BIND 10 #2160: b10-auth should clear Message at the end of request handling

[BIND 10 Development]

#2160: b10-auth should clear Message at the end of request handling
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                   Reporter:         |                 Owner:  UnAssigned
  jinmei                             |                Status:  reviewing
                       Type:         |             Milestone:
  defect                             |  Sprint-20120904
                   Priority:         |            Resolution:
  medium                             |             Sensitive:  0
                  Component:         |           Sub-Project:  DNS
  b10-auth                           |  Estimated Difficulty:  4
                   Keywords:         |           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):

 Replying to [comment:6 jelte]:
 > Ready for review, I did create a separate Holder class for the message,
 and put it at a slightly different location (operator() instead of in
 processMessage() itself), mostly so that the tests can still inspect the
 message is processed correctly.

 - I first thought I'd like to test the case where
   processMessage() throws.  The current test would pass with a more
   straightforward version of cleanup:
 {{{#!cpp
         server_->processMessage(io_message, *message, *buffer, server);
         message->clear(Message::PARSE);
 }}}
   (but this one isn't fully exception safe).  But then I notice most
   of the exceptions are caught in processMessage().  And, if an
   uncaught exception leaks to the operator(), that would kill b10-auth
   anyway, so the cleanup effort will be moot.  At this point I'm not
   sure what to do, but if it's not difficult I'd still test a case
   where processMessage() throws.
 - not really related to this ticket, but with this cleanup we now do
   `Message::clear()` twice, both in the operator() and in
   `SyncUDPServer::handleRead()`.  The latter is effectively waste.
   For a bit longer term, I think we should rather remove the `Message`
   object from the `SyncUDPServer` implementation.
 - Just checking: do we need a changelog entry?  It's a mostly
   invisible internal change, so we probably don't need it, but maybe
   we do.

-- 
Ticket URL: <http://bind10.isc.org/ticket/2160#comment:7>
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