using System;
using System.Threading;
using System.Threading.Tasks;

class AsyncLocal
{
    static AsyncLocal<string> _asyncLocalString = new AsyncLocal<string>();
    static ThreadLocal<string> _threadLocalString = new ThreadLocal<string>();

    static async Task AsyncMethodA()
    {
        // Start multiple async method calls, with different AsyncLocal values.
        // We also set ThreadLocal values, to demonstrate how the two mechanisms differ.
        _asyncLocalString.Value = "Value 1";
        _threadLocalString.Value = "Value 1";
        var t1 = AsyncMethodB("Value 1");

        _asyncLocalString.Value = "Value 2";
        _threadLocalString.Value = "Value 2";
        var t2 = AsyncMethodB("Value 2");

        // Await both calls
        await t1;
        await t2;
     }

    static async Task AsyncMethodB(string expectedValue)
    {
        Console.WriteLine($"Entering AsyncMethodB.  Expected '{expectedValue}', AsyncLocal value is '{_asyncLocalString.Value}, ThreadLocal value is '{_threadLocalString.Value}'");
        await Task.Delay(100);
        Console.WriteLine($"Exiting AsyncMethodB.  Expected '{expectedValue}', got '{_asyncLocalString.Value}, ThreadLocal value is '{_threadLocalString.Value}'");
    }

    static void Main(string[] args)
    {
        AsyncMethodA().Wait();
    }
}

/*
The output should be:

Entering AsyncMethodB.  Expected 'Value 1', AsyncLocal value is 'Value 1, ThreadLocal value is 'Value 1'
Entering AsyncMethodB.  Expected 'Value 2', AsyncLocal value is 'Value 2, ThreadLocal value is 'Value 2'
Exiting AsyncMethodB.  Expected 'Value 2', got 'Value 2, ThreadLocal value is ''
Exiting AsyncMethodB.  Expected 'Value 1', got 'Value 1, ThreadLocal value is ''
*/