異步process.WaitForExit（int32）

Question

我正在使用：https://stackoverflow.com/a/19104345/2713516中提供的解決方案來運行WaitForExit異步，但是，我想使用Int32參數過載（https://msdn.microsoft.com/en-us/library/ty0d8k56(v=vs.110).aspx），如在process.WaitForExit（10000）中一樣。

如何修改此擴展方法，使其與超時參數一起使用？

方問題：我還看到有人提到（https://stackoverflow.com/a/32994778/2713516），我應該處置的CancellationToken在某些時候，不應該使用一個dispose /使用，則該方法內？如何？

/// <summary> 
/// Waits asynchronously for the process to exit. 
/// </summary> 
/// <param name="process">The process to wait for cancellation.</param> 
/// <param name="cancellationToken">A cancellation token. If invoked, the task will return 
/// immediately as canceled.</param> 
/// <returns>A Task representing waiting for the process to end.</returns> 
public static Task WaitForExitAsync(this Process process, 
    CancellationToken cancellationToken = default(CancellationToken)) 
{ 
    var tcs = new TaskCompletionSource<object>(); 
    process.EnableRaisingEvents = true; 
    process.Exited += (sender, args) => tcs.TrySetResult(null); 
    if(cancellationToken != default(CancellationToken)) 
     cancellationToken.Register(tcs.SetCanceled); 

    return tcs.Task; 
} 

Answer 1

您需要更改方法簽名並應用過程本身的結果。例如考慮以下內容：

/// <summary> 
/// Waits asynchronously for the process to exit. 
/// </summary> 
/// <param name="process">The process to wait for cancellation.</param> 
/// <param name="cancellationToken">A cancellation token. If invoked, the task will return 
/// immediately as canceled.</param> 
/// <returns>A Task representing waiting for the process to end.</returns> 
public static Task WaitForExitAsync(this Process process, 
    int milliseconds, 
    CancellationToken cancellationToken = default(CancellationToken)) 
{ 
    var tcs = new TaskCompletionSource<object>(); 
    process.EnableRaisingEvents = true; 
    process.Exited += (sender, args) => tcs.TrySetResult(null); 
    if (cancellationToken != default(CancellationToken)) 
    { 
     cancellationToken.Register(tcs.SetCanceled); 
    } 

    return Task.WhenAny(tcs.Task, Task.Delay(milliseconds)); 
} 

現在，如果進程還沒有結束，任務仍然會在延遲後返回。另一種方法是與調用做Task.Run像這樣希望的過載：

/// <summary> 
/// Waits asynchronously for the process to exit. 
/// </summary> 
/// <param name="process">The process to wait for cancellation.</param> 
/// <param name="cancellationToken">A cancellation token. If invoked, the task will return 
/// immediately as canceled.</param> 
/// <returns>A Task representing waiting for the process to end.</returns> 
public static Task WaitForExitAsync(this Process process, 
    int milliseconds, 
    CancellationToken cancellationToken = default(CancellationToken)) 
{  
    return Task.Run(() => process.WaitForExit(milliseconds), cancellationToken); 
}