The key to a happy Rust/C++ relationship

Pascal Hartig

The history of Rust at Meta goes all the way back to 2016, when we first started using it for source control. Today, it has been widely embraced at Meta and is one of our primary supported server-s…

Overview

The article discusses the integration of Rust and C++ at Meta, highlighting the evolution of Rust usage since 2016 and the challenges faced in interoperability with existing C++ code. It also emphasizes the improvements brought by tools like cxx and async Rust, making collaboration between the two languages more seamless.

What You'll Learn

1

How to improve interoperability between Rust and C++ using the cxx crate

2

Why using async Rust can enhance performance in applications

3

When to adopt Rust in a predominantly C++ codebase

Key Questions Answered

What challenges does Meta face when integrating Rust with C++?

Meta has encountered challenges in getting Rust to interact with a large amount of existing C++ code. These challenges include ensuring safe interoperability and managing the complexities of integrating two different programming paradigms effectively.

How has the release of cxx improved Rust and C++ integration?

The release of cxx has facilitated safe interoperability between Rust and C++, making it easier for developers to integrate Rust code into existing C++ projects without compromising safety or performance.

Technologies & Tools

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Programming Language

Rust

Used for developing new features and improving safety in Meta's codebase.

Programming Language

C++

Existing codebase that Rust needs to interact with at Meta.

Library

Cxx

Facilitates safe interoperability between Rust and C++.

Key Actionable Insights

1
Consider adopting Rust for new projects at Meta to leverage its safety features and performance benefits.
As Rust becomes one of the primary supported server-side languages at Meta, utilizing it for new developments can enhance code safety and reduce bugs.

2
Utilize the cxx crate for projects that require both Rust and C++ to work together.
This tool simplifies the integration process, allowing developers to focus on functionality rather than compatibility issues.

3
Explore async Rust for applications that require high concurrency.
Async Rust can significantly improve performance in scenarios where handling multiple tasks simultaneously is critical.

Common Pitfalls

1

Underestimating the complexity of integrating Rust with existing C++ code can lead to significant development delays.

Many developers may assume that adding a new language is straightforward, but the intricacies of language interoperability require careful planning and understanding of both languages' paradigms.