Как вы используете CreateThread()
для создания потоков функций, являющихся членами класса?
Как вы используете CreateThread для функций, которые являются членами класса?
Ответ 1
Вам нужно создать статический метод для использования в качестве фактической функции запуска потока и передать указатель на экземпляр в качестве аргумента lpParameter
в CreateThread
. Это будет передано статическому методу, который может передать его указателю на объект и вызвать функцию-член.
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);
}
};
Ответ 2
Другие, которые сталкиваются, могут захотеть использовать мое решение. Это полный исходный файл, составленный с помощью VS2008. См. Ниже пример короткой инструкции о том, как использовать!
// 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 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 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 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__
Краткий пример:
// 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;
}