Source code for lightning_ir.retrieve.pytorch.dense_searcher

 1from __future__ import annotations
 2
 3from pathlib import Path
 4from typing import TYPE_CHECKING, Literal
 5
 6import torch
 7
 8from ...modeling_utils.batching import _batch_pairwise_scoring
 9from ...models import ColConfig, DprConfig
10from ..base.searcher import ExactSearchConfig, ExactSearcher
11from .dense_indexer import TorchDenseIndexConfig
12
13if TYPE_CHECKING:
14    from ...bi_encoder import BiEncoderEmbedding, BiEncoderModule
15
16

[docs]
17class TorchDenseIndex:

[docs]
18    def __init__(self, index_dir: Path, similarity_function: Literal["dot", "cosine"], use_gpu: bool = False) -> None:
19        self.index = torch.load(index_dir / "index.pt", weights_only=True)
20        self.config = TorchDenseIndexConfig.from_pretrained(index_dir)
21        if similarity_function == "dot":
22            self.similarity_function = self.dot_similarity
23        elif similarity_function == "cosine":
24            self.similarity_function = self.cosine_similarity
25        else:
26            raise ValueError("Unknown similarity function")
27        self.device = torch.device("cuda") if use_gpu and torch.cuda.is_available() else torch.device("cpu")

28
29    def score(self, embeddings: torch.Tensor) -> torch.Tensor:
30        embeddings = embeddings.to(self.device)
31        similarity = self.similarity_function(embeddings, self.index)
32        return similarity
33
34    @property
35    def num_embeddings(self) -> int:
36        return self.index.shape[0]
37
38    @staticmethod
39    @_batch_pairwise_scoring
40    @torch.autocast(device_type="cuda", enabled=False)
41    def cosine_similarity(x: torch.Tensor, y: torch.Tensor) -> torch.Tensor:
42        return torch.nn.functional.cosine_similarity(x[:, None], y[None], dim=-1)
43
44    @staticmethod
45    @_batch_pairwise_scoring
46    @torch.autocast(device_type="cuda", enabled=False)
47    def dot_similarity(x: torch.Tensor, y: torch.Tensor) -> torch.Tensor:
48        return torch.matmul(x, y.T)
49
50    def to_gpu(self) -> None:
51        self.index = self.index.to(self.device)

52
53

[docs]
54class TorchDenseSearcher(ExactSearcher):

[docs]
55    def __init__(
56        self,
57        index_dir: Path,
58        search_config: TorchDenseSearchConfig,
59        module: BiEncoderModule,
60        use_gpu: bool = True,
61    ) -> None:
62        self.search_config: TorchDenseSearchConfig
63        self.index = TorchDenseIndex(index_dir, module.config.similarity_function, use_gpu)
64        super().__init__(index_dir, search_config, module, use_gpu)
65        self.device = torch.device("cuda") if use_gpu and torch.cuda.is_available() else torch.device("cpu")

66
67    def to_gpu(self) -> None:
68        super().to_gpu()
69        self.index.to_gpu()
70
71    def _score(self, query_embeddings: BiEncoderEmbedding) -> torch.Tensor:
72        if query_embeddings.scoring_mask is None:
73            embeddings = query_embeddings.embeddings[:, 0]
74        else:
75            embeddings = query_embeddings.embeddings[query_embeddings.scoring_mask]
76        scores = self.index.score(embeddings)
77        return scores

78
79

[docs]
80class TorchDenseSearchConfig(ExactSearchConfig):
81    search_class = TorchDenseSearcher
82    SUPPORTED_MODELS = {ColConfig.model_type, DprConfig.model_type}