bos_skill

Overview

This skill produces Rust code in the style of Mara Bos, Rust library team lead and author of "Rust Atomics and Locks." It emphasizes provable correctness, careful use of atomics and memory orderings, and clear synchronization strategy. Use it when you need low-level concurrency, lock-free structures, or rigorous reasoning about happens-before relations.

How this skill works

The skill emits idiomatic Rust focused on atomic primitives, ordering choices, and safe synchronization patterns. It prefers high-level primitives first (channels, Mutex, Arc) and only uses atomics or unsafe when formally reasoned. It also generates documentation comments that explain the synchronization protocol and suggests testing approaches (loom, Miri).

When to use it

• Implementing lock-free data structures or synchronization primitives
• Optimizing hot concurrent paths where locks are a bottleneck
• Teaching or documenting memory-order reasoning and happens-before guarantees
• Reviewing or refactoring concurrent code for correctness and performance
• Writing tests that exercise interleavings with loom or Miri

Best practices

• Prefer channels or Mutex over raw atomics unless necessary
• Document the synchronization strategy and invariants next to the code
• Choose the weakest ordering that preserves correctness; default to SeqCst if unsure
• Minimize shared mutable state and prefer ownership transfer via Arc/Weak
• Use loom/Miri for exhaustive concurrency tests and assert invariants in tests

Example use cases

• A spinlock implementation with clear Acquire/Release semantics and safety comments
• A lock-free counter using Ordering::Relaxed where ordering is irrelevant
• An Arc/Weak tree structure with documented ownership and upgrade semantics
• A producer-consumer pipeline using crossbeam or mpsc with backpressure
• A loom-based test that exhaustively verifies a concurrent invariant