¿Cómo se usa CreateThread para las funciones que son miembros de la clase?

Question

¿Cómo se usa CreateThread() para crear hilos de funciones que son miembros de la clase?

Answer 1

Necesita crear un método estático para utilizar como la función de inicio de subproceso real, y pasar un puntero a la instancia como el argumento lpParameter a CreateThread. Eso pasará al método estático, que puede convertirlo en un puntero de objeto y llamar a la función de miembro.

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); 
    } 
}; 

Answer 2

Otros que se encuentran, pueden querer usar mi solución. Es un archivo fuente completo compilado con VS2008. ¡Vea a continuación un breve ejemplo de instrucciones sobre cómo usar!

// Thread.h 
#ifndef __THREAD_H__ 
#define __THREAD_H__ 
// ############################################################################# 
#define WIN32_LEAN_AND_MEAN 
#include <Windows.h> 
// ============================================================================= 
template<class T> 
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<T>* thread = (Thread<T>*)thread_obj; 
     return (thread->object->*thread->method)(); 
    } 
    // Prevent copying of threads: No sensible implementation! 
    Thread(const Thread<T>& other) {} 
    // Prevent assignment of threads: No sensible implementation! 
    Thread<T>& operator =(const Thread<T>& 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<T>::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__ 

ejemplo corto:

// main.cpp  
#include <iostream> 
#include <string> 

#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<HelloWorld> thread(&world, &HelloWorld::print); 
    if (thread.start()) 
     std::cout << "Thread start()" << std::endl; 
    thread.join(); // wait for thread 
    return 0; 
}