Invalidate the content cache once a new repository version is complete

Repository.new_version() cleared the cache of the distributions serving
the repository when the new version was started. Until that version is
complete, those distributions are still served from the previous one, so
a response computed in that window was put back into the cache and served
until it expired (ten minutes by default), although the new version had
been created in the meantime.

Clear the cache once the new version is complete and committed instead.
A version that changes nothing is discarded and no longer clears the
cache.

Closes: #8246

Author: aevnsvi

CHANGES/8246.bugfix

@@ -0,0 +1 @@
+Fixed responses for a distribution being cached from the previous repository version, and served until the cache entry expired, when they were requested while a new version was being created.

pulpcore/app/models/repository.py

@@ -198,8 +198,6 @@ def new_version(self, base_version=None):
                 resource = CreatedResource(content_object=version)
                 resource.save()
 
-            self.invalidate_cache()
-
             return version
 
     def initialize_new_version(self, new_version):
@@ -1534,6 +1532,7 @@ def __exit__(self, exc_type, exc_value, traceback):
                         self.repository.save()
                         self.save()
                         self._compute_counts()
+                    transaction.on_commit(self.repository.invalidate_cache)
                     self.repository.cleanup_old_versions()
                     repository.on_new_version(self)
             except Exception:

…nit/models/test_publication_retention.py …nit/models/test_caching_and_retention.pypulpcore/tests/unit/models/test_publication_retention.py renamed to pulpcore/tests/unit/models/test_caching_and_retention.py pulpcore/tests/unit/models/test_publication_retention.py renamed to pulpcore/tests/unit/models/test_caching_and_retention.py

@@ -614,3 +614,44 @@ def test_ignores_repository_distribution_when_deleted_not_latest_for_repository(
         assert cache_key(dist_repo.base_path) not in invalidated, (
             "repo dist should NOT be invalidated (pub2 still latest)"
         )
+
+
+@pytest.mark.django_db
+class TestCacheInvalidationOnRepositoryVersionCreate:
+    """
+    While a new repository version is being created, the repository's distributions are still
+    served from the previous one, and a response computed then can be put into the cache.
+    Clearing the cache only when the version is started would leave that response there until
+    it expires, so the cache must be cleared once the new version is complete.
+    """
+
+    def test_invalidates_once_new_version_is_complete(
+        self, settings, django_capture_on_commit_callbacks
+    ):
+        """Creating a repository version invalidates the cache after the version is complete."""
+        settings.CACHE_ENABLED = True
+        repo = FileRepository.objects.create(name=f"repo-{uuid.uuid4().hex[:8]}")
+        dist = dist_factory(repo=repo)
+        complete_at_invalidation = []
+
+        def record(*args, base_key=None, **kwargs):
+            if base_key is not None and cache_key(dist.base_path) in base_key:
+                complete_at_invalidation.append(repo.versions.latest("number").complete)
+
+        with mock.patch("pulpcore.app.models.repository.Cache") as mock_cache:
+            mock_cache.return_value.delete.side_effect = record
+            with django_capture_on_commit_callbacks(execute=True):
+                version = create_version(repo, add=["some-file.txt"])
+        assert version.complete
+        assert True in complete_at_invalidation
+
+    def test_ignores_version_without_changes(self, settings, django_capture_on_commit_callbacks):
+        """A new version that changes nothing is discarded and leaves the cache alone."""
+        settings.CACHE_ENABLED = True
+        repo = FileRepository.objects.create(name=f"repo-{uuid.uuid4().hex[:8]}")
+        dist_factory(repo=repo)
+        with mock.patch("pulpcore.app.models.repository.Cache") as mock_cache:
+            with django_capture_on_commit_callbacks(execute=True):
+                with repo.new_version():
+                    pass
+        mock_cache.return_value.delete.assert_not_called()