InterfaceDispatchBenchmarks

InterfaceDispatchBenchmarks_StaticOrNonStatic.cs

using System.Runtime.CompilerServices;
using BenchmarkDotNet.Attributes;

namespace ConsoleApp_Bench_1;

public class InterfaceDispatchBenchmarks_StaticOrNonStatic
{
    public static Accessor1[] Instances_Typed { get; } = Enumerable.Range(0, OperationsPerInvoke).Select(_ => new Accessor1()).ToArray();
    public static IAccessor[] Instances_SingleType { get; } = Enumerable.Range(0, OperationsPerInvoke).Select(_ => (IAccessor)new Accessor1()).ToArray();
    public static IAccessor[] Instances_MultiTypes { get; } = Enumerable.Range(0, OperationsPerInvoke).Select(CreateAccessor).ToArray();

    private static IAccessor CreateAccessor(int i)
    {
        return (i % 4) switch
        {
            0 => new Accessor1(),
            1 => new Accessor2(),
            2 => new Accessor3(),
            _ => new Accessor4(),
        };
    }

    public const int OperationsPerInvoke = 100_000;

    [Benchmark(OperationsPerInvoke = OperationsPerInvoke)]
    public int NonStatic_SingleType()
        => NonStatic_Impl(Instances_SingleType);

    [Benchmark(OperationsPerInvoke = OperationsPerInvoke)]
    public int NonStatic_MultiTypes()
        => NonStatic_Impl(Instances_MultiTypes);

    [MethodImpl(MethodImplOptions.NoInlining)]
    private static int NonStatic_Impl(IAccessor[] accessors)
    {
        var sum = 0;
        for (var i = 0; i < OperationsPerInvoke; i++)
        {
            var accessor = accessors[i];
            sum += accessor.Read();
        }

        return sum;
    }

    [Benchmark(OperationsPerInvoke = OperationsPerInvoke)]
    public int Static()
        => Static_Impl(Instances_Typed);

    [MethodImpl(MethodImplOptions.NoInlining)]
    private static int Static_Impl<T>(T[] accessors)
        where T : IStaticAccessor<T>
    {
        var sum = 0;
        for (var i = 0; i < OperationsPerInvoke; i++)
        {
            sum += T.ReadStatic(accessors[i]);
        }

        return sum;
    }

    [Benchmark(OperationsPerInvoke = OperationsPerInvoke)]
    public int Static_Inlinable()
        => StaticInterface_Inline_Impl(Instances_Typed);

    private static int StaticInterface_Inline_Impl<T>(T[] accessors)
        where T : IStaticAccessor<T>
    {
        var sum = 0;
        for (var i = 0; i < OperationsPerInvoke; i++)
        {
            sum += T.ReadStatic(accessors[i]);
        }

        return sum;
    }

    public interface IStaticAccessor<T>
    {
        static abstract int ReadStatic(T target);
    }

    public interface IAccessor
    {
        int Read();
    }

    public class Accessor1 : IStaticAccessor<Accessor1>, IAccessor
    {
        public int Value { get; set; }

        public static int ReadStatic(Accessor1 target) => target.Value;

        public int Read() => Value;
    }


    public class Accessor2 : IStaticAccessor<Accessor2>, IAccessor
    {
        public int Value { get; set; }

        public static int ReadStatic(Accessor2 target) => target.Value;

        public int Read() => Value;
    }

    public class Accessor3 : IStaticAccessor<Accessor3>, IAccessor
    {
        public int Value { get; set; }

        public static int ReadStatic(Accessor3 target) => target.Value;

        public int Read() => Value;
    }

    public class Accessor4 : IStaticAccessor<Accessor4>, IAccessor
    {
        public int Value { get; set; }

        public static int ReadStatic(Accessor4 target) => target.Value;

        public int Read() => Value;
    }
}

NonStaticBenchmarks_SingleTypeOrMultiTypes.cs

using System.Runtime.CompilerServices;
using BenchmarkDotNet.Attributes;

namespace ConsoleApp_Bench_1;

/// <summary>
/// Measures the effect of invoking an interface method (static or non-static) at
/// the same call site with multiple types.
/// </summary>
/// <remarks>
/// The goal here is not to measure the exact costs but to identify if there is a
/// difference or not between the single type and the multiple types scenarios.
/// </remarks>
public class InterfaceDispatchBenchmarks_SingleTypeOrMultiTypes
{
    public static IAccessor[] Accessors1 { get; } = Enumerable.Range(0, OperationsPerInvoke).Select(x => (IAccessor)new Accessor1()).ToArray();
    public static IAccessor[] Accessors2 { get; } = Enumerable.Range(0, OperationsPerInvoke).Select(x => (IAccessor)new Accessor2()).ToArray();
    public static IAccessor[] Accessors3 { get; } = Enumerable.Range(0, OperationsPerInvoke).Select(x => (IAccessor)new Accessor3()).ToArray();
    public static Accessor1[] Accessors1_Typed { get; } = Enumerable.Range(0, OperationsPerInvoke).Select(x => new Accessor1()).ToArray();
    public static Accessor2[] Accessors2_Typed { get; } = Enumerable.Range(0, OperationsPerInvoke).Select(x => new Accessor2()).ToArray();
    public static Accessor3[] Accessors3_Typed { get; } = Enumerable.Range(0, OperationsPerInvoke).Select(x => new Accessor3()).ToArray();

    public const int OperationsPerInvoke = 100_000;

