[tor-bugs] #21425 [Core Tor/Tor]: entry_list_is_constrained() should look at the guard_selection_t object

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#21425: entry_list_is_constrained() should look at the guard_selection_t object
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 Reporter:  nickm                                |          Owner:  (none)
     Type:  defect                               |         Status:
                                                 |  needs_revision
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  0.3.3.x-final
Component:  Core Tor/Tor                         |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  guards, 031-deferred-20170425,       |  Actual Points:
  review-group-18                                |
Parent ID:  #20822                               |         Points:  .5
 Reviewer:  asn                                  |        Sponsor:
                                                 |  SponsorV-can
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Comment (by teor):

 Replying to [comment:14 neel]:
 > Sorry for the delay, but I decided to come back to the patch and start
 over from scratch.
 >
 > I have two questions:
 >
 > 1. Is checking the capacity of {{{sampled_entry_guards}}} from the
 {{{guard_selection_t}}} object okay for this patch?

 Checking the current size of sampled entry guards is ok.
 (The capacity of a smartlist is the size it can grow to without allocating
 additional memory.)

 > 2. If #1 is okay, which capacity size should {{{sampled_entry_guards}}}
 be to return 1? Right now, I am guessing 3 guards. Should it be more?
 Less?

 If we want to consider Tor Browser bridge users constrained, the answer is
 around 10 or 20.
 If not, the answer is around 3.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/21425#comment:15>
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