    def get_meter(self, name):
        """[deprecated] Get a specific meter by name."""
        from fairseq import meters

        if "get_meter" not in self._warn_once:
            self._warn_once.add("get_meter")
            utils.deprecation_warning(
                "Trainer.get_meter is deprecated. Please use fairseq.metrics instead."
            )

        train_meters = metrics.get_meters("train")
        if train_meters is None:
            train_meters = {}

        if name == "train_loss" and "loss" in train_meters:
            return train_meters["loss"]
        elif name == "train_nll_loss":
            # support for legacy train.py, which assumed this meter is
            # always initialized
            m = train_meters.get("nll_loss", None)
            return m or meters.AverageMeter()
        elif name == "wall":
            # support for legacy train.py, which assumed this meter is
            # always initialized
            m = metrics.get_meter("default", "wall")
            return m or meters.TimeMeter()
        elif name == "wps":
            m = metrics.get_meter("train", "wps")
            return m or meters.TimeMeter()
        elif name in {"valid_loss", "valid_nll_loss"}:
            # support for legacy train.py, which assumed these meters
            # are always initialized
            k = name[len("valid_") :]
            m = metrics.get_meter("valid", k)
            return m or meters.AverageMeter()
        elif name == "oom":
            return meters.AverageMeter()
        elif name in train_meters:
            return train_meters[name]
        return None
[deprecated] Get a specific meter by name.
fairseq/trainer.py