package roundrobin import ( "sort" "sync" "time" "github.com/micro/go-micro/v3/router" "github.com/micro/go-micro/v3/selector" ) var routeTTL = time.Minute * 15 // NewSelector returns an initalised round robin selector func NewSelector(opts ...selector.Option) selector.Selector { r := &roundrobin{ routes: make(map[uint64]time.Time), ticker: time.NewTicker(time.Minute), } go r.cleanRoutes() return r } type roundrobin struct { ticker *time.Ticker // routes is a map with the key being a route's hash and the value being the last time it // was used to perform a request routes map[uint64]time.Time sync.Mutex } func (r *roundrobin) Init(opts ...selector.Option) error { return nil } func (r *roundrobin) Options() selector.Options { return selector.Options{} } func (r *roundrobin) Select(routes []router.Route, opts ...selector.SelectOption) (*router.Route, error) { // parse the options options := selector.NewSelectOptions(opts...) // apply the filters for _, f := range options.Filters { routes = f(routes) } if len(routes) == 0 { return nil, selector.ErrNoneAvailable } r.Lock() defer r.Unlock() // setLastUsed will update the last used time for a route setLastUsed := func(hash uint64) { r.routes[hash] = time.Now() } // if a route hasn't yet been seen, prioritise it for _, route := range routes { if _, ok := r.routes[route.Hash()]; !ok { setLastUsed(route.Hash()) return &route, nil } } // sort the services by the time they were last used sort.SliceStable(routes, func(i, j int) bool { iLastSeen := r.routes[routes[i].Hash()] jLastSeen := r.routes[routes[j].Hash()] return iLastSeen.UnixNano() < jLastSeen.UnixNano() }) // return the route which was last used setLastUsed(routes[0].Hash()) return &routes[0], nil } func (r *roundrobin) Record(srv router.Route, err error) error { return nil } func (r *roundrobin) Close() error { r.ticker.Stop() return nil } func (r *roundrobin) String() string { return "roundrobin" } func (r *roundrobin) cleanRoutes() { for _ = range r.ticker.C { r.Lock() // copy the slice to prevent concurrent map iteration and map write rts := r.routes for hash, t := range rts { if t.Unix() < time.Now().Add(-routeTTL).Unix() { delete(r.routes, hash) } } r.Unlock() } }