rate_measure.rb

# mixin to measure up/down rate for an EM::Connection
module RateMeasure
  RATE_PERIOD = 5 
  def post_init
    setup_meters
    super
  end

  def receive_data data
    update_meter(data.length, @download_meter)
    super
  end

  def send_data data
    update_meter(data.length, @upload_meter)
    super
  end

  def up_rate
    @upload_meter[:rate] / 1024.0
  end

  def down_rate
    @download_meter[:rate] / 1024.0
  end

  private

  def setup_meters
    now = Time.now - 0.1

    @upload_meter = {
      :rate       => 0.0,
      :total      => 0,
      :ratesince  => now,
      :last       => now
    }

    @download_meter = {
      :rate       => 0.0,
      :total      => 0,
      :ratesince  => now,
      :last       => now
    }
  end

  def update_meter(amount, meter)
    now = Time.now
    meter[:total] += amount
    meter[:rate]   = (meter[:rate] * (meter[:last] - meter[:ratesince]) + amount)/(now - meter[:ratesince])
    meter[:last]   = now

    if meter[:ratesince] < now - RATE_PERIOD
      meter[:ratesince] = now - RATE_PERIOD
    end
  end
end