Wrapping StopWatch timing with a delegate or lambda?

Question

I'm writing code like this, doing a little quick and dirty timing:

var sw = new Stopwatch();
sw.Start();
for (int i = 0; i < 1000; i++)
{
    b = DoStuff(s);
}
sw.Stop();
Console.WriteLine(sw.ElapsedMilliseconds);

Surely there's a way to call this bit of timing code as a fancy-schmancy .NET 3.0 lambda rather than (God forbid) cutting and pasting it a few times and replacing the DoStuff(s) with DoSomethingElse(s)?

I know it can be done as a Delegate but I'm wondering about the lambda way.

Answer 1

You could try writing an extension method for whatever class you're using (or any base class).

I would have the call look like:

StopWatch sw = MyObject.TimedFor(1000, () => DoStuff(s));

Then the extension method:

public static StopWatch TimedFor(this DependencyObject source, Int32 loops, Action action)
{
var sw = new Stopwatch();
sw.Start();
for (int i = 0; i < loops; ++i)
{
    action.Invoke();
}
sw.Stop();

return sw;
}

Any object deriving from DependencyObject can now call TimedFor(..). The function can easily be adjusted to provide return values via ref params.

--

If you didn't want the functionality to be tied to any class / object you could do something like:

public class Timing
{
  public static StopWatch TimedFor(Action action, Int32 loops)
  {
    var sw = new Stopwatch();
    sw.Start();
    for (int i = 0; i < loops; ++i)
    {
      action.Invoke();
    }
    sw.Stop();

    return sw;
  }
}

Then you could use it like:

StopWatch sw = Timing.TimedFor(() => DoStuff(s), 1000);

Failing that, this answer looks like it has some decent "generic" ability:

http://stackoverflow.com/questions/232848/wrapping-stopwatch-timing-with-a-delegate-or-lambda#232878

Answer 2

How about extending the Stopwatch class?

public static class StopwatchExtensions
{
    public static long Time(this Stopwatch sw, Action action, int iterations)
    {
        sw.Reset();
        sw.Start(); 
        for (int i = 0; i < iterations; i++)
        {
            action();
        }
        sw.Stop();

        return sw.ElapsedMilliseconds;
    }
}

Then call it like this:

var s = new Stopwatch();
Console.WriteLine(s.Time(() => DoStuff(), 1000));

You could add another overload which omits the "iterations" parameter and calls this version with some default value (like 1000).

Answer 3

You can overload a number of methods to cover various cases of parameters you might want to pass to the lambda:

public static Stopwatch MeasureTime<T>(int iterations, Action<T> action, T param)
{
    var sw = new Stopwatch();
    sw.Start();
    for (int i = 0; i < iterations; i++)
    {
        action.Invoke(param);
    }
    sw.Stop();

    return sw;
}

public static Stopwatch MeasureTime<T, K>(int iterations, Action<T, K> action, T param1, K param2)
{
    var sw = new Stopwatch();
    sw.Start();
    for (int i = 0; i < iterations; i++)
    {
        action.Invoke(param1, param2);
    }
    sw.Stop();

    return sw;
}

Alternatively, you can use the Func delegate if they must return a value. You can also pass in an array (or more) of parameters if each iteration must use a unique value.

Answer 4

I wrote a simple CodeProfiler class some time ago that wrapped Stopwatch to easily profile a method using an Action: http://www.improve.dk/blog/2008/04/16/profiling-code-the-easy-way

It'll also easily allow you to profile the code multithreaded. The following example will profile the action lambda with 1-16 threads:

using System;

namespace CodeProfiler
{
    class Program
    {
        static void Main(string[] args)
        {
            Action action = () =>
            {
                for (int i = 0; i < 10000000; i++)
                    Math.Sqrt(i);
            };

            for(int i=1; i<=16; i++)
                Console.WriteLine(i + " thread(s):\t" + CodeProfiler.ProfileAction(action, 100, i));

            Console.Read();
        }
    }
}

Answer 5

I like to use the CodeTimer classes from Vance Morrison (one of the performance dudes from .NET).

He made a post on on his blog titled "Measuring managed code quickly and easiliy: CodeTimers".

It includes cool stuff such as a MultiSampleCodeTimer. It does automatic calculation of the mean and standard deviation and its also very easy to print out your results.

