Atomic Enums

Ordering และ memory atomics ใน Rust สำหรับ lock-free programming และ thread synchronization

1. Ordering Enum

Ordering enum กำหนด memory ordering สำหรับ atomic operations มี 5 variants

Ordering Types

use std::sync::atomic::{AtomicU32, Ordering};

fn main() {
    let counter = AtomicU32::new(0);

    println!("=== Ordering Types ===");

    // Relaxed - no synchronization, cheapest
    counter.store(1, Ordering::Relaxed);
    let val = counter.load(Ordering::Relaxed);
    println!("Relaxed: {}", val);

    // Acquire/Release - synchronization pair
    counter.store(2, Ordering::Release);
    let val = counter.load(Ordering::Acquire);
    println!("Acquire/Release: {}", val);

    // SeqCst - sequential consistency (strongest)
    counter.store(3, Ordering::SeqCst);
    let val = counter.load(Ordering::SeqCst);
    println!("SeqCst: {}", val);

    // AcqRel - for read-modify-write operations
    let old = counter.fetch_add(1, Ordering::AcqRel);
    println!("AcqRel fetch_add: {} -> {}", old, counter.load(Ordering::Relaxed));
}