#33882: async transaction.atomic
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Reporter: alex | Owner: nobody
Type: New feature | Status: new
Component: Uncategorized | Version: 4.0
Severity: Normal | Resolution:
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by alex):
django supports db transactions with rollback via the
django.db.transaction.atomic function which can either be used as
decorator or as contextmanager.
Everything wrapped within is executed as transaction, see:
https://docs.djangoproject.com/en/4.0/topics/db/transactions/
That is very nice but now there is a ''little'' problem:
it isn't async safe:
https://forum.djangoproject.com/t/is-it-possible-to-use-transaction-
atomic-with-async-functions/8924
When looking through the contextmanager (which is actually a class named
Atomic in the same file) I saw that __enter__ and __exit__ use simple db
operations.
If we use the wrappers like suggested (`__aenter__` and `__aexit__`) then
everything should be fine in theory. In praxis I need to test the code (I
have not much time so it may be easier if somebody else tries this out)
I build a wrapper class like this (of course it would be better to have it
in Atomic itself so the atomic function can be used and no manual
initialization is required):
{{{
#!python
from asgiref.sync import sync_to_async
from django.db.transaction import Atomic
class AsyncAtomic(Atomic):
__aenter__ = sync_to_async(Atomic.__enter__, thread_sensitive=True)
__aexit__ = sync_to_async(Atomic.__exit__, thread_sensitive=True)
}}}
'''Warning''': untested
I must confess: the use case is very rare and is only useful in
combination with select_for_update for delaying row updates (otherwise it
is an antipattern as it causes slow transactions). And this is why I
haven't a good example code.
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Ticket URL: <https://code.djangoproject.com/ticket/33882#comment:4>
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