Fix passing custom redis client

Author: VojtechVitek

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
+	maxIdle, maxActive := cfg.MaxIdle, cfg.MaxActive
 	if maxIdle <= 0 {
 		maxIdle = 20
 	}
 	if maxActive <= 0 {
 		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,
-
-		DialTimeout:  cfg.FallbackTimeout,
-		ReadTimeout:  cfg.FallbackTimeout,
-		WriteTimeout: cfg.FallbackTimeout,
-		MinIdleConns: 1,
-		MaxRetries:   -1,
-	})
+	if cfg.Client == nil {
+		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,
+			PoolSize:     maxActive,
+			MinIdleConns: 1,
+			MaxIdleConns: maxIdle,
+			MaxRetries:   -1, // -1 disables retries
+		})
+	}
 
 	return rc, nil
 }