asyncio: Support PEP 492. Issue #24017.

1 files changed, 38 insertions, 9 deletions

diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
index 98aadaf..38344a7 100644
--- a/Lib/asyncio/base_events.py
+++ b/Lib/asyncio/base_events.py
@@ -191,8 +191,8 @@ class BaseEventLoop(events.AbstractEventLoop):
         self._thread_id = None
         self._clock_resolution = time.get_clock_info('monotonic').resolution
         self._exception_handler = None
-        self._debug = (not sys.flags.ignore_environment
-                       and bool(os.environ.get('PYTHONASYNCIODEBUG')))
+        self.set_debug((not sys.flags.ignore_environment
+                        and bool(os.environ.get('PYTHONASYNCIODEBUG'))))
         # In debug mode, if the execution of a callback or a step of a task
         # exceed this duration in seconds, the slow callback/task is logged.
         self.slow_callback_duration = 0.1
@@ -360,13 +360,18 @@ class BaseEventLoop(events.AbstractEventLoop):
             return
         if self._debug:
             logger.debug("Close %r", self)
-        self._closed = True
-        self._ready.clear()
-        self._scheduled.clear()
-        executor = self._default_executor
-        if executor is not None:
-            self._default_executor = None
-            executor.shutdown(wait=False)
+        try:
+            self._closed = True
+            self._ready.clear()
+            self._scheduled.clear()
+            executor = self._default_executor
+            if executor is not None:
+                self._default_executor = None
+                executor.shutdown(wait=False)
+        finally:
+            # It is important to unregister "sys.coroutine_wrapper"
+            # if it was registered.
+            self.set_debug(False)
 
     def is_closed(self):
         """Returns True if the event loop was closed."""
@@ -1199,3 +1204,27 @@ class BaseEventLoop(events.AbstractEventLoop):
 
     def set_debug(self, enabled):
         self._debug = enabled
+        wrapper = coroutines.debug_wrapper
+
+        try:
+            set_wrapper = sys.set_coroutine_wrapper
+        except AttributeError:
+            pass
+        else:
+            current_wrapper = sys.get_coroutine_wrapper()
+            if enabled:
+                if current_wrapper not in (None, wrapper):
+                    warnings.warn(
+                        "loop.set_debug(True): cannot set debug coroutine "
+                        "wrapper; another wrapper is already set %r" %
+                        current_wrapper, RuntimeWarning)
+                else:
+                    set_wrapper(wrapper)
+            else:
+                if current_wrapper not in (None, wrapper):
+                    warnings.warn(
+                        "loop.set_debug(False): cannot unset debug coroutine "
+                        "wrapper; another wrapper was set %r" %
+                        current_wrapper, RuntimeWarning)
+                else:
+                    set_wrapper(None)