REPORTs on massive agenda is slow

[chibenwa]

curl 'https://twcalendar-preprod.linagora.com/dav/calendars/5f560a8abdaffe0026292cf3/5f560a8abdaffe0026292cf3.json' \
  -X 'REPORT' \
  -H 'Authorization: Bearer xxx' \
  --data-raw '{"match":{"start":"20250929T000000","end":"20251102T000000"}}'

(Michel Maudet agenda)

Takes 2 seconds to complete.

Investigate and makes it faster. Likely sequential MongoDB requests. Or fetching all recurent events.

[chibenwa]

Ok I got that one.

Turns out user have countless recurring event without end date.
When querying REPORT to get event in range we actually query all events with enddate > time range start, and end date of infinite recurring event being infinite all recurring event are included and post filtered. CF ESN\CalDAV\Backend\Mongo method calendarQuery
The issue lies down on the issue that the calendardata projection is ignored and not passed to the post filtering function validateFilterForObject. Instead this method calls $this->getCalendarObject($object['calendarid'], $object['uri']) resulting in numerous sequential reads on top of MongoDB causing the slowness.

How to solve this? Simply rewrite validateFilterForObject so that we pass event payload instead of getting it.

Expectation: massive performance gains on those power user calendars.

[chibenwa]

#137 did bring a 20-25% performance enhancement.

But it is still not performant enough.

I seems we are CPU bound with huge CPU consumption on Sabre which would tend to point to massive event parsing.