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zhenxun_bot/zhenxun/services/ai/context/rag/retrieval.py
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52f7dbdedf ♻️ refactor(core): 重构 AI 编排框架与记忆及 RAG 子系统 (#2149)
* ♻️ refactor(core): 重构 AI 编排框架与记忆及 RAG 子系统

- 【重构】重构 `BaseRunnable` 并引入统一的 `RunIntent` 意图载体,规范 Agent、Team 和 Workflow 的执行流
- 【解耦】将中期记忆槽和长期向量记忆从 `MemoryConfig` 中解耦,转为独立的能力组件与工具箱进行管理
- 【记忆】移除 `MemoryReader` 和 `MemoryWriter`,统一封装为 `SessionMemoryContext` 会话记忆门面
- 【RAG】重构检索器与存储后端接口,统一采用 `QueryRequest` 进行多维度联合检索,并引入 `InMemoryScorer` 提升打分性能
- 【事件】优化 `EventBus` 异步事件分发机制,引入队列机制确保事件按序处理,避免并发竞态问题
- 【依赖注入】移除 `memory` 注入项,优化 `DependencyInjector` 的签名解析缓存以提升性能

* 🚨 auto fix by pre-commit hooks

---------

Co-authored-by: webjoin111 <455457521@qq.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
2026-07-14 16:48:33 +08:00

