BIND 10 #168: separate ASIO from Boost and remove custom code

[BIND 10 Development]

#168: separate ASIO from Boost and remove custom code
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 Reporter:  larissas      |        Owner:  each                       
     Type:  task          |       Status:  reviewing                  
 Priority:  major         |    Milestone:  04. 2nd Incremental Release
Component:  Unclassified  |   Resolution:                             
 Keywords:                |    Sensitive:  0                          
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Comment(by jinmei):

 Replying to [comment:11 jinmei]:
 > hmm, the ASIO branch doesn't even compile without --with-boost-includes:

 Okay, I figured it out.  That's because there are some functions that hit
 the "unused-parameter" warning in header files of the non boost version of
 ASIO.  I suspect we were free from this in the boost version because we
 used a separate object library where the source code that would hit the
 warning is hidden.

 The whole purpose of the migration to the non boost ASIO is to avoid
 dependency on external object libraries, so we need to deal with it
 anyway.

 I found a workaround in the epoll version of the refactor file:

 {{{
   void cancel_ops(socket_type descriptor UNUSED_PARAM,
 per_descriptor_data& descriptor_data)
   {
 }}}

 that is, {{{UNUSED_PARAM}}} is specified.  I guess Evan explicitly added
 this to the original source code.  Doing this every time we hit this
 problem is one option, but I don't think it a good idea; however, I don't
 like to compromise the warning level due to a problem of an external
 source either.

 I've not come up with a satisfactory solution, but I'm attaching a patch
 that I think is least evil: it introduces a small wrapper module
 (asio_link) as a separate internal "library" (only used for b10-auth), and
 exclude unused-parameter from the erroneous warnings only for that
 library.

 This is a bit tricky and ugly, but this way we can limit the compromise to
 the code directly related to ASIO.  Also, whether or not we have this
 problem, or whether or not we solve this as a separate library, I think we
 should eventually separating this part from main.cc anyway, for making
 tests easier and making the code more modular.

 Also note that the use of pimpl is crucial in this case.  We cannot
 include asio.h in asio_link.h, because other part of b10-auth needs to
 include asio_link.h, and it would subsequently include asio.h and we'd
 encouter the same problem.  (admittedly this can be solved without pimpl.
 but the main point is that it's generally preferable to avoid including
 external header files directly from our own header files)

-- 
Ticket URL: <https://bind10.isc.org/ticket/168#comment:12>
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