Enable distributed package on windows, Gloo backend supported only (#42897)

Summary:
Fixes https://github.com/pytorch/pytorch/issues/42095

For test case part will be committed to this PR later

mrshenli, please help to review

Pull Request resolved: https://github.com/pytorch/pytorch/pull/42897

Reviewed By: osalpekar

Differential Revision: D23841786

Pulled By: mrshenli

fbshipit-source-id: 334ba1ed73eff2f668857390fc32d1bc7f08e5f3

torch/distributed/rendezvous.py

@@ -6,9 +6,12 @@ except ImportError:
 import torch._six as six
 import numbers
 import os
-from . import FileStore, TCPStore
+import sys
+from . import FileStore
 from .constants import default_pg_timeout
 
+if sys.platform != 'win32':
+    from . import TCPStore
 
 _rendezvous_handlers = {}
 
@@ -90,6 +93,10 @@ def _file_rendezvous_handler(url, **kwargs):
 
     result = urlparse(url)
     path = result.path
+    if sys.platform == 'win32':
+        import urllib.request
+        path = urllib.request.url2pathname(result.path)
+
     if not path:
         raise _error("path missing")
     query = dict(pair.split("=") for pair in filter(None, result.query.split("&")))
@@ -175,7 +182,8 @@ def _env_rendezvous_handler(url, timeout=default_pg_timeout, **kwargs):
     # If this configuration is invalidated, there is nothing we can do about it
     raise RuntimeError("Unable to perform rerendezvous using env:// method")
 
+if sys.platform != 'win32':
+    register_rendezvous_handler("tcp", _tcp_rendezvous_handler)
+    register_rendezvous_handler("env", _env_rendezvous_handler)
 
 register_rendezvous_handler("file", _file_rendezvous_handler)
-register_rendezvous_handler("tcp", _tcp_rendezvous_handler)
-register_rendezvous_handler("env", _env_rendezvous_handler)