https://github.com/munawwar/hrw-hash

🤹 HRW / Rendezvous hashing in JS
https://github.com/munawwar/hrw-hash

consistent-hashing hash hashing-algorithm hrw-hashing nodejs rendezvous-hashing

Last synced: about 1 month ago
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🤹 HRW / Rendezvous hashing in JS

• Host: GitHub
• URL: https://github.com/munawwar/hrw-hash
• Owner: Munawwar
• License: mit
• Created: 2022-02-09T19:31:32.000Z (almost 3 years ago)
• Default Branch: master
• Last Pushed: 2024-07-14T06:31:02.000Z (6 months ago)
• Last Synced: 2024-11-28T18:12:27.161Z (about 2 months ago)
• Topics: consistent-hashing, hash, hashing-algorithm, hrw-hashing, nodejs, rendezvous-hashing
• Language: JavaScript
• Homepage:
• Size: 200 KB
• Stars: 7
• Watchers: 3
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# HRW (Highest Random Weight) hashing / Rendezvous hashing

https://en.wikipedia.org/wiki/Rendezvous_hashing.

```

npm install hrw-hash

```

```js

import { hrwHash } from 'hrw-hash'

// or const { hrwHash } = require('hrw-hash')

const servers = ['image-server-1.example.com', 'image-server-2.example.com']

const domainToUse = hrwHash('example.png', servers)[0] // always 'image-server-2.example.com'

```

Advantage of this hashing over other sticky load balancing algorithms is that:

1. it does not use a shared lookup table / ring

2. it is independent of the order of destinations (hrwHash('john', ['a', 'b']) is same as hrwHash('john', ['b', 'a']))

3. it distributes keys evenly (probabilistically) when a destination is added or removed

Disadvantage of this hashing method:

1. Replacing a destination with another one will re-route keys unnecessarily as the algo is order insensitive

The implementation is small (0.5 kb minified) and with no 3rd party dependencies. It uses bigint, unescape and encodeURIComponent, so it supports modern browsers, node.js >= 12.5.0 and cloudflare workers.

It uses `mulberry32(fnv1a32('key'))` as hash function internally for the random hash. In my tests, this gives better distribution than fnv1a-32 alone and still keeps the implementation fast and small.

```js

// for advanced use cases you can import the hash function

import { hashFunc } from 'hrw-hash'

hashFunc('string') // returns positive integer < 2^32

```

# Dev Test

Test the types against https://arethetypeswrong.github.io

# Breaking Change V2

- Removed minified dist files (dist/*.min.js). If you want minified build for browser, then use `import { hrwHash } from 'https://esm.sh/hrw-hash'`

- Removed UMD build

- Changed minimum node.js version requirement from >= v12.0.0 to >= 12.5.0