Function hash_array_primitive

datafusion/common/src/hash_utils.rs:217–256

(
    array: &PrimitiveArray<T>,
    random_state: &RandomState,
    hashes_buffer: &mut [u64],
    rehash: bool,
)

/// and hashes only the new value (avoiding a separate combine step).
#[cfg(not(feature = "force_hash_collisions"))]
fn hash_array_primitive<T>(
    array: &PrimitiveArray<T>,
    random_state: &RandomState,
    hashes_buffer: &mut [u64],
    rehash: bool,
) where
    T: ArrowPrimitiveType<Native: HashValue>,
{
    assert_eq!(
        hashes_buffer.len(),
        array.len(),
        "hashes_buffer and array should be of equal length"
    );

    if array.null_count() == 0 {
        if rehash {
            for (hash, &value) in hashes_buffer.iter_mut().zip(array.values().iter()) {
                let mut hasher = seeded_state(*hash).build_hasher();
                value.hash_write(&mut hasher);
                *hash = hasher.finish();
            }
        } else {
            for (hash, &value) in hashes_buffer.iter_mut().zip(array.values().iter()) {
                *hash = value.hash_one(random_state);
            }
        }
    } else if rehash {
        for i in array.nulls().unwrap().valid_indices() {
            let value = unsafe { array.value_unchecked(i) };
            let mut hasher = seeded_state(hashes_buffer[i]).build_hasher();
            value.hash_write(&mut hasher);
            hashes_buffer[i] = hasher.finish();
        }
    } else {
        for i in array.nulls().unwrap().valid_indices() {
            let value = unsafe { array.value_unchecked(i) };
            hashes_buffer[i] = value.hash_one(random_state);
        }
    }
}

/// Hashes one array into the `hashes_buffer`
/// If `rehash==true` this combines the previous hash value in the buffer