A module to track/output Active Record queries

query_trackable.rb

module QueryTrackable
  extend ActiveSupport::Concern

  #
  # Prints the number of queries and the time spent in milliseconds
  # Useful to track the performance of isolated classes
  #
  # Usage:
  #
  # class MyClass
  #   include QueryTrackable
  #
  #   def my_method
  #     track_active_record_queries do
  #       # your code with queries here
  #     end
  #   end
  # end
  #
  # Example output: `[MyClass] ActiveRecord: 7707.7ms (85 queries, 0 cached)`
  #
  included do
    # inspired by https://github.com/rails/rails/blob/fd49d6a3180244969fb5ab9768d0bc7d9e4df9fe/activerecord/lib/active_record/runtime_registry.rb#L70
    def track_active_record_queries
      cached_queries = 0
      queries = 0
      runtime_before = Time.current

      subscriber = ActiveSupport::Notifications.subscribe("sql.active_record") do |*args|
        payload = args.last
        next if ["SCHEMA", "TRANSACTION"].include?(payload[:name])

        if payload[:cached]
          cached_queries += 1
        else
          queries += 1
        end
      end

      yield

      runtime_after = Time.current
      ActiveSupport::Notifications.unsubscribe(subscriber)
      spent = ((runtime_after - runtime_before) * 1000.0).round(1)

      log_query_stats(spent, queries, cached_queries)
    end

    private

    def log_query_stats(spent, queries, cached_queries)
      Rails.logger.debug do
        "[#{self.class.name}] ActiveRecord: #{spent}ms (#{queries} queries, #{cached_queries} cached)"
      end
    end
  end
end

Alternative: https://github.com/rubysamurai/query_count