BIND 10 #2198: make sure InterprocessSyncLocker is thread safe

[BIND 10 Development]

#2198: make sure InterprocessSyncLocker is thread safe
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                   Reporter:         |                 Owner:  muks
  jinmei                             |                Status:  reviewing
                       Type:         |             Milestone:
  defect                             |  Sprint-20121023
                   Priority:         |            Resolution:
  medium                             |             Sensitive:  0
                  Component:         |           Sub-Project:  Core
  logging                            |  Estimated Difficulty:  5
                   Keywords:         |           Total Hours:  3.85
            Defect Severity:  N/A    |
Feature Depending on Ticket:         |
        Add Hours to Ticket:  0      |
                  Internal?:  0      |
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Changes (by vorner):

 * owner:  vorner => muks
 * totalhours:  3.25 => 3.85


Comment:

 Hello

 First, did you try running it through the build bot? Maybe if there were
 so many problems, it would be worth it.

 Also, the two functions (`InterprocessSyncFile::getSyncMapMutex`,
 `InterprocessSyncFile::getSyncMap`), maybe they could be stand-alone
 functions that live in the anonymous namespace. There is probably no need
 to have them in the header of the class.

 And, the thing with `EDEADLK`, I'm not sure this is the correct behaviour
 ‒ I can't imagine where trying to lock the mutex that is being locked by
 the same thread makes sense in well-designed application. I don't actually
 mind this behaviour much, because the method is probably not going to be
 used outside of unit tests anyway, so I don't care much, but I wanted to
 say that the behaviour of debian might be reasonable approach too.

 Anyway, I don't think I need another review round for the two functions,
 so if you want to change them, go ahead and then after running through the
 build bot, please merge.

 Thank you

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Ticket URL: <http://bind10.isc.org/ticket/2198#comment:26>
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