Performance Monitor Mockup

using System;
using System.Threading;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            System.Diagnostics.Debug.Listeners.Add(new System.Diagnostics.ConsoleTraceListener());
            var rnd = new Random();

            while (!Console.KeyAvailable)  //Simulation loop, in reality the using will usually wrap an entire method!
            {
                using (Performance.Monitor<Program>(100, 300, "This is a test loop!"))
                    Thread.Sleep(rnd.Next(500));
            };
        }
    }

    public static class Performance
    {
        public static Monitor Monitor<T>(int warnMs, int errorMs, string description = null,
            [System.Runtime.CompilerServices.CallerMemberNameAttribute] string methodName = "")
        {
            return new Monitor(typeof(T), methodName, description, warnMs, errorMs);
        }
    }

    public class Monitor : IDisposable
    {
        private readonly System.Diagnostics.Stopwatch _watch;

        Type _callerType;
        private readonly string _methodName;

        string _description;
        int _warnMs, _errorMs;
        public Monitor(Type callerType, string methodName, string description, int warnMs, int errorMs)
        {
            _watch = System.Diagnostics.Stopwatch.StartNew();
            _callerType = callerType;
            _methodName = methodName;
            _description = description;
            _warnMs = warnMs;
            _errorMs = errorMs;
        }

        public void Dispose()
        {
            _watch.Stop();

            var prefix = _watch.ElapsedMilliseconds > _errorMs ? "ERROR: " :
                         _watch.ElapsedMilliseconds > _warnMs ? "WARNING: " : "";

            if (!string.IsNullOrWhiteSpace(_description))
                _description = "\nDescription: " + _description;

            System.Diagnostics.Debug.WriteLine(prefix + _callerType.Name + "." + _methodName + ": " + _watch.Elapsed.TotalSeconds + " seconds." + _description);
        }
    }
}