BIND 10 #2459: call to getCachedZoneWriter must be protected by mutex

[BIND 10 Development]

#2459: call to getCachedZoneWriter must be protected by mutex
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                   Reporter:         |                 Owner:  jinmei
  jinmei                             |                Status:  reviewing
                       Type:         |             Milestone:
  defect                             |  Sprint-20121120
                   Priority:         |            Resolution:
  medium                             |             Sensitive:  0
                  Component:         |           Sub-Project:  DNS
  b10-auth                           |  Estimated Difficulty:  3
                   Keywords:         |           Total Hours:  0
            Defect Severity:  High   |
Feature Depending on Ticket:         |
        Add Hours to Ticket:  0      |
                  Internal?:  0      |
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Comment (by jinmei):

 Replying to [comment:11 muks]:
 > Good to merge now. If you are ok, please commit the attached patch too.
 Though the location where the lock is acquired in the main thread can
 change in the future (from `AuthSrvImpl::processNormalQuery()`), it still
 is better to document it as it was not immediately obvious to find it,
 starting from the loader lock. If you feel the extra comments are too
 much, then please go ahead and merge as-is.

 Thanks for the suggestion.  I've applied the suggested comment to
 auth_srv.cc.  I've skipped the one for datasrc_clients_mgr.h because
 at least architecturally the clients manager/builder should be
 independent from `AuthSrv`, so mentioning specific details of
 `AuthSrv` in this context seemed a bit awkward.

 With this change I'll merge the branch and close the ticket.

-- 
Ticket URL: <http://bind10.isc.org/ticket/2459#comment:12>
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