Handle StaleDataError for ODLNotificationController (#2129)

* Handle StaleDataError for ODLNotificationController
* Mypy fix

src/palace/manager/api/controller/odl_notification.py

@@ -6,6 +6,7 @@
 from pydantic import ValidationError
 from sqlalchemy import select
 from sqlalchemy.orm import Session
+from sqlalchemy.orm.exc import StaleDataError
 
 from palace.manager.api.odl.api import OPDS2WithODLApi
 from palace.manager.api.problem_details import (
@@ -101,6 +102,14 @@ def _process_notification(self, loan: Loan | None) -> Response:
             #   Once we move the OPDS2WithODL scripts to celery this should be possible.
             #   For now we just mark the loan as expired.
             if not status_doc.active:
-                loan.end = utc_now()
+                try:
+                    with self.db.begin_nested():
+                        loan.end = utc_now()
+                except StaleDataError:
+                    # This can happen if this callback happened while we were returning this
+                    # item. We can fetch the loan, but it's deleted by the time we go to do
+                    # the update. This is not a problem, as we were just marking the loan as
+                    # completed anyway so we just continue.
+                    ...
 
         return Response(status=204)

tests/manager/api/controller/test_odl_notify.py

@@ -1,6 +1,9 @@
+from unittest.mock import PropertyMock, create_autospec
+
 import pytest
 from flask import Response
 from freezegun import freeze_time
+from sqlalchemy.orm.exc import StaleDataError
 
 from palace.manager.api.controller.odl_notification import ODLNotificationController
 from palace.manager.api.odl.api import OPDS2WithODLApi
@@ -9,6 +12,7 @@
     NO_ACTIVE_LOAN,
 )
 from palace.manager.core.problem_details import INVALID_INPUT
+from palace.manager.integration.goals import Goals
 from palace.manager.sqlalchemy.model.collection import Collection
 from palace.manager.sqlalchemy.model.licensing import License
 from palace.manager.sqlalchemy.model.patron import Loan, Patron
@@ -249,3 +253,23 @@ def test_notify_errors(
             odl_fixture.controller.notify(
                 odl_fixture.patron_identifier, NON_EXISTENT_LICENSE_IDENTIFIER
             )
+
+    def test__process_notification_already_deleted(
+        self,
+        odl_fixture: ODLFixture,
+        flask_app_fixture: FlaskAppFixture,
+        db: DatabaseTransactionFixture,
+    ) -> None:
+        mock_loan = create_autospec(Loan)
+        type(mock_loan).end = PropertyMock(side_effect=StaleDataError())
+        mock_loan.license_pool.collection.integration_configuration.protocol = (
+            db.protocol_string(Goals.LICENSE_GOAL, OPDS2WithODLApi)
+        )
+        with flask_app_fixture.test_request_context(
+            "/",
+            method="POST",
+            library=odl_fixture.library,
+            data=odl_fixture.loan_status_document("revoked").model_dump_json(),
+        ):
+            response = odl_fixture.controller._process_notification(mock_loan)
+        assert response.status_code == 204