[Python-checkins] GH-96704: Add {Task, Handle}.get_context(), use it in call_exception_handler() (#96756)
gvanrossum
webhook-mailer at python.org
Wed Oct 5 02:49:19 EDT 2022
https://github.com/python/cpython/commit/8079bef56f2249ecedafe0be5a6d7a120a7f3ac3
commit: 8079bef56f2249ecedafe0be5a6d7a120a7f3ac3
branch: main
author: Guido van Rossum <guido at python.org>
committer: gvanrossum <gvanrossum at gmail.com>
date: 2022-10-04T23:49:10-07:00
summary:
GH-96704: Add {Task,Handle}.get_context(), use it in call_exception_handler() (#96756)
Co-authored-by: Kumar Aditya <59607654+kumaraditya303 at users.noreply.github.com>
files:
A Misc/NEWS.d/next/Library/2022-09-18-04-51-30.gh-issue-96704.DmamRX.rst
M Doc/library/asyncio-eventloop.rst
M Doc/library/asyncio-task.rst
M Lib/asyncio/base_events.py
M Lib/asyncio/events.py
M Lib/asyncio/tasks.py
M Lib/test/test_asyncio/test_futures2.py
M Lib/test/test_asyncio/test_tasks.py
M Modules/_asynciomodule.c
M Modules/clinic/_asynciomodule.c.h
diff --git a/Doc/library/asyncio-eventloop.rst b/Doc/library/asyncio-eventloop.rst
index c51990eff8de..6fe95687c151 100644
--- a/Doc/library/asyncio-eventloop.rst
+++ b/Doc/library/asyncio-eventloop.rst
@@ -1271,6 +1271,15 @@ Allows customizing how exceptions are handled in the event loop.
(see :meth:`call_exception_handler` documentation for details
about context).
+ If the handler is called on behalf of a :class:`~asyncio.Task` or
+ :class:`~asyncio.Handle`, it is run in the
+ :class:`contextvars.Context` of that task or callback handle.
+
+ .. versionchanged:: 3.12
+
+ The handler may be called in the :class:`~contextvars.Context`
+ of the task or handle where the exception originated.
+
.. method:: loop.get_exception_handler()
Return the current exception handler, or ``None`` if no custom
@@ -1474,6 +1483,13 @@ Callback Handles
A callback wrapper object returned by :meth:`loop.call_soon`,
:meth:`loop.call_soon_threadsafe`.
+ .. method:: get_context()
+
+ Return the :class:`contextvars.Context` object
+ associated with the handle.
+
+ .. versionadded:: 3.12
+
.. method:: cancel()
Cancel the callback. If the callback has already been canceled
diff --git a/Doc/library/asyncio-task.rst b/Doc/library/asyncio-task.rst
index ade969220ea7..d922f614954f 100644
--- a/Doc/library/asyncio-task.rst
+++ b/Doc/library/asyncio-task.rst
@@ -1097,6 +1097,13 @@ Task Object
.. versionadded:: 3.8
+ .. method:: get_context()
+
+ Return the :class:`contextvars.Context` object
+ associated with the task.
+
+ .. versionadded:: 3.12
+
.. method:: get_name()
Return the name of the Task.
diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
index 66202f09794d..c8a2f9f25634 100644
--- a/Lib/asyncio/base_events.py
+++ b/Lib/asyncio/base_events.py
@@ -1808,7 +1808,22 @@ def call_exception_handler(self, context):
exc_info=True)
else:
try:
- self._exception_handler(self, context)
+ ctx = None
+ thing = context.get("task")
+ if thing is None:
+ # Even though Futures don't have a context,
+ # Task is a subclass of Future,
+ # and sometimes the 'future' key holds a Task.
+ thing = context.get("future")
+ if thing is None:
+ # Handles also have a context.
