Rust part27

[143 デフォルトの名無しさん 2024/12/22(日) 22:27:16.01 ID:K7zRdssG]

>>138
中級者向けにはこれでええんかね

fn new_id() -> Option<usize> {
static ID: AtomicUsize = AtomicUsize::new(0);

let mut old_id = ID.load(Relaxed);
while let Some(new_id) = old_id.checked_add(1) {
match ID.compare_exchange_weak(old_id, new_id, Relaxed, Relaxed) {
Ok(_) => return Some(new_id),
Err(updated_old_id) => old_id = updated_old_id,
}
}
None
}