434 lines
15 KiB
Python

from abc import abstractmethod
import asyncio
import time
from typing import TYPE_CHECKING, Any, Protocol, cast, runtime_checkable
from zhenxun.services.ai.utils.logger import log_rag as logger
from zhenxun.utils.pydantic_compat import model_copy
from .backends.embedders import Embedder
from .models import QueryRequest, SearchResult
if TYPE_CHECKING:
from .backends.storages import StorageBackend
@runtime_checkable
class BaseRetriever(Protocol):
"""
检索器核心协议。
任何实现了 retrieve 方法的对象均可作为检索器
(不仅限于向量检索,也可包含 BM25、SQL 搜索等)。
"""
@abstractmethod
async def retrieve(self, request: QueryRequest) -> list[SearchResult]: ...
@runtime_checkable
class PostProcessor(Protocol):
"""后处理器协议(如重排、时间衰减打分等)。"""
@abstractmethod
async def process(
self, results: list[SearchResult], query: str
) -> list[SearchResult]: ...
@runtime_checkable
class PreProcessor(Protocol):
"""预处理器协议(如 LLM Query 改写、意图提取等)。"""
@abstractmethod
async def process(self, query: str) -> list[str]:
"""接收原始查询,返回一个或多个处理/改写后的查询词"""
...
class FilterEvaluator:
"""纯 Python 内存求值器,用于为轻量级 Storage 提供字典精确匹配过滤"""
@classmethod
def evaluate(
cls, metadata: dict[str, Any], filter_dict: dict[str, Any] | None
) -> bool:
if filter_dict is None:
return True
return all(metadata.get(k) == v for k, v in filter_dict.items())
class VectorDBRetriever(BaseRetriever):
"""基于向量数据库的标准检索器"""
def __init__(
self,
storage: "StorageBackend",
embedder: Embedder,
scope_prefix: str | None = None,
score_threshold: float = 0.4,
):
"""
初始化向量数据库检索器。
参数:
storage: 存储后端,用于执行向量相似度搜索。
embedder: 向量嵌入模型/函数,用于将文本转换为向量。
scope_prefix: 作用域前缀,用于限制检索范围,默认 None。
score_threshold: 分数阈值,过滤掉相似度低于该值的检索结果,默认 0.4。
"""
self.storage = storage
self.embedder = embedder
self.scope_prefix = scope_prefix
self.score_threshold = score_threshold
async def retrieve(self, request: QueryRequest) -> list[SearchResult]:
if not request.embedding and request.text:
vecs = await self.embedder(request.text, task="query")
request.embedding = vecs[0] if vecs else None
if not request.text.strip() and not request.embedding:
return []
request.search_type = "dense"
if not request.scopes and self.scope_prefix:
request.scopes = [self.scope_prefix]
original_limit = request.limit
request.limit = original_limit * 2
results = await self.storage.search(request)
request.limit = original_limit
return [r for r in results if r.score >= self.score_threshold][: request.limit]
class DatabaseSparseRetriever(BaseRetriever):
"""纯数据库下沉的稀疏检索器 (Keyword/FTS)"""
def __init__(
self,
storage: "StorageBackend",
scope_prefix: str | None = None,
score_threshold: float = 0.0,
):
"""
初始化数据库稀疏检索器。
参数:
storage: 存储后端,用于执行全文检索/关键词检索。
scope_prefix: 作用域前缀,用于限制检索范围,默认 None。
score_threshold: 分数阈值,过滤掉相关度低于该值的检索结果,默认 0.0。
"""
self.storage = storage
self.scope_prefix = scope_prefix
self.score_threshold = score_threshold
async def retrieve(self, request: QueryRequest) -> list[SearchResult]:
if not request.text.strip():
return []
request.search_type = "sparse"
if not request.scopes and self.scope_prefix:
request.scopes = [self.scope_prefix]
original_limit = request.limit
request.limit = original_limit * 2
results = await self.storage.search(request)
request.limit = original_limit
return [r for r in results if r.score > self.score_threshold][: request.limit]
class RerankRetriever(BaseRetriever):
"""带大模型交叉注意力重排的高阶检索器 (Decorator Pattern)"""
def __init__(
self,
base_retriever: BaseRetriever,
model_name: str | None = None,
top_n: int = 5,
oversample_factor: int = 2,
min_oversample: int = 20,
):
"""
初始化重排检索器。
参数:
base_retriever: 基础检索器,用于初筛。
model_name: 重排模型的名称,默认 None。
top_n: 重排后保留的前 N 个文档数,默认 5。
oversample_factor: 过采样系数,决定初筛检索的文档数量倍数,默认 2。
min_oversample: 最小过采样文档数,默认 20。
"""
self.base_retriever = base_retriever
self.model_name = model_name
self.top_n = top_n
self.oversample_factor = oversample_factor
self.min_oversample = min_oversample
async def retrieve(self, request: QueryRequest) -> list[SearchResult]:
req_clone = model_copy(request, deep=True)
req_clone.limit = max(
request.limit * self.oversample_factor, self.min_oversample
)
initial_results = await self.base_retriever.retrieve(req_clone)
if not initial_results:
return []
docs: list[str | dict[str, str]] = [
res.record.content for res in initial_results
]
from zhenxun.services.ai.llm.api import rerank
try:
reranked = await rerank(
query=request.text,
documents=docs,
top_n=min(request.limit, self.top_n),
model=self.model_name,
)
except Exception as e:
logger.warning(f"Rerank 重排请求失败,将降级返回初筛结果: {e}")
return initial_results[: request.limit]
final_results = []
for rr in reranked:
original_res = initial_results[rr.index]
original_res.score = rr.relevance_score
final_results.append(original_res)
return final_results
class PipelineRetriever(BaseRetriever):
"""支持挂载多个后处理器的流水线检索器"""
def __init__(
self,
base_retriever: BaseRetriever,
post_processors: list[PostProcessor] | None = None,
pre_processors: list[PreProcessor] | None = None,
):
"""
初始化流水线检索器。
参数:
base_retriever: 基础检索器,执行最初的检索过程。
post_processors: 后处理器列表,用于对检索到的结果进行重排、过滤等后处理,默认 None。
pre_processors: 预处理器列表,用于对查询词进行改写、扩展等预处理,默认 None。
""" # noqa: E501
self.base_retriever = base_retriever
self.post_processors = post_processors or []
self.pre_processors = pre_processors or []
async def retrieve(self, request: QueryRequest) -> list[SearchResult]:
requests_to_search = [request]
