Celluloid application from https://speakerdeck.com/therealadam/big-ruby-conf-bonus-tracks

celluloid_tcpserver.rb

require 'redis'
require 'json'
require 'celluloid'
require 'celluloid/io'

class RedisAdapter
  include Celluloid

  def initialize(redis)
    @redis = redis
  end

  def record(path)
    redis.incr("stats:#{path}")
  end

  def fetch(path)
    redis.get("stats:#{path}")
  end

  protected

  attr_reader :redis
end

class Stats
  include Celluloid

  def handle(msg)
    log(msg)

    case msg
    when %r{^VISIT (.*)$}
      path = $1
      puts path
      redis.async.record(path)
      "OK\n"
    when %r{^STATS (.*)$}
      path = $1
      puts path
      stats = redis.fetch(path)
      JSON.dump(stats: {path => stats})
    else
      "ERR\n"
    end
  end

  def log(msg)
    Celluloid.logger.info(msg)
  end

  def redis
    Celluloid::Actor[:redis]
  end
end

class Listener
  include Celluloid::IO

  def initialize(host, port)
    log("Starting on #{host}:#{port}")
    @server = TCPServer.new(host, port)
    async.run
  end

  def finalize
    return unless @server
    @server.close
  end

  def run
    loop {
      async.handle_connection(@server.accept)
    }
  end

  def handle_connection(socket)
    _, host, port = socket.peeraddr
    log("#{host}:#{port} connected")
    msg = socket.readpartial(4096)
    response = stats.handle(msg)
    socket.write(response)
    socket.close
  rescue EOFError
    log("#{host}:#{port} disconnected")
    socket.close
  end

  def log(msg)
    puts msg
  end

  def stats
    Celluloid::Actor[:stats]
  end
end

class Collector < Celluloid::SupervisionGroup
  supervise Stats, as: :stats
  supervise RedisAdapter, as: :redis, args: [Redis.new]
  supervise Listener, as: :listener, args: ["0.0.0.0", 3000]
end

if __FILE__ == $0
  collector = Collector.run!
  trap("INT") do
    collector.terminate
    exit
  end
  sleep
end

stats.rb

require 'socket'

socket = TCPSocket.open('localhost', 3000)
socket.write("STATS /")
puts socket.read
socket.close

visit.rb

require 'socket'

socket = TCPSocket.open('localhost', 3000)
socket.write("VISIT /")
puts socket.read
socket.close