From: Ben Darnell <ben@bendarnell.com>
Date: Wed, 8 Feb 2023 20:12:47 +0000 (+0000)
Subject: asyncio: Remove obsolete code
X-Git-Tag: v6.3.0b1~10^2~2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a706b98bd8842b190c6a3e16e28186adb6d131a1;p=thirdparty%2Ftornado.git

asyncio: Remove obsolete code

AsyncioLoop.start() used to save, set, and restore the thread-local
event loop. This avoided some edge cases in early versions of asyncio;
this appears to no longer be necessary since Python 3.7 introduced
the get_running_loop() method.

Removing this logic improves compatibility with Python 3.12, where
it is difficult if not impossible to do the same thing without
generating DeprecationWarnings.
---

diff --git a/tornado/platform/asyncio.py b/tornado/platform/asyncio.py
index d839e87d6..a3fbdc37e 100644
--- a/tornado/platform/asyncio.py
+++ b/tornado/platform/asyncio.py
@@ -74,19 +74,6 @@ def _atexit_callback() -> None:
 
 atexit.register(_atexit_callback)
 
-if sys.version_info >= (3, 10):
-
-    def _get_event_loop() -> asyncio.AbstractEventLoop:
-        try:
-            return asyncio.get_running_loop()
-        except RuntimeError:
-            pass
-
-        return asyncio.get_event_loop_policy().get_event_loop()
-
-else:
-    from asyncio import get_event_loop as _get_event_loop
-
 
 class BaseAsyncIOLoop(IOLoop):
     def initialize(  # type: ignore
@@ -205,15 +192,7 @@ class BaseAsyncIOLoop(IOLoop):
         handler_func(fileobj, events)
 
     def start(self) -> None:
-        try:
-            old_loop = _get_event_loop()
-        except (RuntimeError, AssertionError):
-            old_loop = None  # type: ignore
-        try:
-            asyncio.set_event_loop(self.asyncio_loop)
-            self.asyncio_loop.run_forever()
-        finally:
-            asyncio.set_event_loop(old_loop)
+        self.asyncio_loop.run_forever()
 
     def stop(self) -> None:
         self.asyncio_loop.stop()