In order to be able to tell when a thumbnail has been prerendered and is only being pulled from swift to varnish, we need to track this extra response header. Age and Date, which are also needed, are already logged.
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Status | Subtype | Assigned | Task | ||
---|---|---|---|---|---|
Resolved | • Gilles | T78767 Add Last-Modified to performance logging | |||
Resolved | • Gilles | T84852 Update network performance schema queries |
Event Timeline
Actually, as @Tgr pointed out, Varnish's X-Timestamp is the same as Last-Modified, and we're already logging that. Assuming that the clocks of varnish servers and eventlogging http (sql?) servers are in sync, "Date" should be the same as the "timestamp" column of the EL table. I'll run some SQL queries to see if that all holds true.
Actually timestamp != Date for one very obvious reason: the EL event will only be recorded after the image load, and will depend on latency. So we do need to log "Date". We don't really need Last-Modified since it should be identical to X-Timestamp, but I'll add it just in case.
Ah, it turns out that the "timestamp" column IS the Date header. So we only need Last-Modified.
Change 180433 had a related patch set uploaded (by Gilles):
Log Last-Modified header in performance logger
I think timestamp is added by Varnish when it receives the EL request, so it would equal the Date header of the EL request, not the Date header of the thumbnail request that's being logged?
Last-Modified is a simple response header so there should not be any CORS issues with this.
Change 180742 had a related patch set uploaded (by Gilles):
Log Last-Modified header in performance logger
Change 180743 had a related patch set uploaded (by Gilles):
Backport Last-Modified performance logging for Media Viewer
Change 180743 merged by jenkins-bot:
Backport Last-Modified performance logging for Media Viewer