call

# File activerecord/lib/active_record/migration.rb, line 561
      def call(env)
        mtime = ActiveRecord::Base.connection.migration_context.last_migration.mtime.to_i
        if @last_check < mtime
          ActiveRecord::Migration.check_pending!(connection)
          @last_check = mtime
        end
        @app.call(env)
      end