# What does this PR do?

This PR creates the precedent of deprecating models in the library. By deprecating we indicate that we will stop maintaining such models, but there is no intention of actually removing those models and breaking support for them (they might one day move into a separate repo/on the Hub but we would still add the necessary imports to make sure backward compatibility stays). The main point is that we stop testing those models (to ease a bit the burden on our CI).

Deprecated models are moved in models/deprecated so direct import of objects from their modeling files will break (though that's easily fixed by adding the `.deprecated` in the path). They are removed from the `tests` folder and a mention is added in the doc page of the model.

The heuristic to pick the deprecated models in this PR is: models older than a year that got less than a cumulated 1,000 downloads (over all checkpoints) in the last 30 days (counting deduplicated downloads).
Deprecate models. # What does this PR do?

This PR creates the precedent of deprecating models in the library. By deprecating we indicate that we will stop maintaining such models, but there is no intention of actually removing those models and breaking support for them (they might one day move into a separate repo/on the Hub but we would still add the necessary imports to make sure backward compatibility stays). The main point is that we stop testing those models (to ease a bit the burden on our CI).

Deprecated models are moved in models/deprecated so direct import of objects from their modeling files will break (though that's easily fixed by adding the `.deprecated` in the path). They are removed from the `tests` folder and a mention is added in the doc page of the model.

The heuristic to pick the deprecated models in this PR is: models older than a year that got less than a cumulated 1,000 downloads (over all checkpoints) in the last 30 days (counting deduplicated downloads).
import argparse
import logging
import os
from pathlib import Path
from typing import Any, Dict

import pytorch_lightning as pl
from pytorch_lightning.utilities import rank_zero_info

from transformers import (
    AdamW,
    AutoConfig,
    AutoModel,
    AutoModelForPreTraining,
    AutoModelForQuestionAnswering,
    AutoModelForSeq2SeqLM,
    AutoModelForSequenceClassification,
    AutoModelForTokenClassification,
    AutoModelWithLMHead,
    AutoTokenizer,
    PretrainedConfig,
    PreTrainedTokenizer,
)
from transformers.optimization import (
    Adafactor,
    get_cosine_schedule_with_warmup,
    get_cosine_with_hard_restarts_schedule_with_warmup,
    get_linear_schedule_with_warmup,
    get_polynomial_decay_schedule_with_warmup,
)
from transformers.utils.versions import require_version


logger = logging.getLogger(__name__)

require_version("pytorch_lightning>=1.0.4")

MODEL_MODES = {
    "base": AutoModel,
    "sequence-classification": AutoModelForSequenceClassification,
    "question-answering": AutoModelForQuestionAnswering,
    "pretraining": AutoModelForPreTraining,
    "token-classification": AutoModelForTokenClassification,
    "language-modeling": AutoModelWithLMHead,
    "summarization": AutoModelForSeq2SeqLM,
    "translation": AutoModelForSeq2SeqLM,
}


# update this and the import above to support new schedulers from transformers.optimization
arg_to_scheduler = {
    "linear": get_linear_schedule_with_warmup,
    "cosine": get_cosine_schedule_with_warmup,
    "cosine_w_restarts": get_cosine_with_hard_restarts_schedule_with_warmup,
    "polynomial": get_polynomial_decay_schedule_with_warmup,
    # '': get_constant_schedule,             # not supported for now
    # '': get_constant_schedule_with_warmup, # not supported for now
}
arg_to_scheduler_choices = sorted(arg_to_scheduler.keys())
arg_to_scheduler_metavar = "{" + ", ".join(arg_to_scheduler_choices) + "}"


class BaseTransformer(pl.LightningModule):
    def __init__(
        self,
        hparams: argparse.Namespace,
        num_labels=None,
        mode="base",
        config=None,
        tokenizer=None,
        model=None,
        **config_kwargs,
    ):
        """Initialize a model, tokenizer and config."""
        super().__init__()
        # TODO: move to self.save_hyperparameters()
        # self.save_hyperparameters()
        # can also expand arguments into trainer signature for easier reading

        self.save_hyperparameters(hparams)
        self.step_count = 0
        self.output_dir = Path(self.hparams.output_dir)
        cache_dir = self.hparams.cache_dir if self.hparams.cache_dir else None
        if config is None:
            self.config = AutoConfig.from_pretrained(
                self.hparams.config_name if self.hparams.config_name else self.hparams.model_name_or_path,
                **({"num_labels": num_labels} if num_labels is not None else {}),
                cache_dir=cache_dir,
                **config_kwargs,
            )
        else:
            self.config: PretrainedConfig = config

