151 lines
3.6 KiB
Go
151 lines
3.6 KiB
Go
package storage
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import (
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"bytes"
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"encoding/json"
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"fmt"
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"io"
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"math"
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"net/http"
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"os"
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"sync"
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)
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// Embedder bge-m3 编码客户端。优先使用本地 vLLM（端口 8000），fallback 到模力方舟 API。
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type Embedder struct {
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endpoint string // 本地 vLLM: http://localhost:8000/v1/embeddings
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apiKey string // 模力方舟 API key（fallback 用）
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httpClient *http.Client
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cache sync.Map // string → []float32
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dim int
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}
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// NewEmbedder 创建编码客户端。endpoint 默认为本地 vLLM。
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func NewEmbedder(endpoint string) *Embedder {
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if endpoint == "" {
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endpoint = os.Getenv("VLLM_ENDPOINT")
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if endpoint == "" {
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endpoint = "http://localhost:8000/v1/embeddings"
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}
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}
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return &Embedder{
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endpoint: endpoint,
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apiKey: os.Getenv("MOLIFANG_API_KEY"),
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httpClient: &http.Client{},
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dim: 1024,
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}
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}
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// Encode 批量编码文本，返回 1024 维归一化向量。
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func (e *Embedder) Encode(texts []string) ([][]float32, error) {
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// 检查缓存
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result := make([][]float32, len(texts))
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uncached := make([]int, 0)
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for i, t := range texts {
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if v, ok := e.cache.Load(t); ok {
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result[i] = v.([]float32)
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} else {
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uncached = append(uncached, i)
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}
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}
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if len(uncached) == 0 {
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return result, nil
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}
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// 收集未缓存的文本
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uncachedTexts := make([]string, len(uncached))
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for idx, i := range uncached {
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uncachedTexts[idx] = texts[i]
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}
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// 优先本地 vLLM
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vectors, err := e.encodeRemote(e.endpoint, uncachedTexts)
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if err != nil {
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// fallback：模力方舟
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if e.apiKey != "" {
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vectors, err = e.encodeRemote("https://ai.gitee.com/v1/embeddings", uncachedTexts)
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}
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if err != nil {
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return nil, fmt.Errorf("encode: all endpoints failed: %w", err)
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}
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}
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// L2 归一化 + 缓存
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for idx, i := range uncached {
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normalized := l2Normalize(vectors[idx])
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result[i] = normalized
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e.cache.Store(texts[i], normalized)
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}
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return result, nil
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}
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// EncodeSingle 编码单条文本。
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func (e *Embedder) EncodeSingle(text string) ([]float32, error) {
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vecs, err := e.Encode([]string{text})
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if err != nil {
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return nil, err
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}
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return vecs[0], nil
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}
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// encodeRemote 调用远端 OpenAI 兼容 embeddings API。
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func (e *Embedder) encodeRemote(endpoint string, texts []string) ([][]float32, error) {
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reqBody := map[string]any{
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"model": "bge-m3",
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"input": texts,
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}
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body, _ := json.Marshal(reqBody)
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req, _ := http.NewRequest("POST", endpoint, bytes.NewReader(body))
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req.Header.Set("Content-Type", "application/json")
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if e.apiKey != "" {
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req.Header.Set("Authorization", "Bearer "+e.apiKey)
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}
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resp, err := e.httpClient.Do(req)
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if err != nil {
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return nil, err
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}
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
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rbody, _ := io.ReadAll(resp.Body)
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return nil, fmt.Errorf("embedding API: status %d: %s", resp.StatusCode, string(rbody))
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}
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var result struct {
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Data []struct {
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Embedding []float64 `json:"embedding"`
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} `json:"data"`
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}
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if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
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return nil, fmt.Errorf("decode embedding response: %w", err)
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}
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vectors := make([][]float32, len(result.Data))
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for i, d := range result.Data {
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vectors[i] = make([]float32, len(d.Embedding))
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for j, v := range d.Embedding {
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vectors[i][j] = float32(v)
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}
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}
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return vectors, nil
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}
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// l2Normalize L2 归一化。
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func l2Normalize(v []float32) []float32 {
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var sum float64
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for _, x := range v {
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sum += float64(x) * float64(x)
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}
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norm := float32(math.Sqrt(sum))
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if norm == 0 {
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return v
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}
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result := make([]float32, len(v))
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for i, x := range v {
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result[i] = x / norm
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}
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return result
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}
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