mysql patch to make it work with celluloid IO

celluloid_io_mysql2_patch.rb

require 'celluloid/io'
require 'mysql2'

module Mysql2
  module Celluloid
    # https://github.com/brianmario/mysql2/blob/master/lib/mysql2/em.rb
    # Almost direct copy of the eventmachine driver for mysql2. It's even less verbose, which can only be a plus.
    class Client < ::Mysql2::Client
      def query(sql, opts={})
        if ::Celluloid::IO.evented?
          ::Celluloid.mailbox.reactor.wait_writable(IO.new(self.socket))
          puts "Legen..."
          super(sql, opts.merge(async: true))
          puts "#{self.socket}...wait for it..."
          ::Celluloid.mailbox.reactor.wait_readable(IO.new(self.socket))
          puts "...dary!"
          async_result
        else
          super
        end
      end
    end
  end
end


# Here to save from the whole direct sql bla bla bla.
class Sleeper
  def initialize
    @client = Mysql2::Celluloid::Client.new(host: "localhost", username: "root")
  end

  def sleep
    @client.query("SELECT SLEEP(5);")
  end
end


# The real meat is here. The idea is not to multiplex on the same connection, but on different connections. 
# So, this is kind of a poor-man connection pool implementation. But it proves that one can effectively have
# concurrent async IO using only one actor. 
class Sleepers
  include Celluloid::IO
  
  def initialize
    @clients = 50.times.map { Sleeper.new }
    @counter = 50
  end

  def decrement(c)
    c.sleep
    @counter -= 1
    if @counter.zero?
      @end = Time.now
      puts "it took #{@end - @beginning} seconds"
      terminate
    end
  end

  def final_countdown
    @beginning = Time.now
    @clients.each do |c|
      async(:decrement, c)
    end
  end 
end

puts "starting my test..."
c = Sleepers.new
c.async(:final_countdown)
puts "waiting for it to be over..."

sleep