        extra_model_params = ("encoder_layerdrop", "decoder_layerdrop", "dropout", "attention_dropout")
        for p in extra_model_params:
            if getattr(self.hparams, p, None):
                assert hasattr(self.config, p), f"model config doesn't have a `{p}` attribute"
                setattr(self.config, p, getattr(self.hparams, p))

        if tokenizer is None:
            self.tokenizer = AutoTokenizer.from_pretrained(
                self.hparams.tokenizer_name if self.hparams.tokenizer_name else self.hparams.model_name_or_path,
                cache_dir=cache_dir,
            )
        else:
            self.tokenizer: PreTrainedTokenizer = tokenizer
        self.model_type = MODEL_MODES[mode]
        if model is None:
            self.model = self.model_type.from_pretrained(
                self.hparams.model_name_or_path,
                from_tf=bool(".ckpt" in self.hparams.model_name_or_path),
                config=self.config,
                cache_dir=cache_dir,
            )
        else:
            self.model = model

    def load_hf_checkpoint(self, *args, **kwargs):
        self.model = self.model_type.from_pretrained(*args, **kwargs)

    def get_lr_scheduler(self):
        get_schedule_func = arg_to_scheduler[self.hparams.lr_scheduler]
        scheduler = get_schedule_func(
            self.opt, num_warmup_steps=self.hparams.warmup_steps, num_training_steps=self.total_steps()
        )
        scheduler = {"scheduler": scheduler, "interval": "step", "frequency": 1}
        return scheduler

    def configure_optimizers(self):
        """Prepare optimizer and schedule (linear warmup and decay)"""
        model = self.model
        no_decay = ["bias", "LayerNorm.weight"]
        optimizer_grouped_parameters = [
            {
                "params": [p for n, p in model.named_parameters() if not any(nd in n for nd in no_decay)],
                "weight_decay": self.hparams.weight_decay,
            },
            {
                "params": [p for n, p in model.named_parameters() if any(nd in n for nd in no_decay)],
                "weight_decay": 0.0,
            },
        ]
        if self.hparams.adafactor:
            optimizer = Adafactor(
                optimizer_grouped_parameters, lr=self.hparams.learning_rate, scale_parameter=False, relative_step=False
            )

        else:
            optimizer = AdamW(
                optimizer_grouped_parameters, lr=self.hparams.learning_rate, eps=self.hparams.adam_epsilon
            )
        self.opt = optimizer

        scheduler = self.get_lr_scheduler()

        return [optimizer], [scheduler]

    def test_step(self, batch, batch_nb):
        return self.validation_step(batch, batch_nb)

    def test_epoch_end(self, outputs):
        return self.validation_end(outputs)

    def total_steps(self) -> int:
        """The number of total training steps that will be run. Used for lr scheduler purposes."""
        num_devices = max(1, self.hparams.gpus)  # TODO: consider num_tpu_cores
        effective_batch_size = self.hparams.train_batch_size * self.hparams.accumulate_grad_batches * num_devices
        return (self.dataset_size / effective_batch_size) * self.hparams.max_epochs

    def setup(self, mode):
        if mode == "test":
            self.dataset_size = len(self.test_dataloader().dataset)
        else:
            self.train_loader = self.get_dataloader("train", self.hparams.train_batch_size, shuffle=True)
            self.dataset_size = len(self.train_dataloader().dataset)

    def get_dataloader(self, type_path: str, batch_size: int, shuffle: bool = False):
        raise NotImplementedError("You must implement this for your task")

    def train_dataloader(self):
        return self.train_loader

    def val_dataloader(self):
        return self.get_dataloader("dev", self.hparams.eval_batch_size, shuffle=False)

    def test_dataloader(self):
        return self.get_dataloader("test", self.hparams.eval_batch_size, shuffle=False)

    def _feature_file(self, mode):
        return os.path.join(
            self.hparams.data_dir,
            "cached_{}_{}_{}".format(
                mode,
                list(filter(None, self.hparams.model_name_or_path.split("/"))).pop(),
                str(self.hparams.max_seq_length),
            ),
        )

