[tor-bugs] #12505 [BridgeDB]: Refactor Bridges.py and Dist.py in BridgeDB

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#12505: Refactor Bridges.py and Dist.py in BridgeDB
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 Reporter:  isis                           |          Owner:  isis
     Type:  defect                         |         Status:  new
 Priority:  major                          |      Milestone:
Component:  BridgeDB                       |        Version:
 Keywords:  bridgedb-dist, bridgedb-1.0.x  |  Actual Points:
Parent ID:                                 |         Points:
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 I have slowly been refactoring all of BridgeDB. Code which has been
 already refactored is named with "proper" (according to PEP8) lower-cased
 module names in `lib/bridgedb` in the BridgeDB repository.

 Some of the largest, least-unitested, (and most difficult to refactor)
 sections of BridgeDB's code are the `Bridges.py` module and the `Dist.py`
 module. The biggest problems are:

  1. The code for the various types of hashrings in `bridgedb.Bridges` is a
 complete mess. In some places, hashrings are referred to as
 `BridgeHolders`, in other places as `Buckets` (though not to be confused
 with the `Bucket.py` module, and in other places as "hashrings".
 Subclassing is haphazard and confusing to say the least. In addition, the
 hashrings are not algorithmically as efficient as they could be.
 Throughout the hashring code were old-style classes, unused methods, half-
 implemented methods, and unnecessary parameters. All of this code needs
 some serious help.

  2. The Distributors in `bridgedb.Dist` inherit, for some unknown reason,
 from the improperly implemented "base class"
 `bridgedb.Bridges.BridgeHolder`. One, this isn't how one implements a
 proper Python base class (by deriving from a class with `__metaclass__ =
 abc.ABCMeta`). Two, why a `Distributor` should be a subclass of a the
 "base" hashring class is unclear and unnecessary, and we should move away
 from that. A `Distributor` is something which distributes bridges to
 users, not some weird half-thought-out hashring subclass.

  3. The various Distributors in `bridgedb.Dist` should be different
 modules.

  4. Almost none of the code in `Bridges.py` and `Dist.py` is unittested.
 These modules have the highest number of untested lines of code currently
 in BridgeDB.

 After this is finished, I am mostly willing to tag `BridgeDB-1.0.0`. There
 may be a few other refactoring that should get finished before then, but
 this is the main piece remaining to be completed.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/12505>
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