How Can I Asynchronously Wait for a Process to Exit in .NET without Blocking the GUI?

Waiting for Processes to Exit Asynchronously

It can be challenging to wait for a process to finish without blocking the GUI using Process.WaitForExit(). To address this, let's explore an event-driven approach and an alternative solution using the async pattern.

In .NET versions prior to 4.0, it was necessary to create a separate thread to wait for the exit and trigger an event. However, with the introduction of async programming in .NET 4.0 and C# 5, we can now represent this process more elegantly.

Asynchronous Waiting Using async and await

The async pattern allows us to wait for the process to exit asynchronously. Here's an example:

/// <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))
{
    if (process.HasExited) return Task.CompletedTask;

    var tcs = new TaskCompletionSource<object>();
    process.EnableRaisingEvents = true;
    process.Exited += (sender, args) => tcs.TrySetResult(null);
    if(cancellationToken != default(CancellationToken))
        cancellationToken.Register(() => tcs.SetCanceled());

    return process.HasExited ? Task.CompletedTask : tcs.Task;
}

Usage:

public async void Test() 
{
   var process = new Process("processName");
   process.Start();
   await process.WaitForExitAsync();

   //Do some fun stuff here...
}

By using the extension method WaitForExitAsync, you can wait for the process to exit asynchronously without blocking the GUI. The await keyword pauses the execution of the Test method until the process finishes or the cancellation token is triggered.

The above is the detailed content of How Can I Asynchronously Wait for a Process to Exit in .NET without Blocking the GUI?. For more information, please follow other related articles on the PHP Chinese website!