Come usi CreateThread per le funzioni che sono membri della class?

Come usi CreateThread() per creare discussioni di funzioni che sono membri della class?

È necessario creare un metodo statico da utilizzare come effettiva funzione di avvio del thread e passare un puntatore all’istanza come argomento lpParameter su CreateThread . Questo verrà passato al metodo statico, che può lanciarlo su un puntatore a un object e chiamare attraverso la funzione membro.

 class MyClass { static DWORD WINAPI StaticThreadStart(void* Param) { MyClass* This = (MyClass*) Param; return This->ThreadStart(); } DWORD ThreadStart(void) { // Do stuff } void startMyThread() { DWORD ThreadID; CreateThread(NULL, 0, StaticThreadStart, (void*) this, 0, &ThreadID); } }; 

Altri che incontrano potrebbero desiderare di usare la mia soluzione. È un file di origine completo compilato con VS2008. Vedi sotto per un breve esempio di istruzioni su come usare!

 // Thread.h #ifndef __THREAD_H__ #define __THREAD_H__ // ############################################################################# #define WIN32_LEAN_AND_MEAN #include  // ============================================================================= template class Thread { // new type Method: pointer to a object's method (this call) typedef DWORD (T::* Method)(void); // ----------------------------------------------------------------------------- protected: HANDLE hThread; // unique handle to the thread private: DWORD threadID; // thread id - 0 until started T* object; // the object which owns the method Method method; // the method of the object HANDLE hInterrupt; // mutex to signal an interrupt via ReleaseSemaphore() HANDLE hSingleStart; // only one thread allowed to call start() mutex // ----------------------------------------------------------------------------- private: // This function gets executed by a concurrent thread. static DWORD run(LPVOID thread_obj) { Thread* thread = (Thread*)thread_obj; return (thread->object->*thread->method) (); } // Prevent copying of threads: No sensible implementation! Thread(const Thread& other) {} // Prevent assignment of threads: No sensible implementation! Thread& operator =(const Thread& other) {} // ----------------------------------------------------------------------------- public: /* Creates a new Thread object. object: the one which method should be executed. method: pointer to the object's method. */ explicit Thread(T* object, DWORD ( T::* method)(void)) { this->hThread = NULL; this->object = object; this->method = method; this->threadID = 0; this->hInterrupt = CreateSemaphore(NULL, 1, 1, NULL); this->hSingleStart = CreateMutex(NULL, FALSE, NULL); // this->hInterrupt = CreateMutex(NULL, FALSE, NULL); } // ----------------------------------------------------------------------------- ~Thread(void) { if (hInterrupt) CloseHandle(hInterrupt); if (hThread) CloseHandle(hThread); } // ----------------------------------------------------------------------------- /* Starts executing the objects method in a concurrent thread. True if the thread was started successfully; otherwise false. */ bool start() { __try { if (WaitForSingleObject(hSingleStart, 0) != WAIT_OBJECT_0) return false; if (hThread) // Thread had been started sometime in the past { if (WaitForSingleObject(hThread, 0) == WAIT_TIMEOUT) { // if thread's still running deny new start return false; } CloseHandle(hThread); } // (Re-)Set not interrupted semaphore state WaitForSingleObject(hInterrupt, 0); hThread = CreateThread( NULL, 0, (LPTHREAD_START_ROUTINE) Thread::run, this, 0, &this->threadID ); if (hThread) return true; return false; } __finally { ReleaseMutex(hSingleStart); } } // ----------------------------------------------------------------------------- // Blocks the calling thread until this thread has stopped. inline void join() { WaitForSingleObject(hThread, INFINITE); } // ----------------------------------------------------------------------------- /* Asks the thread to exit nicely. Thread function must implement checks. return value indicates if the interrupt could be placed not if the thread reacts on the interrupt. true indicates success, false an error. */ inline bool interrupt() { if (hInterrupt) { return ((ReleaseSemaphore(hInterrupt, 1, NULL) == FALSE) ? false : true); } return false; } // ----------------------------------------------------------------------------- /* True if an interrupt request was set, otherwise false. */ inline bool isInterrupted() { return this->isInterrupted(0); } // ----------------------------------------------------------------------------- /* True if an interrupt request was set, otherwise false. Waits for millisec milliseconds for the interrupt to take place. */ inline bool isInterrupted(DWORD millisec) { if (WaitForSingleObject(hInterrupt, millisec) == WAIT_TIMEOUT) { return false; } ReleaseSemaphore(hInterrupt, 1, NULL); // keep interrupted state return true; } // ----------------------------------------------------------------------------- inline bool isRunning() { DWORD exitCode = 0; if (hThread) GetExitCodeThread(hThread, &exitCode); if (exitCode == STILL_ACTIVE) return true; return false; } // ----------------------------------------------------------------------------- // Getter & Setter // ----------------------------------------------------------------------------- __declspec(property(get = getThreadHandle)) HANDLE ThreadHandle; inline HANDLE getThreadHandle() { return hThread; } // ----------------------------------------------------------------------------- __declspec(property(get = getThreadID)) DWORD ThreadID; inline DWORD getThreadID() { return threadID; } // ----------------------------------------------------------------------------- }; // ############################################################################# #endif // __THREAD_H__ 

Breve esempio:

 // main.cpp #include  #include  #include "Thread.h" class HelloWorld { public: DWORD print () { std::cout << "Hello World!" << std::endl; return 0; } }; int main(void) { // Random object with DWORD method (void) HelloWorld world; // thread should call print method of world. Thread thread(&world, &HelloWorld::print); if (thread.start()) std::cout << "Thread start()" << std::endl; thread.join(); // wait for thread return 0; }