MbUnit : Generative Unit Test Framework

 using System;
using System.Runtime.InteropServices;
using System.ComponentModel;
using System.Threading;

namespace GUnit.Core.Monitoring
{
	/// <summary>
	/// A high performance timer
	/// </summary>
	/// <remarks>
	/// High Precision Timer based on Win32 methods.
	/// </remarks>
	/// <example>
	/// This example times the execution of a method:
	/// <code>
	/// TimeMonitor timer = new TimeMonitor();
	/// timer.Start();
	///    ... // execute code
	/// timer.Stop();
	/// 
	/// Console.WriteLine("Duration: {0}",timer.Duration);
	/// </example>
	public class TimeMonitor
	{
		[DllImport("Kernel32.dll")]
		private static extern bool QueryPerformanceCounter(out long lpPerformanceCount);  

		[DllImport("Kernel32.dll")]
		private static extern bool QueryPerformanceFrequency(out long lpFrequency);
		
		private long startTime, stopTime;
		private long now;
		private long freq;
		
		/// <summary>Default constructor</summary>
		/// <remarks>Initializes the timer.</remarks>
		public TimeMonitor()
		{
			startTime = 0;
			stopTime  = 0;

			if (QueryPerformanceFrequency(out freq) == false)
			{
				// high-performance counter not supported 
				throw new Win32Exception(); 
			}
		}
		
		/// <summary>Gets the clock frequency</summary>
		/// <value>Clock frequency</value>
		public long Frequency
		{
			get
			{
				return this.freq;
			}
		}
		
		/// <summary>Starts the timer</summary>
		/// <remarks>Resets the duration and starts the timer</remarks>
		public void Start()
		{
			// lets do the waiting threads there work
			Thread.Sleep(0);  

			QueryPerformanceCounter(out startTime);
		}
		
		/// <summary>Stops the timer</summary>
		/// <remarks>Stops the timer</remarks>
		public void Stop()
		{
			QueryPerformanceCounter(out stopTime);
		}
		
		/// <summary>Gets the current duration value without stopping the timer</summary>
		/// <value>Current duration value</value>
		public double Now
		{
			get
			{
				QueryPerformanceCounter(out now);
				return (double)(now - startTime) / (double) freq;
			}		
		}

		/// <summary>Gets the timed duration value in seconds</summary>
		/// <value>Timer duration</value>
		public double Duration
		{
			get
			{
				return (double)(stopTime - startTime) / (double) freq;
			}
		}
	}
}