From eed6429fe9fe4033a0c5e7ee344394f66d5d568b Mon Sep 17 00:00:00 2001
From: Min RK <benjaminrk@gmail.com>
Date: Sun, 9 May 2021 13:06:36 +0200
Subject: [PATCH] try piggy-backing on tornado for proactor loop support

---
 zmq/asyncio.py        | 33 ++++++++++++++++++++++++++++++++-
 zmq/tests/conftest.py | 14 --------------
 2 files changed, 32 insertions(+), 15 deletions(-)

diff --git a/zmq/asyncio.py b/zmq/asyncio.py
index aa6fe4447..10bf5b4f2 100644
--- a/zmq/asyncio.py
+++ b/zmq/asyncio.py
@@ -10,10 +10,41 @@
 from asyncio import SelectorEventLoop, Future
 import selectors
 import warnings
+from weakref import WeakKeyDictionary
 
 import zmq as _zmq
 from zmq import _future
 
+# registry of asyncio loop : selector loop
+_selector_loops: WeakKeyDictionary = WeakKeyDictionary()
+
+
+def _get_selector_loop(io_loop):
+    """Get selector-compatible loop
+
+    Workaround Windows proactor removal of
+    *reader methods, which we need.
+    """
+    if io_loop in _selector_loops:
+        return _selector_loops[io_loop]
+
+    # detect add_reader instead of checking for proactor?
+    if hasattr(asyncio, "ProactorEventLoop") and isinstance(
+        io_loop, asyncio.ProactorEventLoop
+    ):
+        try:
+            from tornado.platform.asyncio import AddThreadSelectorEventLoop
+        except ImportError:
+            raise RuntimeError(
+                "pyzmq requires tornado 6.1 for compatibility with ProactorEventLoop on Windows."
+                " Install tornado 6.1 or use `asyncio.set_event_loop_policy(WindowsSelectorEventLoopPolicy())`"
+            )
+        selector_loop = AddThreadSelectorEventLoop(io_loop)
+        _selector_loops[io_loop] = selector_loop
+        return selector_loop
+    else:
+        return io_loop
+
 
 class _AsyncIO(object):
     _Future = Future
@@ -21,7 +52,7 @@ class _AsyncIO(object):
     _READ = selectors.EVENT_READ
 
     def _default_loop(self):
-        return asyncio.get_event_loop()
+        return _get_selector_loop(asyncio.get_event_loop())
 
 
 class Poller(_AsyncIO, _future._AsyncPoller):
diff --git a/zmq/tests/conftest.py b/zmq/tests/conftest.py
index 61862ccd1..86832475b 100644
--- a/zmq/tests/conftest.py
+++ b/zmq/tests/conftest.py
@@ -1,15 +1 @@
 """pytest configuration and fixtures"""
-
-import sys
-
-import pytest
-
-
-@pytest.fixture(scope='session', autouse=True)
-def win_py38_asyncio():
-    """fix tornado compatibility on py38"""
-    if sys.version_info < (3, 8) or not sys.platform.startswith('win'):
-        return
-    import asyncio
-
-    asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())