C / C++ / MFC

<br />
InstanceHandler::InstanceHandler():m_mutex(NULL)<br />
{<br />
}<br />
<br />
InstanceHandler::~InstanceHandler()<br />
{<br />
	// make sure mutex is cleared as we exit<br />
	Release();<br />
}<br />
<br />
BOOL RTMPInstanceHandler::Init()<br />
{<br />
	// Create the named mutex<br />
	m_mutex = CreateMutex(NULL,FALSE,LPCWSTR(mutexname));<br />
	if(m_mutex == NULL)<br />
        {<br />
	        return FALSE;<br />
        }<br />
<br />
	// Check that the mutex didn't already exist<br />
	if (GetLastError() == ERROR_ALREADY_EXISTS)<br />
	{<br />
		return FALSE;<br />
	}<br />
	return TRUE;<br />
}<br />
<br />
//<br />
// allow mutex to be explicitely cleared<br />
//<br />
DWORD RTMPInstanceHandler::Release()<br />
{<br />
	try <br />
	{ <br />
		CloseHandle(m_mutex);<br />
	}<br />
	catch (...)<br />
	{<br />
		//<br />
		// Release() should be called once from the user code,<br />
		// and a second time by the object's destructor. <br />
		// the second call will cause an exception.<br />
		// we can just ignore it.<br />
		//<br />
	}<br />
<br />
	return GetLastError();<br />
}<br />

<br />
<br />
RTMPInstanceHandler instancehan;<br />
        if(!instancehan.Init())<br />
	{<br />
		// We don't allow multiple instances!<br />
		MessageBox(NULL, CString("Another instance of Application is already running!!"), CString("Server Message"), MB_OK);<br />
		instancehan.Release();<br />
	}<br />