メッセージングサーバの習作

messaging_server.rb

# -*- coding: utf-8 -*-
require 'eventmachine'
require 'json'
require 'hashie'

#ログイン済みのコネクションハンドラーのコンテナ
class LoginedConnectionContainer
  @@users = {}

  def self.add(user_id,connection)
    @@users[user_id] = connection
  end

  def self.fetch(user_id)
    @@users[user_id]
  end

  def self.remove(user_id)
    @@users.delete(user_id)
  end

  def self.list
    @@users.keys
  end
end

class ConnectionHandler < EM::Connection
  def post_init
    @state  = ConnectionState::Connected.new(self)
    @buffer = ''
  end

  #クライアントからデータ送られて来たときに呼ばれる
  #Stateに委譲
  def receive_data(chunk)
    @buffer += chunk
    return unless @buffer =~ /\r\n$/

    line = @buffer.gsub(/[[:cntrl:]]/,"").encode("UTF-8") rescue raise("invalid utf-8 string")
    @buffer = ''

    data = Hashie::Mash.new(JSON.parse(line)) rescue raise("invalid JSON")

    next_state = @state.process(data)
    @state = next_state
  rescue => e
    send_error(e.message)
  end

  #接続切れたときに呼ばれる
  #Stateに委譲
  def unbind
    @state.unbind
  end

  def send_line(data)
    send_data(data + "\r\n")
  end

  private
  def to_valid_utf8(line)
    return
  end

  def send_error(msg)
    error = JSON.generate({"event" => "error","message" => msg})
    send_line(error)
    close_connection_after_writing
  end
end

#State
module ConnectionState
  #接続後すぐの状態
  class Connected
    def initialize(connection)
      @connection = connection
    end

    def process(data)
      raise "user_id is required in login request" unless data.user_id

      LoginedConnectionContainer.add(data.user_id, @connection)
      return Logined.new(data.user_id)
    end

    def unbind
      # do nothing
    end
  end

  #ログイン後の状態
  class Logined
    def initialize(user_id)
      @user_id = user_id
    end

    def process(data)
      raise "'to' is required in message" unless data.to
      raise "'message' is required in message" unless data.message
      msg = JSON.generate({"event" => "message", "from" => @user_id, "message" => data.message})
      to = LoginedConnectionContainer.fetch(data.to)

      return unless to
      to.send_line(msg)
      return self
    end

    def unbind
      LoginedConnectionContainer.remove(@user_id)
    end
  end
end

EM::run do
  host,port = "0.0.0.0", 6789
  EM.add_periodic_timer(1) do
    p LoginedConnectionContainer.list
  end
  EM::start_server host, port, ConnectionHandler
end