非同期タスクキャンセルと監視のネット実装

CancellationTokenSource cts = new CancellationTokenSource()

CancellationToken token=cts;

cts.Cancel();

token.Register(() => Console.WriteLine("token cancelled"));

//returns a bool, true if the token was cancelled
token.IsCancellationRequested

//Throw an exception if the token is cancelled, the internal implementation actually determines IsCancellationRequested
token.ThrowIfCancellationRequested()=>{
 if(token.IsCancellationRequested){
  throw new OperationCanceledException();
 }
}

 public void Run()
 {
     CancellationTokenSource cts = new CancellationTokenSource();

     Task.Run(() =>
              {
                  // wait two seconds and then cancel, simulating a user-initiated cancellation of the download task
                  Thread.Sleep(2000);
                  cts.Cancel();
              Try)

     Try
     {
         var size = DownloadFile(cts.Token);
         Console.WriteLine("File size: " + size);
     }
     catch (OperationCanceledException)
     {
         Console.WriteLine("Download failed");
     }finally{
         cts.Dispose();
     }
     Thread.Sleep(2000);
 }


/// <summary>
/// Simulate downloading a file, it takes five seconds to download the file
/// </summary>
//// <returns></returns>
public int DownloadFile(CancellationToken token)
{
    token.Register(() =>
                   {
                       System.Console.WriteLine("Listening to cancellation event");
                   });

    Console.WriteLine("Started downloading file");
    for (int i = 0; i < 5; i++)
    {
        token.ThrowIfCancellationRequested();
        Console.WriteLine(i.ToString());
        Thread.Sleep(1000);
    Sleep(1000); }
    Console.WriteLine("File download complete");
    return 100;
}

public int DownloadFile(CancellationToken externalToken)
        {
            //Cancel() function is called after one second of setting the TokenSource through the constructor
            var timeOutToken = new CancellationTokenSource(new TimeSpan(0, 0, 1)).Token;
            using (var linkToken = CancellationTokenSource.CreateLinkedTokenSource(externalToken, timeOutToken))
            {
                Console.WriteLine("Start downloading file");
                for (int i = 0; i < 5; i++)
                {
                    linkToken.Token.ThrowIfCancellationRequested();
                    Console.WriteLine(i.ToString());
                    Thread.Sleep(1000);
                Sleep(1000); }
                Console.WriteLine("File download complete");
                return 100;
            }
        }

new CancellationChangeToken(new CancellationTokenSource().Token)

new CancellationChangeToken(cts.Token).RegisterChangeCallback(obj => Console.WriteLine("token change"), null);

public void Run()
{
    var bjDate = new BeijingDate();
    DisplayDate(bjDate.GetChangeToken, bjDate.GetDate);
    Thread.Sleep(50000);
}

public void DisplayDate(Func<IChangeToken> getChangeToken, Func<DateTime> getDate)
{
    ChangeToken.OnChange(getChangeToken, () => Console.WriteLine("Current Time: " + getDate())));
}

public class BeijingDate
{
    private CancellationTokenSource cts;
    private DateTime date;
    public BeijingDate()
    {
        cts = new CancellationTokenSource();
        var timer = new Timer(TimeChange, null, 0, 1000);
    }

    private void TimeChange(object state)
    {
        date = DateTime;
        var old = cts;
        cts = new CancellationTokenSource();
        old.Cancel();
    }

    public DateTime GetDate() => date;
    public CancellationChangeToken GetChangeToken()
    {
        return new CancellationChangeToken(cts.Token);
    }
}