Answer 6

Assuming you just need a quick timing of one thing this is easy to use.

  public static class Test {
    public static void Invoke() {
        using( SingleTimer.Start )
            Thread.Sleep( 200 );
        Console.WriteLine( SingleTimer.Elapsed );

        using( SingleTimer.Start ) {
            Thread.Sleep( 300 );
        }
        Console.WriteLine( SingleTimer.Elapsed );
    }
}

public class SingleTimer :IDisposable {
    private Stopwatch stopwatch = new Stopwatch();

    public static readonly SingleTimer timer = new SingleTimer();
    public static SingleTimer Start {
        get {
            timer.stopwatch.Reset();
            timer.stopwatch.Start();
            return timer;
        }
    }

    public void Stop() {
        stopwatch.Stop();
    }
    public void Dispose() {
        stopwatch.Stop();
    }

    public static TimeSpan Elapsed {
        get { return timer.stopwatch.Elapsed; }
    }
}

Answer 7

For me the extension feels a little bit more intuitive on int, you no longer need to instantiate a Stopwatch or worry about resetting it.

So you have:

static class BenchmarkExtension {

    public static void Times(this int times, string description, Action action) {
        Stopwatch watch = new Stopwatch();
        watch.Start();
        for (int i = 0; i < times; i++) {
            action();
        }
        watch.Stop();
        Console.WriteLine("{0} ... Total time: {1}ms ({2} iterations)", 
            description,  
            watch.ElapsedMilliseconds,
            times);
    }
}

With the sample usage of:

var randomStrings = Enumerable.Range(0, 10000)
    .Select(_ => Guid.NewGuid().ToString())
    .ToArray();

50.Times("Add 10,000 random strings to a Dictionary", 
    () => {
        var dict = new Dictionary<string, object>();
        foreach (var str in randomStrings) {
            dict.Add(str, null);
        }
    });

50.Times("Add 10,000 random strings to a SortedList",
    () => {
        var list = new SortedList<string, object>();
        foreach (var str in randomStrings) {
            list.Add(str, null);
        }
    });

Sample output:

Add 10,000 random strings to a Dictionary ... Total time: 144ms (50 iterations)
Add 10,000 random strings to a SortedList ... Total time: 4088ms (50 iterations)

Answer 8

Here's what I've been using:

public class DisposableStopwatch: IDisposable {
    private readonly Stopwatch sw;
    private readonly Action<TimeSpan> f;

    public DisposableStopwatch(Action<TimeSpan> f) {
        this.f = f;
        sw = Stopwatch.StartNew();
    }

    public void Dispose() {
        sw.Stop();
        f(sw.Elapsed);
    }
}

Usage:

using (new DisposableStopwatch(t => Console.WriteLine("{0} elapsed", t)) {
  // do stuff that I want to measure
}

Answer 9

The StopWatch class does not need to be Disposed or Stopped on error. So, the simplest code to time some action is

public partial class With
{
    public static long Benchmark(Action action)
    {
        var stopwatch = Stopwatch.StartNew();
        action();
        stopwatch.Stop();
        return stopwatch.ElapsedMilliseconds;
    }
}

Sample calling code

public void Execute(Action action)
{
    var time = With.Benchmark(action);
    log.DebugFormat(“Did action in {0} ms.”, time);
}

I don't like the idea of including the iterations into the StopWatch code. You can always create another method or extension that handles executing N iterations.

public partial class With
{
    public static void Iterations(int n, Action action)
    {
        for(int count = 0; count < n; count++)
            action();
    }
}

Sample calling code

public void Execute(Action action, int n)
{
    var time = With.Benchmark(With.Iterations(n, action));
    log.DebugFormat(“Did action {0} times in {1} ms.”, n, time);
}

Here are the extension method versions

public static class Extensions
{
    public static long Benchmark(this Action action)
    {
        return With.Benchmark(action);
    }

    public static Action Iterations(this Action action, int n)
    {
        return () => With.Iterations(n, action);
    }
}

And sample calling code

public void Execute(Action action, int n)
{
    var time = action.Iterations(n).Benchmark()
    log.DebugFormat(“Did action {0} times in {1} ms.”, n, time);
}

I tested the static methods and extension methods (combining iterations and benchmark) and the delta of expected execution time and real execution time is <= 1 ms.