MiniProfiler.cs

public class MiniProfiler : IDisposable
{
    private Stopwatch _stopWatch;
    private List<ProfilerEvent> _events;

    public MiniProfiler()
    {
        _events = new List<ProfilerEvent>();
    }

    public void Start()
    {
        if (IsRunning())
        {
            _stopWatch.Restart();
            Step("Restarted");
        }
        else
        {
            if (_stopWatch == null)
                _stopWatch = new Stopwatch();

            _stopWatch.Start();
            Step("Started");
        }
    }

    public void Stop()
    {
        if (!IsRunning())
            return;

        _stopWatch.Stop();
        _stopWatch = null;
    }

    public IDisposable Step(string name)
    {
        return Step(name, null);
    }

    public IDisposable Step(string name, string data)
    {
        if (!IsRunning())
            return NullDisposable.CreateNew();

        var profilerEvent = new ProfilerEvent();
        profilerEvent.Name = name;
        profilerEvent.Data = data;
        profilerEvent.ElapsedMilliseconds = _stopWatch.ElapsedTicks;

        return new ProfilerStep(profilerEvent, (e) => StepFinishedCallback(e));
    }

    private void StepFinishedCallback(ProfilerEvent e)
    {
        if (_stopWatch != null)
            e.TotalMilliseconds = _stopWatch.ElapsedMilliseconds;

        _events.Add(e);
    }

    private bool IsRunning()
    {
        if (_stopWatch == null || !_stopWatch.IsRunning)
            return false;

        return true;
    }

    public void Dispose()
    {
        Stop();
    }

    public override string ToString()
    {
        return string.Join(Environment.NewLine, _events);
    }

    public class ProfilerStep : IDisposable
    {
        private Stopwatch _stopWatch;
        private ProfilerEvent _profilerEvent;
        private Action<ProfilerEvent> _disposeAction;

        public long ElapsedMilliseconds { get; private set; }

        public ProfilerStep(ProfilerEvent profilerEvent, Action<ProfilerEvent> disposeAction)
        {
            if (profilerEvent == null)
                throw new ArgumentException("profilerEvent");

            _profilerEvent = profilerEvent;
            _disposeAction = disposeAction;

            _stopWatch = new Stopwatch();
            _stopWatch.Start();
        }

        public void Dispose()
        {
            _stopWatch.Stop();
            _profilerEvent.ElapsedMilliseconds = _stopWatch.ElapsedMilliseconds;

            if (_disposeAction != null)
            {
                _disposeAction(_profilerEvent);
            }

            _stopWatch = null;
        }
    }

    public class ProfilerEvent
    {
        public long ElapsedMilliseconds { get; set; }

        public long TotalMilliseconds { get; set; }

        public string Name { get; set; }

        public string Data { get; set; }

        public override string ToString()
        {
            return string.Format("{0}\t{1}\t{2}\t{3}", TotalMilliseconds, ElapsedMilliseconds, Name, Data);
        }
    }

    public class NullDisposable : IDisposable
    {
        public void Dispose()
        { }

        public static IDisposable CreateNew()
        {
            return new NullDisposable();
        }
    }
}