.NET Fiddle

CSharp · Console

/Program.cs

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

class Program
{
    static async Task Main()
    {
        var channel = Channel.CreateUnbounded<int>();
        for (int i = 1; i <= 10; i++) channel.Writer.TryWrite(i);
        int itemsRead = 0;
        var cts = new CancellationTokenSource();
        try
        {
            await foreach (var i in channel.Reader.ReadAllAsync(cts.Token))
            {
                Console.WriteLine($"Read item: {i}. Requested cancellation: " +
                    $"{cts.Token.IsCancellationRequested}");

                if (++itemsRead > 4 && !cts.IsCancellationRequested)
                {
                    Console.WriteLine("Cancelling...");
                    cts.Cancel();
                }
            }
        }
        catch (OperationCanceledException)
        {
            Console.WriteLine($"Operation cancelled. Items read: {itemsRead}");
        }
    }
}