@ceejbot/jumphash

Really remarkably trivial node bindings for Google's jump consistent hash.

Tested on nodes 4, 6, and 7. Is probably just fine on node 0.10 too.

npm install --save @ceejbot/jumphash

Usage

This module provides one function: jumphash(key, bucketCount). key must be a non-negative integer or a buffer. bucketCount must be a positive integer (0 is an invalid bucket count).

The return value is a integer in the range [0, bucketCount) that you can use as you wish. The paper linked above describes the intended data storage use.

var jumphash = require('@ceejbot/jumphash')
    assert = require('assert'),
    crypto = require('crypto');

var location = jumphash(23102, 16);
assert(location >= 0);
assert(location < 16);

var buffer = crypto
    .createHash('md5')
    .update('my-string-key-for-some-resource')
    .digest();
var location2 = jumphash(buffer, 16);

Only the first 64 bits of the buffer are considered, with the most significant bit first.

License

ISC