[tor-bugs] #18203 [Metrics/Metrics website]: Base direct user estimates on responses to directory requests, rather than responses

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#18203: Base direct user estimates on responses to directory requests, rather than
responses
-------------------------------------+---------------------
 Reporter:  karsten                  |          Owner:
     Type:  enhancement              |         Status:  new
 Priority:  Medium                   |      Milestone:
Component:  Metrics/Metrics website  |        Version:
 Severity:  Minor                    |     Resolution:
 Keywords:                           |  Actual Points:
Parent ID:                           |         Points:
 Reviewer:                           |        Sponsor:
-------------------------------------+---------------------
Changes (by karsten):

 * priority:  High => Medium


Comment:

 I made another comparison graph for Q4/2016 until mid-January 2017 with
 all users, users from Turkey, and users from the United States:

 [[Image(direct-clients-2017-01-20.png)]]

 The effect is the same: user number estimates based on responses (new
 approach) are slightly lower than those that are based on requests (old
 approach).  But there is no visible difference for users from Turkey.

 I think the reason is that we're counting a response as soon as we
 consider the request as valid and start sending a response document.
 Quoting from `dir-spec.txt`, where the "responses" line in the graph
 corresponds to the "ok" case below:

 {{{
     "dirreq-v3-resp" status=nul,... NL
         [At most once.]

         List of mappings from response statuses to the number of requests
         for v2/v3 network statuses that were answered with that response
         status, rounded up to the nearest multiple of 4. Only response
         statuses with at least 1 response are reported. New response
         statuses can be added at any time. The current list of response
         statuses is as follows:

         "ok": a network status request is answered; this number
            corresponds to the sum of all requests as reported in
            "dirreq-v2-reqs" or "dirreq-v3-reqs", respectively, before
            rounding up.
         "not-enough-sigs: a version 3 network status is not signed by a
            sufficient number of requested authorities.
         "unavailable": a requested network status object is unavailable.
         "not-found": a requested network status is not found.
         "not-modified": a network status has not been modified since the
            If-Modified-Since time that is included in the request.
         "busy": the directory is busy.
 }}}

 I'm also attaching the
 [https://trac.torproject.org/projects/tor/attachment/ticket/18203/0001
 -tmp-msg-Base-direct-user-estimates-on-resp-not-reqs.patch patch] that I
 used to create this comparison graph.  But I'd say let's not merge it yet,
 because we're in the middle of changing user number estimates.  Let's just
 keep this minor improvement in mind when we do so.

 Changing priority back to medium.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/18203#comment:5>
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