    @pl.utilities.rank_zero_only
    def on_save_checkpoint(self, checkpoint: Dict[str, Any]) -> None:
        save_path = self.output_dir.joinpath("best_tfmr")
        self.model.config.save_step = self.step_count
        self.model.save_pretrained(save_path)
        self.tokenizer.save_pretrained(save_path)

    @staticmethod
    def add_model_specific_args(parser, root_dir):
        parser.add_argument(
            "--model_name_or_path",
            default=None,
            type=str,
            required=True,
            help="Path to pretrained model or model identifier from huggingface.co/models",
        )
        parser.add_argument(
            "--config_name", default="", type=str, help="Pretrained config name or path if not the same as model_name"
        )
        parser.add_argument(
            "--tokenizer_name",
            default=None,
            type=str,
            help="Pretrained tokenizer name or path if not the same as model_name",
        )
        parser.add_argument(
            "--cache_dir",
            default="",
            type=str,
            help="Where do you want to store the pre-trained models downloaded from huggingface.co",
        )
        parser.add_argument(
            "--encoder_layerdrop",
            type=float,
            help="Encoder layer dropout probability (Optional). Goes into model.config",
        )
        parser.add_argument(
            "--decoder_layerdrop",
            type=float,
            help="Decoder layer dropout probability (Optional). Goes into model.config",
        )
        parser.add_argument(
            "--dropout",
            type=float,
            help="Dropout probability (Optional). Goes into model.config",
        )
        parser.add_argument(
            "--attention_dropout",
            type=float,
            help="Attention dropout probability (Optional). Goes into model.config",
        )
        parser.add_argument("--learning_rate", default=5e-5, type=float, help="The initial learning rate for Adam.")
        parser.add_argument(
            "--lr_scheduler",
            default="linear",
            choices=arg_to_scheduler_choices,
            metavar=arg_to_scheduler_metavar,
            type=str,
            help="Learning rate scheduler",
        )
        parser.add_argument("--weight_decay", default=0.0, type=float, help="Weight decay if we apply some.")
        parser.add_argument("--adam_epsilon", default=1e-8, type=float, help="Epsilon for Adam optimizer.")
        parser.add_argument("--warmup_steps", default=0, type=int, help="Linear warmup over warmup_steps.")
        parser.add_argument("--num_workers", default=4, type=int, help="kwarg passed to DataLoader")
        parser.add_argument("--num_train_epochs", dest="max_epochs", default=3, type=int)
        parser.add_argument("--train_batch_size", default=32, type=int)
        parser.add_argument("--eval_batch_size", default=32, type=int)
        parser.add_argument("--adafactor", action="store_true")


class LoggingCallback(pl.Callback):
    def on_batch_end(self, trainer, pl_module):
        lr_scheduler = trainer.lr_schedulers[0]["scheduler"]
        lrs = {f"lr_group_{i}": lr for i, lr in enumerate(lr_scheduler.get_lr())}
        pl_module.logger.log_metrics(lrs)

    def on_validation_end(self, trainer: pl.Trainer, pl_module: pl.LightningModule):
        rank_zero_info("***** Validation results *****")
        metrics = trainer.callback_metrics
        # Log results
        for key in sorted(metrics):
            if key not in ["log", "progress_bar"]:
                rank_zero_info("{} = {}\n".format(key, str(metrics[key])))

    def on_test_end(self, trainer: pl.Trainer, pl_module: pl.LightningModule):
        rank_zero_info("***** Test results *****")
        metrics = trainer.callback_metrics
        # Log and save results to file
        output_test_results_file = os.path.join(pl_module.hparams.output_dir, "test_results.txt")
        with open(output_test_results_file, "w") as writer:
            for key in sorted(metrics):
                if key not in ["log", "progress_bar"]:
                    rank_zero_info("{} = {}\n".format(key, str(metrics[key])))
                    writer.write("{} = {}\n".format(key, str(metrics[key])))


def add_generic_args(parser, root_dir) -> None:
    #  To allow all pl args uncomment the following line
    #  parser = pl.Trainer.add_argparse_args(parser)
    parser.add_argument(
        "--output_dir",
        default=None,
        type=str,
        required=True,
        help="The output directory where the model predictions and checkpoints will be written.",
    )
    parser.add_argument(
        "--fp16",
        action="store_true",
        help="Whether to use 16-bit (mixed) precision (through NVIDIA apex) instead of 32-bit",
    )

