在线程之间发送窗口消息时出现 ESP 错误

发布于 2024-09-06 09:51:21 字数 1980 浏览 13 评论 0原文

我有一个 Observer 类和一个 Subscriber 类。
出于测试目的，观察者创建一个线程来生成假消息并调用 CServerCommandObserver::NotifySubscribers()，如下所示：

void CServerCommandObserver::NotifySubscribers(const Command cmd, void const * const pData)
{
    // Executed in worker thread //

    for (Subscribers::const_iterator it = m_subscribers.begin(); it != m_subscribers.end(); ++it)
    {
        const CServerCommandSubscriber * pSubscriber = *it;

        const HWND hWnd = pSubscriber->GetWindowHandle();
        if (!IsWindow(hWnd)) { ASSERT(FALSE); continue; }

        SendMessage(hWnd, WM_SERVERCOMMAND, cmd, reinterpret_cast<LPARAM>(pData));
    }
}

订阅者是一个 CDialog 派生类，它也继承自CServerCommandSubscriber。

在派生类中，我添加了一个消息映射条目，它将服务器命令路由到订阅者类处理程序。

// Derived dialog class .cpp
ON_REGISTERED_MESSAGE(CServerCommandObserver::WM_SERVERCOMMAND, HandleServerCommand)

// Subscriber base class .cpp
void CServerCommandSubscriber::HandleServerCommand(const WPARAM wParam, const LPARAM lParam)
{
    const Command cmd = static_cast<Command>(wParam);

    switch (cmd)
    {
    case something:
        OnSomething(SomethingData(lParam)); // Virtual method call
        break;
    case // ...
    };
}

问题是，我在 HandleServerCommand() 方法中看到奇怪的崩溃：

它看起来像这样：

调试错误！
程序：c:\myprogram.exe
模块：
文件：i386\chkesp.c
线路：42
ESP 的值不正确通过函数调用保存。这是通常是调用的结果通过一次调用声明的函数函数指针约定用不同的调用声明约定。

我检查了 AfxBeginThread() 想要的函数指针：

typedef UINT (AFX_CDECL *AFX_THREADPROC)(LPVOID); // AFXWIN.H

static UINT AFX_CDECL MessageGeneratorThread(LPVOID pParam); // My thread function

对我来说，这看起来是兼容的，不是吗？

我不知道，我还需要寻找什么。有什么想法吗？

我做了另一个奇怪的观察，可能与之相关：在 NotifySubscribers 方法中，我调用 IsWindow() 来检查句柄指向的窗口是否存在。显然确实如此。但调用 CWnd::FromHandlePermanent() 会返回 NULL 指针。

原文

I have an Observer class and a Subscriber class.
For testing purposes, the observer creates a thread that generates fake messages and calls CServerCommandObserver::NotifySubscribers(), which looks like this:

void CServerCommandObserver::NotifySubscribers(const Command cmd, void const * const pData)
{
    // Executed in worker thread //

    for (Subscribers::const_iterator it = m_subscribers.begin(); it != m_subscribers.end(); ++it)
    {
        const CServerCommandSubscriber * pSubscriber = *it;

        const HWND hWnd = pSubscriber->GetWindowHandle();
        if (!IsWindow(hWnd)) { ASSERT(FALSE); continue; }

        SendMessage(hWnd, WM_SERVERCOMMAND, cmd, reinterpret_cast<LPARAM>(pData));
    }
}

The subscriber is a CDialog derived class, that also inherits from CServerCommandSubscriber.

In the derived class, I added a message map entry, that routes server commands to the subscriber class handler.

// Derived dialog class .cpp
ON_REGISTERED_MESSAGE(CServerCommandObserver::WM_SERVERCOMMAND, HandleServerCommand)

// Subscriber base class .cpp
void CServerCommandSubscriber::HandleServerCommand(const WPARAM wParam, const LPARAM lParam)
{
    const Command cmd = static_cast<Command>(wParam);

    switch (cmd)
    {
    case something:
        OnSomething(SomethingData(lParam)); // Virtual method call
        break;
    case // ...
    };
}

The problem is, that I see strange crashes in the HandleServerCommand() method:

It looks something like this:

Debug Error!
Program: c:\myprogram.exe
Module:
File: i386\chkesp.c
Line: 42
The value of ESP was not properly
saved across a function call. This is
usually the result of calling a
function declared with one calling
convention with a function pointer
declared with a different calling
convention.

I checked the function pointer that AfxBeginThread() wants to have:

typedef UINT (AFX_CDECL *AFX_THREADPROC)(LPVOID); // AFXWIN.H

static UINT AFX_CDECL MessageGeneratorThread(LPVOID pParam); // My thread function

To me, this looks compatible, isn't it?

I don't know, what else I have to look for. Any ideas?

I made another strange observation, that might be related:
In the NotifySubscribersmethod, I call IsWindow() to check if the window to which the handle points, exists. Apparently it does. But calling CWnd::FromHandlePermanent() returns a NULL pointer.

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ζ澈沫 2024-09-13 09:51:22

来自afxmsg_.h：

// for Registered Windows messages
#define ON_REGISTERED_MESSAGE(nMessageVariable, memberFxn) \
    { 0xC000, 0, 0, 0, (UINT_PTR)(UINT*)(&nMessageVariable), \
        /*implied 'AfxSig_lwl'*/ \
        (AFX_PMSG)(AFX_PMSGW) \
        (static_cast< LRESULT (AFX_MSG_CALL CWnd::*)(WPARAM, LPARAM) > \
        (memberFxn)) },

所以签名是LRESULT ClassName::FunctionName(WPARAM, LPARAM)，而你的签名是void ClassName::FunctionName(const WPARAM, const LPARAM）。这不应该编译，至少在 VS2008 下不能编译。

CServerCommandSubscriber 类（在头文件中）中的 HandleServerCommand 声明是什么？

From afxmsg_.h:

// for Registered Windows messages
#define ON_REGISTERED_MESSAGE(nMessageVariable, memberFxn) \
    { 0xC000, 0, 0, 0, (UINT_PTR)(UINT*)(&nMessageVariable), \
        /*implied 'AfxSig_lwl'*/ \
        (AFX_PMSG)(AFX_PMSGW) \
        (static_cast< LRESULT (AFX_MSG_CALL CWnd::*)(WPARAM, LPARAM) > \
        (memberFxn)) },

So the signature is LRESULT ClassName::FunctionName(WPARAM, LPARAM), while yours is void ClassName::FunctionName(const WPARAM, const LPARAM). This should not compile, at least under VS2008 it doesn't.

What is your HandleServerCommand declaration in the CServerCommandSubscriber class (in the header file)?

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