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use std::mem::size_of;
use once_cell::sync::OnceCell;
const N_THREADS: usize = 32;
const N_ROUNDS: usize = 100_000_000;
static CELL: OnceCell<usize> = OnceCell::new();
fn main() {
let start = std::time::Instant::now();
let threads =
(0..N_THREADS).map(|i| std::thread::spawn(move || thread_main(i))).collect::<Vec<_>>();
for thread in threads {
thread.join().unwrap();
}
println!("{:?}", start.elapsed());
println!("size_of::<OnceCell<()>>() = {:?}", size_of::<OnceCell<()>>());
println!("size_of::<OnceCell<bool>>() = {:?}", size_of::<OnceCell<bool>>());
println!("size_of::<OnceCell<u32>>() = {:?}", size_of::<OnceCell<u32>>());
}
fn thread_main(i: usize) {
for _ in 0..N_ROUNDS {
let &value = CELL.get_or_init(|| i);
assert!(value < N_THREADS)
}
}
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