[C#/General] Microsoft 제공.. 가장쉬운 async/await 예제.

특정 싸이트에 연결시도하면서 content를 받아오는 도중~~

특정 Key 이벤트가 들어오면 Cancel 하는 예제.

 

> 즉시 비동기 취소

cancelToken.Cancel()

 

> 일정 기간 이후 비동기 작업 취소

cancelToken.CancelAfter(3500);

async_await 예제

using System.Diagnostics;

class Program
{
    static readonly CancellationTokenSource cancelToken = new CancellationTokenSource();

    static readonly HttpClient _httpClient = new HttpClient
    {
        MaxResponseContentBufferSize = 1_000_000
    };

    static readonly IEnumerable<string> s_microsoftUrlList = new string[]
    {
            "https://docs.microsoft.com",
            "https://docs.microsoft.com/aspnet/core",
            "https://docs.microsoft.com/azure",
            "https://docs.microsoft.com/azure/devops",
            "https://docs.microsoft.com/dotnet",
            "https://docs.microsoft.com/dynamics365",
            "https://docs.microsoft.com/education",
            "https://docs.microsoft.com/enterprise-mobility-security",
            "https://docs.microsoft.com/gaming",
            "https://docs.microsoft.com/graph",
            "https://docs.microsoft.com/microsoft-365",
            "https://docs.microsoft.com/office",
            "https://docs.microsoft.com/powershell",
            "https://docs.microsoft.com/sql",
            "https://docs.microsoft.com/surface",
            "https://docs.microsoft.com/system-center",
            "https://docs.microsoft.com/visualstudio",
            "https://docs.microsoft.com/windows",
            "https://docs.microsoft.com/xamarin"
    };

    static async Task Main()
    {
        Console.WriteLine("Application started.");
        Console.WriteLine("Press the ENTER key to cancel...\n");

        Task cancelTask = Task.Run(() =>
        {
            while (Console.ReadKey().Key != ConsoleKey.Enter)
            {
                Console.WriteLine("Press the ENTER key to cancel...");
            }

            Console.WriteLine("\nENTER key pressed: cancelling downloads.\n");
            cancelToken.Cancel();
        });

        Task sumPageSizesTask = SumPageSizesAsync();

        await Task.WhenAny(new[] { cancelTask, sumPageSizesTask });

        Console.WriteLine("Application ending.");
    }

    static async Task SumPageSizesAsync()
    {
        var stopwatch = Stopwatch.StartNew();

        int total = 0;
        foreach (string url in s_microsoftUrlList)
        {
            int contentLength = await ProcessUrlAsync(url, _httpClient, cancelToken.Token);
            total += contentLength;
        }

        stopwatch.Stop();

        Console.WriteLine($"\nTotal bytes returned:  {total:#,#}");
        Console.WriteLine($"Elapsed time:          {stopwatch.Elapsed}\n");
    }

    static async Task<int> ProcessUrlAsync(string url, HttpClient client, CancellationToken token)
    {
        HttpResponseMessage response = await client.GetAsync(url, token);
        byte[] content = await response.Content.ReadAsByteArrayAsync(token);
        Console.WriteLine($"{url,-60} {content.Length,10:#,#}");

        return content.Length;
    }
}