BIND 10 #404: serialize RDATA for in memory data source

[BIND 10 Development]

#404: serialize RDATA for in memory data source
------------------------------+---------------------------------------------
      Reporter:  jinmei       |        Owner:  UnAssigned           
          Type:  task         |       Status:  reviewing            
      Priority:  major        |    Milestone:  y2 12 month milestone
     Component:  data source  |   Resolution:                       
      Keywords:               |    Sensitive:  0                    
Estimatedhours:  0.0          |        Hours:  0                    
      Billable:  1            |   Totalhours:  0                    
      Internal:  0            |  
------------------------------+---------------------------------------------

Comment(by jinmei):

 Additional pre-review comment:

 I've added a benchmark test to measure rendering performance of basic
 Rdata and !RdataFields.

 Surprisingly to me, !RdataFields was much slower than Rdata.  I first
 thought it was due to the inefficient logic for rendering name fields, but
 it was also the case for test data that only contained A and AAAA RDATA.
 I've pasted some results at the end of this note.

 Chasing it a little deeper, I've found that if I omit the "else" part of
 !RdataFields::toWire() the !RdataFields version ran much faster (of
 course, for data that doesn't contain names).

 {{{
         } else {
             InputBuffer buffer(data_ + offset, fields_[i].len);
             renderer.writeName(Name(buffer),
                                fields_[i].type == COMPRESSIBLE_NAME ?
                                true : false);
         }
 }}}

 So, compiling this part made it much slower even if it was not used run
 time.  Maybe this is related to the code size and whether it fits in a
 cache.

 Anyway, rendering performance is not the primary target of this work, so I
 think it's okay for now.  We should revisit this issue when we are in
 performance improvement phase.

 Test results (g++)
 {{{
   Input File: benchmarkdata/rdatarender_data_com
 Benchmark for rendering with standard Rdata
 Performed 280000 iterations in 0.099544s (2812826.49ips)
 Benchmark for rendering with RdataFields
 Performed 280000 iterations in 0.403323s (694232.66ips)

   Input File: benchmarkdata/rdatarender_data_org
 Benchmark for rendering with standard Rdata
 Performed 180000 iterations in 0.073044s (2464268.11ips)
 Benchmark for rendering with RdataFields
 Performed 180000 iterations in 0.213702s (842294.41ips)

   Input File: benchmarkdata/rdatarender_data_nxdomain
 Benchmark for rendering with standard Rdata
 Performed 60000 iterations in 0.046006s (1304177.72ips)
 Benchmark for rendering with RdataFields
 Performed 60000 iterations in 0.127334s (471201.72ips)
 }}}

 Test results (clang++)
 {{{
   Input File: benchmarkdata/rdatarender_data_com
 Benchmark for rendering with standard Rdata
 Performed 280000 iterations in 0.090705s (3086930.16ips)
 Benchmark for rendering with RdataFields
 Performed 280000 iterations in 0.406702s (688464.77ips)

   Input File: benchmarkdata/rdatarender_data_org
 Benchmark for rendering with standard Rdata
 Performed 180000 iterations in 0.063396s (2839295.85ips)
 Benchmark for rendering with RdataFields
 Performed 180000 iterations in 0.201228s (894507.72ips)

   Input File: benchmarkdata/rdatarender_data_nxdomain
 Benchmark for rendering with standard Rdata
 Performed 60000 iterations in 0.044533s (1347315.47ips)
 Benchmark for rendering with RdataFields
 Performed 60000 iterations in 0.135239s (443659.00ips)
 }}}

-- 
Ticket URL: <http://bind10.isc.org/ticket/404#comment:2>
BIND 10 Development <http://bind10.isc.org>
BIND 10 Development