asyncio.TaskGroup and asyncio.Timeout classes now raise proper RuntimeError
if they are improperly used.
* When they are used without entering the context manager.
* When they are used after finishing.
* When the context manager is entered more than once (simultaneously or
sequentially).
* If there is no current task when entering the context manager.
They now remain in a consistent state after an exception is thrown,
so subsequent operations can be performed correctly (if they are allowed).
Co-authored-by: James Hilton-Balfe <gobot1234yt@gmail.com>
Also use `raise TimeOut from <CancelledError instance>` so that the CancelledError is set
in the `__cause__` field rather than in the `__context__` field.
Co-authored-by: Guido van Rossum <gvanrossum@gmail.com>
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
Example:
async with asyncio.timeout(5):
await some_task()
Will interrupt the await and raise TimeoutError if some_task() takes longer than 5 seconds.
Co-authored-by: Guido van Rossum <guido@python.org>
Serhiy Storchaka
Kristján Valur Jónsson
JosephSBoyle
Thomas Grainger
Andrew Svetlov