use jay_algorithms::oserror::OsError;
use jay_algorithms::oserror::OsErrorExt;
use smallvec::SmallVec;
use smallvec::smallvec_inline;
use uapi::c;
#[cfg_attr(not(feature = "it"), expect(unused))]
pub fn num_cpus() -> Result<u32, OsError> {
let mut buf: SmallVec<[usize; 32]> = smallvec_inline![0; 32];
loop {
match uapi::sched_getaffinity(0, &mut buf).to_os_error() {
Ok(_) => return Ok(count(&buf)),
Err(OsError(c::EINVAL)) => buf.extend_from_slice(&[0; 32][..]),
Err(e) => return Err(e),
}
}
}
fn count(buf: &[usize]) -> u32 {
buf.iter().copied().map(|n| n.count_ones()).sum()
}