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import os
from pathlib import Path
from typing import Any, Dict, Optional, Union
import torch
from exllamav2 import ExLlamaV2, ExLlamaV2Cache, ExLlamaV2Config
from torch.nn import CrossEntropyLoss
from transformers import GenerationConfig, PretrainedConfig, PreTrainedModel
from transformers.modeling_outputs import CausalLMOutputWithPast
from modules import shared
from modules.logging_colors import logger
class Exllamav2HF(PreTrainedModel):
def __init__(self, config: ExLlamaV2Config):
super().__init__(PretrainedConfig())
self.ex_config = config
self.ex_model = ExLlamaV2(config)
split = None
if shared.args.gpu_split:
split = [float(alloc) for alloc in shared.args.gpu_split.split(",")]
self.ex_model.load(split)
self.generation_config = GenerationConfig()
self.ex_cache = ExLlamaV2Cache(self.ex_model)
self.past_seq = None
if shared.args.cfg_cache:
self.ex_cache_negative = ExLlamaV2Cache(self.ex_model)
self.past_seq_negative = None
def _validate_model_class(self):
pass
def _validate_model_kwargs(self, model_kwargs: Dict[str, Any]):
pass
def prepare_inputs_for_generation(self, input_ids, **kwargs):
return {'input_ids': input_ids, **kwargs}
@property
def device(self) -> torch.device:
return torch.device(0)
def __call__(self, *args, **kwargs):
use_cache = kwargs.get('use_cache', True)
labels = kwargs.get('labels', None)
past_key_values = kwargs.get('past_key_values', None)
if len(args) > 0:
if not shared.args.cfg_cache:
logger.error("Please enable the cfg-cache option to use CFG with ExLlamav2_HF.")
return
input_ids = args[0]
is_negative = True
past_seq = self.past_seq_negative
ex_cache = self.ex_cache_negative
else:
input_ids = kwargs['input_ids']
is_negative = False
past_seq = self.past_seq
ex_cache = self.ex_cache
seq = input_ids[0].tolist()
if is_negative and past_key_values is not None:
seq = past_key_values + seq
seq_tensor = torch.tensor(seq)
# Make the forward call
if labels is None:
if past_seq is None or not torch.equal(past_seq, seq_tensor[:-1]):
ex_cache.current_seq_len = 0
self.ex_model.forward(torch.tensor([seq[:-1]], dtype=torch.long), ex_cache, preprocess_only=True)
logits = self.ex_model.forward(torch.tensor([seq[-1:]], dtype=torch.long), ex_cache).to(input_ids.device)
else:
ex_cache.current_seq_len = 0
# logits = self.ex_model.forward(torch.tensor([seq], dtype=torch.long), ex_cache, last_id_only=False)
logits = self.ex_model.forward(torch.tensor([seq], dtype=torch.long), ex_cache)
if is_negative:
self.past_seq_negative = seq_tensor
else:
self.past_seq = seq_tensor
loss = None
if labels is not None:
# Shift so that tokens < n predict n
shift_logits = logits[..., :-1, :].contiguous()
shift_labels = labels[..., 1:].contiguous()
# Flatten the tokens
loss_fct = CrossEntropyLoss()
shift_logits = shift_logits.view(-1, logits.shape[-1])
shift_labels = shift_labels.view(-1)
# Enable model parallelism
shift_labels = shift_labels.to(shift_logits.device)
loss = loss_fct(shift_logits, shift_labels)
return CausalLMOutputWithPast(logits=logits, past_key_values=seq if use_cache else None, loss=loss)
@classmethod
def from_pretrained(cls, pretrained_model_name_or_path: Optional[Union[str, os.PathLike]], *model_args, **kwargs):
assert len(model_args) == 0 and len(kwargs) == 0, "extra args is currently not supported"
if isinstance(pretrained_model_name_or_path, str):
pretrained_model_name_or_path = Path(pretrained_model_name_or_path)
pretrained_model_name_or_path = Path(f'{shared.args.model_dir}') / Path(pretrained_model_name_or_path)
config = ExLlamaV2Config()
config.model_dir = str(pretrained_model_name_or_path)
config.prepare()
config.max_seq_len = shared.args.max_seq_len
config.scale_pos_emb = shared.args.compress_pos_emb
config.scale_alpha_value = shared.args.alpha_value
return Exllamav2HF(config)
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