the realtime newrelic

tailor.rb

# Usage, assuming that production.log is your rails log
#
# $ tail -f production.log | grep Completed | ruby tailor.rb <estimate> <size>
#
# * estimate is estimated number of requests per second (make it 50% larger)
# * size is length of every stat block(second, minute, hour)

# a line to print out
#
# @accept [Integer] num number of requests
# @accept [Integer] max estimated maximum of requests to scale graph to
# @accept [Integer] size result line size
# @return [String] graph line
def spark(num, max, size)
  size -= 10
  fill  = (size * num / max.to_f).to_i
  fill  = size if fill > size
  none  = size - fill
  ("% 8d " % num) << ("█" * fill) << (" " * none) << "|"
end

estimate = ARGV.shift.to_i rescue 300
spark_size = ARGV.shift.to_i rescue 40

last_minute,last_hour,requests,time = [],[],0,Time.now.to_i

while gets
  requests += 1

  if Time.now.to_i > time
    last_minute << requests
    last_minute.shift if last_minute.size > 60

    last_hour << last_minute.inject(&:+)
    last_hour.shift if last_hour.size > 60

    puts Time.now.strftime("%y.%m.%d %H:%M") <<
      spark(requests, estimate, spark_size) <<
      spark(last_hour.last, estimate * 60, spark_size) <<
      spark(last_hour.inject(&:+), estimate * 60 * 60, spark_size)

    requests, time = 0, Time.now.to_i
  end
end