Performance fix for collection version list.

[jctanner]

https://issues.redhat.com/browse/AAH-2229

On a system with community.general's versions all synced, continuous queries against the list endpoint will consume all available memory until the worker is OOMKilled.

Thanks to @rochacbruno for the reproducer:

$ cat REPRO.sh 
#!/bin/bash

watch -n 1 \
curl -u admin:admin http://localhost:5001/api/automation-hub/v3/plugin/ansible/content/community/collections/index/community/general/versions/\?limit\=200\&offset\=0

[jctanner]

Test failure is due to a caching lookup bug in ansible-core==2.13.9. We'll be waiting on a fix and a release for that before we can move this forward.

ansible/ansible#80648

[mdellweg]

Is this also beneficial for the detail view? We could just overwrite get_queryset at that point.

[jctanner]

I'm not actually sure, but I can see if it breaks any tests.

[jctanner]

Collection deletion tests are causing tracebacks when get_queryset is overridden ...

oci_env-pulp-1   | pulp [bf8cde0156fa4c4ea86b5c288bb0f390]: 127.0.0.1 - admin [03/May/2023:15:35:01 +0000] "DELETE /pulp_ansible/galaxy/6452de55-d612-432f-a374-a8c0946c32bf/api/v3/collections/jpmipskp/nbzbxzxi/versions/1.0.1/ HTTP/1.0" 302 0 "-" "OpenAPI-Generator/0.17.0/python"
oci_env-pulp-1   | pulp [64213f3b622a4a53a3142eb4da6b6796]: django.request:ERROR: Internal Server Error: /pulp_ansible/galaxy/6452de55-d612-432f-a374-a8c0946c32bf/api/v3/plugin/ansible/content/6452de55-d612-432f-a374-a8c0946c32bf/collections/index/jpmipskp/nbzbxzxi/versions/1.0.1/
oci_env-pulp-1   | Traceback (most recent call last):
oci_env-pulp-1   |   File "/usr/local/lib/python3.8/site-packages/django/core/handlers/exception.py", line 47, in inner
oci_env-pulp-1   |     response = get_response(request)
oci_env-pulp-1   |   File "/usr/local/lib/python3.8/site-packages/django/core/handlers/base.py", line 181, in _get_response
oci_env-pulp-1   |     response = wrapped_callback(request, *callback_args, **callback_kwargs)
oci_env-pulp-1   |   File "/usr/local/lib/python3.8/site-packages/django/views/decorators/csrf.py", line 54, in wrapped_view
oci_env-pulp-1   |     return view_func(*args, **kwargs)
oci_env-pulp-1   |   File "/usr/local/lib/python3.8/site-packages/rest_framework/viewsets.py", line 125, in view
oci_env-pulp-1   |     return self.dispatch(request, *args, **kwargs)
oci_env-pulp-1   |   File "/usr/local/lib/python3.8/site-packages/rest_framework/views.py", line 509, in dispatch
oci_env-pulp-1   |     response = self.handle_exception(exc)
oci_env-pulp-1   |   File "/usr/local/lib/python3.8/site-packages/rest_framework/views.py", line 469, in handle_exception
oci_env-pulp-1   |     self.raise_uncaught_exception(exc)
oci_env-pulp-1   |   File "/usr/local/lib/python3.8/site-packages/rest_framework/views.py", line 480, in raise_uncaught_exception
oci_env-pulp-1   |     raise exc
oci_env-pulp-1   |   File "/usr/local/lib/python3.8/site-packages/rest_framework/views.py", line 506, in dispatch
oci_env-pulp-1   |     response = handler(request, *args, **kwargs)
oci_env-pulp-1   |   File "/src/pulp_ansible/pulp_ansible/app/galaxy/v3/views.py", line 948, in destroy
oci_env-pulp-1   |     exclusive_resources=collection_version.repositories.all(),
oci_env-pulp-1   |   File "/usr/local/lib/python3.8/site-packages/django/db/models/fields/related_descriptors.py", line 536, in __get__
oci_env-pulp-1   |     return self.related_manager_cls(instance)
oci_env-pulp-1   |   File "/usr/local/lib/python3.8/site-packages/django/db/models/fields/related_descriptors.py", line 846, in __init__
oci_env-pulp-1   |     self.core_filters[core_filter_key] = getattr(instance, rh_field.attname)
oci_env-pulp-1   |   File "/usr/local/lib/python3.8/site-packages/django/db/models/query_utils.py", line 142, in __get__
oci_env-pulp-1   |     val = self._check_parent_chain(instance)
oci_env-pulp-1   |   File "/usr/local/lib/python3.8/site-packages/django/db/models/query_utils.py", line 158, in _check_parent_chain
oci_env-pulp-1   |     return getattr(instance, link_field.attname)
oci_env-pulp-1   | AttributeError: 'NoneType' object has no attribute 'attname'

[mdellweg]

It is unclear to me why filter_queryset may already OOM, because it should really only apply filters to the queryset, not evaluate it. And I don't see anything obvious in either inherited filter_queryset nor the CollectionVersionFilter class. Does the paginated version OOM too? Then I would suspect this fix will just by us some time until these two fields are able to fill the memory again. Approving anyway.

[mdellweg]

Maybe add some of these thought to the comment to spark further investigation.