projects/single_transformer/models/modeling_qwen2mm.py

import torch
import torch.nn as nn

from typing import Optional, List, Union, Tuple
from transformers import Qwen2Model, Qwen2ForCausalLM
from transformers.utils import logging, is_torchdynamo_compiling
from transformers.cache_utils import Cache, DynamicCache, StaticCache
from transformers.configuration_utils import PretrainedConfig

from transformers.modeling_outputs import (
    CausalLMOutputWithPast,
    BaseModelOutputWithPast,
)
from transformers.modeling_attn_mask_utils import (
    _prepare_4d_causal_attention_mask,
    _prepare_4d_causal_attention_mask_for_sdpa,
)
from transformers.models.qwen2.modeling_qwen2 import (
    Qwen2DecoderLayer,
    Qwen2RMSNorm,
    Qwen2RotaryEmbedding,
)

logger = logging.get_logger(__name__)


# Impl. for transformers==4.42.0
class Qwen2MMConfig(PretrainedConfig):
    model_type = "qwen"
    keys_to_ignore_at_inference = ["past_key_values"]

    def __init__(
            self,
            vocab_size=151936,
            hidden_size=4096,
            intermediate_size=22016,
            num_hidden_layers=32,
            num_attention_heads=32,
            num_key_value_heads=32,
            hidden_act="silu",
            max_position_embeddings=32768,
            initializer_range=0.02,
            rms_norm_eps=1e-6,
            use_cache=True,
            tie_word_embeddings=False,
            rope_theta=10000.0,
            use_sliding_window=False,
            sliding_window=4096,
            max_window_layers=28,
            attention_dropout=0.0,
            vision_patch_size=32,
            **kwargs,
    ):
        self.vocab_size = vocab_size
        self.max_position_embeddings = max_position_embeddings
        self.hidden_size = hidden_size
        self.intermediate_size = intermediate_size
        self.num_hidden_layers = num_hidden_layers
        self.num_attention_heads = num_attention_heads
        self.use_sliding_window = use_sliding_window
        self.sliding_window = sliding_window
        self.max_window_layers = max_window_layers

        # for backward compatibility
        if num_key_value_heads is None:
            num_key_value_heads = num_attention_heads

        self.num_key_value_heads = num_key_value_heads
        self.hidden_act = hidden_act
        self.initializer_range = initializer_range
        self.rms_norm_eps = rms_norm_eps
        self.use_cache = use_cache
        self.rope_theta = rope_theta
        self.attention_dropout = attention_dropout
        self.vision_patch_size = vision_patch_size

        super().__init__(
            tie_word_embeddings=tie_word_embeddings,
            **kwargs,
        )


class MultimodalQwen2Model(Qwen2Model):

    def __init__(self, config: Qwen2MMConfig):
        super(Qwen2Model, self).__init__(config)
        self.padding_idx = config.pad_token_id
        self.vocab_size = config.vocab_size

        self.embed_tokens = nn.Embedding(config.vocab_size, config.hidden_size, self.padding_idx)
        self.layers = nn.ModuleList(
            [Qwen2DecoderLayer(config, layer_idx) for layer_idx in range(config.num_hidden_layers)]
        )
        self._attn_implementation = config._attn_implementation
        self.norm = Qwen2RMSNorm(config.hidden_size, eps=config.rms_norm_eps)

        self.gradient_checkpointing = False

        # === Vision Patches ===
        assert config.vision_patch_size == 32

        self.vis_embed = nn.Linear(
            config.vision_patch_size * config.vision_patch_size * 3,  # 32 * 32 * 3,
            config.hidden_size,
            bias=False,
        )
        # === Vision Patches ===

