[metrics-bugs] #23367 [Metrics/Metrics website]: Onion address counts ignore descriptor upload overlap

[Tor Bug Tracker & Wiki]

#23367: Onion address counts ignore descriptor upload overlap
-----------------------------------------+--------------------------
     Reporter:  teor                     |      Owner:  metrics-team
         Type:  defect                   |     Status:  new
     Priority:  Medium                   |  Milestone:
    Component:  Metrics/Metrics website  |    Version:
     Severity:  Normal                   |   Keywords:
Actual Points:                           |  Parent ID:
       Points:                           |   Reviewer:
      Sponsor:                           |
-----------------------------------------+--------------------------
 Based on this tor metrics paper:
 https://research.torproject.org/techreports/extrapolating-hidserv-
 stats-2015-01-31.pdf

 We ignore descriptor upload overlap periods (they're not even mentioned in
 the paper).

 During an overlap period, descriptors are published to twice as many
 HSDirs (v2 & v3). If we ignore this, we will double-count:
 * v2: uploads and unique onion addresses and descriptor ids for 1 hour per
 day,
 * v3: uploads and unique descriptor ids for 12 hours per day.

 I'm not sure if assuming that descriptors are seen by 2 sets of HSDirs per
 day covers this, because in v2 they are actually seen by 3 sets of HSDirs
 with probability 1/24, when the service address starts with 00-0B
 (assuming stats are collected from 00:00 UTC and relay clocks are
 accurate).

 And in v3, for half the day (00:00 + typical client consensus download
 delay of 1-2 hours) they are seen by 2 HSDirs, and half the day they are
 seen by 1 HSDir. Not that we measure v3 yet.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/23367>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online