request.py 文件源码

def _setDNSCache():  
    """ 
    Makes a cached version of socket._getaddrinfo to avoid subsequent DNS requests. 
    """  

    def _getaddrinfo(*args, **kwargs):  
        global _dnscache  
        if args in _dnscache: 
            return _dnscache[args]  

        else: 
            _dnscache[args] = socket._getaddrinfo(*args, **kwargs)  
            return _dnscache[args]  

    if not hasattr(socket, '_getaddrinfo'):  
        socket._getaddrinfo = socket.getaddrinfo  
        socket.getaddrinfo = _getaddrinfo