我正在研究一些使用 MFC 的 UI 线程来实现管理器线程工作线程机制的遗留代码。以前在 MFC GUI 应用程序下运行的代码,但现在它在一个单独的 dll 中,并且可以从 GUI 应用程序和控制台应用程序运行。
管理线程、工作线程和主应用程序通过线程消息进行通信(工作线程实际上并不需要向管理线程发送消息,但这是它最初实现和工作的方式,所以你去)。
现在,当我从控制台应用程序运行代码时,会处理从主线程发送到管理器线程的消息并调用我的处理程序。只有当我尝试从管理线程向工作线程发送消息时,我才会遇到问题。调用PostThreadMessage
成功,但从未调用处理程序。这种行为在一个普通的控制台应用程序和一个 Win32 控制台应用程序(包括一个带有所有 MFC 好东西的预编译头文件)中都重现了。
我找到了这篇旧的 Microsoft 文章: http: //support.microsoft.com/kb/142415但我不得不承认我并没有真正理解它。我尝试按照它的建议覆盖该PreTranslateMessage
函数并在那里显式处理我的自定义消息,但调用后从未调用该函数PostThreadMessage
我试图在下面的示例中重现该问题,在我的示例中,甚至从未处理到管理器线程的消息,这证实了我对我做错了什么的怀疑。
编辑:我添加了我的示例代码中缺少的缺失InitInstance
和ExitInstance
重载ManagerThread
,正如 MarsRover 所建议的那样,ManagerThread
现在确实发送了消息,但WorkerThread
没有发送消息,这准确地重现了我在原始代码中遇到的问题。示例代码:
//Common.h
//update the progress message
#define WM_START_RUN (WM_USER + 1)
//update the progress message
#define WM_JOB_DONE (WM_USER + 2)
//run thread has finished
#define WM_RUN (WM_USER + 3)
// ManagerThread.h
class ManagerThread : public CWinThread
{
DECLARE_DYNCREATE(ManagerThread)
protected:
ManagerThread(){} // protected constructor used by dynamic creation
virtual ~ManagerThread();
BOOL InitInstance();
int ExitInstance();
std::vector<WorkerThread*> m_WorkerThreads;
int numOfJobs;
DECLARE_MESSAGE_MAP()
afx_msg void OnStartRun(WPARAM wParam, LPARAM lParam);
afx_msg void OnJobDone(WPARAM wParam, LPARAM lParam);
afx_msg void OnQuit(WPARAM wParam, LPARAM lParam);
};
//WorkerThread.h
class WorkerThread : public CWinThread
{
DECLARE_DYNCREATE(WorkerThread)
protected:
WorkerThread(){} // protected constructor used by dynamic creation
virtual ~WorkerThread(){}
virtual BOOL InitInstance();
virtual int ExitInstance();
public:
void SetManager(CWinThread* pManager) {m_Manager = pManager;}
void SetID(int _id) {id = _id;}
protected:
int id;
CWinThread* m_Manager;
DECLARE_MESSAGE_MAP()
afx_msg void OnRun(WPARAM wParam, LPARAM lParam);
afx_msg void OnQuit(WPARAM wParam, LPARAM lParam);
};
// ManagerThread.cpp
IMPLEMENT_DYNCREATE(ManagerThread, CWinThread)
ManagerThread::~ManagerThread() {
while(!m_WorkerThreads.empty()) {
std::vector<WorkerThread*>::iterator it = m_WorkerThreads.begin();
(*it)->PostThreadMessage(WM_QUIT, 0, 0);
m_WorkerThreads.erase(it);
}
}
BOOL CFilterManagerThread::InitInstance()
{
return CWinThread::InitInstance();
}
int CFilterManagerThread::ExitInstance()
{
return CWinThread::ExitInstance();
}
BEGIN_MESSAGE_MAP(ManagerThread, CWinThread)
ON_THREAD_MESSAGE(WM_START_RUN, OnStartRun)
ON_THREAD_MESSAGE(WM_JOB_DONE, OnJobDone)
ON_THREAD_MESSAGE(WM_QUIT, OnQuit)
END_MESSAGE_MAP()
void ManagerThread::OnJobDone( WPARAM wParam, LPARAM lParam) {
numOfJobs--;
if (!numOfJobs) {
OnQuit(0,0);
}
}
void ManagerThread::OnStartRun(WPARAM wParam, LPARAM lParam) {
numOfJobs = (int) wParam;
for (int i = 0; i < numOfJobs; i++) {
WorkerThread *newThread = (WorkerThread*)AfxBeginThread(RUNTIME_CLASS(WorkerThread), THREAD_PRIORITY_LOWEST, 0, CREATE_SUSPENDED);
newThread->SetID(i);
newThread->SetManager(this);
m_WorkerThreads.push_back(newThread);
newThread->ResumeThread();
Sleep(1000); //sleep 1 second before sending message to allow the thread to strat running
newThread->PostThreadMessage(WM_RUN, 0, 0);
}
}
void ManagerThread::OnQuit(WPARAM wParam, LPARAM lParam) {
AfxEndThread(0);
}
// WorkerThread.cpp
IMPLEMENT_DYNCREATE(WorkerThread, CWinThread)
BOOL WorkerThread::InitInstance() {
// TODO: perform and per-thread initialization here
CoInitializeEx(NULL, COINIT_APARTMENTTHREADED);
return TRUE;
}
int WorkerThread::ExitInstance() {
// TODO: perform any per-thread cleanup here
//uninitialize the COM library
CoUninitialize();
return CWinThread::ExitInstance();
}
BEGIN_MESSAGE_MAP(WorkerThread, CWinThread)
ON_THREAD_MESSAGE(WM_RUN, OnRun)
ON_THREAD_MESSAGE(WM_QUIT, OnQuit)
END_MESSAGE_MAP()
void WorkerThread::OnRun(WPARAM wParam, LPARAM lParam) {
cout << id <<endl;
m_Manager->PostThreadMessage(WM_JOB_DONE, id, 0);
}
void WorkerThread::OnQuit(WPARAM wParam, LPARAM lParam) {
AfxEndThread(0);
}
并在main
:
ManagerThread *manager = (ManagerThread*)AfxBeginThread(RUNTIME_CLASS(ManagerThread), THREAD_PRIORITY_NORMAL, 0, CREATE_SUSPENDED);
manager->ResumeThread();
Sleep(1000); //sleep 1 second before sending message to allow the thread to start running
manager->PostThreadMessage(WM_START_RUN, 10, 0);
while(true){}
这是一个粗略的样本。当然,在我的原始代码中,我使用了更好的机制来确保同步Sleep
并while(true)
避免程序在管理器线程结束之前结束。但它重现了我遇到的问题,所以我没有看到增加任何复杂性的意义。