CancellationTokenSource.Cancel 方法不更改 CancellationToken.IsCancellationRequested 属性

Question

有人知道我在做什么错吗？

Windows 10 - VS2013

C# .NET 4.5.1

我有一个名为 testButton 的按钮和一个 testButton_Click 方法，我试图用它来完成工作，但也能够中止该工作。 正在执行任务中的工作，并且正在执行中止的逻辑（按钮变回灰色的“运行测试”），但 cts.Cancel 方法似乎不会影响令牌的 IsCancellationRequested 标志，或者任务有错误的令牌，或者什么......？

public System.Threading.Tasks.Task DoWorkAsync(CancellationToken ct = default(CancellationToken))
{
    System.Threading.Tasks.Task T1 = new System.Threading.Tasks.Task(() =>
    {
        try
        {
            var capturedToken = ct;
            // do work here
            for (int i = 0; i < work.Length; i++)
            {
                ct.ThrowIfCancellationRequested();
                capturedToken.ThrowIfCancellationRequested();
                if (ct.IsCancellationRequested) throw new OperationCanceledException(ct);
                // sleep 1 second
                System.Threading.Thread.Sleep(1000);
            }
        }
        catch
        {
            MessageBox.Show("Caught :) I can do stuff", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
        finally
        {
            taskRunning = false;
        }
    }, ct);
    return T1;
}


private async void testButton_Click(object sender, EventArgs e)
{
    CancellationTokenSource cts = new CancellationTokenSource();
    CancellationToken ct = cts.Token;
    var task = DoWorkAsync(ct);

    if (!taskRunning)
    {
        Cursor.Current = Cursors.WaitCursor;
        testButton.BackColor = Color.Red;
        testButton.Text = "ABORT";
        taskRunning = true;
        task.Start();
        await task;

        // Release cursor when setup is complete
        Cursor.Current = Cursors.Default;
    }
    else
    {
        cts.Cancel();
        testButton.Text = "Run Test";
        testButton.BackColor = Color.Gray;
    }
}