Using Mutex Objects

Mutex is a kernel object.

//**************************************
* Sample of how to create Mutex
**************************************//

HANDLE hMutex;

// Create a mutex with no initial owner.

hMutex = CreateMutex(
   NULL,                       // no security attributes
   FALSE,                      // initially not owned
   "MutexToProtectDatabase");  // name of mutex

if (hMutex == NULL)
{
   // Check for error.
}

//**************************************
*    Use WaitForSingleObject to use Mutex
**************************************//

BOOL FunctionToWriteToDatabase(HANDLE hMutex)
{
   DWORD dwWaitResult;

   // Request ownership of mutex.

   dwWaitResult = WaitForSingleObject(
       hMutex,   // handle to mutex
       5000L);   // five-second time-out interval

   switch (dwWaitResult)
   {
       // The thread got mutex ownership.
       case WAIT_OBJECT_0:
           __try {
               // Write to the database.
           }

           __finally {
               // Release ownership of the mutex object.
               if (! ReleaseMutex(hMutex)) {
                   // Deal with error.
               }

           break;
       }

       // Cannot get mutex ownership due to time-out.
       case WAIT_TIMEOUT:
           return FALSE;

       // Got ownership of the abandoned mutex object.
       case WAIT_ABANDONED:
           return FALSE;
   }

   return TRUE;
}