Windows核心编程笔记（7）----内核模式下的线程同步

HANDLE g_hSemaphore;
volatile LONG g_nThreadIndex = 0;

UINT WINAPI HelpThread(LPVOID lpParam)
{
	//这里给每个线程来一个唯一的ID标识
	InterlockedExchangeAdd(&g_nThreadIndex, 1);
	int nCurIndex = g_nThreadIndex;
	cout<<"进入线程，线程ID="<<nCurIndex<<endl;
	WaitForSingleObject(g_hSemaphore, INFINITE);
	cout<<"线程"<<nCurIndex<<"获得信号量资源…………"<<endl;
	int i = 0;
	while( i<2 )
	{
		i++;
		cout<<"线程"<<nCurIndex<<"正在执行任务中…………"<<endl;
		Sleep(1000);
	}
	LONG lPrevCount;
	//信号量资源使用完毕，释放掉，好让其他等待的线程继续执行
	ReleaseSemaphore(g_hSemaphore, 1, &lPrevCount);//把信号量的资源计数+1，返回前一个资源计数的值
	cout<<"前一个资源计数为"<<lPrevCount<<"释放信号量资源，线程"<<nCurIndex<<"退出…………"<<endl;
	return 0;
}

void	SemaphoreTest()
{
	//创建信号量
	g_hSemaphore = CreateSemaphore(NULL, 3, 4, NULL);
	HANDLE hThreads[6];
	int i = 0;

<span style="white-space:pre">	</span>//测试多个线程抢占信号量资源
	for (; i<6; ++i)
	{
		hThreads[i] = (HANDLE)_beginthreadex(NULL, 0, HelpThread, NULL, 0, NULL);
	}
	WaitForMultipleObjects(6, hThreads, TRUE, INFINITE);
	//关闭线程句柄
	for ( i=0; i<6; ++i )
		CloseHandle(hThreads[i]);
	cout<<"辅助线程执行完毕…………"<<endl;
	//任何进程都可以使用OpenSemaphore来得到一个已经存在的信号量句柄，该句柄与当前进程相关联
	DWORD dwRet = WaitForSingleObject(g_hSemaphore, 5*1000);
	switch( dwRet )
	{
	case WAIT_OBJECT_0:
		cout<<"信号量可用…………"<<endl;
		break;
	case WAIT_TIMEOUT:
		cout<<"等待超时…………"<<endl;
		break;
	case WAIT_FAILED:
		cout<<"WaitForSingleObject调用失败，系统错误码：%u"<<GetLastError()<<endl;
		break;
	}
	//OpenSemaphore()
	CloseHandle(g_hSemaphore);
}


UINT __stdcall MutexHelpThread(LPVOID lpParam)
{
	HANDLE hMutex = (HANDLE)lpParam;
	DWORD dwRet = WaitForSingleObject(hMutex, INFINITE);
	cout<<"互斥量对象触发"<<endl;
	return 0;
}

void	MutexTest()
{
	HANDLE hMutex = CreateMutex(NULL, TRUE, NULL);
	HANDLE hThread = (HANDLE)_beginthreadex(NULL, 0, MutexHelpThread, (LPVOID)hMutex, 0, NULL);
	//释放互斥量，避免两个线程相互等待死锁
	ReleaseMutex(hMutex);
	WaitForSingleObject(hThread, INFINITE);
	CloseHandle(hThread);
	
	DWORD dwRet = WaitForSingleObject(hMutex, INFINITE);
	switch( dwRet )
	{
	case WAIT_OBJECT_0:
		break;
	case WAIT_TIMEOUT:
		break;
	case WAIT_FAILED:
		break;
	}
	CloseHandle(hMutex);
}