c# - 如何获取线程句柄以传递给 CancelSynchronousIO？

Question

以正常方式在 C# 中创建后台线程 -

Thread t = new Thread(....);
t.IsBackground = true;
t.Start();
etc etc

想要从主线程调用 CancelSynchronousIO 来取消后台线程上的阻塞 IO 调用。不知道如何以 IntPtr 的形式获取线程句柄以传递给函数:

[DllImport("kernel32.dll", SetLastError=true)]
static extern bool CancelSynchronousIo(IntPtr threadHandle);

似乎有多种方法可以获取线程ID，但不能获取句柄？获取线程 ID 的方法似乎只在托管环境中为您提供一个 ID，因此对 PInvoke 调用没有用？我猜我遗漏了什么。

我是否需要执行其他 PInvoke 调用来获取线程句柄，还是有更简单的方法？

Answer 1

你可以这样做，但强烈不推荐。

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Threading;

class Program
{
    [DllImport("kernel32.dll", SetLastError = true)]
    static extern uint GetCurrentThreadId();

    [DllImport("kernel32.dll", SetLastError = true)]
    static extern IntPtr OpenThread(uint desiredAccess, bool inheritHandle, uint threadId);

    [DllImport("kernel32.dll", SetLastError = true)]
    static extern bool CloseHandle(IntPtr handle);

    [DllImport("kernel32.dll", SetLastError = true)]
    static extern bool CancelSynchronousIo(IntPtr threadHandle);

    static bool CancelSynchronousIo(uint threadId)
    {
        // GENERIC_WRITE, Non-inheritable
        var threadHandle = OpenThread(0x40000000, false, (uint)threadId);
        var ret = CancelSynchronousIo(threadHandle);

        CloseHandle(threadHandle);

        return ret;
    }

    static void Main(string[] args)
    {
        uint threadId = 0;

        using (var threadStarted = new AutoResetEvent(false))
        {
            var thread = new Thread(() =>
            {
                try
                {
                    Thread.BeginThreadAffinity();
                    threadId = GetCurrentThreadId();

                    threadStarted.Set();

                    // will throws System.OperationCanceledException
                    Console.ReadLine();
                }
                finally
                {
                    Thread.EndThreadAffinity();
                }
            });

            thread.Start();

            threadStarted.WaitOne();
        }

        Debugger.Break();

        CancelSynchronousIo(threadId);
    }
}