profiler.rb

class Profiler
  SUBSCRIPTIONS = [
    'sql.active_record',
    'render_template.action_view',
    'render_partial.action_view',
    'process_action.action_controller'
  ].freeze

  PATH = './log/profiler.log'

  IGNORE_SQL_NAMES = %w(SCHEMA CACHE).freeze
  IGNORE_SQL_QUERIES = %w(COMMIT BEGIN).freeze

  class << self
    attr_reader :instance

    def run
      @instance ||= Profiler.new.run
    end
  end

  def run
    SUBSCRIPTIONS.each do |subscription|
      ActiveSupport::Notifications.subscribe(subscription) do |_name, start, finish, _id, payload|
        if Thread.current[:request_id].present?
          message = build_message(start: start, finish: finish, payload: payload , subscription: subscription)

          logger.info message if message.present?
        end
      end
    end
  end

  private

  def build_message(start: ,finish: , payload:, subscription: )
    duration = (finish.to_f - start.to_f) * 1000

    message = case subscription
              when 'render_partial.action_view', 'render_template.action_view'
                render_partial_message(payload)
              when 'sql.active_record'
                sql_request_message(payload)
              end

    [Time.now.to_s, Thread.current[:request_id], subscription, duration.round(2), message].join(':') if message.present?
  end

  def render_partial_message(payload)
    path = payload[:identifier].split('/')
    app_index = path.index('app')
    path[app_index..path.length].join('/')
  end

  def sql_request_message(payload)
    return if IGNORE_SQL_NAMES.include? payload[:name]
    return if IGNORE_SQL_QUERIES.map { |query| payload[:sql].strip.start_with?(query) }.reduce(:&)

    payload[:sql].strip
  end

  def logger
    @logger ||= ActiveSupport::Logger.new Rails.root.join(PATH)
  end
end

Profiler.run if Settings.profiler_enable?