Fixed listEvents intermittent exception: (#9661)

com.mysql.cj.jdbc.ClientPreparedStatement: SELECT event_view.id, event_view.uuid, event_view.type, event_view.state, event_view.description, event_view.created, event_view.user_id, event_view.user_name, event_view.level, event_view.start_id, event_view.start_uuid, event_view.parameters, event_view.account_id, event_view.account_uuid, event_view.account_name, event_view.account_type, event_view.domain_id, event_view.domain_uuid, event_view.domain_name, event_view.domain_path, event_view.resource_id, event_view.resource_type, event_view.project_id, event_view.project_uuid, event_view.project_name, event_view.archived, event_view.display FROM event_view WHERE event_view.id IN )

server/src/main/java/com/cloud/api/query/QueryManagerImpl.java

@@ -818,8 +818,14 @@ private Pair<List<EventJoinVO>, Integer> searchForEventsInternal(ListEventsCmd c
         Integer count = eventIdPage.second();
         Long[] idArray = eventIdPage.first().toArray(new Long[0]);
 
-        if (count == 0) {
-            return new Pair<>(new ArrayList<>(), count);
+        /**
+         * Need to check array empty, because {@link com.cloud.utils.db.GenericDaoBase#searchAndCount(SearchCriteria, Filter, boolean)}
+         * makes two calls: first to get objects and second to get count.
+         * List events has start date filter, there is highly possible cause where no objects loaded
+         * and next millisecond new event added and finally we ended up with count = 1 and no ids.
+         */
+        if (count == 0 || idArray.length < 1) {
+            count = 0;
         }
 
         List<EventJoinVO> events = _eventJoinDao.searchByIds(idArray);

server/src/main/java/com/cloud/event/dao/EventJoinDaoImpl.java

@@ -131,6 +131,10 @@ public EventResponse newEventResponse(EventJoinVO event) {
 
     @Override
     public List<EventJoinVO> searchByIds(Long... ids) {
+        // return empty collection if there are no ids.
+        if (ids.length == 0) {
+            return List.of();
+        }
         SearchCriteria<EventJoinVO> sc = vrSearch.create();
         sc.setParameters("idIN", ids);
         return searchIncludingRemoved(sc, null, null, false);