Rohan Varma c941730b96 [JIT/Futures] support set_exception api (#50983) ... Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/50983 There is currently no way to handle/propagate errors with the python-based futures API (they are raised correctly if set with an error, but this is only possible from C++). This diff allows the Future's `unwrap_func` to be set in python optionally, so users can set futures completed with an exception and the error will throw as expected. This is mostly to support the following use case in the next diff: ``` ret_fut = torch.futures.Future(unwrap_func = lambda python_result: { # throw exception if needed if isinstance(python_result, Exception): throw python_result }) rpc_fut = rpc.rpc_async(...) # RPC future that times out # Goal is to propagate RPC error to this future rpc_fut.add_done_callback( res => { # Note that ret_fut.set_result(res.wait()) won't propagate the error try: ret_fut.set_result(res.wait()) except Exception as e: ret_fut.set_result(e) } ) ``` ghstack-source-id: 121021434 Test Plan: unittest ``` buck test mode/dev-nosan mode/no-gpu //caffe2/test:futures -- te st_unwrap --print-passing-details ``` Reviewed By: mrshenli Differential Revision: D25950304 fbshipit-source-id: 7ee61e98fcd783b3f515706fa141d538e6d2174d		2021-02-04 20:22:19 -08:00
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__init__.py	[JIT/Futures] support set_exception api (#50983)	2021-02-04 20:22:19 -08:00