114 lines
3.5 KiB
Go
114 lines
3.5 KiB
Go
package middleware
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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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"log"
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"net/http"
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"strings"
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"time"
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"github.com/LoveLosita/smartflow/backend/dao"
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"github.com/LoveLosita/smartflow/backend/respond"
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"github.com/gin-gonic/gin"
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)
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type IdempotencyValue struct {
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Status int `json:"status"` // HTTP 状态码
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Body string `json:"body"` // JSON 响应体
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}
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type responseRecorder struct {
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gin.ResponseWriter
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body *bytes.Buffer
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}
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func (r *responseRecorder) Write(b []byte) (int, error) {
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r.body.Write(b) // 录制到缓冲区
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return r.ResponseWriter.Write(b) // 正常发送给前端
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}
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func IdempotencyMiddleware(cache *dao.CacheDAO) gin.HandlerFunc {
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return func(c *gin.Context) {
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// 1. 获取 IKey
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ikey := c.GetHeader("X-Idempotency-Key")
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if ikey == "" {
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c.JSON(http.StatusBadRequest, respond.MissingIdempotencyKey) // 400 错误，缺少 IKey
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c.Abort()
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return
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}
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userID := c.GetInt("user_id") // 假设 JWT 已存入
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routeKey := idempotencyScopeKey(c)
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redisKey := fmt.Sprintf("idempotency:%d:%s:%s:%s", userID, c.Request.Method, routeKey, ikey)
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// 2. 查 Redis 缓存
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cachedData, err := cache.GetRecord(c, redisKey)
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if err != nil { // 💡 Fail-Open：Redis 挂了也别卡住用户，记个日志继续走
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log.Printf("[Idempotency] Redis Get error: %v", err)
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} else if cachedData != "" {
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// 命中缓存，直接回放录像
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var val IdempotencyValue
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json.Unmarshal([]byte(cachedData), &val)
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c.Data(val.Status, "application/json", []byte(val.Body))
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c.Abort()
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return
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}
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// 3. 分布式锁：防止微秒级的并发碰撞 (SetNX)
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// 锁 10 秒，防止请求卡死导致 key 永久锁定
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lockKey := redisKey + ":lock"
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success, err := cache.AcquireLock(c, lockKey, 10*time.Second)
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if err != nil { // 如果加锁报错，为了保险我们依然放行，让底层的数据库唯一索引去兜底
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log.Printf("[Idempotency] Redis Lock error: %v", err)
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} else if !success {
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c.JSON(http.StatusConflict, respond.RequestIsProcessing)
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c.Abort()
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return
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}
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// 💡 只有在加锁成功时才需要 defer 删锁
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if err == nil && success {
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defer cache.ReleaseLock(c, lockKey)
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}
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// 4. 装饰 ResponseWriter 开始录制
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recorder := &responseRecorder{
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ResponseWriter: c.Writer,
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body: bytes.NewBufferString(""),
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}
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c.Writer = recorder
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// 5. 执行后续 Handler (你的 Service 逻辑)
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c.Next()
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// 6. 录制完成，存入 Redis (缓存 24 小时)
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// 只有状态码 < 500 时才存入 Redis，这样如果是服务器临时抽风，用户重试依然有机会成功
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if c.Writer.Status() < 500 {
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respVal := IdempotencyValue{
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Status: c.Writer.Status(),
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Body: recorder.body.String(),
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}
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data, _ := json.Marshal(respVal)
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if err := cache.SaveRecord(c, redisKey, string(data), 24*time.Hour); err != nil {
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log.Printf("[Idempotency] Redis Save error: %v", err)
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}
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}
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}
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}
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func idempotencyScopeKey(c *gin.Context) string {
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// 1. 路由模板用于区分接口语义，避免同一路径被不同 handler 复用时串缓存。
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// 2. 实际路径用于区分资源实例，避免 /orders/1/mock-paid 和 /orders/2/mock-paid 复用同一个幂等响应。
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// 3. 若异常情况下拿不到模板，则退回实际路径，保证至少不会跨资源串响应。
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route := strings.TrimSpace(c.FullPath())
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actualPath := ""
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if c.Request != nil && c.Request.URL != nil {
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actualPath = strings.TrimSpace(c.Request.URL.Path)
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}
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if route == "" {
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route = actualPath
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}
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return strings.ReplaceAll(route+"|"+actualPath, ":", "_")
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}
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