server.rb

require 'bundler/setup'
Bundler.require


# Gem versions:

# celluloid (0.15.1)
# celluloid-io (0.15.0)
# nio4r (0.5.0)
# timers (1.1.0)

class Server
  attr_reader :users
  include Celluloid::IO
  include Celluloid::Logger

  finalizer :shutdown

  trap_exit :actor_died

  def initialize
    @users = []

    @server = TCPServer.new '0.0.0.0', 1024
    @server.listen 10

    async.start
  end

  def start
    info "listening on port 1024"
    loop { handle_connection @server.accept }
  end

  def handle_connection socket
    user = User.new_link socket
    users.push user
  end

  def actor_died(actor, reason)
    p "#{actor.inspect} has died because of a #{reason.class}"
  end

  def shutdown
    @server.close
  end
end


class User
  class CrashyError < StandardError; end

  attr_reader :socket

  include Celluloid::IO
  include Celluloid::Logger

  finalizer :close_connection!

  def initialize socket
    @socket = socket

    info "New user connected"

    async.start
  end

  def start
    info "Starting main loop"

    # command = readline.other_method_that_does_not_exist

    loop do
      command = socket.gets.strip
      info "Received command #{command}"
      case command
        when "crash"
          raise CrashyError
        when "exit"
          terminate
        else
          # echo
          socket.puts command
        end
    end
  end

  def server
    Actor[:server]
  end

  def close_connection!
    info "Closing connection"
    socket.close
    server.users.delete current_actor
    info "Removed user from user list"
  end

end


class SupervisionGroup < Celluloid::SupervisionGroup
  supervise Server, as: :server
end

SupervisionGroup.run