[tor-bugs] #16529 [Tor]: stable flag calculation

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#16529: stable flag calculation
-----------------------------+-------------------------------
     Reporter:  cypherpunks  |      Owner:
         Type:  defect       |     Status:  needs_information
     Priority:  minor        |  Milestone:  Tor: 0.2.???
    Component:  Tor          |    Version:
   Resolution:               |   Keywords:
Actual Points:               |  Parent ID:
       Points:               |    Sponsor:
-----------------------------+-------------------------------
Changes (by teor):

 * status:  new => needs_information
 * milestone:   => Tor: 0.2.???


Comment:

 From torspec/dir-spec.txt:

    "Stable" -- A router is 'Stable' if it is active, and either its
 Weighted
    MTBF is at least the median for known active routers or its Weighted
 MTBF
    corresponds to at least 7 days. Routers are never called Stable if they
 are
    running a version of Tor known to drop circuits stupidly.
 (0.1.1.10-alpha
    through 0.1.1.16-rc are stupid this way.)

         To calculate weighted MTBF, compute the weighted mean of the
 lengths
         of all intervals when the router was observed to be up, weighting
         intervals by $\alpha^n$, where $n$ is the amount of time that has
         passed since the interval ended, and $\alpha$ is chosen so that
         measurements over approximately one month old no longer influence
 the
         weighted MTBF much.

 As far as I understand, the stable flag is awarded after 7 days or 'more
 stable than the median', whichever is less. Tor's definition of median is
 the low-median, and it uses the MTBF, so the actual threshold would be
 2023456 seconds.

 Given this definition, is getting the stable flag after 5 days still an
 issue?

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/16529#comment:2>
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