    parser.add_argument(
        "--fp16_opt_level",
        type=str,
        default="O2",
        help=(
            "For fp16: Apex AMP optimization level selected in ['O0', 'O1', 'O2', and 'O3']."
            "See details at https://nvidia.github.io/apex/amp.html"
        ),
    )
    parser.add_argument("--n_tpu_cores", dest="tpu_cores", type=int)
    parser.add_argument("--max_grad_norm", dest="gradient_clip_val", default=1.0, type=float, help="Max gradient norm")
    parser.add_argument("--do_train", action="store_true", help="Whether to run training.")
    parser.add_argument("--do_predict", action="store_true", help="Whether to run predictions on the test set.")
    parser.add_argument(
        "--gradient_accumulation_steps",
        dest="accumulate_grad_batches",
        type=int,
        default=1,
        help="Number of updates steps to accumulate before performing a backward/update pass.",
    )
    parser.add_argument("--seed", type=int, default=42, help="random seed for initialization")
    parser.add_argument(
        "--data_dir",
        default=None,
        type=str,
        required=True,
        help="The input data dir. Should contain the training files for the CoNLL-2003 NER task.",
    )


def generic_train(
    model: BaseTransformer,
    args: argparse.Namespace,
    early_stopping_callback=None,
    logger=True,  # can pass WandbLogger() here
    extra_callbacks=[],
    checkpoint_callback=None,
    logging_callback=None,
    **extra_train_kwargs,
):
    pl.seed_everything(args.seed)

    # init model
    odir = Path(model.hparams.output_dir)
    odir.mkdir(exist_ok=True)

    # add custom checkpoints
    if checkpoint_callback is None:
        checkpoint_callback = pl.callbacks.ModelCheckpoint(
            filepath=args.output_dir, prefix="checkpoint", monitor="val_loss", mode="min", save_top_k=1
        )
    if early_stopping_callback:
        extra_callbacks.append(early_stopping_callback)
    if logging_callback is None:
        logging_callback = LoggingCallback()

    train_params = {}

    # TODO: remove with PyTorch 1.6 since pl uses native amp
    if args.fp16:
        train_params["precision"] = 16
        train_params["amp_level"] = args.fp16_opt_level

    if args.gpus > 1:
        train_params["distributed_backend"] = "ddp"

    train_params["accumulate_grad_batches"] = args.accumulate_grad_batches
    train_params["accelerator"] = extra_train_kwargs.get("accelerator", None)
    train_params["profiler"] = extra_train_kwargs.get("profiler", None)

    trainer = pl.Trainer.from_argparse_args(
        args,
        weights_summary=None,
        callbacks=[logging_callback] + extra_callbacks,
        logger=logger,
        checkpoint_callback=checkpoint_callback,
        **train_params,
    )

    if args.do_train:
        trainer.fit(model)

    return trainer

import argparse
import logging
import os
from pathlib import Path
from typing import Any, Dict

import pytorch_lightning as pl
from pytorch_lightning.utilities import rank_zero_info

from transformers import (
    AdamW,
    AutoConfig,
    AutoModel,
    AutoModelForPreTraining,
    AutoModelForQuestionAnswering,
    AutoModelForSeq2SeqLM,
    AutoModelForSequenceClassification,
    AutoModelForTokenClassification,
    AutoModelWithLMHead,
    AutoTokenizer,
    PretrainedConfig,
    PreTrainedTokenizer,
)
from transformers.optimization import (
    Adafactor,
    get_cosine_schedule_with_warmup,
    get_cosine_with_hard_restarts_schedule_with_warmup,
    get_linear_schedule_with_warmup,
    get_polynomial_decay_schedule_with_warmup,
)
from transformers.utils.versions import require_version


logger = logging.getLogger(__name__)

require_version("pytorch_lightning>=1.0.4")

MODEL_MODES = {
    "base": AutoModel,
    "sequence-classification": AutoModelForSequenceClassification,
    "question-answering": AutoModelForQuestionAnswering,
    "pretraining": AutoModelForPreTraining,
    "token-classification": AutoModelForTokenClassification,
    "language-modeling": AutoModelWithLMHead,
    "summarization": AutoModelForSeq2SeqLM,
    "translation": AutoModelForSeq2SeqLM,
}


