package router import ( "regexp" "strconv" "strings" "sync" ) type weightScaler func(value, weight float64) float64 var numberFinder = regexp.MustCompile(`\d+(\.\d+)?`) // NewWeightManager creates a new WeightManager with settings func NewWeightManager(s []*StrategyWeight, defaultWeight float64, scaler weightScaler) *WeightManager { return &WeightManager{ settings: s, cache: make(map[string]float64), scaler: scaler, defaultWeight: defaultWeight, } } // WeightManager manages weights for specific settings type WeightManager struct { settings []*StrategyWeight cache map[string]float64 scaler weightScaler defaultWeight float64 mu sync.Mutex } // Get gets the weight of specified tag func (s *WeightManager) Get(tag string) float64 { s.mu.Lock() defer s.mu.Unlock() weight, ok := s.cache[tag] if ok { return weight } weight = s.findValue(tag) s.cache[tag] = weight return weight } // Apply applies weight to the value func (s *WeightManager) Apply(tag string, value float64) float64 { return s.scaler(value, s.Get(tag)) } func (s *WeightManager) findValue(tag string) float64 { for _, w := range s.settings { matched := s.getMatch(tag, w.Match, w.Regexp) if matched == "" { continue } if w.Value > 0 { return float64(w.Value) } // auto weight from matched numStr := numberFinder.FindString(matched) if numStr == "" { return s.defaultWeight } weight, err := strconv.ParseFloat(numStr, 64) if err != nil { newError("unexpected error from ParseFloat: ", err).AtError().WriteToLog() return s.defaultWeight } return weight } return s.defaultWeight } func (s *WeightManager) getMatch(tag, find string, isRegexp bool) string { if !isRegexp { idx := strings.Index(tag, find) if idx < 0 { return "" } return find } r, err := regexp.Compile(find) if err != nil { newError("invalid regexp: ", find, "err: ", err).AtError().WriteToLog() return "" } return r.FindString(tag) }