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README.md

@thi.ng/ksuid

npm version npm downloads Mastodon Follow

This project is part of the @thi.ng/umbrella monorepo.

About

Configurable K-sortable unique IDs, ULIDs, binary & base-N encoded, 32/48/64bit time resolutions.

Idea based on segmentio/ksuid, though the added flexibility in terms of configuration & implementation also enables the creation of ULIDs:

Feature KSUID default ULID default
Configurable bit size 160 bits 128 bits
Base-N encoding scheme base62(1) base32 (Crockford)
Timestamp resolution seconds (32 bits) milliseconds (48 bits)
milliseconds (64 bits)
Epoch start time offset approx. 2020-09-13(2) none
Time-only base ID generation ✅ ✅
ID parsing / decomposition ✅ ✅
Configurable RNG source(3) ✅ ✅
  • (1) See @thi.ng/base-n for alternatives
  • (2) With the default offset, the max. supported date for KSUID32 is 2156-10-20T18:54:55Z
  • (3) Default: window.crypto, Math.random as fallback

IDs generated w/ this package are composed of a 32, 48 or 64 bit Unix epochs and N additional bits of a random payload (from a configurable source). By default all timestamps are shifted to free up bits for the future. IDs can be generated as byte arrays or base-N encoded strings. For the latter, the JS runtime MUST support BigInt.

KSUID bit layout diagram

CLI usage

Since v3.1.0 a small CLI for ad-hoc KSUID generation is included. Currently only KSUID32 is supported and IDs are always based on the current time:

npx @thi.ng/ksuid
# 0dwncLZE8byaQdccncWDmsNmlYt

# optionally provide number of random bytes to be used (default: 16)
npx @thi.ng/ksuid 8
# 01ogp9KDpWlQ0pXCY

Status

STABLE - used in production

Search or submit any issues for this package

Breaking changes

Since v3.0.0 all epoch time-shift config values are to be given in milliseconds. This change is unifying this behavior and is only a breaking change if using KSUID32 and specifying custom epoch offsets (using defaults is not impacted). Previously, KSUID32 used an offset given in seconds, whereas the other implementations already used milliseconds.

Related packages

  • @thi.ng/base-n - Arbitrary base-n conversions w/ presets for base8/16/32/36/58/62/64/85, support for bigints and encoding/decoding of byte arrays
  • @thi.ng/idgen - Generator of opaque numeric identifiers with optional support for ID versioning and efficient re-use
  • @thi.ng/random - Pseudo-random number generators w/ unified API, distributions, weighted choices, ID generation

Installation

yarn add @thi.ng/ksuid

ES module import:

<script type="module" src="https://cdn.skypack.dev/@thi.ng/ksuid"></script>

Skypack documentation

For Node.js REPL:

const ksuid = await import("@thi.ng/ksuid");

Package sizes (brotli'd, pre-treeshake): ESM: 809 bytes

Dependencies

API

Generated API docs

import { defKSUID32, defKSUID64, defULID } from "@thi.ng/ksuid";

// init 32bit epoch (resolution: seconds) w/ defaults
const id = defKSUID32();
// init 64bit epoch (resolution: milliseconds), same API
const id = defKSUID64();
// init 48bit epoch (resolution: milliseconds), same API
const id = defULID();

id.next();
// '05XCWbXa3akRqLDBUw4ogCVKGkd'

const a = id.nextBinary()
// Uint8Array(20) [
//     0, 160,  48, 77, 101, 251,
//   244,  17, 155, 97,  24, 101,
//    70,  71, 207, 23,  32,  21,
//   244, 116
// ]

// format a binary KSUID
id.format(a);
// '05XCZ32AaDZfZt0SWE2C22o6cqK'

id.parse("05XCZ32AaDZfZt0SWE2C22o6cqK")
// {
//   epoch: 1610498125000,
//   id: Uint8Array(16) [
//     101, 251, 244,  17, 155, 97,
//      24, 101,  70,  71, 207, 23,
//      32,  21, 244, 116
//   ]
// }

new Date(1610498125000).toISOString()
// '2021-01-13T00:35:25.000Z'

Creating custom IDs:

import { BASE36 } from "@thi.ng/base-n";

// no time shift, 64bit random
const id36 = defKSUID32({ base: BASE36, epoch: 0, bytes: 8 });

id32.next();
// '2VOUKH4K59AG0RXR4XH'

Benchmarks

yarn bench

benchmarking: b62, 128bit, n=10000
        warmup... 659.22ms (10 runs)
        executing...
        total: 6402.18ms, runs: 100
        mean: 64.02ms, median: 63.50ms, range: [59.98..96.15]
        q1: 62.64ms, q3: 64.41ms
        sd: 6.93%
benchmarking: b62, 64bit, n=10000
        warmup... 363.35ms (10 runs)
        executing...
        total: 3469.28ms, runs: 100
        mean: 34.69ms, median: 34.41ms, range: [32.61..56.58]
        q1: 33.35ms, q3: 35.41ms
        sd: 7.47%
benchmarking: b62, 32bit, n=10000
        warmup... 218.78ms (10 runs)
        executing...
        total: 2118.93ms, runs: 100
        mean: 21.19ms, median: 20.95ms, range: [20.20..25.74]
        q1: 20.71ms, q3: 21.30ms
        sd: 4.14%

Authors

If this project contributes to an academic publication, please cite it as:

@misc{thing-ksuid,
  title = "@thi.ng/ksuid",
  author = "Karsten Schmidt",
  note = "https://thi.ng/ksuid",
  year = 2020
}

License

© 2020 - 2023 Karsten Schmidt // Apache License 2.0