a-README.md

Making async or network based protocols appear synchronous

With Celluloid, we can hide the async flow of a protocol using Signals. The comparison is that in the Celluloid version, the #start method now has the logic which describes the flow of the protocol.

b-old.rb

# OLD

class Connection
  def start(&block)
    handshake
    @result_callback = block
  end

  def handshake
    send_data "handshake"
  end

  def on_handshake_completed
    start_work
  end

  def start_work
    send_data "start_work"
  end

  def on_work_done(result)
    if result.ok?
      @result_callback.call(result)
    else
      start_work
    end
  end
end

class Parser
  def process_pkt(packet)
    case packet.type
    when 'handshake_complete'
      @connection.on_handshake_complete
    when 'work_done'
      @connection.on_work_done(packet.payload)
    end
  end
end

c-new.rb

# NEW

class Connection
  include Celluloid

  def start
    handshake
    loop do
      result = start_work
      return result if result.ok?
    end
  end

  def handshake
    send_data "handshake"
    wait :handshake
  end

  def on_handshake_complete
    signal :handshake
  end

  def start_work
    send_data "start_work"
    wait :work_done
  end

  def on_work_done(result)
    signal :work_done, result
  end
end

class Parser
  def process_pkt(packet)
    case packet
    when 'handshake_complete'
      @connection.on_handshake_complete
    when 'work_done'
      @connection.on_work_done(packet.payload)
    end
  end
end