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# Copyright (c) Facebook, Inc. and its affiliates.
#
# This source code is licensed under the MIT license found in the
# LICENSE file in the root directory of this source tree.
import math
from dataclasses import dataclass, field
from typing import List, Optional
import torch
import torch.nn.functional as F
from fairseq import metrics, utils
from fairseq.criterions import FairseqCriterion, register_criterion
from fairseq.dataclass import FairseqDataclass
from fairseq.logging.meters import safe_round
from fairseq.utils import is_xla_tensor
@dataclass
class Wav2VecCriterionConfig(FairseqDataclass):
infonce: bool = field(
default=False,
metadata={
"help": "if set, uses cross entropy instead of binary cross entropy (i.e. InfoNCE loss)"
},
)
loss_weights: Optional[List[float]] = field(
default=None,
metadata={"help": "weights for additional loss terms (not first one)"},
)
log_keys: List[str] = field(
default_factory=lambda: [],
metadata={"help": "output keys to log"},
)
@register_criterion("wav2vec", dataclass=Wav2VecCriterionConfig)
class Wav2vecCriterion(FairseqCriterion):
def __init__(self, task, infonce=False, loss_weights=None, log_keys=None):
super().__init__(task)
self.infonce = infonce
self.loss_weights = loss_weights
self.log_keys = [] if log_keys is None else log_keys
def forward(self, model, sample, reduce=True):
"""Compute the loss for the given sample.
Returns a tuple with three elements:
1) the loss
2) the sample size, which is used as the denominator for the gradient
3) logging outputs to display while training
"""
net_output = model(**sample["net_input"])
logits = model.get_logits(net_output).float()
target = model.get_targets(sample, net_output)
self.xla = is_xla_tensor(logits)
# XXX: handle weights on xla.
weights = None
if hasattr(model, "get_target_weights") and not self.infonce:
weights = model.get_target_weights(target, net_output)
if torch.is_tensor(weights):
weights = weights.float()
losses = []
reduction = "none" if ((not reduce) or self.xla) else "sum"
if self.infonce:
loss = F.cross_entropy(logits, target, reduction=reduction)
else:
loss = F.binary_cross_entropy_with_logits(
logits, target.float(), weights, reduction=reduction
)
if self.xla:
# tpu-comment: since dynamic shapes lead to recompilations on xla,
# we don't shrink tensors using mask_indices.
# Instead, we use mask indices to adjust loss.
mi = (
sample['net_input']['mask_indices']
.transpose(0, 1) # logits are transposed in `model.get_logits`
.reshape(logits.size(0))
)
loss = (loss * mi).sum() if reduce else (loss * mi)
if 'sample_size' in sample:
sample_size = sample['sample_size']
elif 'mask_indices' in sample['net_input']:
sample_size = sample['net_input']['mask_indices'].sum()
else:
sample_size = target.numel() if self.infonce else target.long().sum().item()
losses.append(loss.detach().clone())
if self.loss_weights is not None:
assert hasattr(model, "get_extra_losses")
extra_losses = model.get_extra_losses(net_output)
if torch.is_tensor(extra_losses):
extra_losses = [extra_losses]
if len(self.loss_weights) == 1 and len(extra_losses) != 1:
self.loss_weights = [self.loss_weights[0]] * len(extra_losses)
assert len(extra_losses) == len(
self.loss_weights
), f"{len(extra_losses)}, {len(self.loss_weights)}"
for p, coef in zip(extra_losses, self.loss_weights):
if coef != 0 and p is not None:
p = coef * p.float() * sample_size
loss += p
losses.append(p)
logging_output = {
"loss": loss.item() if (reduce and not self.xla) else loss.detach(),
"ntokens": sample_size,
"nsentences": sample["id"].numel(),
"sample_size": sample_size,
}
for lk in self.log_keys:
# Only store "logits" and "target" for computing MAP and MAUC
# during validation
if lk == "logits":
if not self.training:
logging_output["logits"] = logits.cpu().numpy()
elif lk == "target":
if not self.training:
# If the targets have been mixed with the predictions of
# teacher models, find the original targets
if hasattr(model, "get_original_targets"):
original_target = model.get_original_targets(sample, net_output)
else:
original_target = target
logging_output["target"] = original_target.cpu().numpy()
elif lk in net_output:
value = net_output[lk]
if not is_xla_tensor(value):
value = float(value)
logging_output[lk] = value
if len(losses) > 1:
for i, l in enumerate(losses):
logging_output[f"loss_{i}"] = l.item() if not self.xla else l.detach()
if self.infonce:
with torch.no_grad():
if logits.numel() == 0:
corr = 0
count = 0
else:
assert logits.dim() > 1, logits.shape
max = logits.argmax(-1) == 0
min = logits.argmin(-1) == 0
if is_xla_tensor(logits):
max, min = max * mi, min * mi
both = max & min
corr = max.long().sum() - both.long().sum()
count = mi.sum()
else:
both = max & min
corr = max.long().sum().item() - both.long().sum().item()
count = float(max.numel())
logging_output["correct"] = corr
logging_output["count"] = count
return loss, sample_size, logging_output
@staticmethod
def reduce_metrics(logging_outputs) -> None:
"""Aggregate logging outputs from data parallel training."""
loss_sum = utils.item(sum(log.get("loss", 0) for log in logging_outputs))
ntokens = utils.item(sum(log.get("ntokens", 0) for log in logging_outputs))
nsentences = utils.item(
sum(log.get("nsentences", 0) for log in logging_outputs)
)
sample_size = utils.item(
sum(log.get("sample_size", 0) for log in logging_outputs)
)
metrics.log_scalar(
"loss", loss_sum / (sample_size or 1) / math.log(2), sample_size, round=3
)
metrics.log_scalar("ntokens", ntokens)
metrics.log_scalar("nsentences", nsentences)
correct = sum(log.get("correct", 0) for log in logging_outputs)
metrics.log_scalar("_correct", correct)
total = sum(log.get("count", 0) for log in logging_outputs)
metrics.log_scalar("_total", total)
if total > 0:
metrics.log_derived(
"accuracy",
lambda meters: safe_round(
meters["_correct"].sum / meters["_total"].sum, 5
)
if meters["_total"].sum > 0
else float("nan"),
)
builtin_keys = {
"loss",
"ntokens",
"nsentences",
"sample_size",
"correct",
"count",
}
for k in logging_outputs[0]:
if k not in builtin_keys:
val = sum(log.get(k, 0) for log in logging_outputs)
if k.startswith("loss"):
metrics.log_scalar(
k, val / (sample_size or 1) / math.log(2), sample_size, round=3
)
else:
metrics.log_scalar(k, val / len(logging_outputs), round=3)
# FIXME: revert when gather based xla reduction is implemented
#@staticmethod
#def logging_outputs_can_be_summed() -> bool:
def logging_outputs_can_be_summed(self) -> bool:
"""
Whether the logging outputs returned by `forward` can be summed
across workers prior to calling `reduce_metrics`. Setting this
to True will improves distributed training speed.
"""
# XXX: Gather based reduction not implemented for xla yet.
# So we fall to sum based reduction for xla.
return self.xla
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