🚀 go-pugleaf

I require a global mutex for my application to sync resources across 
different instances of the app, even running in different user sessions.

I created a class to manage this for me, all I have to do is create an 
instance to aquire the mutex and detroy it to release it.

int GlobalMutexReferenceCount = 0;
__fastcall TLicenseMutexHandler::TLicenseMutexHandler(const AnsiString 
LicenseProjectName)
{

  SetMutexName(LicenseProjectName);

  if (++GlobalMutexReferenceCount > 1)
    return;

  FMutexHandle = CreateMutex(NULL, false, FMutexName.c_str());
  WaitForSingleObject(FMutexHandle, INFINITE);
}

__fastcall TLicenseMutexHandler::~TLicenseMutexHandler()
{
  if (--GlobalMutexReferenceCount > 0)
    return;

  ReleaseMutex(FMutexHandle);
  CloseHandle(FMutexHandle);
}

void __fastcall TLicenseMutexHandler::SetMutexName(const AnsiString 
ALicenseProjectName)
{
  FMutexName = "Global\\" + AnsiReplaceText(ALicenseProjectName, "\\", "_");
}

Looks good - OK - so now an example. In the scope of a function that 
accesses the protected resource I have:

void __fastcall Func()
{
  std::auto_ptr<TLicenseMutexHandler>pLMH(new 
TLicenseMutexHandler(MainLFName));
  // do stuff to resource
}

** When the function exits, I can see the object gets destroyed correctly 
and themutex gets released and closed. However, immediately upon the return 
(after the destruction), I get an access violation in the kernel:
First chance exception at 0x7C812A5B. Exception class EAccessViolation with 
message 'Access violation at address 00000000...

** Now - here is the BIZARRE part: All I do is change the code to be:

void __fastcall Func()
{
  TLicenseMutexHandler * pLMH = new TLicenseMutexHandler(MainLFName);
  // do stuff to resource
  delete  pLMH;
}

And the AV goes away!

Any ideas why?

TIA