bench/shootout/chameneos.ruby-2.ruby

   1 #########################################
   2 #     The Computer Language Shootout    #
   3 #   http://shootout.alioth.debian.org/  #
   4 #                                       #
   5 #      Contributed by Jesse Millikan    #
   6 #    Based on version by Gordon Innes   #
   7 #########################################
   8
   9 require 'thread'
  10
  11 creature_meetings = Queue.new
  12 meeting_point = Mutex.new
  13 wait_signal = ConditionVariable.new
  14 meetings_left = ARGV[0].to_i
  15 waiting_colour, incoming_colour = nil, nil
  16
  17 # Each chameneo is represented here by a thread
  18 # and its colour variable, rather than explicitly
  19 # by an object
  20 #
  21 # This is all packed into one place for speed and
  22 # clarity (It's clear to *me* :)
  23 [:blue, :red, :yellow, :blue].each { |colour|
  24   Thread.new {
  25     met = 0
  26     while true
  27       # The form meeting_point.synchronize { } is slow
  28       meeting_point.lock
  29
  30       if meetings_left <= 0
  31         meeting_point.unlock
  32         # colour = :faded
  33         break
  34       end
  35
  36       # Both threads emerge with variable other_colour set
  37       if waiting_colour
  38         other_colour = waiting_colour
  39         incoming_colour = colour
  40         wait_signal.signal
  41         meetings_left-=1
  42         waiting_colour = nil
  43       else
  44         waiting_colour = colour
  45         wait_signal.wait(meeting_point)
  46         other_colour = incoming_colour
  47       end
  48       meeting_point.unlock
  49
  50       met += 1
  51
  52       # Take the complement colour
  53       colour =
  54         case other_colour
  55           when :blue
  56            colour == :red ? :yellow : :red
  57           when :red
  58            colour == :blue ? :yellow : :blue
  59           when :yellow
  60            colour == :blue ? :red : :blue
  61         end
  62     end
  63
  64     # Leave the total on the queue for the main thread
  65     creature_meetings.push(met)
  66   }
  67 }
  68
  69 total = 0
  70 4.times { total += creature_meetings.pop }
  71 puts total