ustc-course-search-index.timer

[Unit]
Description=Rebuild the USTC iCourse search index when it needs it

[Timer]
# Fires often, but the service runs with --if-needed and exits immediately
# unless there is work: either a segment has aged past --max-age (one hour) or
# the application has asked for a rebuild.
#
# Firing often is what makes a *requested* rebuild land within a couple of
# minutes: an administrator changing a course's teachers asks for one directly,
# because the catalogue has no freshness overlay.
#
# Nothing is rebuilt merely because time passed until it is a day old (see
# MAX_AGE in app/search/builder.py).  Reviews do not need it sooner -- the
# overlay in app/search/delta.py serves everything written since the last build,
# exactly -- and rebuilding them hourly cost ~7% of a core doing nothing useful.
#
# OnCalendar, not OnUnitActiveSec: the latter arms itself relative to the last
# time the service was *active*, and a run skipped by ExecCondition never
# becomes active -- so after the first skip the timer would stop scheduling
# itself entirely and the index would never be rebuilt again.
OnCalendar=*:0/2
AccuracySec=30s
Persistent=true

[Install]
WantedBy=timers.target