Ruby event source without event machine

README.md

1. Run the server

   % thin -R server.ru start
   

2. Run the client

   % ruby threaded_clients.rb
   

Gemfile

source "http://rubygems.org"

gem 'thin'
gem 'cramp'
gem 'rack'

server.ru

require 'cramp'

class Pump < Cramp::Action
  self.transport = :sse

  periodic_timer :pump, :every => 1

  def pump
    begin
      render "#{times} times"
    rescue TooManyTimesError
      finish
    end
  end

  class TooManyTimesError < StandardError; end

  def times
    @times = 0 unless defined?(@times)
    @times += 1

    raise TooManyTimesError unless @times <= 10
    @times
  end
end

run Pump

threaded_clients.rb

require 'socket'

class HttpRequest
  def initialize(host, port=80)
    @host = host
    @port = port
    @socket = TCPSocket.new host, port
    @callbacks = { }
  end

  def start
    socket.puts "GET / HTTP/1.1\r\n"
    socket.puts "User-Agent: ruby\r\n"
    socket.puts "Host: #{host}:#{port}\r\n"
    socket.puts "Accept: */*\r\n"
    socket.puts "\r\n"
    read
  end

  def close
    socket.close
  end

  def on(event, &block)
    @callbacks[event] = block
  end

  def callback(event, *args)
    find_callback(event).call(*args)
  end

  private
  
  def find_callback(event)
    @callbacks.fetch(event)
  end

  def read
    # blocking IO causes threads 
    # to switch, hooray!
    while data = socket.gets
      callback(:data, data)
    end

    callback(:end)
    close
  end

  attr_reader :host, :port, :socket, :block
end

threads = [ ]

10.times do |i|
  threads << Thread.new do
    request = HttpRequest.new('localhost', 3000) do |data|
      puts "Request #{i} >> #{data}"
    end

    request.on(:data) do |data|
      puts "Request #{i} >> #{data}"
    end

    request.on(:end) do
      puts "Request #{i} >> END"
    end

    request.start
  end
end

threads.map(&:join)