Fix passing custom redis client

Author: VojtechVitek

_example/main.go

@@ -37,6 +37,7 @@ func main() {
 			})
 		})
 
+		// Rate-limit at 50 req/s per IP address.
 		r.Use(httprate.Limit(
 			50, time.Second,
 			httprate.WithKeyByIP(),

config.go

@@ -22,9 +22,9 @@ type Config struct {
 	// the system will use the local counter unless it is explicitly disabled.
 	FallbackTimeout time.Duration `toml:"fallback_timeout"` // default: 50ms
 
-	// Client if supplied will be used and below fields will be ignored.
+	// Client if supplied will be used and the below fields will be ignored.
 	//
-	// NOTE: It's recommended to set short Dial/Read/Write timeouts and disable
+	// NOTE: It's recommended to set short dial/read/write timeouts and disable
 	// retries on the client, so the local in-memory fallback can activate quickly.
 	Client    *redis.Client `toml:"-"`
 	Host      string        `toml:"host"`

httprateredis.go

@@ -40,6 +40,7 @@ func NewRedisLimitCounter(cfg *Config) (*redisCounter, error) {
 		cfg.PrefixKey = "httprate"
 	}
 	if cfg.FallbackTimeout == 0 {
+		// Activate local in-memory fallback fairly quickly, as this would slow down all requests.
 		cfg.FallbackTimeout = 50 * time.Millisecond
 	}
 
@@ -50,29 +51,30 @@ func NewRedisLimitCounter(cfg *Config) (*redisCounter, error) {
 		rc.fallbackCounter = httprate.NewLocalLimitCounter(cfg.WindowLength)
 	}
 
-	var maxIdle, maxActive = cfg.MaxIdle, cfg.MaxActive
-	if maxIdle <= 0 {
-		maxIdle = 20
-	}
-	if maxActive <= 0 {
-		maxActive = 50
-	}
+	if cfg.Client == nil {
+		maxIdle, maxActive := cfg.MaxIdle, cfg.MaxActive
+		if maxIdle < 1 {
+			maxIdle = 20
+		}
+		if maxActive < 1 {
+			maxActive = 50
+		}
 
-	address := fmt.Sprintf("%s:%d", cfg.Host, cfg.Port)
-	rc.client = redis.NewClient(&redis.Options{
-		Addr:         address,
-		Password:     cfg.Password,
-		DB:           cfg.DBIndex,
-		PoolSize:     maxActive,
-		MaxIdleConns: maxIdle,
-		ClientName:   cfg.ClientName,
+		rc.client = redis.NewClient(&redis.Options{
+			Addr:       fmt.Sprintf("%s:%d", cfg.Host, cfg.Port),
+			Password:   cfg.Password,
+			DB:         cfg.DBIndex,
+			ClientName: cfg.ClientName,
 
-		DialTimeout:  cfg.FallbackTimeout,
-		ReadTimeout:  cfg.FallbackTimeout,
-		WriteTimeout: cfg.FallbackTimeout,
-		MinIdleConns: 1,
-		MaxRetries:   -1,
-	})
+			DialTimeout:  cfg.FallbackTimeout,
+			ReadTimeout:  cfg.FallbackTimeout,
+			WriteTimeout: cfg.FallbackTimeout,
+			PoolSize:     maxActive,
+			MinIdleConns: 1,
+			MaxIdleConns: maxIdle,
+			MaxRetries:   -1, // -1 disables retries
+		})
+	}
 
 	return rc, nil
 }
@@ -109,7 +111,7 @@ func (c *redisCounter) IncrementBy(key string, currentWindow time.Time, amount i
 				var netErr net.Error
 				if errors.As(err, &netErr) || errors.Is(err, redis.ErrClosed) {
 					go c.fallback()
-					err = c.fallbackCounter.IncrementBy(key, currentWindow, amount) // = nil
+					err = c.fallbackCounter.IncrementBy(key, currentWindow, amount)
 				}
 			}
 		}()