6650e6a930
Signed-off-by: Kevin-Yang <ykcha9@gmail.com> Co-authored-by: Kevin-Yang <ykcha9@gmail.com>
79 lines
2.6 KiB
Python
79 lines
2.6 KiB
Python
from enum import IntEnum
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import torch
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import torch.nn as nn
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from vllm.model_executor.pooling_metadata import (PoolingMetadata,
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PoolingTensors)
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from vllm.sequence import EmbeddingSequenceGroupOutput, PoolerOutput
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class PoolingType(IntEnum):
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"""Enumeration for different types of pooling methods."""
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LAST = 0
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ALL = 1
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CLS = 2
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class Pooler(nn.Module):
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"""A layer that pools specific information from hidden states.
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This layer does the following:
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1. Extracts specific tokens or aggregates data based on pooling method.
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2. Normalizes output if specified.
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3. Returns structured results as `PoolerOutput`.
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Attributes:
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pooling_type: The type of pooling to use (LAST, ALL, CLS).
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normalize: Whether to normalize the pooled data.
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"""
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def __init__(self,
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pooling_type: PoolingType,
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normalize: bool,
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softmax: bool = False):
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super().__init__()
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self.pooling_type = pooling_type
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self.normalize = normalize
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self.softmax = softmax
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def forward(
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self,
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hidden_states: torch.Tensor,
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pooling_metadata: PoolingMetadata,
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) -> PoolerOutput:
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"""Pools specific information from hidden states based on metadata."""
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prompt_lens = PoolingTensors.from_pooling_metadata(
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pooling_metadata, hidden_states.device).prompt_lens
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if self.pooling_type is PoolingType.CLS:
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first_token_flat_indices = torch.zeros_like(prompt_lens)
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first_token_flat_indices[1:] += torch.cumsum(prompt_lens,
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dim=0)[:-1]
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pooled_data = hidden_states[first_token_flat_indices]
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elif self.pooling_type == PoolingType.LAST:
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last_token_flat_indices = torch.cumsum(prompt_lens, dim=0) - 1
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pooled_data = hidden_states[last_token_flat_indices]
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elif self.pooling_type == PoolingType.ALL:
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offset = 0
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pooled_data = []
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for prompt_len in prompt_lens:
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pooled_data.append(hidden_states[offset:offset + prompt_len])
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offset += prompt_len
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else:
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raise ValueError(f"Invalid pooling type: {self.pooling_type}")
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if self.normalize:
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pooled_data = nn.functional.normalize(pooled_data, p=2, dim=1)
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if self.softmax:
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pooled_data = nn.functional.softmax(pooled_data, dim=-1)
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pooled_outputs = [
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EmbeddingSequenceGroupOutput(data.tolist()) for data in pooled_data
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]
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return PoolerOutput(outputs=pooled_outputs)
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