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|
#########################################
# The Computer Language Shootout #
# http://shootout.alioth.debian.org/ #
# #
# Contributed by Jesse Millikan #
# Based on version by Gordon Innes #
#########################################
require 'thread'
creature_meetings = Queue.new
meeting_point = Mutex.new
wait_signal = ConditionVariable.new
meetings_left = ARGV[0].to_i
waiting_colour, incoming_colour = nil, nil
# Each chameneo is represented here by a thread
# and its colour variable, rather than explicitly
# by an object
#
# This is all packed into one place for speed and
# clarity (It's clear to *me* :)
[:blue, :red, :yellow, :blue].each { |colour|
Thread.new {
met = 0
while true
# The form meeting_point.synchronize { } is slow
meeting_point.lock
if meetings_left <= 0
meeting_point.unlock
# colour = :faded
break
end
# Both threads emerge with variable other_colour set
if waiting_colour
other_colour = waiting_colour
incoming_colour = colour
wait_signal.signal
meetings_left-=1
waiting_colour = nil
else
waiting_colour = colour
wait_signal.wait(meeting_point)
other_colour = incoming_colour
end
meeting_point.unlock
met += 1
# Take the complement colour
colour =
case other_colour
when :blue
colour == :red ? :yellow : :red
when :red
colour == :blue ? :yellow : :blue
when :yellow
colour == :blue ? :red : :blue
end
end
# Leave the total on the queue for the main thread
creature_meetings.push(met)
}
}
total = 0
4.times { total += creature_meetings.pop }
puts total
|