# update this and the import above to support new schedulers from transformers.optimization
arg_to_scheduler = {
    "linear": get_linear_schedule_with_warmup,
    "cosine": get_cosine_schedule_with_warmup,
    "cosine_w_restarts": get_cosine_with_hard_restarts_schedule_with_warmup,
    "polynomial": get_polynomial_decay_schedule_with_warmup,
    # '': get_constant_schedule,             # not supported for now
    # '': get_constant_schedule_with_warmup, # not supported for now
}
arg_to_scheduler_choices = sorted(arg_to_scheduler.keys())
arg_to_scheduler_metavar = "{" + ", ".join(arg_to_scheduler_choices) + "}"


class BaseTransformer(pl.LightningModule):
    def __init__(
        self,
        hparams: argparse.Namespace,
        num_labels=None,
        mode="base",
        config=None,
        tokenizer=None,
        model=None,
        **config_kwargs,
    ):
        """Initialize a model, tokenizer and config."""
        super().__init__()
        # TODO: move to self.save_hyperparameters()
        # self.save_hyperparameters()
        # can also expand arguments into trainer signature for easier reading

        self.save_hyperparameters(hparams)
        self.step_count = 0
        self.output_dir = Path(self.hparams.output_dir)
        cache_dir = self.hparams.cache_dir if self.hparams.cache_dir else None
        if config is None:
            self.config = AutoConfig.from_pretrained(
                self.hparams.config_name if self.hparams.config_name else self.hparams.model_name_or_path,
                **({"num_labels": num_labels} if num_labels is not None else {}),
                cache_dir=cache_dir,
                **config_kwargs,
            )
        else:
            self.config: PretrainedConfig = config

        extra_model_params = ("encoder_layerdrop", "decoder_layerdrop", "dropout", "attention_dropout")
        for p in extra_model_params:
            if getattr(self.hparams, p, None):
                assert hasattr(self.config, p), f"model config doesn't have a `{p}` attribute"
                setattr(self.config, p, getattr(self.hparams, p))

        if tokenizer is None:
            self.tokenizer = AutoTokenizer.from_pretrained(
                self.hparams.tokenizer_name if self.hparams.tokenizer_name else self.hparams.model_name_or_path,
                cache_dir=cache_dir,
            )
        else:
            self.tokenizer: PreTrainedTokenizer = tokenizer
        self.model_type = MODEL_MODES[mode]
        if model is None:
            self.model = self.model_type.from_pretrained(
                self.hparams.model_name_or_path,
                from_tf=bool(".ckpt" in self.hparams.model_name_or_path),
                config=self.config,
                cache_dir=cache_dir,
            )
        else:
            self.model = model

    def load_hf_checkpoint(self, *args, **kwargs):
        self.model = self.model_type.from_pretrained(*args, **kwargs)

    def get_lr_scheduler(self):
        get_schedule_func = arg_to_scheduler[self.hparams.lr_scheduler]
        scheduler = get_schedule_func(
            self.opt, num_warmup_steps=self.hparams.warmup_steps, num_training_steps=self.total_steps()
        )
        scheduler = {"scheduler": scheduler, "interval": "step", "frequency": 1}
        return scheduler

    def configure_optimizers(self):
        """Prepare optimizer and schedule (linear warmup and decay)"""
        model = self.model
        no_decay = ["bias", "LayerNorm.weight"]
        optimizer_grouped_parameters = [
            {
                "params": [p for n, p in model.named_parameters() if not any(nd in n for nd in no_decay)],
                "weight_decay": self.hparams.weight_decay,
            },
            {
                "params": [p for n, p in model.named_parameters() if any(nd in n for nd in no_decay)],
                "weight_decay": 0.0,
            },
        ]
        if self.hparams.adafactor:
            optimizer = Adafactor(
                optimizer_grouped_parameters, lr=self.hparams.learning_rate, scale_parameter=False, relative_step=False
            )

        else:
            optimizer = AdamW(
                optimizer_grouped_parameters, lr=self.hparams.learning_rate, eps=self.hparams.adam_epsilon
            )
        self.opt = optimizer

        scheduler = self.get_lr_scheduler()

        return [optimizer], [scheduler]

    def test_step(self, batch, batch_nb):
        return self.validation_step(batch, batch_nb)

    def test_epoch_end(self, outputs):
        return self.validation_end(outputs)

