bpo-32591: Add native coroutine origin tracking (#5250)

* Add coro.cr_origin and sys.set_coroutine_origin_tracking_depth
* Use coroutine origin information in the unawaited coroutine warning
* Stop using set_coroutine_wrapper in asyncio debug mode
* In BaseEventLoop.set_debug, enable debugging in the correct thread

2 files changed, 16 insertions, 66 deletions

diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
index 00c84a8..a10e706 100644
--- a/Lib/asyncio/base_events.py
+++ b/Lib/asyncio/base_events.py
@@ -34,6 +34,7 @@ try:
 except ImportError:  # pragma: no cover
     ssl = None
 
+from . import constants
 from . import coroutines
 from . import events
 from . import futures
@@ -224,7 +225,8 @@ class BaseEventLoop(events.AbstractEventLoop):
         self.slow_callback_duration = 0.1
         self._current_handle = None
         self._task_factory = None
-        self._coroutine_wrapper_set = False
+        self._coroutine_origin_tracking_enabled = False
+        self._coroutine_origin_tracking_saved_depth = None
 
         if hasattr(sys, 'get_asyncgen_hooks'):
             # Python >= 3.6
@@ -382,7 +384,7 @@ class BaseEventLoop(events.AbstractEventLoop):
         if events._get_running_loop() is not None:
             raise RuntimeError(
                 'Cannot run the event loop while another loop is running')
-        self._set_coroutine_wrapper(self._debug)
+        self._set_coroutine_origin_tracking(self._debug)
         self._thread_id = threading.get_ident()
         if self._asyncgens is not None:
             old_agen_hooks = sys.get_asyncgen_hooks()
@@ -398,7 +400,7 @@ class BaseEventLoop(events.AbstractEventLoop):
             self._stopping = False
             self._thread_id = None
             events._set_running_loop(None)
-            self._set_coroutine_wrapper(False)
+            self._set_coroutine_origin_tracking(False)
             if self._asyncgens is not None:
                 sys.set_asyncgen_hooks(*old_agen_hooks)
 
@@ -1531,39 +1533,20 @@ class BaseEventLoop(events.AbstractEventLoop):
                 handle._run()
         handle = None  # Needed to break cycles when an exception occurs.
 
-    def _set_coroutine_wrapper(self, enabled):
-        try:
-            set_wrapper = sys.set_coroutine_wrapper
-            get_wrapper = sys.get_coroutine_wrapper
-        except AttributeError:
-            return
-
-        enabled = bool(enabled)
-        if self._coroutine_wrapper_set == enabled:
+    def _set_coroutine_origin_tracking(self, enabled):
+        if bool(enabled) == bool(self._coroutine_origin_tracking_enabled):
             return
 
-        wrapper = coroutines.debug_wrapper
-        current_wrapper = get_wrapper()
-
         if enabled:
-            if current_wrapper not in (None, wrapper):
-                warnings.warn(
-                    f"loop.set_debug(True): cannot set debug coroutine "
-                    f"wrapper; another wrapper is already set "
-                    f"{current_wrapper!r}",
-                    RuntimeWarning)
-            else:
-                set_wrapper(wrapper)
-                self._coroutine_wrapper_set = True
+            self._coroutine_origin_tracking_saved_depth = (
+                sys.get_coroutine_origin_tracking_depth())
+            sys.set_coroutine_origin_tracking_depth(
+                constants.DEBUG_STACK_DEPTH)
         else:
-            if current_wrapper not in (None, wrapper):
-                warnings.warn(
-                    f"loop.set_debug(False): cannot unset debug coroutine "
-                    f"wrapper; another wrapper was set {current_wrapper!r}",
-                    RuntimeWarning)
-            else:
-                set_wrapper(None)
-                self._coroutine_wrapper_set = False
+            sys.set_coroutine_origin_tracking_depth(
+                self._coroutine_origin_tracking_saved_depth)
+
+        self._coroutine_origin_tracking_enabled = enabled
 
     def get_debug(self):
         return self._debug
@@ -1572,4 +1555,4 @@ class BaseEventLoop(events.AbstractEventLoop):
         self._debug = enabled
 
         if self.is_running():
-            self._set_coroutine_wrapper(enabled)
+            self.call_soon_threadsafe(self._set_coroutine_origin_tracking, enabled)
diff --git a/Lib/asyncio/coroutines.py b/Lib/asyncio/coroutines.py
index 9c860a4..5a29100 100644
--- a/Lib/asyncio/coroutines.py
+++ b/Lib/asyncio/coroutines.py
@@ -32,14 +32,6 @@ def _is_debug_mode():
 _DEBUG = _is_debug_mode()
 
 
-def debug_wrapper(gen):
-    # This function is called from 'sys.set_coroutine_wrapper'.
-    # We only wrap here coroutines defined via 'async def' syntax.
-    # Generator-based coroutines are wrapped in @coroutine
-    # decorator.
-    return CoroWrapper(gen, None)
-
-
 class CoroWrapper:
     # Wrapper for coroutine object in _DEBUG mode.
 
@@ -87,39 +79,16 @@ class CoroWrapper:
         return self.gen.gi_code
 
     def __await__(self):
-        cr_await = getattr(self.gen, 'cr_await', None)
-        if cr_await is not None:
-            raise RuntimeError(
-                f"Cannot await on coroutine {self.gen!r} while it's "
-                f"awaiting for {cr_await!r}")
         return self
 
     @property
     def gi_yieldfrom(self):
         return self.gen.gi_yieldfrom
 
-    @property
-    def cr_await(self):
-        return self.gen.cr_await
-
-    @property
-    def cr_running(self):
-        return self.gen.cr_running
-
-    @property
-    def cr_code(self):
-        return self.gen.cr_code
-
-    @property
-    def cr_frame(self):
-        return self.gen.cr_frame
-
     def __del__(self):
         # Be careful accessing self.gen.frame -- self.gen might not exist.
         gen = getattr(self, 'gen', None)
         frame = getattr(gen, 'gi_frame', None)
-        if frame is None:
-            frame = getattr(gen, 'cr_frame', None)
         if frame is not None and frame.f_lasti == -1:
             msg = f'{self!r} was never yielded from'
             tb = getattr(self, '_source_traceback', ())
@@ -141,8 +110,6 @@ def coroutine(func):
     if inspect.iscoroutinefunction(func):
         # In Python 3.5 that's all we need to do for coroutines
         # defined with "async def".
-        # Wrapping in CoroWrapper will happen via
-        # 'sys.set_coroutine_wrapper' function.
         return func
 
     if inspect.isgeneratorfunction(func):