Summary:
This diff is to support python user defined function over rpc for https://github.com/pytorch/pytorch/issues/23110, work flow is like this:
1. pickle python udf
2. pass pickle to C++
3. C++ pass over rpc from client to server
4. server call runPythonUDF() python function to unpickle and run python udf and pickle the udf result using python embedder
6. pass back serialized result from server to client
7. client call loadPythonUDFResult() python function to unpickle result
7. return it to python
right now, put rpc_sync_builtin() and rpc_async_builtin() as temporary interfaces for builtin operator remote calls, they accept qualified name string, this interface can execute builtin operators in C++ land.
rpc_sync() and rpc_async() accept python callables only right now, it could be user define python functions or builtin operator python functions, the python functions will be executed in python land.
once we can resolve builtin operator python callables to qualified name string, we can merge rpc_sync_builtin() into rpc_sync() then
Pull Request resolved: https://github.com/pytorch/pytorch/pull/23569
Test Plan: unit tests
Differential Revision: D16390764
Pulled By: zhaojuanmao
fbshipit-source-id: 2cf2c22a979646830b5581bd75eabf8b3cca564c
