reindex_updater_store.rb

module ElasticsearchSupport
  class ReindexUpdaterStore

    class << self

      def redis
        $redis
      end

      def start(klass)
        key = key_for_reindex(klass)
        redis.set(key, "true")
      end

      def stop(klass)
        key = key_for_reindex(klass)
        redis.expire(key, 1)
        drain!(klass)
      end

      def store(klass, id)
        if reindex_running?(klass)
          old_ids = retrieve(klass)
          ids = (old_ids << id).uniq.to_json
          redis.set(key_for_updated_records(klass), ids)
        end
      end


      private

      def drain!(klass)
        ids = retrieve(klass)
        klass.where(id: ids).each(&:refresh_in_elasticsearch)
        redis.expire(key_for_updated_records(klass), 1)
        ids
      end

      def key_for_reindex(klass)
        "#{klass.table_name}_reindex_running"
      end

      def key_for_updated_records(klass)
        "updated_#{klass.table_name}_during_reindex"
      end

      def reindex_running?(klass)
        key = key_for_reindex(klass)
        redis.get(key) == "true"
      end

      def retrieve(klass)
        key = key_for_updated_records(klass)
        if value = redis.get(key)
          JSON.parse(value)
        else
          []
        end
      end

    end
  end
end