// Attempt to compare virtual and interface call efficiency.  

// 2002-04-21: Running Microsoft CLR .NET Framework version 1.0.3705
// from January 2002 under Win2000 under VMWare 3.0 under Linux on a
// 850 MHz Mobile P3:

// invokevirtual:   2.43 sec
// invokeinterface: 2.35 sec 

// Rather strange that invokeinterface is faster than invokevirtual.

using System;

class Invokevirtual {
  static B1 o1 = new B1();
  static B1 o2 = new B2();

  static void Main(string[] args) {
    int count = int.Parse(args[0]);
    int res = 13;
    {
      Timer t = new Timer();
      for (int i=0; i<count; i++) {
	B1 o = geto(i);		
	res = res ^ o.m();		// invokevirtual
      }
      Console.WriteLine("invokevirtual:   " + t.Check() + " sec");
    }
    { 
      Timer t = new Timer();
      for (int i=0; i<count; i++) {
	A o = geto(i);		
	res = res ^ o.m();		// invokeinterface
      }
      Console.WriteLine("invokeinterface: " + t.Check() + " sec");
    }
    Console.WriteLine(res); // Necessary to keep res live
  }
  
  private static B1 geto(int i) {
    return i%2>=0 ? o1 : o1;
  }
}

interface A { 
  int m();
}

class B1 : A {
  protected int k;

  public virtual int m() { return k++; }
}
  
class B2 : B1 { 
  public override int m() { return ++k; }
}

// Crude timing utility ----------------------------------------
   
public class Timer {
  private DateTime start;

  public Timer() {
    start = DateTime.Now;
  }

  public double Check() {
    TimeSpan dur = DateTime.Now - start;
    return dur.TotalSeconds;
  }
}