























class Student
{
public string Name { get; set; }
}static double Test(int loop, Student stu, Func<Student, string> action)
{
var watch = Stopwatch.StartNew();
string s = null;
for (var i = 0; i < loop; i++)
s = action(stu);return watch.ElapsedTicks;
}static Func<Student, string> NativeGetter()
{
return s => s.Name;
}static Func<Student, string> ReflectedGetter()
{
var type = typeof (Student);
var prop = type.GetProperty("Name");return s => (string)prop.GetValue(s, null);
}static Func<Student, string> EmittedGetter()
{
var dm = new DynamicMethod(name: "EmittedGetter", returnType: typeof(string), parameterTypes: new[] { typeof(Student) }, owner: typeof(Student));var type
= typeof (Student);
var prop = type.GetMethod("get_Name");
var il = dm.GetILGenerator();
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Call, prop);
il.Emit(OpCodes.Ret);return (Func<Student, string>)dm.CreateDelegate(typeof(Func<Student, string>));
}static Func<Student, string> ExpressionGetter()
{
var type = typeof(Student);
var prop = type.GetMethod("get_Name");ParameterExpression pa
= Expression.Parameter(typeof(Student));
Expression body = Expression.Call(pa, prop);return Expression.Lambda<Func<Student, string>>(body, pa).Compile();
}static Func<Student, string> DynamicGetter()
{
return s => { dynamic d = s; return d.Name; };
}[MethodImpl(MethodImplOptions.NoOptimization)]
public static void Run()
{
const int loop = 5000000;var stu
= new Student {Name = "Mike"};var dynamic
=
Test(loop, stu, DynamicGetter());var expression
=
Test(loop, stu, ExpressionGetter());var native
=
Test(loop, stu, NativeGetter());var emitted
=
Test(loop, stu, EmittedGetter());var reflected
=
Test(loop, stu, ReflectedGetter());Console.WriteLine(
"native:{0}\ndynamic:{1}\nemit:{2}\nexpression:{3}\nreflection:{4}", 1, dynamic / native, emitted / native, expression / native, reflected / native);Console.ReadKey();
}
1. 当循环次数比较小的时候, loop=1000
native:1
dynamic:540.444964871194
emit:0.704918032786885
expression:0.224824355971897
reflection:8.37002341920375
2. loop=5000000
native:1
dynamic:4.37328053807767
emit:0.96159470600998
expression:1.00412887828162
reflection:35.909097418095
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