BIND 10 #537: Make asiolink::UDPServer smaller to copy

[BIND 10 Development]

#537: Make asiolink::UDPServer smaller to copy
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                 Reporter:  vorner   |                Owner:  jinmei
                     Type:  task     |               Status:  reviewing
                 Priority:  major    |            Milestone:  A-Team-
                Component:           |  Sprint-20110209
  Unclassified                       |           Resolution:
                 Keywords:           |            Sensitive:  0
Estimated Number of Hours:  6.0      |  Add Hours to Ticket:  0
                Billable?:  1        |          Total Hours:  0
                Internal?:  0        |
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Comment (by vorner):

 Oh, and it probably should have a changelog entry. What about this?

 {{{
 [refactor]
 The pimpl design pattern is used in IOServer, with a shared pointer. This
 makes it smaller to copy (which is done a lot as a sideeffect of being
 coroutine) and speeds the server up by around 10%.
 }}}

 (I asked on the jabber room and we agreed this is not a feature nor a bug,
 and the refactor category was suggested.)

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Ticket URL: <https://bind10.isc.org/ticket/537#comment:8>
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