#!/usr/bin/env ruby

require 'fiber'
require 'benchmark'

DEBUG=false

class FiberRing
  attr_reader :id
  def initialize(id)
    @id = id
    DEBUG and puts "Creating ring #{@id}"
    @fiber = Fiber.new do
      pass_msg
    end
  end

  def |(nxt)
    DEBUG and puts "attaching #{@id} to #{nxt.id}"
    @next = nxt
    nxt
  end

  def resume
    @fiber.resume
  end

  def pass_msg
    DEBUG and puts "#{@id} pass_msg called"
    while msg = msg_in
      DEBUG and puts "#{@id} received \"#{msg}\""
      msg_out msg
    end
  end
  
  def msg_in
    DEBUG and puts "#{@id} msg_in called"
    unless @next.nil?
      DEBUG and puts "#{@id} resuming #{@next.id}"
      @next.resume
      DEBUG and puts "#{@id} returned from #{@next.id}.resume"
    end
    DEBUG and puts "#{@id} msg_in returning \"#{@id} message\""
    "#{@id} message"
  end
  
  def msg_out msg
    DEBUG and puts "#{@id} msg_out called"
    DEBUG and puts "#{@id} calling Fiber.yield(#{msg})"
    Fiber.yield msg
  end
end


n=ARGV[0].to_i
m=ARGV[1].to_i
tm = Benchmark.measure do

  #build chain
  f0 = f = FiberRing.new(0)
  1.upto(n-1) { |i| f = f | FiberRing.new(i) }
  
  #run chain m times
  m.times { |j| DEBUG and puts "--- #{j} ---"; f0.resume }

end

puts "#{n}, #{m}, #{tm}"