An example of a function that processess an atomic as a transaction, using 0 to indicate a locked state

atomic_transaction.rs

pub fn use_atomic(value: &AtomicU64, op: impl FnOnce(NonZeroU64) -> NonZeroU64) {
    loop {
        let current = value.swap(0, Ordering::AcqRel);
        match NonZeroU64::new(current) {
            Some(current) => {
                let computed = op(current);

                // It might be more appropriate to use compare_exchange here
                value.store(computed.get(), Ordering::Release);
                break;
            }
            // Some other thread is currently working with the atomic, give it
            // a chance to run
            None => yield_now(),
        }
    }
}

Some notes:

• Not reentrant; calling use_atomic from the same thread will deadlock
• If op panics, the next call to use_atomic will deadlock