using System;

using System.Threading;

using System.Threading.Tasks;

​

using System.Diagnostics;

​

public class Program

{

    //Used for logging duration 

    private static Stopwatch _stopwatch = new Stopwatch();

    public static void Main()

    {

        MakeBreakfastSync();

        MakeBreakfastAsync().GetAwaiter().GetResult();

        MakeBreakfastParallel();

    }

    public static void MakeBreakfastSync()

    {

        Console.WriteLine("\n============================");

        Console.WriteLine("\nMakeBreakfastSync\n");

​

        Console.WriteLine("\nNOTE: The number before the time is current threadId\n");

        StartTimer();

        WriteLog("MakeBreakfastSync Start");

        BoilCoffee();

        ToastBread();

        FryEggs();

        WriteLog("MakeBreakfastSync End");

        Console.WriteLine($"\nTotal time: {_stopwatch.Elapsed.TotalMilliseconds}ms\n");

    }

    private static void StartTimer()

    {

        _stopwatch.Reset();

        _stopwatch.Start();

    }

    private static void BoilCoffee()

    {

        WriteLog("BoilCoffee Start");

        Thread.Sleep(100);   //Do something for 100ms

        WriteLog("BoilCoffee End");

    }

    private static void ToastBread()

    {

        WriteLog("ToastBread Start");

        Thread.Sleep(100);   

        WriteLog("ToastBread End");

    }

    private static void FryEggs()

    {

        WriteLog("FryEggs Start");

        Thread.Sleep(100);   

        WriteLog("FryEggs End");

    }

    public static void WriteLog(string text)

    {

        string message = Thread.CurrentThread.ManagedThreadId + " " + _stopwatch.Elapsed.ToString(@"mm\:ss\.fff").PadRight(12) + text;

        Console.WriteLine(message);

    }

    public static async Task MakeBreakfastAsync()

    {

        Console.WriteLine("\n============================");

        Console.WriteLine("\nMakeBreakfastAsync");

        Console.WriteLine("\nNOTE: tasks maybe using different threads provided by ThreadPool, but unlike parallel programming, it is only one thread at a time\n");

        StartTimer();

        WriteLog("MakeBreakfastAsync Start");

        Task boilCoffeeTask = BoilCoffeeAsync();

        Task toastBreadTask = ToastBreadAsync();

        Task fryEggsTask =  FryEggsAsync(); 

        await boilCoffeeTask;

        await toastBreadTask;

        await fryEggsTask;

        WriteLog("MakeBreakfastAsync End");

        Console.WriteLine($"\nTotal time: {_stopwatch.Elapsed.TotalMilliseconds}ms\n");

    }

    private static async Task BoilCoffeeAsync()

    {

        WriteLog("BoilCoffeeAsync Start");

        await Task.Delay(100);  //Do steps to boil coffee for 100ms, usually a thread blocking operation that requires async

        WriteLog("BoilCoffeeAsync End");

    }

    private static async Task ToastBreadAsync()

    {

        WriteLog("ToastBreadAsync Start");

        await Task.Delay(100);  

        WriteLog("ToastBreadAsync End");

    }

    private static async Task FryEggsAsync()

    {

        WriteLog("FryEggsAsync Start");

        await Task.Delay(100);  

        WriteLog("FryEggsAsync End");

    }

    public static void MakeBreakfastParallel()

    {

        Console.WriteLine("\n============================");

        Console.WriteLine("\nMakeBreakfastParallel\n");

        //On .NET FIddle default is 4. We will print it out.

        Console.WriteLine("Available processors: " + Environment.ProcessorCount + "\n");

        //Let's see what happens if only 2 processors are available, since in many cases like IIS under load

        //you will have a lot less processors than tasks running in parallel

        //If you change 2 to 4 than Parallel will work at a bit more like Async, but there is still extra time to start the new threads

        var useProcessors = 2;

        var parallelOptions = new ParallelOptions

        {

            MaxDegreeOfParallelism = useProcessors

        };

        Console.WriteLine("Using processors: " + useProcessors + "\n");

        StartTimer();

        WriteLog("MakeBreakfastParallel Start");

        Parallel.Invoke(parallelOptions, 

                       () => BoilCoffee(),

                       () => ToastBread(),

                       () => FryEggs()

                       );

        Console.WriteLine("\nMakeBreakfastParallel End\n");

        Console.WriteLine($"\nTotal time: {_stopwatch.Elapsed.TotalMilliseconds}ms\n");

    }

}