BIND 10 #2310: In-memory version of ZoneFinder::findAtOrigin()

[BIND 10 Development]

#2310: In-memory version of ZoneFinder::findAtOrigin()
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            Reporter:  jinmei        |                        Owner:
                Type:  task          |  jinmei
            Priority:  medium        |                       Status:
           Component:  data source   |  accepted
            Keywords:                |                    Milestone:
           Sensitive:  0             |  Sprint-20130205
         Sub-Project:  DNS           |                   Resolution:
Estimated Difficulty:  5             |                 CVSS Scoring:
         Total Hours:  0             |              Defect Severity:  N/A
                                     |  Feature Depending on Ticket:
                                     |          Add Hours to Ticket:  0
                                     |                    Internal?:  0
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Comment (by jinmei):

 trac2310 is ready for review.

 It's basically a straightforward implementation of the ticket
 description, but several related classes had to be updated.
 As such, the branch consists of a set up changes, each corresponds
 to make part of the goal.

 - first commit (555bf4c) is an independent refactoring for
   preparation.  maybe it's better to review this separately.
 - changes up to 9dbce1a are initial half of in-memory version of
   `findAtOrigin`.  this should be quite straightforward.
 - the rest is updates to various related classes to support
   "use_minttl".  in general, each commit corresponds to updates to one
   related class, and later commits depend on their ancestors.  if it's
   not deemed to be too complicated, I'd suggest reviewing these
   changes at once; otherwise, they can be reviewed commit by commit.

 I don't plan to provide a changelog entry for this task.  This is
 basically an internal refactoring, and according to benchmark,
 performance improvement was not that substantial compared to
 the beta version.

-- 
Ticket URL: <http://bind10.isc.org/ticket/2310#comment:8>
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