Ride

Scala global unique identifier (GUID) generator for large systems.

Description

Ride uses Mongo Object ID algorithm to generate globally unique IDs with a custom base32 serialization to make it shorter when transported as a string. See docs.

Internally it consists of:

• first 4 bytes representing the seconds since the Unix epoch
• next 3 bytes are the current machine identifier (hostname)
• next 2 bytes are process ID
• the last 3 bytes are 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.

Features

• Size: 12 bytes (96 bits). See comparison
• Guaranteed uniqueness for 16,777,216 (24 bits) IDs per second and per host/process
• Base32 hex encoded by default (20 chars when transported as printable string, sortable)
• K-ordered
• No need to set up a unique machine and/or data center ID
• Embedded time with 1 second precision
• Lock-free

Usage

Install

In your build.sbt add

libraryDependencies += "com.github.kolotaev" %% "ride" % "$VERSION_YOU_NEED"

Generating IDs

import com.github.kolotaev.ride.Id

val guid = Id()

println(guid)
// String => b8uhqvioith6uqnvvvq0

guid.getBytes
// => Array[Byte] = Array(90, 61, 29, 126, 88, -105, 98, 111, 106, -1, -1, -12)
// Byte representation of ID

val ids = Array.fill[Id](3) { Id() }
// Array(b8ui8kioith721fvvvj0, b8ui8kioith721fvvvjg, b8ui8kioith721fvvvk0)

Reproducing IDs

val guid2 = Id("b8uhqvioith6uqnvvvq0")

println(guid == guid2)
// true. guid and guid2 are considered equal objects, since they represent the same Id value

println(s"$guid" == s"$guid2")
// true. guid and guid2 are the same strings

// Creating ID from malformed string throws IllegalArgumentException exception
val guid3 = Id("bad-string")


// Id can be reconstructed with byte-array representation (useful when you save it as bytes, for example in DB)
val guid4 = Id(Array[Byte](90, 61, 13, 107, 88, -105, 98, 106, -53, -1, -1, -3))

// Creating ID from incorrect byte-array throws IllegalArgumentException exception
val guid5 = Id(Array[Byte](90, 61, 13))

Obtaining embedded info

guid.time
// => java.time.LocalDateTime = 2017-12-22T23:58:06
// Local time embedded into ID

guid.pid
// => Array[Byte] = Array(88, -105, 98)
// Prints PID embedded into ID. It's a truncated version of the real PID

guid.machine
// Array[Byte] = Array(88, -105, 98)
// Stored machine identifier bytes

guid.counter
// Int = 56

Other

Ride implements Serializable and Ordered[T].

Comparison with other unique identifiers

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. Ride 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.

Benchmarks

Approximate relative performance metrics.

References

The library is a JVM implementation of the awesome Golang library xid.

License

The source code is licensed under the MIT License.