Commits on Oct 26, 2017

1. Rewrite old attribute mapping to save many object allocations …

   Stringifying the keys of a hash can be done without allocating many
   arrays like the previous approach did.
   
   ```ruby
   begin
     require "bundler/inline"
   rescue LoadError => e
     $stderr.puts "Bundler version 1.10 or later is required. Please update
                   your Bundler"
     raise e
   end
   
   gemfile(true) do
     source "https://rubygems.org"
   
     gem "benchmark-ips"
   end
   
   def allocate_count
     GC.disable
     before = ObjectSpace.count_objects
     yield
     after = ObjectSpace.count_objects
     after.each { |k,v| after[k] = v - before[k] }
     after[:T_HASH] -= 1 # probe effect - we created the before hash.
     GC.enable
     result = after.reject { |k,v| v == 0 }
     GC.start
     result
   end
   
   @old = {a: :b, c: :d, e: :f}
   
   def master_version
     Hash[@old.map { |k, v| [k.to_s, v] }]
   end
   
   def fast_version
     result = {}
     @old.each { |k, v| result[k.to_s] = v }
   end
   
   puts "master_version"
   puts allocate_count { 1000.times { master_version } }
   puts "fast_version"
   puts allocate_count { 1000.times { fast_version } }
   
   Benchmark.ips do |x|
     x.report("master_version") { master_version }
     x.report("fast_version")     { fast_version }
     x.compare!
   end
   ```
   
   ```ruby
   master_version
   {:FREE=>-14768, :T_STRING=>6054, :T_ARRAY=>7000, :T_HASH=>1000, :T_IMEMO=>1000}
   fast_version
   {:FREE=>-7001, :T_STRING=>6000, :T_HASH=>1000}
   Warming up --------------------------------------
         master_version    38.137k i/100ms
           fast_version    50.133k i/100ms
   Calculating -------------------------------------
         master_version    451.898k (±19.2%) i/s -      2.174M in   5.002186s
           fast_version    633.579k (±19.4%) i/s -      3.058M in   5.019391s
   
   Comparison:
           fast_version:   633578.7 i/s
         master_version:   451897.6 i/s - same-ish: difference falls within error
   ```

   

   dillonwelch committed Oct 26, 2017
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   1043a6d View commit details

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2. CHANGELOG.md note

   

   dillonwelch committed Oct 26, 2017
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   3bba452 View commit details

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