feat: 支持配置渠道被禁用后是否清空渠道粘性 (#5306)

* fix: evict stale channel affinity

* feat: configure disabled channel affinity retention

---------

Co-authored-by: Seefs <i@seefs.me>

middleware/distributor.go

@@ -102,14 +102,10 @@ func Distribute() func(c *gin.Context) {
 				}
 
 				if preferredChannelID, found := service.GetPreferredChannelByAffinity(c, modelRequest.Model, usingGroup); found {
+					affinityUsable := false
 					preferred, err := model.CacheGetChannel(preferredChannelID)
-					if err == nil && preferred != nil {
-						if preferred.Status != common.ChannelStatusEnabled {
-							if service.ShouldSkipRetryAfterChannelAffinityFailure(c) {
-								abortWithOpenAiMessage(c, http.StatusForbidden, i18n.T(c, i18n.MsgDistributorAffinityChannelDisabled))
-								return
-							}
-						} else if usingGroup == "auto" {
+					if err == nil && preferred != nil && preferred.Status == common.ChannelStatusEnabled {
+						if usingGroup == "auto" {
 							userGroup := common.GetContextKeyString(c, constant.ContextKeyUserGroup)
 							autoGroups := service.GetUserAutoGroup(userGroup)
 							for _, g := range autoGroups {
@@ -117,6 +113,7 @@ func Distribute() func(c *gin.Context) {
 									selectGroup = g
 									common.SetContextKey(c, constant.ContextKeyAutoGroup, g)
 									channel = preferred
+									affinityUsable = true
 									service.MarkChannelAffinityUsed(c, g, preferred.Id)
 									break
 								}
@@ -124,9 +121,13 @@ func Distribute() func(c *gin.Context) {
 						} else if model.IsChannelEnabledForGroupModel(usingGroup, modelRequest.Model, preferred.Id) {
 							channel = preferred
 							selectGroup = usingGroup
+							affinityUsable = true
 							service.MarkChannelAffinityUsed(c, usingGroup, preferred.Id)
 						}
 					}
+					if !affinityUsable && !service.ShouldKeepChannelAffinityOnChannelDisabled() {
+						service.ClearCurrentChannelAffinityCache(c)
+					}
 				}
 
 				if channel == nil {