gxid

A Gleam implementation of xid

Quick start

gleam run   # Run the project
gleam test  # Run the tests
gleam shell # Run an Erlang shell

Installation

This package can be added to your Gleam project:

gleam add gxid

and its documentation can be found at https://hexdocs.pm/gxid.

Usage

Generate a new XID

import gxid.{type XID}

let assert Ok(channel) = gxid.start()

let xid: XID = gxid.generate(channel)
let str_xid = xid
             |> gxid.string()

From an existing XID

import gxid.{type XID}

let xid: XID = gxid.parse("h8a8u4o00de6hq6tsc00")
let str_xid = xid
             |> gxid.string()

About XID

Xid uses the Mongo Object ID algorithm to generate globally unique ids with a different serialization (base64) to make it shorter when transported as a string: https://docs.mongodb.org/manual/reference/object-id/

• 4-byte value representing the seconds since the Unix epoch,
• 3-byte machine identifier,
• 2-byte process id, and
• 3-byte counter, starting with a random value.

The binary representation of the id is compatible with Mongo 12 bytes Object IDs. The string representation is using base32 hex (w/o padding) for better space efficiency when stored in that form (20 bytes). The hex variant of base32 is used to retain the sortable property of the id.

Xid doesn’t use base64 because case sensitivity and the 2 non alphanum chars may be an issue when transported as a string between various systems. Base36 wasn’t retained either because 1/ it’s not standard 2/ the resulting size is not predictable (not bit aligned) and 3/ it would not remain sortable. To validate a base32 xid, expect a 20 chars long, all lowercase sequence of a to v letters and 0 to 9 numbers ([0-9a-v]{20}).

UUIDs are 16 bytes (128 bits) and 36 chars as string representation. Twitter Snowflake ids are 8 bytes (64 bits) but require machine/data-center configuration and/or central generator servers. xid stands in between with 12 bytes (96 bits) and a more compact URL-safe string representation (20 chars). No configuration or central generator server is required so it can be used directly in server’s code.

References:

• http://www.slideshare.net/davegardnerisme/unique-id-generation-in-distributed-systems
• https://en.wikipedia.org/wiki/Universally_unique_identifier
• https://blog.twitter.com/2010/announcing-snowflake
• Go port by Olivier Poitrey: https://github.com/rs/xid
• Python port by Graham Abbott: https://github.com/graham/python_xid
• Scala port by Egor Kolotaev: https://github.com/kolotaev/ride
• Rust port by Jérôme Renard: https://github.com/jeromer/libxid
• Ruby port by Valar: https://github.com/valarpirai/ruby_xid
• Java port by 0xShamil: https://github.com/0xShamil/java-xid
• Dart port by Peter Bwire: https://pub.dev/packages/xid
• PostgreSQL port by Rasmus Holm: https://github.com/modfin/pg-xid
• Swift port by Uditha Atukorala: https://github.com/uditha-atukorala/swift-xid
• C++ port by Uditha Atukorala: https://github.com/uditha-atukorala/libxid