Slug: conc-atomic-01 · Paired reading: Chapter 12
Prompt
fn bump_relaxed(n: usize) -> usize — AtomicUsize counter with
Ordering::Relaxed fetch_add from several threads (counter only).
fn publish(flag: &AtomicBool, data: &mut i32) — write data, then
store(true, Release). fn observe(...) -> Option<i32> — load(Acquire)
then read data if flag set. Demonstrate the pairing.