[metrics-bugs] #26035 [Metrics/Statistics]: Streamline sample quantile types used in the various modules

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#26035: Streamline sample quantile types used in the various modules
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 Reporter:  karsten             |          Owner:  karsten
     Type:  enhancement         |         Status:  accepted
 Priority:  Medium              |      Milestone:
Component:  Metrics/Statistics  |        Version:
 Severity:  Normal              |     Resolution:
 Keywords:                      |  Actual Points:
Parent ID:                      |         Points:
 Reviewer:                      |        Sponsor:  Sponsor13
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Changes (by karsten):

 * status:  needs_revision => accepted


Comment:

 Alright, I finally worked on a revision of my earlier patch series. I'd
 really like to get these fixes in, so that we're using the same definition
 of percentile everywhere in our code.

 So, I went through all of iwakeh's remarks and suggestions and implemented
 most of them.

 The suggestion that I did ''not'' implement is generalize and share the
 percentile computation code, for several reasons:
  - While I think that sharing code between modules will be useful, I'd
 rather want to approach that top-down rather than bottom-up from this
 rather small method.
  - These two methods are similar, but different. It's certainly possible
 to generalize them, but this has so far delayed this patch for too long.
  - We're talking about 15 to 25 lines of code here, and the hard parts
 happen in the Apache Commons Math library. Things might be different if we
 implemented our own percentile logic, but that's not the case here.

 Instead I went for separating the percentile computation code in both
 modules into their own methods and added unit tests.

 irl, please review [https://gitweb.torproject.org/user/karsten/metrics-
 web.git/log/?h=task-26035-2 my task-26035-2 branch], which contains the
 rebased patches discussed above plus three new commits with unit test
 fixes and implementations of iwakeh's remarks and suggestions.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/26035#comment:19>
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