Function create_string_array_for_runs

arrow/src/util/bench_util.rs:628–658

Create string array to be used by run array builder. The string array will result in run array with physical length of `physical_array_len` and logical length of `logical_array_len`

(
    physical_array_len: usize,
    logical_array_len: usize,
    string_len: usize,
)

/// will result in run array with physical length of `physical_array_len`
/// and logical length of `logical_array_len`
pub fn create_string_array_for_runs(
    physical_array_len: usize,
    logical_array_len: usize,
    string_len: usize,
) -> Vec<String> {
    assert!(logical_array_len >= physical_array_len);
    let mut rng = rng();

    // typical length of each run
    let run_len = logical_array_len / physical_array_len;

    // Some runs should have extra length
    let mut run_len_extra = logical_array_len % physical_array_len;

    let mut values: Vec<String> = (0..physical_array_len)
        .map(|_| (0..string_len).map(|_| rng.random::<char>()).collect())
        .flat_map(|s| {
            let mut take_len = run_len;
            if run_len_extra > 0 {
                take_len += 1;
                run_len_extra -= 1;
            }
            std::iter::repeat_n(s, take_len)
        })
        .collect();
    while values.len() < logical_array_len {
        let last_val = values[values.len() - 1].clone();
        values.push(last_val);
    }
    values
}

/// Creates an random (but fixed-seeded) binary array of a given size and null density
pub fn create_binary_array<Offset: OffsetSizeTrait>(