_cache = None
def get_localhost():
    '''
    Should return 127.0.0.1 in ipv4 and ::1 in ipv6
    
    localhost is not used because on windows vista/windows 7, there can be issues where the resolving doesn't work
    properly and takes a lot of time (had this issue on the pyunit server). 
    
    Using the IP directly solves the problem.
    '''
    #TODO: Needs better investigation!
    
    global _cache
    if _cache is None:
        try:
            import socket
            for addr_info in socket.getaddrinfo("localhost", 80, 0, 0, socket.SOL_TCP):
                config = addr_info[4]
                if config[0] == '127.0.0.1':
                    _cache = '127.0.0.1'
                    return _cache
        except:
            #Ok, some versions of Python don't have getaddrinfo or SOL_TCP... Just consider it 127.0.0.1 in this case.
            _cache = '127.0.0.1'
        else:
            _cache = 'localhost'

    return _cache