如何在 C# 控制台应用中捕获 Ctrl+C (SIGINT)

本文关键字:Ctrl+C SIGINT 控制台 应用 | 更新日期: 2023-09-27 17:47:21

我希望能够在 C# 控制台应用程序中捕获 Ctrl+C,以便在退出之前执行一些清理。最好的方法是什么?

如何在 C# 控制台应用中捕获 Ctrl+C (SIGINT)

Console.CancelKeyPress 事件用于此目的。它是这样使用的:

public static void Main(string[] args)
{
    Console.CancelKeyPress += delegate {
        // call methods to clean up
    };
    while (true) {}
}

当用户按 Ctrl+C 时,将运行委托中的代码,程序将退出。这允许您通过调用必要的方法来执行清理。请注意,执行委托后没有代码。

在其他情况下,这不会削减它。例如,如果程序当前正在执行无法立即停止的重要计算。在这种情况下,正确的策略可能是告诉程序在计算完成后退出。以下代码给出了如何实现这一点的示例:

class MainClass
{
    private static bool keepRunning = true;
    public static void Main(string[] args)
    {
        Console.CancelKeyPress += delegate(object? sender, ConsoleCancelEventArgs e) {
            e.Cancel = true;
            MainClass.keepRunning = false;
        };
        
        while (MainClass.keepRunning) {
            // Do your work in here, in small chunks.
            // If you literally just want to wait until Ctrl+C,
            // not doing anything, see the answer using set-reset events.
        }
        Console.WriteLine("exited gracefully");
    }
}

此代码与第一个示例之间的区别在于e.Cancel设置为 true,这意味着在委托后继续执行。如果运行,程序将等待用户按 Ctrl+C。发生这种情况时,keepRunning变量会更改值,从而导致 while 循环退出。这是一种使程序正常退出的方法。

请参阅 MSDN:

控制台.取消按键事件

包含代码示例的文章:

Ctrl-C 和 .NET 控制台应用程序

我想

补充一下乔纳斯的答案。在bool上旋转会导致 100% 的 CPU 利用率,并在等待 CTRL+C 时浪费大量精力做很多事情。

更好的解决方案是使用ManualResetEvent实际"等待"CTRL + C

static void Main(string[] args) {
    var exitEvent = new ManualResetEvent(false);
    Console.CancelKeyPress += (sender, eventArgs) => {
                                  eventArgs.Cancel = true;
                                  exitEvent.Set();
                              };
    var server = new MyServer();     // example
    server.Run();
    exitEvent.WaitOne();
    server.Stop();
}

这是一个完整的工作示例。 粘贴到空的 C# 控制台项目中:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;
namespace TestTrapCtrlC {
    public class Program {
        static bool exitSystem = false;
        #region Trap application termination
        [DllImport("Kernel32")]
        private static extern bool SetConsoleCtrlHandler(EventHandler handler, bool add);
        private delegate bool EventHandler(CtrlType sig);
        static EventHandler _handler;
        enum CtrlType {
            CTRL_C_EVENT = 0,
            CTRL_BREAK_EVENT = 1,
            CTRL_CLOSE_EVENT = 2,
            CTRL_LOGOFF_EVENT = 5,
            CTRL_SHUTDOWN_EVENT = 6
        }
        private static bool Handler(CtrlType sig) {
            Console.WriteLine("Exiting system due to external CTRL-C, or process kill, or shutdown");
            //do your cleanup here
            Thread.Sleep(5000); //simulate some cleanup delay
            Console.WriteLine("Cleanup complete");
            //allow main to run off
            exitSystem = true;
            //shutdown right away so there are no lingering threads
            Environment.Exit(-1);
            return true;
        }
        #endregion
        static void Main(string[] args) {
            // Some biolerplate to react to close window event, CTRL-C, kill, etc
            _handler += new EventHandler(Handler);
            SetConsoleCtrlHandler(_handler, true);
            //start your multi threaded program here
            Program p = new Program();
            p.Start();
            //hold the console so it doesn’t run off the end
            while (!exitSystem) {
                Thread.Sleep(500);
            }
        }
        public void Start() {
            // start a thread and start doing some processing
            Console.WriteLine("Thread started, processing..");
        }
    }
}

