class DeferredBookLoader
  include EM::Deferrable
  def load_books
    pg = PG::EM::Client.new(:user => "user",:password => "password",:dbname => 'library_development')

   q = pg.query("select * from books")

    q.callback do |res|
      long_op = proc do
        res.map {|e| e["name"]}
      end

      finished = proc {|results| succeed(results)}
      EM.defer(long_op,finished)
    end

    q.errback do |ex|
      fail(ex)
    end

  end
end

EM.run do
  $stdout.sync = true

  last_tick = Time.now
  EM.add_periodic_timer(0.5) do
    current = Time.now
    puts "Last tick:#{last_tick} now: #{current}"
    last_tick = current
  end

  EM.add_periodic_timer(13) do      deferred = DeferredBookLoader.new
      deferred.load_books

      deferred.callback do |results|
        puts "Loaded #{results.size}"
        puts results[3]
      end

      deferred.errback do |results|
        puts "Failed #{results}"
      end
  end

end

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Book 133681
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Book 133681
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