Improved CPLCreateOrAcquireMutex

gistfile1.cpp

#ifndef CPL_MULTIPROC_PTHREAD

#ifndef MUTEX_NONE
static void *hCOAMutex = NULL;
#endif

int CPLCreateOrAcquireMutex( void **phMutex, double dfWaitInSeconds )
{
    int bSuccess = FALSE;
#ifndef MUTEX_NONE
    /*
    ** ironically, creation of this initial mutex is not threadsafe
    ** even though we use it to ensure that creation of other mutexes
    ** is threadsafe.
    */
    if ( NULL != *phMutex )
        return CPLAcquireMutex( *phMutex, dfWaitInSeconds );

    if( hCOAMutex == NULL )
    {
        hCOAMutex = CPLCreateMutex();
        if (hCOAMutex == NULL)
        {
          *phMutex = NULL;
          return FALSE;
        }
    }
    else
    {
        CPLAcquireMutex( hCOAMutex, dfWaitInSeconds );
    }

    if( *phMutex == NULL )
    {
        *phMutex = CPLCreateMutex();
        bSuccess = *phMutex != NULL;
        CPLReleaseMutex( hCOAMutex );
    }
    else
    {
        CPLReleaseMutex( hCOAMutex );
        bSuccess = CPLAcquireMutex( *phMutex, dfWaitInSeconds );
    }
#endif /* ndef MUTEX_NONE */
    return bSuccess;
}
#endif