c# - WriteLineAsync 与取消

Question

我将我的方法扩展到 async，但我希望可以通过用户请求和超时时间取消，但 WriteLineAsync 不支持取消 token 的移交。我尝试了嵌套任务，但没有用。有人可以支持我吗？

public async Task tapAsync(int x, int y, int timeouttime)
{
    CancellationTokenSource cts;
    cts = new CancellationTokenSource();
    await Task.Run(async() =>
    {
       try
       {
           cts.CancelAfter(timeouttime);
           await myWriter.WriteLineAsync("input tap " + x.ToString() + " " + y.ToString());
           await myWriter.FlushAsync();
           await Task.Delay(2000);
       }
       catch (OperationCanceledException)
       {
           Console.WriteLine("canceled");
       }
    }, cts.Token);
    cts = null;
}

Answer 1

至少到目前为止，您无法取消 WriteLineAsync 本身。

您能做的最好的事情就是在操作之间取消:

public async Task TapAsync(int x, int y, int timeouttime)
{
    CancellationTokenSource cts;
    cts = new CancellationTokenSource();
    cts.CancelAfter(timeouttime);
    return TapAsync(x, y, source.Token);
    await myWriter.WriteLineAsync("input tap " + x.ToString() + " " + y.ToString());
    token.ThrowIfCancellationRequested();
    await myWriter.FlushAsync();
    token.ThrowIfCancellationRequested();
    await Task.Delay(2000, token);
}

为了清晰和灵活，我可能将其拆分为:

public Task TapAsync(int x, int y, int timeouttime)
{
    CancellationTokenSource cts;
    cts = new CancellationTokenSource();
    cts.CancelAfter(timeouttime);
    return TapAsync(x, y, source.Token);
}

public async Task TapAsync(int x, int y, CancellationToken token)
{
    token.ThrowIfCancellationRequested();
    await myWriter.WriteLineAsync("input tap " + x.ToString() + " " + y.ToString());
    token.ThrowIfCancellationRequested();
    await myWriter.FlushAsync();
    token.ThrowIfCancellationRequested();
    await Task.Delay(2000, token);
}