Perf - low overhead, dead simple way to time you code, useful when you want to time things in prod

perf.rb

# frozen_string_literal: true

# time some code with name, and dump it in logfile
# can be used to find how much time is going in each part
#
# set perf markers in the code
# pros:
# - low overhead, gives high level picture
# cons:
# - needs marking
#
# start = Perf.start('precomp')
# # <code we want to time>
# Perf.end(start)
#
# this can be part of code, and common parts can be instrumented using this
# TODO: move away from logger to sending data to ELK or graphite(in async way) so we can
# plot it as stack chart
class Perf
  LOGGER = Logger.new('log/perf_time.log')

  def self.start(name)
    start_time = Process.clock_gettime(Process::CLOCK_MONOTONIC)
    return { name: name, start_time: start_time }
  end

  # @param [Hash] return of start call
  def self.end(start)
    end_time = Process.clock_gettime(Process::CLOCK_MONOTONIC)
    LOGGER.info("tid: #{Thread.current.object_id}, "\
                "name: #{start[:name]}, "\
                "duration: #{end_time - start[:start_time]}")
  end
end