paligemma.py

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
from collections.abc import Iterable, Mapping, Sequence
from typing import Annotated, Literal, TypeAlias

import torch
from torch import nn
from transformers import BatchFeature, PaliGemmaConfig

from vllm.config import VllmConfig
from vllm.config.multimodal import BaseDummyOptions
from vllm.logger import init_logger
from vllm.multimodal import MULTIMODAL_REGISTRY
from vllm.multimodal.inputs import (
    MultiModalDataDict,
    MultiModalFieldConfig,
    MultiModalInputs,
    MultiModalKwargsItems,
    MultiModalUUIDDict,
)
from vllm.multimodal.parse import (
    ImageEmbeddingItems,
    ImageProcessorItems,
    MultiModalDataItems,
)
from vllm.multimodal.processing import (
    BaseMultiModalProcessor,
    BaseProcessingInfo,
    PromptIndexTargets,
    PromptInsertion,
    PromptUpdate,
    PromptUpdateDetails,
)
from vllm.multimodal.profiling import BaseDummyInputsBuilder
from vllm.sequence import IntermediateTensors
from vllm.utils.tensor_schema import TensorSchema, TensorShape

from .interfaces import MultiModalEmbeddings, SupportsMultiModal, SupportsPP
from .siglip import SiglipVisionModel
from .utils import (
    AutoWeightsLoader,
    WeightsMapper,
    flatten_bn,
    init_vllm_registered_model,
    maybe_prefix,
)
from .vision import get_vision_encoder_info

logger = init_logger(__name__)


class PaliGemmaImagePixelInputs(TensorSchema):
    """
    Dimensions:
        - bn: Batch size * number of images
        - c: Number of channels (3)
        - h: Height
        - w: Width
    """

    type: Literal["pixel_values"] = "pixel_values"
    data: Annotated[torch.Tensor, TensorShape("bn", 3, "h", "w")]


class PaliGemmaImageEmbeddingInputs(TensorSchema):
    """
    Dimensions:
        - bn: Batch size * number of images
        - ifs: Image feature size
        - hs: Hidden size (must match language model backbone)
    """

    type: Literal["image_embeds"] = "image_embeds"
    data: Annotated[torch.Tensor, TensorShape("bn", "ifs", "hs")]


PaliGemmaImageInputs: TypeAlias = (
    PaliGemmaImagePixelInputs | PaliGemmaImageEmbeddingInputs
)


class PaliGemmaMultiModalProjector(nn.Module):
    def __init__(self, vision_hidden_size: int, projection_dim: int):
        super().__init__()

        self.linear = nn.Linear(vision_hidden_size, projection_dim, bias=True)

    def forward(self, image_features: torch.Tensor) -> torch.Tensor:
        hidden_states = self.linear(image_features)
        return hidden_states


class PaliGemmaProcessingInfo(BaseProcessingInfo):
    def get_hf_config(self):
        return self.ctx.get_hf_config(PaliGemmaConfig)

    def get_vision_encoder_info(self):
        return get_vision_encoder_info(self.get_hf_config())

    def get_supported_mm_limits(self) -> Mapping[str, int | None]:
        return {"image": 1}

    def get_num_image_tokens(
        self,
        *,
        image_width: int,
        image_height: int,
    ) -> int:
        vision_encoder_info = self.get_vision_encoder_info()

        return vision_encoder_info.get_num_image_tokens(
            image_width=image_width,
            image_height=image_height,
        )


class PaliGemmaDummyInputsBuilder(BaseDummyInputsBuilder[PaliGemmaProcessingInfo]):
    def get_dummy_text(self, mm_counts: Mapping[str, int]) -> str:
        return ""

    def get_dummy_mm_data(
        self,
        seq_len: int,
        mm_counts: Mapping[str, int],
        mm_options: Mapping[str, BaseDummyOptions] | None = None,
    ) -> MultiModalDataDict:
        hf_config = self.info.get_hf_config()
        vision_config = hf_config.vision_config
        max_image_size = vision_config.image_size

        num_images = mm_counts.get("image", 0)

        image_overrides = mm_options.get("image") if mm_options else None

        return {
            "image": self._get_dummy_images(
                width=max_image_size,
                height=max_image_size,
                num_images=num_images,
                overrides=image_overrides,
            )
        }


