In this episode of Crust of Rust, we go over Rust’s atomic types, including the mysterious Ordering enum. In particular, we explore the std::sync::atomic module, and look at how its components can be used to implement concurrency primitives like mutexes. We also investigate some of the gotchas and sometimes counter-intuitive behaviors of the atomic primitives with different memory orderings, as well as strategies for testing for and debugging errors in concurrent code.

• 0:00:00 Introduction
• 0:02:03 What are atomics?
• 0:05:26 The Memory Model
• 0:07:33 AtomicUsize
• 0:12:23 Questions so far
• 0:20:20 Implementing a (bad) Mutex
• 0:27:39 Our Mutex works!
• 0:33:04 Pesky thread interleavings
• 0:39:42 compare_exchange
• 0:44:54 Mitigating compare_exchange contention
• 0:50:43 compare_exchange_weak
• 0:57:02 Ordering::Relaxed
• 1:12:13 Ordering::Acquire/Release
• 1:26:00 The fetch_ methods
• 1:34:07 Ordering::SeqCst
• 2:00:08 Breather
• 2:00:40 ThreadSanitizer
• 2:05:49 loom
• 2:22:09 Atomic fences
• 2:27:27 volatile
• 2:32:18 AtomicPtr
• 2:35:13 Atomics through FFI
• 2:36:44 Consume ordering?
• 2:38:08 Closing thoughts

#rust