C# 泛型编译特性对性能的影响小结

using System.Diagnostics;
namespace ConsoleApp1 {
    internal interface IValueGetter {
        int GetValue(int index);
    }
    internal class MyTestClass<T> where T : IValueGetter {
        private readonly T _valueGetter;
        public MyTestClass(T valueGetter) {
            _valueGetter = valueGetter;
        }
        public void Run() {
            long r = 0L;
            for (int i = 0; i < int.MaxValue; i++) {
                r += _valueGetter.GetValue(i);
            }
        }
    }
    internal struct StructValueGetter : IValueGetter {
        public readonly int GetValue(int index) {
            return index + 3;
        }
    }
    internal struct StructValueGetter2(int someField) : IValueGetter {
        public readonly int GetValue(int index) {
            return index + 5;
        }
    }
    internal class ClassValueGetter1 : IValueGetter {
        public int GetValue(int index) {
            return index + 5;
        }
    }
    internal class ClassValueGetter2 : IValueGetter {
        public int GetValue(int index) {
            return index + 7;
        }
    }
    internal static class Demo2 {
        public static  void Run() {
            var t1 = new MyTestClass<StructValueGetter>(new StructValueGetter());
            RunDemo("StructValueGetter ", t1.Run);
            var t2 = new MyTestClass<ClassValueGetter1>(new ClassValueGetter1());
            RunDemo("ClassValueGetter1 ", t2.Run);
            var t3 = new MyTestClass<ClassValueGetter2>(new ClassValueGetter2());
            RunDemo("ClassValueGetter2 ", t3.Run);
            var t4 = new MyTestClass<IValueGetter>(new ClassValueGetter1());
            RunDemo("IValueGetter-1    ", t4.Run);
            var t5 = new MyTestClass<ClassValueGetter1>(new ClassValueGetter1());
            RunDemo("ClassValueGetter1 ", t5.Run);
            var t6 = new MyTestClass<StructValueGetter2>(new StructValueGetter2());
            RunDemo("StructValueGetter2", t6.Run);
            var t7 = new MyTestClass<IValueGetter>(new ClassValueGetter2());
            RunDemo("IValueGetter-2    ", t7.Run);
            var t8 = new MyTestClass<IValueGetter>(new StructValueGetter());
            RunDemo("IValueGetter-3    ", t8.Run);
            var t9 = Activator.CreateInstance(typeof(MyTestClass<>).MakeGenericType(typeof(StructValueGetter)), new StructValueGetter());
            Action action9 = (Action)Delegate.CreateDelegate(typeof(Action), t9, t9.GetType().GetMethod("Run"));
            RunDemo("Dynamic-Struct    ", action9);
        }
        static void RunDemo(string caption, Action action) {
            var stopWatch = Stopwatch.StartNew();
            action();
            stopWatch.Stop();
            Console.WriteLine($"{caption} time = {stopWatch.Elapsed}");
        }
    }
}
Demo2.Run();