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):
        """Send an unacknowledged message to MongoDB.

        Can raise ConnectionFailure.

        :Parameters:
          - `message`: (request_id, data).
          - `all_credentials`: dict, maps auth source to MongoCredential.
        """
        _, 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)