LinqExpansion.cs

using BenchmarkDotNet.Attributes;

using DistIL.Attributes;

public class LinqExpansion
{
    [Params(4096)]
    public int ElemCount {
        set {
            var rng = new Random(value - 1);

            _sourceItems = Enumerable.Range(0, value)
                .Select(i => new Item() {
                    Id = RandStr(12),
                    Timestamp = _currDate.AddDays(rng.NextDouble() * -7),
                    Weight = rng.NextSingle(),
                    Payload = new() {
                        Data = RandStr(512)
                    }
                }).ToList();

            _sourceText = RandStr(value);
            _elemCount = value;

            string RandStr(int length)
            {
                var buffer = new byte[length];
                rng.NextBytes(buffer);
                return Convert.ToBase64String(buffer);
            }
        }
    }

    static readonly DateTime _currDate = new(2023, 02, 22);

    List<Item> _sourceItems = null!;
    string _sourceText = null!;
    int _elemCount;

    [Benchmark]
    public List<ItemPayload> FilterObjects()
    {
        return _sourceItems
            .Where(x => x.Weight > 0.5f && x.Timestamp >= _currDate.AddDays(-3))
            .Select(x => x.Payload)
            .ToList();
    }

    [Benchmark]
    public string? FirstPredicate()
    {
        string id = _sourceItems[^3].Id;
        return _sourceItems.FirstOrDefault(x => x.Id == id)?.Payload.Data;
    }

    [Benchmark]
    public float Aggregate()
    {
        return _sourceItems
            .Select(x => x.Weight)
            .Where(x => x > 0.0f && x < 1.0f)
            .Aggregate(0.0f, (r, x) => r + (x < 0.5f ? -x : x));
    }

    [Benchmark]
    public int CountLetters()
    {
        return _sourceText.Count(ch => ch is >= 'A' and <= 'Z');
    }

    [Benchmark]
    public byte[] RayTracer()
    {
        int width = (int)Math.Sqrt(_elemCount);
        int height = width;

        // Render into a netpbm file
        var header = System.Text.Encoding.UTF8.GetBytes($"P6\n{width} {height}\n255\n");
        var data = new byte[width * height * 3 + header.Length];
        header.CopyTo(data, 0);

        var tracer = new LinqRayTracer.RayTracer(width, height, (x, y, color) => {
            int offset = (x + y * width) * 3 + header.Length;
            data[offset + 0] = color.R;
            data[offset + 1] = color.G;
            data[offset + 2] = color.B;
        });
        tracer.Render(tracer.DefaultScene);

        return data;
    }

    public class Item
    {
        public string Id { get; init; } = null!;
        public DateTime Timestamp { get; init; }
        public float Weight { get; init; }
        public ItemPayload Payload { get; init; } = null!;
    }
    public class ItemPayload
    {
        public string Data { get; init; } = null!;
    }
}