I wrote a simple object copier that copies public properties.
I can't figure out why the Dynamic method is a lot slower than the c# version.
Durations
C# method : 4,963 ms
Dynamic method : 19,924 ms
Note that - as I run the dynamic method before starting the stopwatch - the duration do not include the compilation phase.
I run that in Debug and Release mode, in x86 and x64 mode, and from VS and from the command line with roughly the same result (dynamic method is 400% slower).
const int NBRECORDS = 100 * 1000 * 1000;
public class Person
{
private int mSomeNumber;
public string FirstName { get; set; }
public string LastName { get; set; }
public DateTime DateOfBirth { get; set; }
public int SomeNumber
{
get { return mSomeNumber; }
set { mSomeNumber = value; }
}
}
public static Action<T1, T2> CreateCopier<T1, T2>()
{
var meth = new DynamicMethod("copy", null, new Type[] { typeof(T1), typeof(T2) }, restrictedSkipVisibility: true);
ILGenerator il = meth.GetILGenerator();
int cpt = 0;
var stopHere = typeof(Program).GetMethod("StopHere");
foreach (var mi1 in typeof(T1).GetProperties(BindingFlags.Public | BindingFlags.Instance))
{
var mi2 = typeof(T2).GetProperty(mi1.Name, BindingFlags.Public | BindingFlags.Instance);
if (mi1 != null && mi2 != null)
{
cpt++;
il.Emit(OpCodes.Ldarg_1);
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Callvirt, mi1.GetMethod);
il.Emit(OpCodes.Callvirt, mi2.SetMethod);
}
}
il.Emit(OpCodes.Ret);
var dlg = meth.CreateDelegate(typeof(Action<T1, T2>));
return (Action<T1, T2>)dlg;
}
static void Main(string[] args)
{
var person1 = new Person() { FirstName = "Pascal", LastName = "Ganaye", DateOfBirth = new DateTime(1909, 5, 1), SomeNumber = 23456 };
var person2 = new Person();
var copyUsingAMethod = (Action<Person, Person>)CopyPerson;
var copyUsingADynamicMethod = CreateCopier<Person, Person>();
copyUsingAMethod(person1, person2); // 4882 ms
var sw = Stopwatch.StartNew();
for (int i = 0; i < NBRECORDS; i++)
{
copyUsingAMethod(person1, person2);
}
Console.WriteLine("{0} ms", sw.ElapsedMilliseconds);
copyUsingADynamicMethod(person1, person2); // 19920 ms
sw = Stopwatch.StartNew();
for (int i = 0; i < NBRECORDS; i++)
{
copyUsingADynamicMethod(person1, person2);
}
Console.WriteLine("{0} ms", sw.ElapsedMilliseconds);
Console.ReadKey(intercept: true);
}
private static void CopyPerson(Person person1, Person person2)
{
person2.FirstName = person1.FirstName;
person2.LastName = person1.LastName;
person2.DateOfBirth = person1.DateOfBirth;
person2.SomeNumber = person1.SomeNumber;
}
From what I can debug the two methods have the same IL code.
IL_0000: nop
IL_0001: ldarg.1
IL_0002: ldarg.0
IL_0003: callvirt System.String get_FirstName()/DuckCopy.SpeedTests.Program+Person
IL_0008: callvirt Void set_FirstName(System.String)/DuckCopy.SpeedTests.Program+Person
IL_000d: nop
IL_000e: ldarg.1
IL_000f: ldarg.0
IL_0010: callvirt System.String get_LastName()/DuckCopy.SpeedTests.Program+Person
IL_0015: callvirt Void set_LastName(System.String)/DuckCopy.SpeedTests.Program+Person
IL_001a: nop
IL_001b: ldarg.1
IL_001c: ldarg.0
IL_001d: callvirt System.DateTime get_DateOfBirth()/DuckCopy.SpeedTests.Program+Person
IL_0022: callvirt Void set_DateOfBirth(System.DateTime)/DuckCopy.SpeedTests.Program+Person
IL_0027: nop
IL_0028: ldarg.1
IL_0029: ldarg.0
IL_002a: callvirt Int32 get_SomeNumber()/DuckCopy.SpeedTests.Program+Person
IL_002f: callvirt Void set_SomeNumber(Int32)/DuckCopy.SpeedTests.Program+Person
IL_0034: nop
IL_0035: ret
I applogize if you read this twice.
I posted this originally in: http://www.codeproject.com/Answers/494714/Can-27tplusfigureplusoutpluswhyplusthisplusDynamic
but did not get all the answers I hoped.
edited 17 nov 2012 15:11:
removed the nop
removed the extra ="" which came from I don't where.
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