use std::fs;

use std::num::NonZeroUsize;

pub(crate) fn num_threads() -> Option<NonZeroUsize> {

    fs::read_to_string("/proc/self/stat")

        .ok()

        .as_ref()

        // Skip past the pid and (process name) fields

        .and_then(|stat| stat.rsplit(')').next())

        // 20th field, less the two we skipped

        .and_then(|rstat| rstat.split_whitespace().nth(17))

        .and_then(|num_threads| num_threads.parse::<usize>().ok())

        .and_then(NonZeroUsize::new)

}