'Send an unacknowledged message to MongoDB.
Can raise ConnectionFailure.
:Parameters:
- `message`: (request_id, data).
- `all_credentials`: dict, maps auth source to MongoCredential.'

def send_message(self, message, all_credentials):

    (_, data, max_doc_size) = self._split_message(message)
    with self.get_socket(all_credentials) as sock_info:
        sock_info.send_message(data, max_doc_size)
