require "benchmark"
frames = nil
Benchmark.bm 10 do |r|
  r.report "OpenStruct" do
    frames = frames = exception.backtrace.map { |line|
      frame = OpenStruct.new
      if line =~ /(.*?):(\d+)(:in `(.*)')?/
        frame.filename = $1
        frame.lineno = $2.to_i
        frame.function = $4

        begin
          lineno = frame.lineno - 1
          lines = ::File.readlines(frame.filename)
          frame.pre_context_lineno = [lineno - CONTEXT, 0].max
          frame.pre_context = lines[frame.pre_context_lineno...lineno]
          frame.context_line = lines[lineno].chomp
          frame.post_context_lineno = [lineno + CONTEXT, lines.size].min
          frame.post_context = lines[lineno + 1..frame.post_context_lineno]
        rescue
        end

        frame
      else
        nil
      end
    }.compact
  end

  r.report "Struct" do
    frames = frames = exception.backtrace.map { |line|
      frame = Frame.new
      if line =~ /(.*?):(\d+)(:in `(.*)')?/
        frame.filename = $1
        frame.lineno = $2.to_i
        frame.function = $4

        begin
          lineno = frame.lineno - 1
          lines = ::File.readlines(frame.filename)
          frame.pre_context_lineno = [lineno - CONTEXT, 0].max
          frame.pre_context = lines[frame.pre_context_lineno...lineno]
          frame.context_line = lines[lineno].chomp
          frame.post_context_lineno = [lineno + CONTEXT, lines.size].min
          frame.post_context = lines[lineno + 1..frame.post_context_lineno]
        rescue
        end

        frame
      else
        nil
      end
    }.compact
  end
end

  it "benchmark OpenStruct and Struct" do
    res = nil

    req = Rack::MockRequest.new(
      show_exceptions(
        lambda{|env| raise RuntimeError, "foo", ["nonexistent.rb:2:in `a': adf (RuntimeError)"] * 100 }
      ))

    res = req.get("/", "HTTP_ACCEPT" => "text/html")
  end