Windows 线程 - 如何使方法成为 Windows 中的线程函数？
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Windows threads - how to make a method a thread function in windows?
提问by KOLANICH
I can't pass a pointer to method to the CreateThread function, of course. What should I do?
当然，我不能将指向方法的指针传递给 CreateThread 函数。我该怎么办？
回答by DanDan
If using a class, some pattern like this usually works well:
如果使用一个类，像这样的一些模式通常很有效：
.h
。H
static UINT __cdecl StaticThreadFunc(LPVOID pParam);
UINT ThreadFunc();
.cpp
.cpp
// Somewhere you launch the thread
AfxBeginThread(
StaticThreadFunc,
this);
UINT __cdecl CYourClass::StaticThreadFunc(LPVOID pParam)
{
CYourClass *pYourClass = reinterpret_cast<CYourClass*>(pParam);
UINT retCode = pYourClass->ThreadFunc();
return retCode;
}
UINT CYourClass::ThreadFunc()
{
// Do your thing, this thread now has access to all the classes member variables
}
回答by J?rgen Sigvardsson
I often do this:
我经常这样做：
class X {
private:
static unsigned __stdcall ThreadEntry(void* pUserData) {
return ((X*)pUserData)->ThreadMain();
}
unsigned ThreadMain() {
...
}
};
And then I pass thisas user data to the thread creator function (_beginthread[ex], CreateThread, etc)
然后我将this用户数据作为用户数据传递给线程创建者函数（_beginthread[ex]、CreateThread 等）
回答by Fabio Ceconello
The most common way is to create a Thread class that has a run() method and a start() method (these names borrowed from the Java Thread class). run() is a pure virtual that you overload in a class derived from Thread to do the actual work. The method start() internally calls CreateThread passing the this pointer via reinterpret_cast to void*. The Thread class has also a threadEntryPoint() static function that you pass to CreateThread. In threadEntryPoint() you do a reinterpret_cast back to Thread* and then call run() on it.
最常见的方法是创建一个具有 run() 方法和 start() 方法（这些名称借自 Java Thread 类）的 Thread 类。run() 是一个纯虚拟的，您可以在从 Thread 派生的类中重载它以执行实际工作。方法 start() 在内部调用 CreateThread，通过 reinterpret_cast 将 this 指针传递给 void*。Thread 类还有一个传递给 CreateThread 的 threadEntryPoint() 静态函数。在 threadEntryPoint() 中，您对 Thread* 执行 reinterpret_cast，然后对其调用 run()。
If there's one situation in which you just want a method of another class to be executed on a separated thread (without having to inherit from the Thread class) you can create a Thread-derived class that receives a pair object+method pointers in the constructor, and calls them in run(). To ease things up, make this derived class a template. Also take a look on boost for functor adaptors.
如果有一种情况，您只想在单独的线程上执行另一个类的方法（不必从 Thread 类继承），则可以创建一个 Thread 派生类，该类在构造函数中接收一对对象 + 方法指针, 并在 run() 中调用它们。为了让事情变得简单，让这个派生类成为一个模板。还可以查看函子适配器的 boost。
回答by pepsi
CreateThread won't take a pointer to a member function. You can wrap the member function in a static function which takes the object pointer through lpParameter.
CreateThread 不会使用指向成员函数的指针。您可以将成员函数包装在一个静态函数中，该函数通过 lpParameter 获取对象指针。
回答by Vishal
CreateThread's lpStartAddress is of type DWORD (WINAPI *PTHREAD_START_ROUTINE)(LPVOID lpThreadParameter) and this is incompatible with the member function since the member function has an implicit thispointer in its signature. So create a static function and pass the class pointer as the argument to the thread function.
CreateThread 的 lpStartAddress 是 DWORD (WINAPI *PTHREAD_START_ROUTINE)(LPVOID lpThreadParameter) 类型，这与成员函数不兼容，因为成员函数在其签名中具有隐式this指针。所以创建一个静态函数并将类指针作为参数传递给线程函数。
回答by crypted
If you are talking about NativeCreateThreadMethod you would probably need to do following
如果您正在谈论本机CreateThread方法，您可能需要执行以下操作
CreateThread(NULL,0,(LPTHREAD_START_ROUTINE)&MyThreadProc,NULL,NULL,&threadId);
Where your callback method is defined as
您的回调方法定义为
void MyThreadProc()
{
}