        # Initialize weights and apply final processing
        self.post_init()

    def forward(
            self,
            input_ids: torch.LongTensor = None,
            attention_mask: Optional[torch.Tensor] = None,
            vision_patch_indices: torch.LongTensor = None,  # (batch_size, seq_length), "-1" for text token
            vision_patches: torch.FloatTensor = None,  # (n_patches, 32 * 32 * 3)
            position_ids: Optional[torch.LongTensor] = None,
            past_key_values: Optional[List[torch.FloatTensor]] = None,
            inputs_embeds: Optional[torch.FloatTensor] = None,
            use_cache: Optional[bool] = None,
            output_attentions: Optional[bool] = None,
            output_hidden_states: Optional[bool] = None,
            return_dict: Optional[bool] = None,
            cache_position: Optional[torch.LongTensor] = None,
    ) -> Union[Tuple, BaseModelOutputWithPast]:
        output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
        output_hidden_states = (
            output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
        )
        use_cache = use_cache if use_cache is not None else self.config.use_cache

        return_dict = return_dict if return_dict is not None else self.config.use_return_dict

        if (input_ids is None) ^ (inputs_embeds is not None):
            raise ValueError(
                "You cannot specify both input_ids and inputs_embeds at the same time, and must specify either one"
            )

        if self.gradient_checkpointing and self.training:
            if use_cache:
                logger.warning_once(
                    "`use_cache=True` is incompatible with gradient checkpointing. Setting `use_cache=False`..."
                )
                use_cache = False

        use_legacy_cache = False
        if use_cache and not isinstance(past_key_values, Cache):
            use_legacy_cache = True
            past_key_values = DynamicCache.from_legacy_cache(past_key_values)
            logger.warning_once(
                "We detected that you are passing `past_key_values` as a tuple and this is deprecated and will be removed in v4.43. "
                "Please use an appropriate `Cache` class (https://huggingface.co/docs/transformers/v4.41.3/en/internal/generation_utils#transformers.Cache)"
            )

        if inputs_embeds is None:
            inputs_embeds = self.embed_tokens(input_ids)

            if vision_patch_indices is not None:
                assert (
                        vision_patch_indices.shape == input_ids.shape
                ), "vision_patch_indices and input_ids should have the same shape"

            # === Handle vision patches ===
            if vision_patches is not None and vision_patches.size(0) > 0:
                assert vision_patch_indices is not None, "HF QwenMM model requires vision_patch_indices for vision_patches input."
                vision_embeds = self.vis_embed(vision_patches)  # (n_patches, hidden_size)
                vision_embeds = torch.cat(
                    [
                        vision_embeds,
                        torch.zeros(1, self.config.hidden_size).to(
                            vision_embeds.device
                        ),  # add a dummy token (for text)
                    ],
                )  # (n_patches + 1, hidden_size)
                # arrange embeddings according to vision_patch_indices
                # - text tokens are -1 (map to the dummy zero tensor)
                # - vision tokens are 0~n_patches (map to the corresponding vision_embeds)
                vision_embeds = vision_embeds[vision_patch_indices]  # (batch_size, seq_length, hidden_size)

                # merge vision_embeds with inputs_embeds
                inputs_embeds += vision_embeds

        if cache_position is None:
            past_seen_tokens = past_key_values.get_seq_length() if past_key_values is not None else 0
            cache_position = torch.arange(
                past_seen_tokens, past_seen_tokens + inputs_embeds.shape[1], device=inputs_embeds.device
            )
        if position_ids is None:
            position_ids = cache_position.unsqueeze(0)

        causal_mask = self._update_causal_mask(
            attention_mask, inputs_embeds, cache_position, past_key_values, output_attentions
        )

        hidden_states = inputs_embeds

        # decoder layers
        all_hidden_states = () if output_hidden_states else None
        all_self_attns = () if output_attentions else None
        next_decoder_cache = None

        for decoder_layer in self.layers:
            if output_hidden_states:
                all_hidden_states += (hidden_states,)

            if self.gradient_checkpointing and self.training:
                layer_outputs = self._gradient_checkpointing_func(
                    decoder_layer.__call__,
                    hidden_states,
                    causal_mask,
                    position_ids,
                    past_key_values,
                    output_attentions,
                    use_cache,
                    cache_position,
                )
            else:
                layer_outputs = decoder_layer(
                    hidden_states,
                    attention_mask=causal_mask,
                    position_ids=position_ids,
                    past_key_value=past_key_values,
                    output_attentions=output_attentions,
                    use_cache=use_cache,
                    cache_position=cache_position,
                )

            hidden_states = layer_outputs[0]

            if use_cache:
                next_decoder_cache = layer_outputs[2 if output_attentions else 1]

            if output_attentions:
                all_self_attns += (layer_outputs[1],)

        hidden_states = self.norm(hidden_states)

