从 Windows 窗体类调用 PThread 到 Windows 窗体类中的函数

Question

我在 Visual Studio 2008 Professional 中的 Windows 窗体上使用 pthread，但在示例源代码中显示的行中出现错误。可能是因为它是 C++/CLI，因为这通常在常规类中工作。问题出在这一行：

((TestGUI*)context)->TestxFunc();

在函数StaticCallFunc中

public ref class TestGUI : public System::Windows::Forms::Form {
        /...
    public:

void TestxFunc(std::string test, std::string test2){
        this->btn_next->Enabled = false;
        cout << "HI, Test: " << test << "," << " Test 2: " << test2 << endl;

 }

static void *StaticCallFunc(void *context){
    std::string test = "foo";
    std::string test2 = "bar";
    printf("\nStarting Thread");
    ((TestGUI*)context)->TestxFunc(); //Line with the error down.
    return 0;

} 

System::Void tester_Click(System::Object^  sender, System::EventArgs^  e) {
      pthread_t t;
      pthread_create(&t, NULL, &TestGUI::StaticCallFunc, this);
}

//...

错误 C3699: '' : 不能在类型 'Test::TestxFunc' 1 上使用此间接寻址> 编译器将 '*' 替换为 '^' 以继续解析

错误 C2227：'->TestxFunc' 的左侧必须指向 类/结构/联合/泛型类型

我该怎么做才能解决这个问题？这个调用通常适用于常规类，但在 Windows 窗体中它确实没有

Answer 1

由于TestGUI 是一个CLI/C++ 类，你应该使用^ 而不是* 来取消引用它的指针，但这不是唯一的问题。您似乎想在 pthread 中执行 CLI/C++ 类成员方法。要使其工作，您可以尝试以下方式：

*从 TestGUI 类中删除 StaticCallFunc 并使其成为全局方法。
*要将TestGUI 指针传递给非托管函数，您可以使用gcroot。所以定义一个容器类，例如PtrContainer 有 gcroot 作为成员。

//dont forget forward declerations
void *StaticCallFunc(void *context); //forward decleration
ref class TestGUI; //forward decleration

//Define a simple argument class to pass pthread_create
struct PtrContainer{
     gcroot<TestGUI^> guiPtr; //you need to include vcclr.h for this
};

当您绑定到pthread_create 时，您可以使用PtrContainer，如下所示：

System::Void tester_Click(System::Object^  sender, System::EventArgs^  e) {

    //init. container pointer,
    //we use dynamically allocated object because the thread may use it after this method return
    PtrContainer* ptr = new PtrContainer;
    ptr->guiPtr = this;

    pthread_t t;
    pthread_create(&t, NULL, StaticCallFunc, ptr );
}

你应该删除驱动方法中的容器指针 (StaticCallFunc) 完成后：

void *StaticCallFunc(void *context){
    std::string test = "foo";
    std::string test2 = "bar";
    printf("\nStarting Thread");
    PtrContainer* ptr = reinterpret_cast<PtrContainer*>(context);
    ptr->guiPtr->TestxFunc(test, test2);

    //dont forget to delete the container ptr.
    delete ptr;

    return 0;
}

还有一个注意事项；当您以多线程方式访问 .NET gui 组件时，you must be careful to make calls to your controls in a thread-safe way.

编辑：我添加了以下在 Visual Studio 11、Windows7 下编译和工作的完整源代码。

//sample.cpp

#include <iostream>
#include <string>
#include <vcclr.h>
#include <sstream>
using namespace std;
using namespace System;
using namespace System::Windows::Forms;

#include "pthread.h"
#include <stdio.h>

#define PTW32_THREAD_NULL_ID {NULL,0}
#define int64_t _int64

void *StaticCallFunc(void *context); //forward decleration
ref class TestGUI; //forward decleration

//Define a simple argument class to pass pthread_create
struct PtrContainer{
    gcroot<TestGUI^> guiPtr; //you need to include vcclr.h for this
};

ref class TestGUI : public System::Windows::Forms::Form  
{
public:
    TestGUI(void) {
        this->Click += gcnew System::EventHandler(this, &TestGUI::tester_Click );
    }

    void TestxFunc(std::string test, std::string test2){
            cout << "HI, Test: " << test << "," << " Test 2: " << test2 << endl;
    }

    System::Void tester_Click(System::Object^  sender, System::EventArgs^  e) {
        //init. container pointer,
        //we use dynamically allocated object because the thread may use it after this method return
        PtrContainer* ptr = new PtrContainer;
        ptr->guiPtr = this;

        pthread_t t;
        pthread_create(&t, NULL, StaticCallFunc, ptr );
    }
};

void *StaticCallFunc(void *context){
    std::string test = "foo";
    std::string test2 = "bar";
    printf("\nStarting Thread");
    PtrContainer* ptr = reinterpret_cast<PtrContainer*>(context);
    ptr->guiPtr->TestxFunc(test, test2);

    //dont forget to delete the container ptr.
    delete ptr;
    return 0;
}

int main()
{
    TestGUI^ testGui = gcnew TestGUI();
    testGui->ShowDialog();
    return 0;
}

编译：

/analyze- /clr /Od /nologo /MDd /Gm- /Fa".\Debug\" /I".." /Oy- /FU"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0\mscorlib.dll" /FU"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0\System.dll" /FU"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0\System.Windows.Forms.dll" /Zc:forScope /Fo".\Debug\" /Gy- /Fp".\Debug\Debug.pch" /D "WIN32" /D "_DEBUG" /D "_CONSOLE" /D "CLEANUP_C" /D "_VC80_UPGRADE=0x0600" /D "_MBCS" /WX /errorReport:queue /GS /Fd".\Debug\" /fp:precise /FR".\Debug\" /W3 /Z7 /Zc:wchar_t /EHa