GeezerVison is showing github.com — GH-96704: Add task.get_context(), use it in call_exception_handler() by gvanrossum · Pull Request #96756 · python/cpython
GH-96704: Add task.get_context(), use it in call_exception_handler()
#96756
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@@ -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
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@@ -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
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@@ -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.
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@@ -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:
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@@ -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
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@@ -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
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@@ -1,5 +1,6 @@
# IsolatedAsyncioTestCase based tests
import asyncio
import contextvars
import traceback
import unittest
from asyncio import tasks
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@@ -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):
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@@ -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
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@@ -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.
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@@ -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]*/
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@@ -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 */
};
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