import of blaine's mapreducerb

Author: defunkt

README

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+By Blaine Cook.
+
+http://romeda.org/blog/2007/04/mapreduce-in-36-lines-of-ruby.html
+
+If you want to add `dinject` (reduce) please do.
+
+In your shell:
+$ sudo gem install RingyDingy
+$ sudo gem install ruby2ruby
+$ ring_server &
+$ ruby mapreduce_runner &
+$ ruby mapreduce_runner &
+
+In IRB:
+>> require 'mapreduce_enumerable'
+>> (1..100).to_a.dmap { |v| v * 2 }

mapreduce_enumerable.rb

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+require 'rubygems'
+require 'ringy_dingy'
+require 'ruby2ruby'
+
+module Enumerable
+  def dmap(&block)
+    self.each_with_index do |element,idx|
+      ring_server.write([:dmap, Process.pid, block.to_ruby, element, idx])
+    end
+
+    results = []
+    while results.size < self.size
+      result, idx = ring_server.take([:dmap, Process.pid, nil, nil]).last(2)
+      results[idx] = result
+    end
+
+    results
+  end
+
+  def ring_server
+    return @ring_server if @ring_server
+
+    ringy_dingy = RingyDingy.new nil
+    @ring_server = ringy_dingy.ring_server
+  end
+end

mapreduce_runner.rb

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+require 'rubygems'
+require 'ruby2ruby'
+require 'ringy_dingy'
+
+ringy_dingy = RingyDingy.new nil
+ring_server = ringy_dingy.ring_server
+
+loop do
+  pid, block, element, idx = ring_server.take([:dmap, nil, nil, nil, nil]).last(4)
+  begin
+    result = eval(block).call(element)
+  rescue Object => err
+    result = err
+  end
+  puts "Got #{result} from #{element} for #{pid}."
+  ring_server.write([:dmap, pid, result, idx])
+end