        # add hidden states from the last decoder layer
        if output_hidden_states:
            all_hidden_states += (hidden_states,)

        next_cache = None
        if use_cache:
            next_cache = next_decoder_cache.to_legacy_cache() if use_legacy_cache else next_decoder_cache

        if not return_dict:
            return tuple(v for v in [hidden_states, next_cache, all_hidden_states, all_self_attns] if v is not None)
        return BaseModelOutputWithPast(
            last_hidden_state=hidden_states,
            past_key_values=next_cache,
            hidden_states=all_hidden_states,
            attentions=all_self_attns,
        )


class Qwen2MMForCausalLM(Qwen2ForCausalLM):

    def __init__(self, config: Qwen2MMConfig):
        super().__init__(config)
        self.model = MultimodalQwen2Model(config)
        self.vocab_size = config.vocab_size
        self.lm_head = nn.Linear(config.hidden_size, config.vocab_size, bias=False)

        # Initialize weights and apply final processing
        self.post_init()

    def forward(
            self,
            input_ids: torch.LongTensor = None,
            attention_mask: Optional[torch.Tensor] = None,
            vision_patch_indices: torch.LongTensor = None,  # (batch_size, seq_length), "-1" for text token
            vision_patches: torch.FloatTensor = None,  # (n_patches, 32 * 32 * 3)
            position_ids: Optional[torch.LongTensor] = None,
            past_key_values: Optional[List[torch.FloatTensor]] = None,
            inputs_embeds: Optional[torch.FloatTensor] = None,
            labels: Optional[torch.LongTensor] = None,
            use_cache: Optional[bool] = None,
            output_attentions: Optional[bool] = None,
            output_hidden_states: Optional[bool] = None,
            return_dict: Optional[bool] = None,
            cache_position: Optional[torch.LongTensor] = None,
            num_logits_to_keep: int = 0,
    ) -> Union[Tuple, CausalLMOutputWithPast]:

        output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
        output_hidden_states = (
            output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
        )
        return_dict = return_dict if return_dict is not None else self.config.use_return_dict

        # decoder outputs consists of (dec_features, layer_state, dec_hidden, dec_attn)
        outputs = self.model(
            input_ids=input_ids,
            attention_mask=attention_mask,
            vision_patch_indices=vision_patch_indices,
            vision_patches=vision_patches,
            position_ids=position_ids,
            past_key_values=past_key_values,
            inputs_embeds=inputs_embeds,
            use_cache=use_cache,
            output_attentions=output_attentions,
            output_hidden_states=output_hidden_states,
            return_dict=return_dict,
            cache_position=cache_position,
        )

        hidden_states = outputs[0]
        if labels is None and not is_torchdynamo_compiling():
            logger.warning_once(
                "Starting from v4.46, the `logits` model output will have the same type as the model (except at train time, where it will always be FP32)"
            )
        # Only compute necessary logits, and do not upcast them to float if we are not computing the loss
        # TODO: remove the float() operation in v4.46
        logits = self.lm_head(hidden_states[:, -num_logits_to_keep:, :]).float()

        loss = None
        if labels is not None:
            # Upcast to float if we need to compute the loss to avoid potential precision issues
            logits = logits.float()
            # Shift so that tokens < n predict n
            shift_logits = logits[..., :-1, :].contiguous()
            shift_labels = labels[..., 1:].contiguous()
            # Flatten the tokens
            loss_fct = nn.CrossEntropyLoss()
            shift_logits = shift_logits.view(-1, self.config.vocab_size)
            shift_labels = shift_labels.view(-1)
            # Enable model parallelism
            shift_labels = shift_labels.to(shift_logits.device)
            loss = loss_fct(shift_logits, shift_labels)

        if not return_dict:
            output = (logits,) + outputs[1:]
            return (loss,) + output if loss is not None else output

        return CausalLMOutputWithPast(
            loss=loss,
            logits=logits,
            past_key_values=outputs.past_key_values,
            hidden_states=outputs.hidden_states,
            attentions=outputs.attentions,
        )

