Scaling Rust Adoption By way of Coaching

Android 14 is the third main Android launch with Rust help. We’re already seeing an a variety of benefits:

These optimistic early outcomes supplied an attractive motivation to extend the pace and scope of Rust adoption. We hoped to perform this by investing closely in coaching to develop from the early adopters.

Early adopters are sometimes prepared to just accept extra threat to check out a brand new know-how. They know there will likely be some inconveniences and a steep studying curve however are prepared to be taught, usually on their very own time.

Scaling up Rust adoption required shifting past early adopters. For that we have to guarantee a baseline stage of consolation and productiveness inside a set time period. An necessary a part of our technique for conducting this was coaching. Sadly, the kind of coaching we wished to supply merely didn’t exist. We made the choice to put in writing and implement our personal Rust coaching.

Our objectives for the coaching have been to:

• Shortly ramp up engineers: It’s onerous to take individuals away from their common work for a protracted time period, so we aimed to supply a strong basis for utilizing Rust in days, not weeks. We couldn’t make anyone a Rust professional in so little time, however we might give individuals the instruments and basis wanted to be productive whereas they continued to develop. The purpose is to allow individuals to make use of Rust to be productive members of their groups. The time constraints meant we couldn’t educate individuals programming from scratch; we additionally determined to not educate macros or unsafe Rust intimately.
• Make it participating (and enjoyable!): We wished individuals to see a variety of Rust whereas additionally getting hands-on expertise. Given the scope and time constraints talked about above, the coaching was essentially information-dense. This referred to as for an interactive setting the place individuals might rapidly ask inquiries to the trainer. Analysis reveals that retention improves when individuals can rapidly confirm assumptions and observe new ideas.
• Make it related for Android: The Android-specific tooling for Rust was already documented, however we wished to point out engineers use it by way of labored examples. We additionally wished to doc rising requirements, equivalent to utilizing thiserror and anyhow crates for error dealing with. Lastly, as a result of Rust is a brand new language within the Android Platform (AOSP), we would have liked to point out interoperate with present languages equivalent to Java and C++.

With these three objectives as a place to begin, we appeared on the present materials and obtainable instruments.

Present Materials

Documentation is a key worth of the Rust group and there are various nice sources obtainable for studying Rust. First, there may be the freely obtainable Rust E book, which covers nearly all the language. Second, the usual library is extensively documented.

As a result of we knew our target market, we might toughen assumptions than most materials discovered on-line. We created the course for engineers with no less than 2–3 years of coding expertise in both C, C++, or Java. This allowed us to maneuver rapidly when explaining ideas acquainted to our viewers, equivalent to “management circulation”, “stack vs heap”, and “strategies”. Individuals with different backgrounds can be taught Rust from the various different sources freely obtainable on-line.

Know-how

At no cost-form documentation, mdBook has grow to be the de facto commonplace within the Rust group. It’s used for official documentation such because the Rust E book and Rust Reference.

A very attention-grabbing characteristic is the power to embed executable snippets of Rust code. That is key to creating the coaching participating for the reason that code will be edited stay and executed instantly within the slides:

Along with being a well-recognized group commonplace, mdBook presents the next necessary options:

• Maintainability: mdbook take a look at compiles and executes each code snippet within the course. This allowed us to evolve the category over time whereas guaranteeing that we at all times confirmed legitimate code to the members.
• Extensibility: mdBook has a plugin system which allowed us to increase the software as wanted. We relied on this characteristic for translations and ASCII artwork diagrams.

These options made it simple for us to decide on mdBook. Whereas mdBook will not be designed for shows, the output appeared OK on a projector after we restricted the vertical dimension of every web page.

Supporting Translations

Android has builders and OEM companions in lots of international locations. It’s essential that they’ll adapt present Rust code in AOSP to suit their wants. To help translations, we developed mdbook-i18n-helpers. Help for multilingual documentation has been a group want since 2015 and we’re glad to see the plugins being adopted by a number of different initiatives to supply maintainable multilingual documentation for everyone.

With the know-how and format nailed down, we began writing the course. We roughly adopted the define from the Rust E book because it lined most of what we have to cowl. This gave us a 3 day course which we referred to as Rust Fundamentals. We designed it to run for 3 days for 5 hours a day and embody Rust syntax, semantics, and necessary ideas equivalent to traits, generics, and error dealing with.

We then prolonged Rust Fundamentals with three deep dives:

• Rust in Android: a half-day course on utilizing Rust for AOSP improvement. It contains interoperability with C, C++, and Java.
• Naked-metal Rust: a full-day class on utilizing Rust for bare-metal improvement. Android units ship important quantities of firmware. These elements are sometimes foundational in nature (for instance, the bootloader, which establishes the belief for the remainder of the system), thus they should be safe.
• Concurrency in Rust: a full-day class on concurrency in Rust. We cowl each multithreading with blocking synchronization primitives (equivalent to mutexes) and async/await concurrency (cooperative multitasking utilizing futures).

A big set of in-house and group translators have helped translate the course into a number of languages. The complete translations have been Brazilian Portuguese and Korean. We’re engaged on Simplified Chinese language and Conventional Chinese language translations as effectively.

Course Reception

We began educating the category in late 2022. In 2023, we employed a vendor, Immunant, to show the vast majority of courses for Android engineers. This was necessary for scalability and for high quality: devoted instructors quickly found the place the course members struggled and will adapt the supply. As well as, over 30 Googlers have taught the course worldwide.

Greater than 500 Google engineers have taken the category. Suggestions has been very optimistic: 96% of members agreed it was value their time. Individuals constantly advised us that they beloved the interactive fashion, highlighting the way it helped to have the ability to ask clarifying questions at any time. Instructors famous that folks gave the course their undivided consideration as soon as they realized it was stay. Stay-coding calls for lots from the trainer, however it’s value it because of the excessive engagement it achieves.

Most significantly, individuals exited this course and have been capable of be instantly productive with Rust of their day jobs. When members have been requested three months later, they confirmed that they have been capable of write and overview Rust code. This matched the outcomes from the a lot bigger survey we made in 2022.

Now we have been educating Rust courses at Google for a 12 months now. There are some things that we need to enhance: higher matter ordering, extra workout routines, and extra speaker notes. We might additionally like to increase the course with extra deep dives. Pull requests are very welcome!

The complete course is obtainable without spending a dime at https://google.github.io/comprehensive-rust/. We’re thrilled to see individuals beginning to use Complete Rust for courses around the globe. We hope it may be a helpful useful resource for the Rust group and that it’s going to assist each small and huge groups get began on their Rust journey!

We’re grateful to the 190+ contributors from all around the world who created greater than 1,000 pull requests and points on GitHub. Their bug reviews, fixes, and suggestions improved the course in numerous methods. This contains the 50+ individuals who labored onerous on writing and sustaining the various translations.

Particular due to Andrew Walbran for writing Naked-metal Rust and to Razieh Behjati, Dustin Mitchell, and Alexandre Senges for writing Concurrency in Rust.

We additionally owe quite a lot of due to the various volunteer instructors at Google who’ve been spending their time educating courses across the globe. Your suggestions has helped form the course.

Lastly, due to Jeffrey Vander Stoep, Ivan Lozano, Matthew Maurer, Dmytro Hrybenko, and Lars Bergstrom for offering suggestions on this publish.