[tor-bugs] #20535 [Core Tor/Tor]: A 304 "Not Modified" should update the time to when we next expect a modification

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#20535: A 304 "Not Modified" should update the time to when we next expect a
modification
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 Reporter:  teor          |          Owner:
     Type:  defect        |         Status:  new
 Priority:  Medium        |      Milestone:  Tor: 0.3.0.x-final
Component:  Core Tor/Tor  |        Version:
 Severity:  Normal        |     Resolution:
 Keywords:  regression    |  Actual Points:
Parent ID:  #20499        |         Points:  0.5
 Reviewer:                |        Sponsor:
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Comment (by teor):

 Replying to [comment:3 teor]:
 > After downloading the consensus:
 > * download_status_increment_failure doesn't increase the schedule on 503
 (server unavailable), even though it probably should, rather than retrying
 immediately

 Part of my code review in #20499.

 > * download_status_schedule_get_delay uses the schedule to increase the
 backoff, if the schedule isn't increased, the backoff isn't either (rather
 than using the actual hard-coded Bootstrap schedules)

 Part of my code review in #20499.

 Replying to [comment:4 teor]:
 > We took schedules carefully tuned in 0.2.8 to make sure that it could
 survive 7 relay failures and still bootstrap in 30 seconds with 99.9%
 reliability, and implemented exponential backoff in 0.2.9 in a way that
 causes retries 5 times in 10 seconds in some cases, and in other cases
 retries twice in the first 30 seconds.

 I'm going to suggest some schedule tweaks in #20534.

 I can't see anything else in this bug that we would ever fix. Perhaps
 someone else can work out how to deal with 304s sensibly.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/20535#comment:6>
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