如何通过CancellationToken停止异步处理？(How can I stop async Process by CancellationToken?)

 我发现在代码下执行某些进程而没有冻结UI。 按下“开始工作”按钮时执行此代码。 我认为用户可以通过“停止”按钮停止这项工作。 所以我在MSDN上发现了这篇文章.. https://msdn.microsoft.com/en-us/library/jj155759.aspx 。 但是，在此代码中应用此CancellationToken很难..任何人都可以帮助解决这个问题吗？ 
 
 我只使用public static async Task<int> RunProcessAsync(string fileName, string args)方法。 
 
 代码（来自https://stackoverflow.com/a/31492250 ）： 
 
public static async Task<int> RunProcessAsync(string fileName, string args)
{
    using (var process = new Process
    {
        StartInfo =
        {
            FileName = fileName, Arguments = args,
            UseShellExecute = false, CreateNoWindow = true,
            RedirectStandardOutput = true, RedirectStandardError = true
        },
        EnableRaisingEvents = true
    })
    {
        return await RunProcessAsync(process).ConfigureAwait(false);
    }
}

// This method is used only for internal function call.
private static Task<int> RunProcessAsync(Process process)
{
    var tcs = new TaskCompletionSource<int>();

    process.Exited += (s, ea) => tcs.SetResult(process.ExitCode);
    process.OutputDataReceived += (s, ea) => Console.WriteLine(ea.Data);
    process.ErrorDataReceived += (s, ea) => Console.WriteLine("ERR: " + ea.Data);

    bool started = process.Start();
    if (!started)
    {
        //you may allow for the process to be re-used (started = false) 
        //but I'm not sure about the guarantees of the Exited event in such a case
        throw new InvalidOperationException("Could not start process: " + process);
    }

    process.BeginOutputReadLine();
    process.BeginErrorReadLine();

    return tcs.Task;
}
 
 用法： 
 
var cancelToken = new CancellationTokenSource();
int returnCode = async RunProcessAsync("python.exe", "foo.py", cancelToken.Token);
if (cancelToken.IsCancellationRequested) { /* something */ }
 
 单击开始按钮时，它会启动一些python脚本。 当脚本运行并且用户想要停止它时，用户按下停止按钮。 然后程序在代码下执行。 
 
cancelToken.Cancel();
 
 非常感谢你阅读这个问题。 

I found beneath code for execute some process without freezing UI. This code is executed when 'Start Work' button is pressed. And I think users would stop this work by 'Stop' button. So I found this article at MSDN.. https://msdn.microsoft.com/en-us/library/jj155759.aspx . But, It was hard that applying this CancellationToken at this code.. Anyone can help this problem? 
 
I use public static async Task<int> RunProcessAsync(string fileName, string args) method only.
 
Code (From https://stackoverflow.com/a/31492250):
 
public static async Task<int> RunProcessAsync(string fileName, string args)
{
    using (var process = new Process
    {
        StartInfo =
        {
            FileName = fileName, Arguments = args,
            UseShellExecute = false, CreateNoWindow = true,
            RedirectStandardOutput = true, RedirectStandardError = true
        },
        EnableRaisingEvents = true
    })
    {
        return await RunProcessAsync(process).ConfigureAwait(false);
    }
}

// This method is used only for internal function call.
private static Task<int> RunProcessAsync(Process process)
{
    var tcs = new TaskCompletionSource<int>();

    process.Exited += (s, ea) => tcs.SetResult(process.ExitCode);
    process.OutputDataReceived += (s, ea) => Console.WriteLine(ea.Data);
    process.ErrorDataReceived += (s, ea) => Console.WriteLine("ERR: " + ea.Data);

    bool started = process.Start();
    if (!started)
    {
        //you may allow for the process to be re-used (started = false) 
        //but I'm not sure about the guarantees of the Exited event in such a case
        throw new InvalidOperationException("Could not start process: " + process);
    }

    process.BeginOutputReadLine();
    process.BeginErrorReadLine();

    return tcs.Task;
}
 
Usage :
 
var cancelToken = new CancellationTokenSource();
int returnCode = async RunProcessAsync("python.exe", "foo.py", cancelToken.Token);
if (cancelToken.IsCancellationRequested) { /* something */ }
 
When the start button clicked, it starts some python script. When script is running and user wants to stop it, user presses stop button. Then program executes below code.
 
cancelToken.Cancel();
 
Thank you very much for reading this question.

原文：https://stackoverflow.com/questions/34199628