C / C++ / MFC

<big>bool WaitForMutex(void)<br />
{<br />
      /* This procedure will wait for a Mutex before <br />
allowing any write access to the shared area. */<br />
<br />
m_hMutex = ::CreateMutex(NULL,FALSE,"CSLSharedMemLock");<br />
if(m_hMutex)<br />
{<br />
      if (::WaitForSingleObject(m_hMutex,INFINITE) ==    WAIT_OBJECT_0)<br />
      {<br />
         return true;<br />
     ReleaseMutex(m_hMutex);<br />
  }<br />
      return false;<br />
    	 }<br />
}</big>

hMutex = ::CreateMutex ( 0, FALSE, "CSLSharedMemLock" ) ;

void EnterMutex ()
{
   ::WaitForSingleObject ( hMutex, INFINITE ) ;
}

void LeaveMutex ()
{
   ::ReleaseMutex ( hMutex ) ;
}

class CBusyState
{
public:

	// Constructor - by default the busy state is entered
	CBusyState(BOOL bEnterBusyState = TRUE, 
		SERVERCALL scBusyReply = SERVERCALL_RETRYLATER)
		: m_bBusy(FALSE)
	{
		// get the MFC message filter implementation. This will return NULL if called from a DLL.
		m_pMessageFilter = AfxOleGetMessageFilter();
		if (bEnterBusyState)
		   Begin(scBusyReply); // enter the busy state
	}

	// Destructor - ends the busy state (if previously entered)
	~COasisBusyState()
	{	
		End(); // end the busy state
	};

	// Begins the busy state. By default, any incoming COM calls will be
	// rejected, but retried later
	BOOL Begin(SERVERCALL scBusyReply = SERVERCALL_RETRYLATER)
	{	// check that we have a message filter, and that we're not already
		// busy.
		if (m_pMessageFilter && !m_bBusy)
		{	// set the reply code for IMessageFilter::HandlingIncomingCall()
			m_pMessageFilter->SetBusyReply(scBusyReply);
			// enter the busy state
			m_pMessageFilter->BeginBusyState();
			m_bBusy = TRUE;
		}
		return m_bBusy;
	}

	// Ends the busy state, if previously entered
	void End()
	{	// check that we have a message filter, and that we're busy
		if (m_pMessageFilter && m_bBusy)
		{	// end the busy state
			m_pMessageFilter->EndBusyState();
			m_bBusy = FALSE;
		}
	}

private:
	BOOL			m_bBusy;
	COleMessageFilter*	m_pMessageFilter;
};