Validate execCPUAffinity of the runtime process spec

[keisku]

execCPUAffinity, which was added in #174, expects a particular format.

Ref: https://github.com/opencontainers/runtime-spec/blob/701738418b9555d5213337a0991fd0ffd6c37808/config.md?plain=1#L343-L353

[saschagrunert]

@keisku thank you for the PR, do you mind a rebase?

[keisku]

@saschagrunert I did!

[saschagrunert]

@utam0k PTAL

[utam0k]

I'm worried about performance by introducing regex. WDYT? @saschagrunert

[saschagrunert]

Yeah I agree, not sure I like that dependency right here.

[keisku]

@saschagrunert @utam0k Reimplemented the validation logic without regex and once_cell!

[utam0k]

@keisku Thanks, but apparently, the regex implementation is faster than the current implementation you updated. Depending on the length of the string, both are fast enough to merge. Sorry, can you revert to the regex implementation?

$ cargo bench
simple_perf             time:   [99.829 ns 100.50 ns 101.24 ns]
                        change: [-0.6423% +0.6216% +1.7508%] (p = 0.33 > 0.05)
                        No change in performance detected.
Found 8 outliers among 100 measurements (8.00%)
  7 (7.00%) high mild
  1 (1.00%) high severe

regex_perf              time:   [24.250 ns 24.451 ns 24.669 ns]
                        change: [-2.0247% -0.9518% +0.1010%] (p = 0.08 > 0.05)
                        No change in performance detected.
Found 4 outliers among 100 measurements (4.00%)
  4 (4.00%) high mild

use criterion::{black_box, criterion_group, criterion_main, Criterion};
use regex::Regex;

fn regex_benchmark(c: &mut Criterion) {
    c.bench_function("regex_perf", |b| {
        let re = Regex::new(r"^(\d+(-\d+)?)(,\d+(-\d+)?)*$").unwrap();
        b.iter(|| re.is_match(black_box("123,456-789,22,1,2,4,5,6")));
    });
}

fn simple_benchmark(c: &mut Criterion) {
    c.bench_function("simple_perf", |b| {
        b.iter(|| {
            let s = black_box("123,456-789,22,1,2,4,5,6");
            let iter = s.split(',');

            for part in iter {
                let mut range_iter = part.split('-');
                range_iter
                    .next()
                    .ok_or_else(|| format!("Invalid execCPUAffinity format: {}", s))
                    .unwrap();

                // Check if there's a range and if the end is a valid number
                if let Some(end) = range_iter.next() {
                    end.parse::<usize>().unwrap();
                }

                // Ensure there's no extra data after the end of a range
                if range_iter.next().is_some() {
                    panic!("Invalid execCPUAffinity format: {}", s);
                }
            }
        });
    });
}

criterion_group!(benches, simple_benchmark, regex_benchmark);
criterion_main!(benches);