Django.fun

Using Memcached with Django and using cache page decorator for guest users but in one condition I need to invalidate the cache but dont know cache key

My Decorator

def cache_auth(*cache_args, **cache_kwargs):
    def inner_decorator(func):
        @wraps(func)
        def inner_function(request, *args, **kwargs):
            if not request.user.is_authenticated:
                return cache_page(*cache_args, **cache_kwargs)(func)(request, *args, **kwargs)
            return func(request, *args, **kwargs)
        return inner_function
    return inner_decorator

in my views.py

@cache_auth(60*60, key_prefix='index')
def index(request, **kwargs):
    doing something