support customized key prefix

Author: dcb9

rate.go

@@ -73,14 +73,34 @@ func PerHour(rate int) Limit {
 
 // Limiter controls how frequently events are allowed to happen.
 type Limiter struct {
-	rdb rediser
+	rdb       rediser
+	keyPrefix string
 }
 
+type Option func(*Limiter)
+
 // NewLimiter returns a new Limiter.
-func NewLimiter(rdb rediser) *Limiter {
-	return &Limiter{
+func NewLimiter(rdb rediser, options ...Option) *Limiter {
+	limiter := &Limiter{
 		rdb: rdb,
 	}
+
+	for _, opt := range options {
+		opt(limiter)
+	}
+
+	if limiter.keyPrefix == "" {
+		limiter.keyPrefix = redisPrefix
+	}
+
+	return limiter
+}
+
+// WithKeyPrefix is a functional option to set the redis key prefix.
+func WithKeyPrefix(keyPrefix string) Option {
+	return func(l *Limiter) {
+		l.keyPrefix = keyPrefix
+	}
 }
 
 // Allow is a shortcut for AllowN(ctx, key, limit, 1).
@@ -96,7 +116,7 @@ func (l Limiter) AllowN(
 	n int,
 ) (*Result, error) {
 	values := []interface{}{limit.Burst, limit.Rate, limit.Period.Seconds(), n}
-	v, err := allowN.Run(ctx, l.rdb, []string{redisPrefix + key}, values...).Result()
+	v, err := allowN.Run(ctx, l.rdb, []string{l.keyPrefix + key}, values...).Result()
 	if err != nil {
 		return nil, err
 	}
@@ -132,7 +152,7 @@ func (l Limiter) AllowAtMost(
 	n int,
 ) (*Result, error) {
 	values := []interface{}{limit.Burst, limit.Rate, limit.Period.Seconds(), n}
-	v, err := allowAtMost.Run(ctx, l.rdb, []string{redisPrefix + key}, values...).Result()
+	v, err := allowAtMost.Run(ctx, l.rdb, []string{l.keyPrefix + key}, values...).Result()
 	if err != nil {
 		return nil, err
 	}
@@ -161,7 +181,7 @@ func (l Limiter) AllowAtMost(
 
 // Reset gets a key and reset all limitations and previous usages
 func (l *Limiter) Reset(ctx context.Context, key string) error {
-	return l.rdb.Del(ctx, redisPrefix+key).Err()
+	return l.rdb.Del(ctx, l.keyPrefix+key).Err()
 }
 
 func dur(f float64) time.Duration {

rate_test.go

@@ -21,10 +21,22 @@ func rateLimiter() *redis_rate.Limiter {
 	return redis_rate.NewLimiter(ring)
 }
 
+func TestAllow_WithKeyPrefix(t *testing.T) {
+	ring := redis.NewRing(&redis.RingOptions{
+		Addrs: map[string]string{"server0": ":6379"},
+	})
+	if err := ring.FlushDB(context.TODO()).Err(); err != nil {
+		panic(err)
+	}
+	testAllow(t, redis_rate.NewLimiter(ring, redis_rate.WithKeyPrefix("redis_rate:")))
+}
+
 func TestAllow(t *testing.T) {
-	ctx := context.Background()
+	testAllow(t, rateLimiter())
+}
 
-	l := rateLimiter()
+func testAllow(t *testing.T, l *redis_rate.Limiter) {
+	ctx := context.Background()
 
 	limit := redis_rate.PerSecond(10)
 	require.Equal(t, limit.String(), "10 req/s (burst 10)")