这个问题与

捕获控制台出口 C#

以下是我如何解决这个问题,并处理用户点击X和Ctrl-C.请注意ManualResetEvents的使用。这些将导致主线程休眠,从而释放 CPU 在等待退出或清理时处理其他线程。注意:有必要在主节点的末尾设置终止已完成事件。如果不这样做,则会导致不必要的终止延迟,因为操作系统在终止应用程序时超时。

namespace CancelSample
{
    using System;
    using System.Threading;
    using System.Runtime.InteropServices;
    internal class Program
    {
        /// <summary>
        /// Adds or removes an application-defined HandlerRoutine function from the list of handler functions for the calling process
        /// </summary>
        /// <param name="handler">A pointer to the application-defined HandlerRoutine function to be added or removed. This parameter can be NULL.</param>
        /// <param name="add">If this parameter is TRUE, the handler is added; if it is FALSE, the handler is removed.</param>
        /// <returns>If the function succeeds, the return value is true.</returns>
        [DllImport("Kernel32")]
        private static extern bool SetConsoleCtrlHandler(ConsoleCloseHandler handler, bool add);
        /// <summary>
        /// The console close handler delegate.
        /// </summary>
        /// <param name="closeReason">
        /// The close reason.
        /// </param>
        /// <returns>
        /// True if cleanup is complete, false to run other registered close handlers.
        /// </returns>
        private delegate bool ConsoleCloseHandler(int closeReason);
        /// <summary>
        ///  Event set when the process is terminated.
        /// </summary>
        private static readonly ManualResetEvent TerminationRequestedEvent;
        /// <summary>
        /// Event set when the process terminates.
        /// </summary>
        private static readonly ManualResetEvent TerminationCompletedEvent;
        /// <summary>
        /// Static constructor
        /// </summary>
        static Program()
        {
            // Do this initialization here to avoid polluting Main() with it
            // also this is a great place to initialize multiple static
            // variables.
            TerminationRequestedEvent = new ManualResetEvent(false);
            TerminationCompletedEvent = new ManualResetEvent(false);
            SetConsoleCtrlHandler(OnConsoleCloseEvent, true);
        }
        /// <summary>
        /// The main console entry point.
        /// </summary>
        /// <param name="args">The commandline arguments.</param>
        private static void Main(string[] args)
        {
            // Wait for the termination event
            while (!TerminationRequestedEvent.WaitOne(0))
            {
                // Something to do while waiting
                Console.WriteLine("Work");
            }
            // Sleep until termination
            TerminationRequestedEvent.WaitOne();
            // Print a message which represents the operation
            Console.WriteLine("Cleanup");
            // Set this to terminate immediately (if not set, the OS will
            // eventually kill the process)
            TerminationCompletedEvent.Set();
        }
        /// <summary>
        /// Method called when the user presses Ctrl-C
        /// </summary>
        /// <param name="reason">The close reason</param>
        private static bool OnConsoleCloseEvent(int reason)
        {
            // Signal termination
            TerminationRequestedEvent.Set();
            // Wait for cleanup
            TerminationCompletedEvent.WaitOne();
            // Don't run other handlers, just exit.
            return true;
        }
    }
}

检测 SIGTERM 和 Ctrl+C

CancellationTokenSource ctSource = new();
CancellationToken ct = ctSource.Token;
void ExitHandler()
{
    // You can add any arbitrary global clean up
    Console.WriteLine("Exiting...");
    ctSource.Cancel();
}
// Assign exit handler to be called when the process is terminated
// or the user hits CTRL+C
AppDomain.CurrentDomain.ProcessExit += (sender, args) => ExitHandler();
Console.CancelKeyPress += (sender, args) => ExitHandler();
// Then you can use the cancellation token to check for exit:
Console.WriteLine("Ready to gracefully shut down!");
while (!ct.IsCancellationRequested)
{
    Console.WriteLine($"Exit not detected, waiting another 10s.");
    Task.Delay(10000, ct).Wait(ct);
}

我可以在退出之前进行一些清理。最好的方法是什么 这才是真正的目标:陷阱出口,自己做东西。而上面的回答是不对的。因为,Ctrl + C只是退出应用程序的众多方法之一。

dotnet c# 中需要什么 - 所谓的取消令牌传递给Host.RunAsync(ct)然后,在退出信号陷阱中,对于 Windows,它将是

    private static readonly CancellationTokenSource cts = new CancellationTokenSource();
    public static int Main(string[] args)
    {
        // For gracefull shutdown, trap unload event
        AppDomain.CurrentDomain.ProcessExit += (sender, e) =>
        {
            cts.Cancel();
            exitEvent.Wait();
        };
        Console.CancelKeyPress += (sender, e) =>
        {
            cts.Cancel();
            exitEvent.Wait();
        };
        host.RunAsync(cts);
        Console.WriteLine("Shutting down");
        exitEvent.Set();
        return 0;
     }

Console.TreatControlCAsInput = true;

我有用。