saturating-time

A trait for limits and saturations on types inside [std::time].

• Easy: saturating-time only adds a single trait, [SaturatingTime] that is implemented for various types from the standard library.
• Future-Proof: In the case that [SaturatingTime::saturating_add()] and [SaturatingTime::saturating_sub()] become a part of the standard library, developers would only have to remove the use saturating_time::SaturatingTime line from their code.[^1] [^2].
• Portable: The algorithm for determining the limits is portable across operating systems: enjoy this crate from Windows, Darwin, and Linux, across the BSD systems, up to exotic ones such as Hermit OS and Redox.
• Secure: This crate does not make any use of unsafe Rust code.

Overview

saturating-time is a very minimal crate that only exposes a minimal trait: [SaturatingTime].

The trait itself offers the following methods:

• [SaturatingTime::max_value()] – Returns the maximum value for this type.
• [SaturatingTime::min_value()] – Returns the minimum value for this type.
• [SaturatingTime::saturating_add()] – Saturating addition for this type.
• [SaturatingTime::saturating_sub()] – Saturating subtraction for this type.
• [SaturatingTime::saturating_duration_since()] - Saturating time deltas for this type.

This trait is sealed, meaning applications may not implement it themselves. However, this crate implements this trait for two structures:

• [std::time::Instant]
• [std::time::SystemTime]

Example

Add the following to your Cargo.toml:

[dependencies]
saturating-time = "0.4.0"

If you use Rust nightly, you may want to do:

[dependencies]
saturating-time = { version = "0.4.0", features = ["nightly"] }

Now, you can use saturating-time in your code:

use std::time::{Duration, SystemTime};
use saturating_time::SaturatingTime;

// Get the maximum and minimum.
let max = SystemTime::max_value();
let min = SystemTime::min_value();

assert_eq!(max.saturating_add(Duration::new(1, 0)), max);
assert_eq!(min.saturating_sub(Duration::new(1, 0)), min);
assert!(max.saturating_duration_since(SystemTime::UNIX_EPOCH) >= Duration::ZERO);

Standardization Efforts

The eventual goal is to get this functionality into the Rust standard library.

SystemTime

SystemTime::MIN and SystemTime::MAX

In December 2025, SystemTime::MIN and SystemTime::MAX got merged into nightly.[^3]

This feature is guarded behind time_systemtime_limits and a tracking issue regarding the stabilization of it exists.[^4]

SystemTime::saturating_add(), et, al.

In January 2025, SystemTime::saturating_add(), SystemTime::saturating_sub(), and SystemTime::saturating_duration_since() got merged into nightly.[^5]

This feature is guarded behind time_saturating_systemtime and a tracking issue regarding the stabilization of it exists.[^6]

Instant

None yet.

[^1]: This is an effort the maintainers are actively working upon. [^2]: Assuming the name, signature, and behavior does not change. Unfortunately, we likely have to change the signature for the parameters because we currently use self whereas the standard library uses &self. It should not be a big problem though, because both Instant and SystemTime implement Copy. [^3]: https://github.com/rust-lang/rust/pull/149979 [^4]: https://github.com/rust-lang/rust/issues/149067 [^5]: https://github.com/rust-lang/rust/pull/151200 [^6]: https://github.com/rust-lang/rust/issues/151199

License and Copyright

This crate is licensed under MIT OR Apache-2.0. See the respective LICENSE-* files in the repository for more information.