make the signer stub as a poll and make the sign support 4 time retry (#149)
make the signer stub as a poll and make the sign support 4 time retry (#149)

Co-authored-by: fangchenliaohui <b0a7eda151111aba96a65c4028d9d9455b781b05@bytedance.com>
bytedance/fedlearner,bytedance/fedlearner,bytedance/fedlearner,bytedance/fedlearner,bytedance/fedlearner,bytedance/fedlearner,bytedance/fedlearner