grit-lib 0.5.18

Core library for the grit Git implementation
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//! Integration coverage for [`grit_lib::objects::hash`] parallel batch helpers.

use std::num::NonZeroUsize;
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::Arc;

use grit_lib::objects::hash::hash_object;
use grit_lib::objects::hash::{
    hash_objects_parallel, par_hash_with, parallel_hash_worthwhile, try_par_hash_with,
    ParallelHashError, Parallelism, PAR_HASH_MIN_ITEMS, PAR_HASH_MIN_TOTAL_BYTES,
};
use grit_lib::objects::{HashAlgo, ObjectKind};

#[test]
fn hash_objects_parallel_public_api_matches_serial() {
    let data = b"parallel batch hashing integration test payload";
    let items = [(ObjectKind::Blob, data.as_slice()); 64];
    let serial: Vec<_> = items
        .iter()
        .map(|(k, d)| hash_object(HashAlgo::Sha1, *k, d).expect("hash"))
        .collect();
    let parallel = hash_objects_parallel(
        HashAlgo::Sha1,
        &items,
        NonZeroUsize::new(4).expect("threads"),
    )
    .expect("parallel hash");
    assert_eq!(parallel, serial);
}

#[test]
fn try_par_hash_with_returns_typed_task_error() {
    let items = [1_i32, 2, 3];
    let err = try_par_hash_with(&items, NonZeroUsize::new(2).expect("threads"), 3, |&x| {
        if x == 2 {
            Err(42_u8)
        } else {
            Ok(x)
        }
    })
    .unwrap_err();
    assert_eq!(err, ParallelHashError::Task(42));
}

#[test]
fn parallelism_and_threshold_constants_are_documented() {
    let p = Parallelism::resolve(Some(2));
    assert!(p.threads().get() >= 1);
    assert!(!parallel_hash_worthwhile(
        PAR_HASH_MIN_ITEMS - 1,
        PAR_HASH_MIN_TOTAL_BYTES,
        8
    ));
    assert!(parallel_hash_worthwhile(
        PAR_HASH_MIN_ITEMS,
        PAR_HASH_MIN_TOTAL_BYTES,
        8
    ));
}

#[test]
fn try_par_hash_with_drops_completed_values_on_error() {
    struct TrackDrop(Arc<AtomicUsize>);

    impl Drop for TrackDrop {
        fn drop(&mut self) {
            self.0.fetch_add(1, Ordering::SeqCst);
        }
    }

    let items: Vec<i32> = (0..128).collect();
    let made = Arc::new(AtomicUsize::new(0));
    let dropped = Arc::new(AtomicUsize::new(0));
    let result = try_par_hash_with(
        &items,
        NonZeroUsize::new(8).expect("threads"),
        items.len(),
        {
            let made = Arc::clone(&made);
            let dropped = Arc::clone(&dropped);
            move |&x| {
                if x == 127 {
                    while made.load(Ordering::Acquire) < 127 {
                        std::hint::spin_loop();
                    }
                    return Err("stop");
                }
                made.fetch_add(1, Ordering::SeqCst);
                Ok(TrackDrop(Arc::clone(&dropped)))
            }
        },
    );
    assert!(matches!(result, Err(ParallelHashError::Task("stop"))));
    assert_eq!(made.load(Ordering::SeqCst), 127);
    assert_eq!(dropped.load(Ordering::SeqCst), 127);
}

#[test]
fn par_hash_with_lazy_file_style_closure() {
    let paths = ["a", "b", "c", "d"];
    let got = par_hash_with(&paths, NonZeroUsize::new(2).expect("threads"), 0, |s| {
        s.len()
    });
    assert_eq!(got, vec![1, 1, 1, 1]);
}