class PaliGemmaMultiModalProcessor(BaseMultiModalProcessor[PaliGemmaProcessingInfo]):
    def _call_hf_processor(
        self,
        prompt: str,
        mm_data: Mapping[str, object],
        mm_kwargs: Mapping[str, object],
        tok_kwargs: Mapping[str, object],
    ) -> BatchFeature:
        tokenizer = self.info.get_tokenizer()
        if not mm_data:
            prompt_ids = tokenizer.encode(prompt, add_special_tokens=False)
            return BatchFeature(dict(input_ids=[prompt_ids]), tensor_type="pt")

        return super()._call_hf_processor(
            prompt=prompt,
            mm_data=mm_data,
            mm_kwargs=mm_kwargs,
            tok_kwargs=tok_kwargs,
        )

    def _get_mm_fields_config(
        self,
        hf_inputs: BatchFeature,
        hf_processor_mm_kwargs: Mapping[str, object],
    ) -> Mapping[str, MultiModalFieldConfig]:
        return dict(pixel_values=MultiModalFieldConfig.batched("image"))

    def _get_prompt_updates(
        self,
        mm_items: MultiModalDataItems,
        hf_processor_mm_kwargs: Mapping[str, object],
        out_mm_kwargs: MultiModalKwargsItems,
    ) -> Sequence[PromptUpdate]:
        hf_config = self.info.get_hf_config()
        image_token_id = hf_config.image_token_index

        tokenizer = self.info.get_tokenizer()

        bos_token_id = tokenizer.bos_token_id
        assert isinstance(bos_token_id, int)

        def get_insertion(item_idx: int):
            images = mm_items.get_items(
                "image", (ImageEmbeddingItems, ImageProcessorItems)
            )

            if isinstance(images, ImageEmbeddingItems):
                num_image_tokens = images.get_feature_size(item_idx)
            else:
                image_size = images.get_image_size(item_idx)
                num_image_tokens = self.info.get_num_image_tokens(
                    image_width=image_size.width,
                    image_height=image_size.height,
                )

            image_tokens = [image_token_id] * num_image_tokens

            return PromptUpdateDetails.select_token_id(
                image_tokens + [bos_token_id],
                embed_token_id=image_token_id,
            )

        # Paligemma 1 and 2 have different tokenizer.add_bos_token
        # Insert <image>*n + <bos> after <bos> for Paligemma 1
        # Insert <image>*n + <bos> for Paligemma 2
        return [
            PromptInsertion(
                modality="image",
                target=PromptIndexTargets.prefix(
                    [bos_token_id] if tokenizer.add_bos_token else []
                ),
                insertion=get_insertion,
            )
        ]

    def apply(
        self,
        prompt: str | list[int],
        mm_data: MultiModalDataDict,
        hf_processor_mm_kwargs: Mapping[str, object],
        tokenization_kwargs: Mapping[str, object] | None = None,
        mm_uuids: MultiModalUUIDDict | None = None,
    ) -> MultiModalInputs:
        mm_inputs = super().apply(
            prompt,
            mm_data,
            hf_processor_mm_kwargs,
            tokenization_kwargs,
            mm_uuids=mm_uuids,
        )
        prompt_token_ids = mm_inputs["prompt_token_ids"]

        tokenizer = self.info.get_tokenizer()
        newline_prompt = "\n"
        newline_token_id = tokenizer.encode(newline_prompt)[-1]  # 108
        # Force to add newline at the end of prompt for paligemma's format
        # This step can NOT be replacemented by current PromptUpdate methods
        if len(prompt_token_ids) and prompt_token_ids[-1] != newline_token_id:
            prompt_token_ids.append(newline_token_id)
            mm_inputs["prompt_token_ids"] = prompt_token_ids

        return mm_inputs


@MULTIMODAL_REGISTRY.register_processor(
    PaliGemmaMultiModalProcessor,
    info=PaliGemmaProcessingInfo,
    dummy_inputs=PaliGemmaDummyInputsBuilder,
)
class PaliGemmaForConditionalGeneration(nn.Module, SupportsMultiModal, SupportsPP):
    packed_modules_mapping = {
        "qkv_proj": [
            "q_proj",
            "k_proj",
            "v_proj",
        ],
        "gate_up_proj": [
            "gate_proj",
            "up_proj",
        ],
    }

    hf_to_vllm_mapper = WeightsMapper(
        orig_to_new_prefix={
            # mapping for new names in checkpoint saved after transformers v4.52
            "model.language_model.": "language_model.model.",
            "model.vision_tower.": "vision_tower.",
            "model.multi_modal_projector.": "multi_modal_projector.",
            "lm_head.": "language_model.lm_head.",
        }
    )

