#include "stdafx.h"
#include "windows.h"
#include <iostream>

using namespace std;

class MaxClientLimitInstance
{
public:
	static bool Lock(int MaxInstanceCount)
	{
		int ret = 0;

		for(int i = 0; i < MaxInstanceCount; ++i)
		{
			HANDLE h = ::CreateMutex(0, 1, L"test program");
			if (GetLastError() == 0)
			{
				m_Handle = h;
				break;
			}
			else
			{
				CloseHandle(h);
				ret++;
			}
		}
		return ret < MaxInstanceCount;
	}

	static void UnLock()
	{
		if (m_Handle != NULL)
		{
			ReleaseMutex(m_Handle);
			CloseHandle(m_Handle);
		}
	}

	static HANDLE m_Handle;
};
HANDLE MaxClientLimitInstance::m_Handle = 0;

int _tmain(int argc, _TCHAR* argv[])
{
	int MaxNumber = 1;	

	if (!MaxClientLimitInstance::Lock(MaxNumber))
	{
		cout << "You have already run a program! This program will be closed." << endl;
		system("pause");
		return 0;
	}
	else
	{
		cout << "Run program success! " << endl;
	}

	system("pause");					//< 等待用户输入，在游戏程序中可以对应理解为在游戏主循环中执行逻辑

	MaxClientLimitInstance::UnLock();	//< 注意，要在“等待用户输入"之后ReleaseMutex，否则互斥量被释放，无法达到预期
	return 0;
}