+ thing = context.get("handle")
+ if thing is not None and hasattr(thing, "get_context"):
+ ctx = thing.get_context()
+ if ctx is not None and hasattr(ctx, "run"):
+ ctx.run(self._exception_handler, self, context)
+ else:
+ self._exception_handler(self, context)
except (SystemExit, KeyboardInterrupt):
raise
except BaseException as exc:
diff --git a/Lib/asyncio/events.py b/Lib/asyncio/events.py
index 0d26ea545baa..a327ba54a323 100644
--- a/Lib/asyncio/events.py
+++ b/Lib/asyncio/events.py
@@ -61,6 +61,9 @@ def __repr__(self):
info = self._repr_info()
return '<{}>'.format(' '.join(info))
+ def get_context(self):
+ return self._context
+
def cancel(self):
if not self._cancelled:
self._cancelled = True
diff --git a/Lib/asyncio/tasks.py b/Lib/asyncio/tasks.py
index e48da0f20088..8d6dfcd81b73 100644
--- a/Lib/asyncio/tasks.py
+++ b/Lib/asyncio/tasks.py
@@ -139,6 +139,9 @@ def __repr__(self):
def get_coro(self):
return self._coro
+ def get_context(self):
+ return self._context
+
def get_name(self):
return self._name
diff --git a/Lib/test/test_asyncio/test_futures2.py b/Lib/test/test_asyncio/test_futures2.py
index 71279b69c792..9e7a5775a703 100644
--- a/Lib/test/test_asyncio/test_futures2.py
+++ b/Lib/test/test_asyncio/test_futures2.py
@@ -1,5 +1,6 @@
# IsolatedAsyncioTestCase based tests
import asyncio
+import contextvars
import traceback
import unittest
from asyncio import tasks
@@ -27,6 +28,46 @@ async def raise_exc():
else:
self.fail('TypeError was not raised')
+ async def test_task_exc_handler_correct_context(self):
+ # see https://github.com/python/cpython/issues/96704
+ name = contextvars.ContextVar('name', default='foo')
+ exc_handler_called = False
+
+ def exc_handler(*args):
+ self.assertEqual(name.get(), 'bar')
+ nonlocal exc_handler_called
+ exc_handler_called = True
+
+ async def task():
+ name.set('bar')
+ 1/0
+
+ loop = asyncio.get_running_loop()
+ loop.set_exception_handler(exc_handler)
+ self.cls(task())
+ await asyncio.sleep(0)
+ self.assertTrue(exc_handler_called)
+
+ async def test_handle_exc_handler_correct_context(self):
+ # see https://github.com/python/cpython/issues/96704
+ name = contextvars.ContextVar('name', default='foo')
+ exc_handler_called = False
+
+ def exc_handler(*args):
+ self.assertEqual(name.get(), 'bar')
+ nonlocal exc_handler_called
+ exc_handler_called = True
+
+ def callback():
+ name.set('bar')
+ 1/0
+
+ loop = asyncio.get_running_loop()
+ loop.set_exception_handler(exc_handler)
+ loop.call_soon(callback)
+ await asyncio.sleep(0)
+ self.assertTrue(exc_handler_called)
+
@unittest.skipUnless(hasattr(tasks, '_CTask'),
'requires the C _asyncio module')
class CFutureTests(FutureTests, unittest.IsolatedAsyncioTestCase):
diff --git a/Lib/test/test_asyncio/test_tasks.py b/Lib/test/test_asyncio/test_tasks.py
index 04bdf6483131..2491285206bc 100644
--- a/Lib/test/test_asyncio/test_tasks.py
+++ b/Lib/test/test_asyncio/test_tasks.py
@@ -2482,6 +2482,17 @@ def test_get_coro(self):
finally:
loop.close()
+ def test_get_context(self):
+ loop = asyncio.new_event_loop()
+ coro = coroutine_function()
+ context = contextvars.copy_context()
+ try:
+ task = self.new_task(loop, coro, context=context)
+ loop.run_until_complete(task)
+ self.assertIs(task.get_context(), context)
+ finally:
+ loop.close()
+
def add_subclass_tests(cls):
BaseTask = cls.Task
diff --git a/Misc/NEWS.d/next/Library/2022-09-18-04-51-30.gh-issue-96704.DmamRX.rst b/Misc/NEWS.d/next/Library/2022-09-18-04-51-30.gh-issue-96704.DmamRX.rst
new file mode 100644
index 000000000000..6ac99197e685
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-09-18-04-51-30.gh-issue-96704.DmamRX.rst
@@ -0,0 +1 @@
+Pass the correct ``contextvars.Context`` when a ``asyncio`` exception handler is called on behalf of a task or callback handle. This adds a new ``Task`` method, ``get_context``, and also a new ``Handle`` method with the same name. If this method is not found on a task object (perhaps because it is a third-party library that does not yet provide this method), the context prevailing at the time the exception handler is called is used.
