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Taskgroup tweaks (GH-31559)

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Now uses .cancel()/.uncancel(), for even fewer broken edge cases.
This commit is contained in:
Tin Tvrtković 2022-02-26 17:18:48 +01:00 • committed by GitHub
parent 41ddcd3f40
commit edbee56d69
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2 changed files with 41 additions and 33 deletions
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48
Lib/asyncio/taskgroups.py
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@ -66,31 +66,28 @@ class TaskGroup:
self._base_error is None):
self._base_error = exc
if et is exceptions.CancelledError:
if self._parent_cancel_requested:
# Only if we did request task to cancel ourselves
# we mark it as no longer cancelled.
self._parent_task.uncancel()
else:
propagate_cancellation_error = et
if et is not None and not self._aborting:
# Our parent task is being cancelled:
#
# async with TaskGroup() as g:
# g.create_task(...)
# await ... # <- CancelledError
#
if et is not None:
if et is exceptions.CancelledError:
propagate_cancellation_error = et
if self._parent_cancel_requested and not self._parent_task.uncancel():
# Do nothing, i.e. swallow the error.
pass
else:
propagate_cancellation_error = exc
# or there's an exception in "async with":
#
# async with TaskGroup() as g:
# g.create_task(...)
# 1 / 0
#
self._abort()
if not self._aborting:
# Our parent task is being cancelled:
#
# async with TaskGroup() as g:
# g.create_task(...)
# await ... # <- CancelledError
#
# or there's an exception in "async with":
#
# async with TaskGroup() as g:
# g.create_task(...)
# 1 / 0
#
self._abort()
# We use while-loop here because "self._on_completed_fut"
# can be cancelled multiple times if our parent task
@ -118,7 +115,6 @@ class TaskGroup:
self._on_completed_fut = None
assert self._unfinished_tasks == 0
self._on_completed_fut = None # no longer needed
if self._base_error is not None:
raise self._base_error
@ -199,8 +195,7 @@ class TaskGroup:
})
return
self._abort()
if not self._parent_task.cancelling():
if not self._aborting and not self._parent_cancel_requested:
# If parent task *is not* being cancelled, it means that we want
# to manually cancel it to abort whatever is being run right now
# in the TaskGroup. But we want to mark parent task as
@ -219,5 +214,6 @@ class TaskGroup:
# pass
# await something_else # this line has to be called
# # after TaskGroup is finished.
self._abort()
self._parent_cancel_requested = True
self._parent_task.cancel()