多线程中的临界区

临界区又叫关键代码段.在多线程共享变量时,用来安全读写共享变量.代码如下:

CRITICAL_SECTION   g_csSync = {};//临界区
INT   g_iData = 0;

DWORD  WINAPI  WriteThreadProc(LPVOID lpParameter)
{//写线程
	while (1)
	{
		Sleep(30);
		__try
		{
			EnterCriticalSection(&g_csSync);
			g_iData++;
		}
		__finally
		{
			LeaveCriticalSection(&g_csSync);
		}
	}
	return 0;
}

DWORD WINAPI  ReadThreadProc(LPVOID lpParameter)
{//读线程
	while (true)
	{
		Sleep(30);
		__try
		{
			EnterCriticalSection(&g_csSync);//进入临界区

			char str[20] = {};
			itoa(g_iData, str, 10);
			TRACE(str);
		}
		__finally
		{
			LeaveCriticalSection(&g_csSync);//离开临界区
		}
	}
	return 0;
}
void CtestThreadDlg::OnBnClickedButton16()
{
	InitializeCriticalSectionAndSpinCount(&g_csSync, 0x4000);//初始化临界区

	DWORD  ThreadID = 0;
	HANDLE  hThread[2] = {};
	hThread[0] = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)WriteThreadProc, 
	                     NULL, CREATE_SUSPENDED, &ThreadID);
	hThread[1] = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)ReadThreadProc, 
	                     NULL, CREATE_SUSPENDED, &ThreadID);

	ResumeThread(hThread[0]);
	ResumeThread(hThread[1]);

	WaitForMultipleObjects(2, hThread, TRUE, INFINITE);

	CloseHandle(hThread[0]);
	CloseHandle(hThread[1]);

	DeleteCriticalSection(&g_csSync);//删除临界区
}