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use std::num::NonZeroU64;
#[derive(Eq, PartialEq, Clone, Copy, Hash, Debug)]
pub(crate) struct ThreadId(NonZeroU64);
impl ThreadId {
pub(crate) fn next() -> Self {
use crate::loom::sync::atomic::{Ordering::Relaxed, StaticAtomicU64};
static NEXT_ID: StaticAtomicU64 = StaticAtomicU64::new(0);
let mut last = NEXT_ID.load(Relaxed);
loop {
let id = match last.checked_add(1) {
Some(id) => id,
None => exhausted(),
};
match NEXT_ID.compare_exchange_weak(last, id, Relaxed, Relaxed) {
Ok(_) => return ThreadId(NonZeroU64::new(id).unwrap()),
Err(id) => last = id,
}
}
}
}
#[cold]
#[allow(dead_code)]
fn exhausted() -> ! {
panic!("failed to generate unique thread ID: bitspace exhausted")
}