[tor-bugs] #19836 [Metrics/CollecTor]: Prepare relay descriptor downloader for consensuses published at :30 of the hour

[Tor Bug Tracker & Wiki]

#19836: Prepare relay descriptor downloader for consensuses published at :30 of the
hour
-------------------------------+---------------------
 Reporter:  karsten            |          Owner:
     Type:  defect             |         Status:  new
 Priority:  Low                |      Milestone:
Component:  Metrics/CollecTor  |        Version:
 Severity:  Normal             |     Resolution:
 Keywords:                     |  Actual Points:
Parent ID:                     |         Points:
 Reviewer:                     |        Sponsor:
-------------------------------+---------------------

Comment (by karsten):

 Replying to [comment:1 iwakeh]:
 > Replying to [ticket:19836 karsten]:
 > > Consensuses have always been published once per hour, so with valid-
 after time :00 in the past.  This might change in the future, as has been
 discussed in the context of consensus diffs, but which might also happen
 independent of those.
 > >
 > > However, CollecTor is not ready for such a change, because
 `currentValidAfter` in `RelayDescriptorDownloader` is always initialized
 with :00 of the hour.  This would prevent us from accepting a consensus
 published at :30.  Of course, when we make such a change we should also
 accept other valid-after times that :00 and :30.
 >
 > Is :30 just an example or will there always be a set of valid values
 like for example {30,00,25}?

 Quoting from dir-spec.txt:

 {{{
    Authorities divide time into Intervals.  Authority administrators
 SHOULD
    try to all pick the same interval length, and SHOULD pick intervals
 that
    are commonly used divisions of time (e.g., 5 minutes, 15 minutes, 30
    minutes, 60 minutes, 90 minutes).  Voting intervals SHOULD be chosen to
    divide evenly into a 24-hour day.
 }}}

 > > Testing a fix might require setting up a testing network using Chutney
 and archiving network data produced by that.  That is, we could also
 create a testing environment and write unit tests for this, which we
 should do anyway.  But that shouldn't block us here, unless the fix is
 more complex than I currently anticipate.
 >
 > I think, the testing should be doable by (j)unit tests.
 > The (system) test environment using Chutney or similar might be useful
 in general, but should not be necessary here.

 Okay.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/19836#comment:2>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online