    def total_steps(self) -> int:
        """The number of total training steps that will be run. Used for lr scheduler purposes."""
        num_devices = max(1, self.hparams.gpus)  # TODO: consider num_tpu_cores
        effective_batch_size = self.hparams.train_batch_size * self.hparams.accumulate_grad_batches * num_devices
        return (self.dataset_size / effective_batch_size) * self.hparams.max_epochs

    def setup(self, mode):
        if mode == "test":
            self.dataset_size = len(self.test_dataloader().dataset)
        else:
            self.train_loader = self.get_dataloader("train", self.hparams.train_batch_size, shuffle=True)
            self.dataset_size = len(self.train_dataloader().dataset)

    def get_dataloader(self, type_path: str, batch_size: int, shuffle: bool = False):
        raise NotImplementedError("You must implement this for your task")

    def train_dataloader(self):
        return self.train_loader

    def val_dataloader(self):
        return self.get_dataloader("dev", self.hparams.eval_batch_size, shuffle=False)

    def test_dataloader(self):
        return self.get_dataloader("test", self.hparams.eval_batch_size, shuffle=False)

    def _feature_file(self, mode):
        return os.path.join(
            self.hparams.data_dir,
            "cached_{}_{}_{}".format(
                mode,
                list(filter(None, self.hparams.model_name_or_path.split("/"))).pop(),
                str(self.hparams.max_seq_length),
            ),
        )

    @pl.utilities.rank_zero_only
    def on_save_checkpoint(self, checkpoint: Dict[str, Any]) -> None:
        save_path = self.output_dir.joinpath("best_tfmr")
        self.model.config.save_step = self.step_count
        self.model.save_pretrained(save_path)
        self.tokenizer.save_pretrained(save_path)

    @staticmethod
    def add_model_specific_args(parser, root_dir):
        parser.add_argument(
            "--model_name_or_path",
            default=None,
            type=str,
            required=True,
            help="Path to pretrained model or model identifier from huggingface.co/models",
        )
        parser.add_argument(
            "--config_name", default="", type=str, help="Pretrained config name or path if not the same as model_name"
        )
        parser.add_argument(
            "--tokenizer_name",
            default=None,
            type=str,
            help="Pretrained tokenizer name or path if not the same as model_name",
        )
        parser.add_argument(
            "--cache_dir",
            default="",
            type=str,
            help="Where do you want to store the pre-trained models downloaded from huggingface.co",
        )
        parser.add_argument(
            "--encoder_layerdrop",
            type=float,
            help="Encoder layer dropout probability (Optional). Goes into model.config",
        )
        parser.add_argument(
            "--decoder_layerdrop",
            type=float,
            help="Decoder layer dropout probability (Optional). Goes into model.config",
        )
        parser.add_argument(
            "--dropout",
            type=float,
            help="Dropout probability (Optional). Goes into model.config",
        )
        parser.add_argument(
            "--attention_dropout",
            type=float,
            help="Attention dropout probability (Optional). Goes into model.config",
        )
        parser.add_argument("--learning_rate", default=5e-5, type=float, help="The initial learning rate for Adam.")
        parser.add_argument(
            "--lr_scheduler",
            default="linear",
            choices=arg_to_scheduler_choices,
            metavar=arg_to_scheduler_metavar,
            type=str,
            help="Learning rate scheduler",
        )
        parser.add_argument("--weight_decay", default=0.0, type=float, help="Weight decay if we apply some.")
        parser.add_argument("--adam_epsilon", default=1e-8, type=float, help="Epsilon for Adam optimizer.")
        parser.add_argument("--warmup_steps", default=0, type=int, help="Linear warmup over warmup_steps.")
        parser.add_argument("--num_workers", default=4, type=int, help="kwarg passed to DataLoader")
        parser.add_argument("--num_train_epochs", dest="max_epochs", default=3, type=int)
        parser.add_argument("--train_batch_size", default=32, type=int)
        parser.add_argument("--eval_batch_size", default=32, type=int)
        parser.add_argument("--adafactor", action="store_true")


class LoggingCallback(pl.Callback):
    def on_batch_end(self, trainer, pl_module):
        lr_scheduler = trainer.lr_schedulers[0]["scheduler"]
        lrs = {f"lr_group_{i}": lr for i, lr in enumerate(lr_scheduler.get_lr())}
        pl_module.logger.log_metrics(lrs)