if request.text.strip():
processed_texts = [request.text]
for pp in self.pre_processors:
new_texts = []
for t in processed_texts:
new_texts.extend(await pp.process(t))
processed_texts = new_texts
if len(processed_texts) > 1 or (
len(processed_texts) == 1 and processed_texts[0] != request.text
):
requests_to_search = []
for pt in processed_texts:
new_req = model_copy(request, deep=True)
new_req.text = pt
requests_to_search.append(new_req)
all_results = []
seen_ids = set()
for req in requests_to_search:
original_limit = req.limit
req.limit = original_limit * 2
res = await self.base_retriever.retrieve(req)
req.limit = original_limit
for r in res:
if r.record.id not in seen_ids:
seen_ids.add(r.record.id)
all_results.append(r)
results = sorted(all_results, key=lambda x: x.score, reverse=True)
for pp in self.post_processors:
results = await pp.process(results, request.text)
return results[: request.limit]
class LifecyclePostProcessor(PostProcessor):
"""生命周期后处理器(融合时间衰减与惰性访问强化)"""
def __init__(
self,
half_life_days: int = 30,
decay_weight: float = 0.3,
semantic_weight: float = 0.7,
importance_weight: float = 0.0,
reinforcement_weight: float = 0.2,
):
"""
初始化生命周期后处理器。
参数:
half_life_days: 记忆衰减半衰期天数,控制信息随时间的降权速度,默认 30。
decay_weight: 时间衰减得分的权重,默认 0.3。
semantic_weight: 语义相关度得分的权重,默认 0.7。
importance_weight: 信息重要性得分的权重,默认 0.0。
reinforcement_weight: 惰性访问强化(如访问次数得分)的权重,默认 0.2。
"""
self.half_life_days = half_life_days
self.decay_weight = decay_weight
self.semantic_weight = semantic_weight
self.importance_weight = importance_weight
self.reinforcement_weight = reinforcement_weight
async def process(
self, results: list[SearchResult], query: str
) -> list[SearchResult]:
now = time.time()
import math
for res in results:
created_at = res.record.metadata.get("created_at", now)
importance = res.record.metadata.get("importance", 0.5)
access_count = res.record.metadata.get("access_count", 0)
last_accessed_at = res.record.metadata.get("last_accessed_at", created_at)
age_days = max(0.0, (now - last_accessed_at) / 86400.0)
decay = 0.5 ** (age_days / self.half_life_days)
access_score = min(1.0, math.log1p(access_count) / 5.0)
res.score = (
(self.semantic_weight * res.score)
+ (self.decay_weight * decay)
+ (self.importance_weight * importance)
+ (self.reinforcement_weight * access_score)
)
results.sort(key=lambda x: x.score, reverse=True)
return results
class HybridRetriever(BaseRetriever):
"""
双轨混合检索器 (Hybrid Search Engine)。
并发调用 Dense (VectorDB) 和 Sparse (BM25),并使用倒数秩融合 (RRF) 算法合并结果。
"""
def __init__(
self,
dense_retriever: BaseRetriever,
sparse_retriever: BaseRetriever,
dense_weight: float = 0.7,
sparse_weight: float = 0.3,
rrf_k: int = 60,
oversample_factor: int = 2,
min_oversample: int = 20,
):
"""
初始化双轨混合检索器。
参数:
dense_retriever: 稠密向量检索器,用于语义召回。
sparse_retriever: 稀疏文本检索器,用于关键词召回(如 BM25)。
dense_weight: 稠密向量检索的加权权重,默认 0.7。
sparse_weight: 稀疏文本检索的加权权重,默认 0.3。
rrf_k: 倒数秩融合(RRF)算法中的常数参数,默认 60。
"""
self.dense_retriever = dense_retriever
self.sparse_retriever = sparse_retriever
self.dense_weight = dense_weight
self.sparse_weight = sparse_weight
self.rrf_k = rrf_k
self.oversample_factor = oversample_factor
self.min_oversample = min_oversample
async def retrieve(self, request: QueryRequest) -> list[SearchResult]:
oversample_limit = max(
request.limit * self.oversample_factor, self.min_oversample
)
dense_req = model_copy(request, deep=True)
dense_req.limit = oversample_limit
dense_req.search_type = "dense"
sparse_req = model_copy(request, deep=True)
sparse_req.limit = oversample_limit
sparse_req.search_type = "sparse"
results = await asyncio.gather(
self.dense_retriever.retrieve(dense_req),
self.sparse_retriever.retrieve(sparse_req),
return_exceptions=True,
)
for res in results:
if isinstance(res, ImportError):
raise res
dense_res = (
cast(list[SearchResult], results[0])
if not isinstance(results[0], BaseException)
else []
)
sparse_res = (
cast(list[SearchResult], results[1])
if not isinstance(results[1], BaseException)
else []
)
if isinstance(results[0], BaseException):
logger.error(f"[HybridSearch] 向量检索异常: {results[0]}")
if isinstance(results[1], BaseException):
logger.error(f"[HybridSearch] BM25 检索异常: {results[1]}")
rrf_scores: dict[str, float] = {}
merged_records = {}
for rank, res in enumerate(dense_res):
record_id = res.record.id
merged_records[record_id] = res.record
rrf_score = 1.0 / (self.rrf_k + rank + 1)
rrf_scores[record_id] = rrf_scores.get(record_id, 0.0) + (
self.dense_weight * rrf_score
)
for rank, res in enumerate(sparse_res):
record_id = res.record.id
merged_records[record_id] = res.record
rrf_score = 1.0 / (self.rrf_k + rank + 1)
rrf_scores[record_id] = rrf_scores.get(record_id, 0.0) + (
self.sparse_weight * rrf_score
)
max_possible_score = (self.dense_weight * (1.0 / (self.rrf_k + 1))) + (
self.sparse_weight * (1.0 / (self.rrf_k + 1))
)
final_results = []
for record_id, score in sorted(
rrf_scores.items(), key=lambda x: x[1], reverse=True
):
normalized_score = (
score / max_possible_score if max_possible_score > 0 else 0.0
)
final_results.append(
SearchResult(record=merged_records[record_id], score=normalized_score)
)
logger.debug(
f"⚖️ [HybridSearch] 融合完成: "
f"Dense({len(dense_res)}) + Sparse({len(sparse_res)}) "
f"-> Merged({len(final_results)}), 截取 Top {request.limit}"
)
return final_results[: request.limit]