text-generation-webui/modules/LoRA.py

from pathlib import Path

import modules.shared as shared
from modules.logging_colors import logger


def add_lora_to_model(lora_names):
    add_lora_transformers(lora_names)


def get_lora_path(lora_name):
    p = Path(lora_name)
    if p.exists():
        lora_name = p.parts[-1]

    return Path(f"{shared.args.lora_dir}/{lora_name}")


def add_lora_transformers(lora_names):
    from peft import PeftModel

    from modules.torch_utils import get_device

    prior_set = set(shared.lora_names)
    added_set = set(lora_names) - prior_set
    removed_set = prior_set - set(lora_names)

    # If no LoRA needs to be added or removed, exit
    if len(added_set) == 0 and len(removed_set) == 0:
        return

    # Add a LoRA when another LoRA is already present
    if len(removed_set) == 0 and len(prior_set) > 0 and "__merged" not in shared.model.peft_config.keys():
        logger.info(f"Adding the LoRA(s) named {added_set} to the model")
        for lora in added_set:
            shared.model.load_adapter(get_lora_path(lora), lora)

        if len(lora_names) > 1:
            merge_loras()

        shared.lora_names = lora_names
        return

    # If any LoRA needs to be removed, start over
    if len(removed_set) > 0:
        shared.model = shared.model.unload()

    if len(lora_names) > 0:
        params = {}
        if not shared.args.cpu:
            if not shared.args.load_in_4bit and not shared.args.load_in_8bit:
                params['dtype'] = shared.model.dtype
                if hasattr(shared.model, "hf_device_map"):
                    params['device_map'] = {"base_model.model." + k: v for k, v in shared.model.hf_device_map.items()}

        logger.info("Applying the following LoRAs to {}: {}".format(shared.model_name, ', '.join(lora_names)))
        shared.model = PeftModel.from_pretrained(shared.model, get_lora_path(lora_names[0]), adapter_name=lora_names[0], **params)
        for lora in lora_names[1:]:
            shared.model.load_adapter(get_lora_path(lora), lora)

        if len(lora_names) > 1:
            merge_loras()

        if not shared.args.load_in_8bit and not shared.args.cpu:
            shared.model.half()
            if not hasattr(shared.model, "hf_device_map"):
                device = get_device()
                if device:
                    shared.model = shared.model.to(device)

    shared.lora_names = lora_names


def merge_loras():
    if len(list({shared.model.peft_config[adapter].r for adapter in shared.model.peft_config.keys()})) > 1:
        logger.warning("The loaded LoRAs cannot be merged, as they have dissimilar ranks. Only the first one will be active.")
        return

    shared.model.add_weighted_adapter(shared.lora_names, [1] * len(shared.lora_names), "__merged")
    shared.model.set_adapter("__merged")