using System;

using System.Threading;

using System.Threading.Tasks;

using Microsoft.Extensions.DependencyInjection;

​

public class Program

{

    public static async Task Main()

    {

​

        Console.WriteLine("--- START ---");

        // UseSemaphoreSlim();

        await UseReaderWriterLockSlim();

​

        Console.WriteLine("--- END ---");

    }

    public static async Task UseSemaphoreSlim(){

        var sem = new SemaphoreSlim(1);

        var func = async () => {

            Console.WriteLine($"--- FUNC START {Thread.CurrentThread.ManagedThreadId} ---");

            await sem.WaitAsync();

            Console.WriteLine($"--- FUNC END {Thread.CurrentThread.ManagedThreadId} ---");

        };

        await Task.WhenAll(new [] {

            func(),

            func()

        });

    }

    public static async Task UseReaderWriterLockSlim (){

        var lockObject =  new ReaderWriterLockSlim();

        var func = async () => {

            Console.WriteLine($"--- FUNC START {Thread.CurrentThread.ManagedThreadId} ---");

            lockObject.EnterWriteLock();

            Console.WriteLine($"--- FUNC END {Thread.CurrentThread.ManagedThreadId} ---");

        };

        await Task.WhenAll(new [] {

            func(),

            func()

        });

    }

}