    def on_validation_end(self, trainer: pl.Trainer, pl_module: pl.LightningModule):
        rank_zero_info("***** Validation results *****")
        metrics = trainer.callback_metrics
        # Log results
        for key in sorted(metrics):
            if key not in ["log", "progress_bar"]:
                rank_zero_info("{} = {}\n".format(key, str(metrics[key])))

    def on_test_end(self, trainer: pl.Trainer, pl_module: pl.LightningModule):
        rank_zero_info("***** Test results *****")
        metrics = trainer.callback_metrics
        # Log and save results to file
        output_test_results_file = os.path.join(pl_module.hparams.output_dir, "test_results.txt")
        with open(output_test_results_file, "w") as writer:
            for key in sorted(metrics):
                if key not in ["log", "progress_bar"]:
                    rank_zero_info("{} = {}\n".format(key, str(metrics[key])))
                    writer.write("{} = {}\n".format(key, str(metrics[key])))


def add_generic_args(parser, root_dir) -> None:
    #  To allow all pl args uncomment the following line
    #  parser = pl.Trainer.add_argparse_args(parser)
    parser.add_argument(
        "--output_dir",
        default=None,
        type=str,
        required=True,
        help="The output directory where the model predictions and checkpoints will be written.",
    )
    parser.add_argument(
        "--fp16",
        action="store_true",
        help="Whether to use 16-bit (mixed) precision (through NVIDIA apex) instead of 32-bit",
    )

    parser.add_argument(
        "--fp16_opt_level",
        type=str,
        default="O2",
        help=(
            "For fp16: Apex AMP optimization level selected in ['O0', 'O1', 'O2', and 'O3']."
            "See details at https://nvidia.github.io/apex/amp.html"
        ),
    )
    parser.add_argument("--n_tpu_cores", dest="tpu_cores", type=int)
    parser.add_argument("--max_grad_norm", dest="gradient_clip_val", default=1.0, type=float, help="Max gradient norm")
    parser.add_argument("--do_train", action="store_true", help="Whether to run training.")
    parser.add_argument("--do_predict", action="store_true", help="Whether to run predictions on the test set.")
    parser.add_argument(
        "--gradient_accumulation_steps",
        dest="accumulate_grad_batches",
        type=int,
        default=1,
        help="Number of updates steps to accumulate before performing a backward/update pass.",
    )
    parser.add_argument("--seed", type=int, default=42, help="random seed for initialization")
    parser.add_argument(
        "--data_dir",
        default=None,
        type=str,
        required=True,
        help="The input data dir. Should contain the training files for the CoNLL-2003 NER task.",
    )


def generic_train(
    model: BaseTransformer,
    args: argparse.Namespace,
    early_stopping_callback=None,
    logger=True,  # can pass WandbLogger() here
    extra_callbacks=[],
    checkpoint_callback=None,
    logging_callback=None,
    **extra_train_kwargs,
):
    pl.seed_everything(args.seed)

    # init model
    odir = Path(model.hparams.output_dir)
    odir.mkdir(exist_ok=True)

    # add custom checkpoints
    if checkpoint_callback is None:
        checkpoint_callback = pl.callbacks.ModelCheckpoint(
            filepath=args.output_dir, prefix="checkpoint", monitor="val_loss", mode="min", save_top_k=1
        )
    if early_stopping_callback:
        extra_callbacks.append(early_stopping_callback)
    if logging_callback is None:
        logging_callback = LoggingCallback()

    train_params = {}

    # TODO: remove with PyTorch 1.6 since pl uses native amp
    if args.fp16:
        train_params["precision"] = 16
        train_params["amp_level"] = args.fp16_opt_level

    if args.gpus > 1:
        train_params["distributed_backend"] = "ddp"

    train_params["accumulate_grad_batches"] = args.accumulate_grad_batches
    train_params["accelerator"] = extra_train_kwargs.get("accelerator", None)
    train_params["profiler"] = extra_train_kwargs.get("profiler", None)

    trainer = pl.Trainer.from_argparse_args(
        args,
        weights_summary=None,
        callbacks=[logging_callback] + extra_callbacks,
        logger=logger,
        checkpoint_callback=checkpoint_callback,
        **train_params,
    )

    if args.do_train:
        trainer.fit(model)

    return trainer
