BIND 10 #2212: support "load zone" command in the configurator thread

[BIND 10 Development]

#2212: support "load zone" command in the configurator thread
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                   Reporter:         |                 Owner:  jinmei
  jinmei                             |                Status:  accepted
                       Type:  task   |             Milestone:
                   Priority:         |  Sprint-20121106
  medium                             |            Resolution:
                  Component:         |             Sensitive:  0
  b10-auth                           |           Sub-Project:  DNS
                   Keywords:         |  Estimated Difficulty:  5
            Defect Severity:  N/A    |           Total Hours:  0
Feature Depending on Ticket:         |
  background zone loading            |
        Add Hours to Ticket:  0      |
                  Internal?:  0      |
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Comment (by jinmei):

 This task is ready for review at the trac2212-2 branch (note: not
 "trac2212", which has also been pushed).

 I first merged a snapshot of trac2209 (03499b1), which should be
 ignored.

 The main changes (in datasrc_clients_mgr.h) should be pretty
 straightforward.  For tests, I mainly ported current tests using
 the old interface in command_unittest.  Porting them is mostly
 straightforward, but see commit logs starting with "ported command
 test".

 There's one thing I may have to update when trac2209 is merged:
 {{{#!cpp
     case datasrc::ConfigurableClientList::ZONE_RELOADED: // XXX misleading
 name
         assert(writerpair.second);
         return (writerpair.second);
 }}}
 IMO this result code is misleading, and I pointed it out in my review
 for trac2209.  If we agree on changing this, we'll need to update this
 code too.  But this should be a trivial adjustment and I believe can
 be done on merge of this branch.

-- 
Ticket URL: <http://bind10.isc.org/ticket/2212#comment:8>
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