Get a perf message for the given datetime.

def _get_daily_message(self, dt, algo, metrics_tracker):
        """
        Get a perf message for the given datetime.
        """
        perf_message = metrics_tracker.handle_market_close(
            dt,
            self.data_portal,
        )
        perf_message['daily_perf']['recorded_vars'] = algo.recorded_vars
        return perf_message