BIND 10 #1599: introduce "asiodns::UDPSyncServer"

[BIND 10 Development]

#1599: introduce "asiodns::UDPSyncServer"
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                   Reporter:         |                 Owner:  vorner
  jinmei                             |                Status:  reviewing
                       Type:  task   |             Milestone:
                   Priority:  major  |  Sprint-20120306
                  Component:         |            Resolution:
  Unclassified                       |             Sensitive:  0
                   Keywords:         |           Sub-Project:  DNS
            Defect Severity:  N/A    |  Estimated Difficulty:  7
Feature Depending on Ticket:  auth   |           Total Hours:  0
  performance                        |
        Add Hours to Ticket:  0      |
                  Internal?:  0      |
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Changes (by kevin_tes):

 * owner:  kevin_tes => vorner


Comment:

 Replying to [comment:10 vorner]:
 > Hello
 >
 > Replying to [comment:8 kevin_tes]:
 > > A litter things I take here.
 > > {{{
 > >     if (ec) {
 > >         using namespace asio::error;
 > >         if (ec.value() != would_block && ec.value() != try_again &&
 > >             ec.value() != interrupted) {
 > >             return;
 > >         }
 > >             // Some kind of interrupt, spurious wakeup, or like that.
 Just try reading
 > >             // again.
 > >             if (0 == length) {
 > >             scheduleRead();
 > >             return;
 > >             }
 > >     }
 > > }}}
 > > Instead of this one,may be better for performance consider.
 >
 > But your version is different ‒ if the error did not happen (eg. `ec` is
 false), but no data was read (`length` is zero), your version tries to
 process it, while mine does not. I'm not sure if this ever happens (maybe
 it could, on a spurious wakeup), but it is copied from the udp_server this
 way, so I expect there was a reason for this.
 >
 > And the performance difference should be non-measurably small (if any at
 all, compiler should be able to optimise the check of ec out if it would
 be faster that way) anyway.
 >
 > Do you agree on keeping it this way?
 Yeah, i see that, i agree with it.
 >
 > > May be the comments for this method should be changed in order to
 explain why it throws here.
 >
 > OK, explanation was added.
 >
 > Thank you

 All is ok to me, please merge it.

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Ticket URL: <http://bind10.isc.org/ticket/1599#comment:11>
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