitation.

```javascript

this.rateLimiter.limit(

  this.http.get(`https://my-api.co/`)

).pipe(retry())

```

This will produce an observable that will retry the HTTP request until it succeeds. The rate limiter also applies to the retries so at most one request can happen per second, less if the rate limiter is being used for other requests. To have the rate limiter apply to the initial request but not the retries the following modification can be made:

```javascript

this.rateLimiter.limit(this.http.get(`https://some.api/`).pipe(retry()))

```

## rxjs 5 support

Version 0.1.1 supports rxjs5. Versions 1.0.0 and onward will only support rxjs 6 (and later).