Extend System.Guid with a new creation API for v7 #103658
Description
Rationale
The UUID specification (https://datatracker.ietf.org/doc/rfc9562) defines several different UUID versions which can be created and which allow developers to produce and consume UUIDs that have a particular structure.
As such, we should expose helpers to allow creating such UUIDs. For .NET 9, the set of potential versions is detailed below, but only UUIDv7 is proposed for the time being.
As per the UUID spec, GUID is a valid alternative name and so the name of the new APIs remains NewGuid* for consistency with our existing APIs:
This specification defines UUIDs (Universally Unique IDentifiers) -- also known as GUIDs (Globally Unique IDentifiers)
API Proposal
namespace System;
public partial struct Guid
{
// Alternatively: MaxValue -or- AllBitsSet
public static Guid Max { get; }
public int Variant { get; }
public int Version { get; }
// v1
// 60-bit timestamp 100ns ticks since 00:00:00.00, 15 October 1582 UTC
// 14-bit clock sequence, intended to be random once in the lifetime of system
// 48-bit node identifier, as in IEEE 802 Node IDs
// v2
// DCE Security UUIDs
// v3
// 128-bit MD5 of namespaceId + name converted to canonical octet sequence
// 6-bits then replaced with the version/variant fields
// v4
// Already exposed as NewGuid()
// v5
// 192-bit SHA1 of namespaceId + name converted to canonical octet sequence, taking the most significant 128-bits
// 6-bits then replaced with the version/variant fields
// v6
// 60-bit timestamp 100ns ticks since 00:00:00.00, 15 October 1582 UTC
// 14-bit clock sequence, intended to be random for every new UUID, can be compatible with v1
// 48-bit node identifier, intended to be random for every new UUID, can be compatible with v1
// v7
// 48-bit timestamp millisecond ticks since Unix Epoch
// 12-bits of random data -or- submillisecond timestamp (M3)
// M3 - Scale remaining precision to fit into the 12-bits at even intervals
// 62-bits of random data -or- carefully seeded counter (M1 or M2)
// M1 - Dedicated counter, simply increment per UUID created within a given tick stamp
// M2 - Monotonic random, seed random then increment by random amount within a given tick stamp
public static Guid NewGuidv7(); // uses DateTime.UtcNow
public static Guid NewGuidv7(DateTime timestamp);
// v8
// 48-bits of custom data
// 12-bits of custom data
// 62-bits of custom data
}