[PP-2055] Use Ensure that local analytics events are committed to the…

… database by running the event collection within a transaction. (#2250)

Also use one transaction per event collected to minimize database lock durations.

src/palace/manager/api/monitor.py

@@ -64,9 +64,13 @@ def delete(self, row) -> None:
     def after_commit(self) -> None:
         super().after_commit()
         copy_of_list = list(self._events_to_be_logged)
+
         for event in copy_of_list:
-            self.services.analytics.collect_event(**event)
-            self._events_to_be_logged.remove(event)
+            # start a separate transaction for each event in order to
+            # minimize database lock durations
+            with self._db.begin() as transaction:
+                self.services.analytics.collect_event(**event)
+                self._events_to_be_logged.remove(event)
 
 
 class LoanReaper(LoanlikeReaperMonitor):

src/palace/manager/celery/tasks/opds_odl.py

@@ -216,8 +216,10 @@ def collect_events(
     We perform this operation outside after completed the transaction to ensure that any row locks
     are held for the shortest possible duration in case writing to the s3 analytics provider is slow.
     """
-    with task.session() as session:
-        for e in events:
+
+    for e in events:
+        with task.transaction() as session:
+            # one transaction per event to minimize possible database lock durations
             library = session.merge(e.library)
             license_pool = session.merge(e.license_pool)
             patron = session.merge(e.patron)