Measure ruby vm variance

runtime_instrumentation.rb

require 'hitimes'
require 'librato/metrics'
require 'thread'

class RuntimeInstrumentation
  def self.queue
    @queue ||= Librato::Metrics::Queue
      .new(source: ENV.fetch('SOURCE_NAME'),
           autosubmit_interval: ENV.fetch('METRIC_SUBMIT_INTERVAL', 10).to_i)
  end

  def queue
    self.class.queue
  end

  attr_reader :interval, :mutex, :thread

  def initialize
    @interval = 1.0
    @mutex    = Mutex.new
    @running  = false
  end

  def running?
    mutex.synchronize { @running }
  end

  def start
    return self if thread && thread.alive?

    mutex.synchronize { @running = true }

    @thread = Thread.new do
      while running?
        measure_time  = Time.now
        ruby_interval = Hitimes::Interval.now
        sleep @interval.to_f
        variance = ruby_interval.duration - @interval.to_f

        record_variance variance, measure_time
      end
    end

    self
  end

  def stop
    mutex.synchronize { @running = false }
  end

  def record_variance(value, measure_time)
    data = { 'sonar.ruby.variance' =>
             { :measure_time => measure_time,
               :value        => value }}

    queue.add data
  end
end