diff --git a/Modules/_asynciomodule.c b/Modules/_asynciomodule.c
index 909171150bdd..efa0d2d6906e 100644
--- a/Modules/_asynciomodule.c
+++ b/Modules/_asynciomodule.c
@@ -2409,6 +2409,18 @@ _asyncio_Task_get_coro_impl(TaskObj *self)
return self->task_coro;
}
+/*[clinic input]
+_asyncio.Task.get_context
+[clinic start generated code]*/
+
+static PyObject *
+_asyncio_Task_get_context_impl(TaskObj *self)
+/*[clinic end generated code: output=6996f53d3dc01aef input=87c0b209b8fceeeb]*/
+{
+ Py_INCREF(self->task_context);
+ return self->task_context;
+}
+
/*[clinic input]
_asyncio.Task.get_name
[clinic start generated code]*/
@@ -2536,6 +2548,7 @@ static PyMethodDef TaskType_methods[] = {
_ASYNCIO_TASK_GET_NAME_METHODDEF
_ASYNCIO_TASK_SET_NAME_METHODDEF
_ASYNCIO_TASK_GET_CORO_METHODDEF
+ _ASYNCIO_TASK_GET_CONTEXT_METHODDEF
{"__class_getitem__", Py_GenericAlias, METH_O|METH_CLASS, PyDoc_STR("See PEP 585")},
{NULL, NULL} /* Sentinel */
};
diff --git a/Modules/clinic/_asynciomodule.c.h b/Modules/clinic/_asynciomodule.c.h
index daf524c3456c..ddec54c8d7c2 100644
--- a/Modules/clinic/_asynciomodule.c.h
+++ b/Modules/clinic/_asynciomodule.c.h
@@ -772,6 +772,23 @@ _asyncio_Task_get_coro(TaskObj *self, PyObject *Py_UNUSED(ignored))
return _asyncio_Task_get_coro_impl(self);
}
+PyDoc_STRVAR(_asyncio_Task_get_context__doc__,
+"get_context($self, /)\n"
+"--\n"
+"\n");
+
+#define _ASYNCIO_TASK_GET_CONTEXT_METHODDEF \
+ {"get_context", (PyCFunction)_asyncio_Task_get_context, METH_NOARGS, _asyncio_Task_get_context__doc__},
+
+static PyObject *
+_asyncio_Task_get_context_impl(TaskObj *self);
+
+static PyObject *
+_asyncio_Task_get_context(TaskObj *self, PyObject *Py_UNUSED(ignored))
+{
+ return _asyncio_Task_get_context_impl(self);
+}
+
PyDoc_STRVAR(_asyncio_Task_get_name__doc__,
"get_name($self, /)\n"
"--\n"
@@ -1172,4 +1189,4 @@ _asyncio__leave_task(PyObject *module, PyObject *const *args, Py_ssize_t nargs,
exit:
return return_value;
}
-/*[clinic end generated code: output=459a7c7f21bbc290 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=f117b2246eaf7a55 input=a9049054013a1b77]*/
More information about the Python-checkins
mailing list