horovod/mxnet/mpi_ops.py
horovod/torch/mpi_ops.py

horovod/mxnet/adapter.cc
horovod/torch/adapter_v2.cc

horovod/mxnet/functions.py
horovod/torch/functions.py

horovod/mxnet/adapter.h
horovod/torch/adapter_v2.h