pytorch

250c7112 - Create a DDPLoggingData and expose it to python interface (#50622)

Create a DDPLoggingData and expose it to python interface (#50622) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/50622 1. Define a DDPLoggingData struct that is the placeholder for all the ddp related logging fields 2. Put the DDPLoggingData struct in the C10 directory so that it can be easily imported by c10 and torch files 3. Expose get_ddp_logging_data() method in python so that users can get the logging data and dump in their applications 4. Unit test tested the logging data can be set and got as expected 5. Follow up will add more logging fields such as perf stats, internal states, env variables and etc ghstack-source-id: 120275870 Test Plan: unit tests Reviewed By: SciPioneer Differential Revision: D25930527 fbshipit-source-id: 290c200161019c58e28eed9a5a2a7a8153113f99