rack middleware ごとの経過時間をはかるやつ

patch.rb

# ref: http://blog.mirakui.com/entry/2012/04/03/slow-middleware
module RackMiddlewareBenchmarker
  module Benchmarker
    def call(env)
      result = nil
      ms = Benchmark.ms { result = super }
      puts "MIDDLEWARE END #{self.class.to_s} (#{ms.to_i}ms)"
      result
    end
  end

  def build(app)
    app.class.prepend(Benchmarker)
    super
  end
end
ActionDispatch::MiddlewareStack::Middleware.prepend(RackMiddlewareBenchmarker)