    @classmethod
    def get_placeholder_str(cls, modality: str, i: int) -> str | None:
        if modality.startswith("image"):
            return None

        raise ValueError("Only image modality is supported")

    def __init__(self, *, vllm_config: VllmConfig, prefix: str = ""):
        super().__init__()
        config = vllm_config.model_config.hf_config
        quant_config = vllm_config.quant_config
        multimodal_config = vllm_config.model_config.multimodal_config
        self.config = config
        self.multimodal_config = multimodal_config

        self.vision_tower = SiglipVisionModel(
            config.vision_config,
            quant_config,
            prefix=maybe_prefix(prefix, "vision_tower"),
        )
        self.multi_modal_projector = PaliGemmaMultiModalProjector(
            vision_hidden_size=config.vision_config.hidden_size,
            projection_dim=config.vision_config.projection_dim,
        )

        self.quant_config = quant_config

        if config.text_config.model_type == "gemma":
            config.text_config.architectures = ["GemmaForCausalLM"]
        else:
            config.text_config.architectures = ["Gemma2ForCausalLM"]
        self.language_model = init_vllm_registered_model(
            vllm_config=vllm_config,
            hf_config=config.text_config,
            prefix=maybe_prefix(prefix, "language_model"),
        )
        logit_scale = getattr(config, "logit_scale", 1.0)
        self.language_model.logits_processor.scale *= logit_scale

        self.make_empty_intermediate_tensors = (
            self.language_model.make_empty_intermediate_tensors
        )

    def _parse_and_validate_image_input(
        self, **kwargs: object
    ) -> PaliGemmaImageInputs | None:
        pixel_values = kwargs.pop("pixel_values", None)
        image_embeds = kwargs.pop("image_embeds", None)

        if pixel_values is None and image_embeds is None:
            return None

        if pixel_values is not None:
            pixel_values = flatten_bn(pixel_values, concat=True)

            h = w = self.config.vision_config.image_size
            return PaliGemmaImagePixelInputs(
                type="pixel_values",
                data=pixel_values,
                resolve_bindings={"h": h, "w": w},
            )

        if image_embeds is not None:
            image_embeds = flatten_bn(image_embeds, concat=True)

            return PaliGemmaImageEmbeddingInputs(
                type="image_embeds",
                data=image_embeds,
            )

        raise AssertionError("This line should be unreachable.")

    def _image_pixels_to_features(
        self,
        vision_tower: SiglipVisionModel,
        pixel_values: torch.Tensor,
    ) -> torch.Tensor:
        target_dtype = vision_tower.get_input_embeddings().weight.dtype
        image_features = vision_tower(pixel_values.to(dtype=target_dtype))

        return image_features

    def _process_image_input(
        self,
        image_input: PaliGemmaImageInputs,
    ) -> torch.Tensor:
        if image_input["type"] == "image_embeds":
            return image_input["data"]

        assert self.vision_tower is not None
        pixel_values = image_input["data"]
        image_features = self._image_pixels_to_features(
            self.vision_tower,
            pixel_values,
        )

        return self.multi_modal_projector(image_features)

    def get_language_model(self) -> torch.nn.Module:
        return self.language_model

    def get_multimodal_embeddings(self, **kwargs: object) -> MultiModalEmbeddings:
        image_input = self._parse_and_validate_image_input(**kwargs)
        if image_input is None:
            return []
        vision_embeddings = self._process_image_input(image_input)
        # https://github.com/huggingface/transformers/blob/main/src/transformers/models/paligemma/modeling_paligemma.py#L294 # noqa
        vision_embeddings = vision_embeddings * (self.config.hidden_size**-0.5)
        return vision_embeddings

    def forward(
        self,
        input_ids: torch.Tensor,
        positions: torch.Tensor,
        intermediate_tensors: IntermediateTensors | None = None,
        inputs_embeds: torch.Tensor | None = None,
        **kwargs: object,
    ) -> IntermediateTensors:
        if intermediate_tensors is not None:
            inputs_embeds = None

        hidden_states = self.language_model.model(
            input_ids, positions, intermediate_tensors, inputs_embeds=inputs_embeds
        )

        return hidden_states

    def compute_logits(
        self,
        hidden_states: torch.Tensor,
    ) -> torch.Tensor | None:
        return self.language_model.compute_logits(hidden_states)

    def load_weights(self, weights: Iterable[tuple[str, torch.Tensor]]) -> set[str]:
        loader = AutoWeightsLoader(self)
        return loader.load_weights(weights, mapper=self.hf_to_vllm_mapper)