Dining Philosophers solution using Celluloid

dining_philosophers.rb

#!/usr/bin/env ruby

require 'rubygems'
require 'bundler/setup'
require 'celluloid'

class Table
  include Celluloid
  CHOPSTICK_FREE = 0
  CHOPSTICK_USED = 1
  attr_reader :philosophers
  attr_reader :chopsticks
  attr_reader :eating

  def initialize(chopsticks)
    @philosophers = []
    @eating = []
    @chopsticks = Array.new(chopsticks, CHOPSTICK_FREE)
  end

  def welcome(philosopher)
    @philosophers << philosopher
    philosopher.async.think
  end

  def hungry(philosopher)
    pos = @philosophers.index(philosopher)
    abort RuntimeError.new('A philosopher is not even sat down') if pos.nil?

    left_pos = pos
    right_pos = (pos + 1) % @chopsticks.size
    if [@chopsticks[left_pos], @chopsticks[right_pos]].all? {|status| status == CHOPSTICK_FREE}
      @chopsticks[left_pos] = CHOPSTICK_USED
      @chopsticks[right_pos] = CHOPSTICK_USED
      @eating << philosopher
      print_table_status(pos)
      philosopher.async.eat

      abort RuntimeError.new('TOO MANY PHILOSOPHER ARE EATING') if @eating.size == @chopsticks.size
      puts "TABLE: #{@eating.size} are eating"
    else
      # it's not your turn, keep thinking
      print_table_status(pos)
      philosopher.async.think
    end
  end

  def drop_chopsticks(philosopher)
    pos = @philosophers.index(philosopher)
    abort RuntimeError.new('A philosopher is not even sat down') if pos.nil?

    left_pos = pos
    right_pos = (pos + 1) % @chopsticks.size
    if ! [@chopsticks[left_pos], @chopsticks[right_pos]].all? {|status| status == CHOPSTICK_USED}
      abort RuntimeError.new('A philosopher without both chopsticks thinks he had eaten')
    end

    @chopsticks[left_pos] = CHOPSTICK_FREE
    @chopsticks[right_pos] = CHOPSTICK_FREE
    @eating -= [philosopher]
    print_table_status(pos)
    philosopher.async.think
  end

  def print_table_status(pos)
    puts "TABLE: EATING: #{eating.map {|p| philosophers.index(p)}}; CHOPSTICKS #{chopsticks}; MY POS: #{pos}"
  end
end

class Philosopher
  include Celluloid
  attr_reader :name
  attr_reader :table

  def initialize(name, table)
    @name = name
    @table = table
    table.async.welcome(Actor.current)
  end

  def think
    puts "#{name} is thinking"
    sleep(rand)
    puts "#{name} gets hungry"
    table.async.hungry(Actor.current)
  end

  def eat
    puts "#{name} is eating"
    sleep(rand)
    puts "#{name} burps"
    table.async.drop_chopsticks(Actor.current)
  end
end

#
# Run the simulation
#

names = %w{Heraclitus Aristotle Epictetus Schopenhauer Popper}
table = Table.new(names.size)
philosophers = names.map {|name| Philosopher.new(name, table)}

# The main thread is done! Sleep forever
sleep