Question

When I run ruby filename.rb, the thin webserver startsup but when I try to view the (Sinatra) application on localhost:4567 I’m getting this error message. Googling it revealed nothing. Does anyone know what I might do to get past this?

gems/eventmachine-0.12.10/lib/em/connection.rb:39:in `block in new': undefined method `associate_callback_target' for #<Thin::Connection:0x00000100fc7500> (NoMethodError)
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@rails3tutorial/gems/eventmachine-0.12.10/lib/em/connection.rb:36:in `instance_eval'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@rails3tutorial/gems/eventmachine-0.12.10/lib/em/connection.rb:36:in `new'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@rails3tutorial/gems/eventmachine-0.12.10/lib/eventmachine.rb:1430:in `event_callback'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@rails3tutorial/gems/eventmachine-0.12.10/lib/pr_eventmachine.rb:815:in `block in eventable_read'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@rails3tutorial/gems/eventmachine-0.12.10/lib/pr_eventmachine.rb:812:in `times'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@rails3tutorial/gems/eventmachine-0.12.10/lib/pr_eventmachine.rb:812:in `eventable_read'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@rails3tutorial/gems/eventmachine-0.12.10/lib/pr_eventmachine.rb:369:in `block in crank_selectables'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@rails3tutorial/gems/eventmachine-0.12.10/lib/pr_eventmachine.rb:369:in `each'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@rails3tutorial/gems/eventmachine-0.12.10/lib/pr_eventmachine.rb:369:in `crank_selectables'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@rails3tutorial/gems/eventmachine-0.12.10/lib/pr_eventmachine.rb:324:in `block in run'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@rails3tutorial/gems/eventmachine-0.12.10/lib/pr_eventmachine.rb:318:in `loop'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@rails3tutorial/gems/eventmachine-0.12.10/lib/pr_eventmachine.rb:318:in `run'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@rails3tutorial/gems/eventmachine-0.12.10/lib/pr_eventmachine.rb:64:in `run_machine'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@rails3tutorial/gems/eventmachine-0.12.10/lib/eventmachine.rb:256:in `run'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@rails3tutorial/gems/thin-1.4.1/lib/thin/backends/base.rb:63:in `start'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@rails3tutorial/gems/thin-1.4.1/lib/thin/server.rb:159:in `start'
    from /Users/mm/.rvm/gems/ruby-1.9.2-p290@rails3tutorial/gems/rack-1.4.1/lib/rack/handler/thin.rb:13:in `run'
    from /Users/mm/.rvm/gems/ruby-1.9.2-p290@rails3tutorial/gems/sinatra-1.3.3/lib/sinatra/base.rb:1350:in `run!'
    from /Users/mm/.rvm/gems/ruby-1.9.2-p290@rails3tutorial/gems/sinatra-1.3.3/lib/sinatra/main.rb:25:in `block in <module:Sinatra>'

The code is from a book Cloning Internet Applications in Ruby. It’s happening with each of its demo applications…

Route code

get '/' do haml :index end

post '/' do
  uri = URI::parse(params[:original])
  custom = params[:custom].empty? ? nil : params[:custom]
  raise "Invalid URL" unless uri.kind_of? URI::HTTP or uri.kind_of? URI::HTTPS
  @link = Link.shorten(params[:original], custom) 
  haml :index
end

['/info/:short_url', '/info/:short_url/:num_of_days', '/info/:short_url/:num_of_days/:map'].each do |path|
  get path do
    @link = Link.first(:identifier => params[:short_url])
    raise 'This link is not defined yet' unless @link
    @num_of_days = (params[:num_of_days] || 15).to_i
    @count_days_bar = Visit.count_days_bar(params[:short_url], @num_of_days)
    chart = Visit.count_country_chart(params[:short_url], params[:map] || 'world')
    @count_country_map = chart[:map]
    @count_country_bar = chart[:bar]
    haml :info
  end
end

get '/:short_url' do 
  link = Link.first(:identifier => params[:short_url])
  link.visits << Visit.create(:ip => get_remote_ip(env))
  link.save
  redirect link.url.original, 301
end

error do haml :index end

def get_remote_ip(env)
  if addr = env['HTTP_X_FORWARDED_FOR']
    addr.split(',').first.strip
  else
    env['REMOTE_ADDR']
  end
end

Answer 1

I’m the author of the Cloning Internet Applications with Ruby book. I tried running the code in the GitHub repository, and barring for a few changes (due to changes in Sinatra) I can run it successfully. Perhaps you can try the answer given by Prakash Murthy, to upgrade to EventMachine 1.0.0 but I’m running the same version as you are (0.12.10) and that doesn’t give me any problems.

If you drop me an email directly we can figure this out (and update Stack Overflow later).