csharp_async

gistfile1.txt

using System.Net;
class Program {
    static async Task Main(string[] args)
    {
        // Example 1. await-foreach
        static async IAsyncEnumerable<int> YieldReturnNumbers(List<int> numbers)   
        {  
            foreach (int number in numbers)  
            {  
                await Task.Delay(1000);  
                yield return number;  
            }  
        }

        static async Task TestAwaitForEach() {
            List<int> numbers = new List<int>() { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };  

            await foreach(int number in YieldReturnNumbers(numbers))  
            {  
                Console.WriteLine(number);  
            } 
        }

        await TestAwaitForEach();

        
        // Example 2. Simple async method call and ConfigureAwait
        static async Task SimpleFetch()
        { 
            using(var client = new HttpClient()) {
                Console.WriteLine($"Simple Async #2. Thread ID: {Thread.CurrentThread.ManagedThreadId}");
                var response = await client.GetAsync(new Uri("http://bbc.co.uk")).ConfigureAwait(true);
                Console.WriteLine($"Simple Async #3. Thread ID: {Thread.CurrentThread.ManagedThreadId}");
            }           
        }

        Console.WriteLine($"Simple Async #1. Thread ID: {Thread.CurrentThread.ManagedThreadId}");
        await SimpleFetch().ConfigureAwait(true);
        await Task.Delay(100).ConfigureAwait(true);
        /*
        Why after 'await', even with ConfigureAwait(true), thread id not returning to main thread? 
        Essentially for dotnet core console and aspnet core/webapi's, ConfigureAwait essentially making random decision which thread to execute continuation tasks, because no synchronization context present.
            https://stackoverflow.com/questions/78229368/dotnet-core-console-app-configureawaittrue
            https://stackoverflow.com/questions/13489065/best-practice-to-call-configureawait-for-all-server-side-code
        */
        Console.WriteLine($"Simple Async #4. Thread ID: {Thread.CurrentThread.ManagedThreadId}");
    }
}