    # Copied from transformers.models.llama.modeling_llama.LlamaForCausalLM.prepare_inputs_for_generation
    def prepare_inputs_for_generation(
            self,
            input_ids,
            past_key_values=None,
            attention_mask=None,
            inputs_embeds=None,
            cache_position=None,
            use_cache=True,
            **kwargs,
    ):
        vision_patches = kwargs.get("vision_patches", None)
        vision_patch_indices = kwargs.get("vision_patch_indices", None)

        has_vision_inp = False
        if vision_patches is not None and vision_patch_indices is not None:
            has_vision_inp = True
            # make vision_patch_indices to be the same shape as input_ids by padding -1
            _padding = torch.full_like(input_ids, -1, dtype=vision_patch_indices.dtype)
            _padding[:, : vision_patch_indices.shape[1]] = vision_patch_indices
            vision_patch_indices = _padding

        past_length = 0
        # Omit tokens covered by past_key_values
        if past_key_values is not None:
            # Past key values are always initialized with a `Cache` object -> no need for if-else anymore
            past_length = cache_position[0] if cache_position is not None else past_key_values.get_seq_length()
            max_cache_length = (
                torch.tensor(past_key_values.get_max_length(), device=input_ids.device)
                if past_key_values.get_max_length() is not None
                else None
            )
            cache_length = past_length if max_cache_length is None else torch.min(max_cache_length, past_length)

            # Keep only the unprocessed tokens:
            # 1 - If the length of the attention_mask exceeds the length of input_ids, then we are in a setting where
            # some of the inputs are exclusively passed as part of the cache (e.g. when passing input_embeds as
            # input)
            if attention_mask is not None and attention_mask.shape[1] > input_ids.shape[1]:
                input_ids = input_ids[:, -(attention_mask.shape[1] - past_length):]
                if has_vision_inp:
                    vision_patch_indices = vision_patch_indices[:, -(attention_mask.shape[1] - past_length):]
            # 2 - If the past_length is smaller than input_ids', then input_ids holds all input tokens. We can discard
            # input_ids based on the past_length.
            elif past_length < input_ids.shape[1]:
                input_ids = input_ids[:, past_length:]
                if has_vision_inp:
                    vision_patch_indices = vision_patch_indices[:, past_length:]
            # 3 - Otherwise (past_length >= input_ids.shape[1]), let's assume input_ids only has unprocessed tokens.

            # If we are about to go beyond the maximum cache length, we need to crop the input attention mask.
            if (
                    max_cache_length is not None
                    and attention_mask is not None
                    and cache_length + input_ids.shape[1] > max_cache_length
            ):
                attention_mask = attention_mask[:, -max_cache_length:]

        position_ids = kwargs.get("position_ids", None)
        if attention_mask is not None and position_ids is None:
            # create position_ids on the fly for batch generation
            position_ids = attention_mask.long().cumsum(-1) - 1
            position_ids.masked_fill_(attention_mask == 0, 1)
            if past_key_values:
                position_ids = position_ids[:, -input_ids.shape[1]:]

        # if `inputs_embeds` are passed, we only want to use them in the 1st generation step
        if inputs_embeds is not None and past_length == 0:
            model_inputs = {"inputs_embeds": inputs_embeds}
        else:
            model_inputs = {"input_ids": input_ids}

        input_length = position_ids.shape[-1] if position_ids is not None else input_ids.shape[-1]
        if cache_position is None:
            cache_position = torch.arange(past_length, past_length + input_length, device=input_ids.device)
        elif use_cache:
            cache_position = cache_position[-input_length:]

        if vision_patch_indices is not None:
            assert vision_patch_indices.shape == input_ids.shape

        model_inputs.update(
            {
                "position_ids": position_ids,
                "past_key_values": past_key_values,
                "use_cache": use_cache,
                "attention_mask": attention_mask,
                "cache_position": cache_position,
                "vision_patch_indices": vision_patch_indices,
                "vision_patches": vision_patches,
            }
        )
        return model_inputs


if __name__ == "__main__":
    mmqwen = Qwen2MMForCausalLM.from_pretrained("Qwen2-0.5B")
    print(mmqwen)