uuid

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Generate and parse UUIDs.

Provides support for Universally Unique Identifiers (UUIDs). A UUID is a unique 128-bit number, stored as 16 octets. UUIDs are used to assign unique identifiers to entities without requiring a central allocating authority.

They are particularly useful in distributed systems, though they can be used in disparate areas, such as databases and network protocols. Typically a UUID is displayed in a readable string form as a sequence of hexadecimal digits, separated into groups by hyphens.

The uniqueness property is not strictly guaranteed, however for all practical purposes, it can be assumed that an unintentional collision would be extremely unlikely.

Getting started

To get started with generating random UUIDs, add this to your Cargo.toml:

[dependencies.uuid]
version = "0.8"
features = ["v4", "fast-rng"]

and then call Uuid::new_v4 in your code:

use uuid::Uuid;

let my_uuid = Uuid::new_v4();

You can also parse UUIDs without needing any crate features:

use uuid::{Uuid, Version};

let my_uuid = Uuid::parse_str("67e55044-10b1-426f-9247-bb680e5fe0c8")?;

assert_eq!(Some(Version::Random), my_uuid.get_version());

If you add the macros feature then you can parse UUIDs at compile time instead of at runtime:

#[macro_use]
extern crate uuid;

let my_uuid = uuid!("67e55044-10b1-426f-9247-bb680e5fe0c8")?;

assert_eq!(Some(Version::Random), my_uuid.get_version());

Dependencies

By default, this crate depends on nothing but std and cannot generate Uuids. You need to enable the following Cargo features to enable various pieces of functionality:

• v1 - adds the Uuid::new_v1 function and the ability to create a V1 using an implementation of uuid::v1::ClockSequence (usually uuid::v1::Context) and a timestamp from time::timespec.
• v3 - adds the Uuid::new_v3 function and the ability to create a V3 UUID based on the MD5 hash of some data.
• v4 - adds the Uuid::new_v4 function and the ability to randomly generate a Uuid.
• v5 - adds the Uuid::new_v5 function and the ability to create a V5 UUID based on the SHA1 hash of some data.
• macros - adds the uuid! macro that can parse UUIDs at compile time.
• serde - adds the ability to serialize and deserialize a Uuid using the serde crate.
• arbitrary - adds an Arbitrary trait implementation to Uuid.
• fast-rng - when combined with v4 uses a faster algorithm for generating random UUIDs. This feature requires more dependencies to compile, but is just as suitable for UUIDs as the default algorithm.

You need to enable one of the following Cargo features together with the v4 feature if you're targeting wasm32-unknown-unknown target:

• js - enables support for randomness on wasm32-unknown-unknown via [getrandom]

Alternatively, you can provide a custom getrandom implementation yourself via getrandom::register_custom_getrandom.

Unstable features

Some features are unstable. They may be incomplete or depend on other unstable libraries. These include:

• zerocopy-unstable - adds support for zero-copy deserialization using the zerocopy library.

Unstable features may break between minor releases.

To allow unstable features, you'll need to enable the Cargo feature as normal, but also pass an additional flag through your environment to opt-in to unstable uuid features:

RUSTFLAGS="--cfg uuid_unstable"

References

• Wikipedia: Universally Unique Identifier
• RFC4122: A Universally Unique IDentifier (UUID) URN Namespace

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License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or https://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.