A helper library to manage expotential backoff intervals of different resources.
This can be used to manage retry interval of login attempts per IP address and apply rate limit on abnormal request / rare API calls.
npm install backoff-poolimport from typescript:
import { BackoffPool } from 'backoff-pool'Or import from javascript:
const { BackoffPool } = require('backoff-pool')export class BackoffPool<Key = string | number> {
constructor(options?: BackoffPoolOptions)
success(key: Key): void
fail(key: Key): void
applyRandomBackoff(key: Key, range?: number): void
getInterval(key: Key): number
getUnlockTime(key: Key): number | undefined
isLocked(key: Key): boolean
isAvailable(key: Key): boolean
}
export interface BackoffPoolOptions {
defaultInterval?: number // default 0
initialBackoffInterval?: number // default 1 second
maxBackoffInterval?: number // default unlimited
backoffFactor?: number // default 2
randomBackoffRatio?: number // default 0.2 (20%)
}
export let defaultBackoffPoolOptions: Required<BackoffPoolOptions>Login attempt cooldown example
let backoffPool = new BackoffPool({
defaultInterval: 0,
initialBackoffInterval: 2000,
backoffFactor: 2,
})
let clientIP = 'stub'
console.log('0', backoffPool.isAvailable(clientIP)) // true: is available
console.log('0', backoffPool.isLocked(clientIP)) // false: not locked
console.log('0', backoffPool.getUnlockTime(clientIP)) // undefined: not locked
backoffPool.fail(clientIP) // lock for 2 seconds
console.log('1', backoffPool.isAvailable(clientIP)) // false: not available
console.log('1', backoffPool.getUnlockTime(clientIP)) // Date.now() + 2000
backoffPool.fail(clientIP) // failed again, lock for 4 seconds
backoffPool.fail(clientIP) // failed again, lock for 8 seconds
console.log('2', backoffPool.getInterval(clientIP)) // 8000: 8 seconds
await sleep(7 * 1000)
console.log('7', backoffPool.isAvailable(clientIP)) // false: still locked
await sleep(1 * 1000)
console.log('8', backoffPool.isAvailable(clientIP)) // true: unlocked now
backoffPool.success(clientIP) // reset the interval
console.log('9', backoffPool.getInterval(clientIP)) // 0: same as defaultInterval
backoffPool.fail(clientIP) // lock for 2 seconds instead of 16 seconds
await sleep(2 * 1000)
console.log('10', backoffPool.isLocked(clientIP)) // false: unlocked nowMore examples see test/example.ts and test/core.test.ts
This project is licensed with BSD-2-Clause
This is free, libre, and open-source software. It comes down to four essential freedoms [ref]:
- The freedom to run the program as you wish, for any purpose
- The freedom to study how the program works, and change it so it does your computing as you wish
- The freedom to redistribute copies so you can help others
- The freedom to distribute copies of your modified versions to others
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