fix(ratelimit): ratelimiter's unexpected behavior

rate.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"hash/maphash"
+	"reflect"
 	"time"
 
 	"github.com/cespare/xxhash/v2"
@@ -10,6 +11,48 @@ import (
 	"golang.org/x/time/rate"
 )
 
+var rateLimiterPrivateReserveNMethodFunc reflect.Value
+
+func init() {
+	rl := &rate.Limiter{}
+	t := reflect.TypeOf(rl)
+	m, ok := t.MethodByName("reserveN")
+	if !ok {
+		panic(`cannot get "reserveN" method in "rate.Limiter"`)
+	}
+
+	mt := m.Type
+	if mt.NumIn() != 4 || mt.NumOut() != 1 {
+		panic(`"reserveN" method in "rate.Limiter" has wrong signature: ` + mt.String())
+	}
+
+	if in := mt.In(0); in != reflect.TypeFor[*rate.Limiter]() {
+		panic(`"reserveN" method in "rate.Limiter": argument 0 must be "rate.Limiter", but got ` + in.String())
+	}
+	if in := mt.In(1); in != reflect.TypeFor[time.Time]() {
+		panic(`"reserveN" method in "rate.Limiter": argument 1 must be "time.Time", but got ` + in.String())
+	}
+	if in := mt.In(2); in != reflect.TypeFor[int]() {
+		panic(`"reserveN" method in "rate.Limiter": argument 2 must be "int", but got ` + in.String())
+	}
+	if in := mt.In(3); in != reflect.TypeFor[time.Duration]() {
+		panic(`"reserveN" method in "rate.Limiter": argument 3 must be "time.Duration", but got ` + in.String())
+	}
+	if out := mt.Out(0); out != reflect.TypeFor[rate.Reservation]() {
+		panic(`"reserveN" method in "rate.Limiter": return value must be "rate.Reservation", but got ` + out.String())
+	}
+
+	fn := m.Func
+	rateLimiterPrivateReserveNMethodFunc = fn
+}
+
+func callRateLimiterReserveN(r *rate.Limiter, t time.Time, n int, maxFutureReserve time.Duration) *rate.Reservation {
+	ret := rateLimiterPrivateReserveNMethodFunc.Call([]reflect.Value{reflect.ValueOf(r), reflect.ValueOf(t), reflect.ValueOf(n), reflect.ValueOf(maxFutureReserve)})[0]
+
+	x := ret.Interface().(rate.Reservation)
+	return &x
+}
+
 type RateLimiter struct {
 	limiters []*rate.Limiter
 }
@@ -62,7 +105,7 @@ func (r *RateLimiter) AllowN(n int) Reservation {
 	var taken []*rate.Reservation
 	now := time.Now()
 	for _, l := range r.limiters {
-		if rsv := l.ReserveN(now, n); !rsv.OK() {
+		if rsv := callRateLimiterReserveN(l, now, n, 0); !rsv.OK() {
 			for _, x := range taken {
 				x.CancelAt(now)
 			}