    [Benchmark(OperationsPerInvoke = OperationsPerInvoke)]
    public int NonStatic_SingleType()
        => NonStatic_Impl(Accessors1, Accessors1, Accessors1);

    [Benchmark(OperationsPerInvoke = OperationsPerInvoke)]
    public int NonStatic_MultiTypes()
        => NonStatic_Impl(Accessors1, Accessors2, Accessors3);

    [MethodImpl(MethodImplOptions.NoInlining)]
    private static int NonStatic_Impl(IAccessor[] accessors1, IAccessor[] accessors2, IAccessor[] accessors3)
    {
        var sum = 0;
        for (var i = 0; i < OperationsPerInvoke; i++)
        {
            sum += Read(accessors1[i]);
            sum += Read(accessors2[i]);
            sum += Read(accessors3[i]);
        }

        return sum;

        // Forces a unique call site.
        [MethodImpl(MethodImplOptions.NoInlining)]
        static int Read(IAccessor accessor)
            => accessor.Read();
    }

    [Benchmark(OperationsPerInvoke = OperationsPerInvoke)]
    public int Static_SingleType()
        => Static_Impl(Accessors1_Typed, Accessors1_Typed, Accessors1_Typed);

    [Benchmark(OperationsPerInvoke = OperationsPerInvoke)]
    public int Static_MultiTypes()
        => Static_Impl(Accessors1_Typed, Accessors2_Typed, Accessors3_Typed);

    [MethodImpl(MethodImplOptions.NoInlining)]
    private static int Static_Impl<T1, T2, T3>(T1[] accessors1, T2[] accessors2, T3[] accessors3)
        where T1 : IStaticAccessor<T1>
        where T2 : IStaticAccessor<T2>
        where T3 : IStaticAccessor<T3>
    {
        var sum = 0;
        for (var i = 0; i < OperationsPerInvoke; i++)
        {
            sum += Read(accessors1[i]);
            sum += Read(accessors2[i]);
            sum += Read(accessors3[i]);
        }

        return sum;

        // Forces a unique call site.
        [MethodImpl(MethodImplOptions.NoInlining)]
        static int Read<T>(T accessor) where T : IStaticAccessor<T>
            => T.ReadStatic(accessor);
    }

    public interface IStaticAccessor<T>
    {
        static abstract int ReadStatic(T target);
    }

    public interface IAccessor
    {
        int Read();
    }

    public class Accessor1 : IStaticAccessor<Accessor1>, IAccessor
    {
        public int Value { get; set; }

        public static int ReadStatic(Accessor1 target) => target.Value;

        public int Read() => Value;
    }

    public class Accessor2 : IStaticAccessor<Accessor2>, IAccessor
    {
        public int Value { get; set; }

        public static int ReadStatic(Accessor2 target) => target.Value;

        public int Read() => Value;
    }

    public class Accessor3 : IStaticAccessor<Accessor3>, IAccessor
    {
        public int Value { get; set; }

        public static int ReadStatic(Accessor3 target) => target.Value;

        public int Read() => Value;
    }
}

RESULTS.md

InterfaceDispatchBenchmarks_StaticOrNonStatic

|               Method |      Mean |     Error |    StdDev |
|--------------------- |----------:|----------:|----------:|
| NonStatic_SingleType | 1.6293 ns | 0.0153 ns | 0.0143 ns |
| NonStatic_MultiTypes | 4.9330 ns | 0.0985 ns | 0.1412 ns |
|               Static | 1.7086 ns | 0.0057 ns | 0.0053 ns |
|     Static_Inlinable | 0.5637 ns | 0.0100 ns | 0.0094 ns |

InterfaceDispatchBenchmarks_SingleTypeOrMultiTypes

|               Method |     Mean |     Error |    StdDev |
|--------------------- |---------:|----------:|----------:|
| NonStatic_SingleType | 6.953 ns | 0.0224 ns | 0.0209 ns |
| NonStatic_MultiTypes | 8.104 ns | 0.0279 ns | 0.0261 ns |
|    Static_SingleType | 9.668 ns | 0.0506 ns | 0.0474 ns |
|    Static_MultiTypes | 9.984 ns | 0.0663 ns | 0.0620 ns |