Fallback on all Redis errors

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ jobs:
 
     services:
       redis:
-        image: redis:6
+        image: redis:7
         ports:
           - 6379:6379
 

config.go

@@ -20,7 +20,7 @@ type Config struct {
 	// Timeout for each Redis command after which we fall back to a local
 	// in-memory counter. If Redis does not respond within this duration,
 	// the system will use the local counter unless it is explicitly disabled.
-	FallbackTimeout time.Duration `toml:"fallback_timeout"` // default: 50ms
+	FallbackTimeout time.Duration `toml:"fallback_timeout"` // default: 100ms
 
 	// Client if supplied will be used and the below fields will be ignored.
 	//
@@ -31,6 +31,6 @@ type Config struct {
 	Port      uint16        `toml:"port"`
 	Password  string        `toml:"password"`   // optional
 	DBIndex   int           `toml:"db_index"`   // default: 0
-	MaxIdle   int           `toml:"max_idle"`   // default: 4
-	MaxActive int           `toml:"max_active"` // default: 8
+	MaxIdle   int           `toml:"max_idle"`   // default: 5
+	MaxActive int           `toml:"max_active"` // default: 10
 }

httprateredis.go

@@ -2,9 +2,7 @@ package httprateredis
 
 import (
 	"context"
-	"errors"
 	"fmt"
-	"net"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -40,8 +38,13 @@ 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 = 100 * time.Millisecond
+		if cfg.FallbackDisabled {
+			cfg.FallbackTimeout = time.Second
+		} else {
+			// Activate local in-memory fallback fairly quickly,
+			// so we don't slow down incoming requests too much.
+			cfg.FallbackTimeout = 100 * time.Millisecond
+		}
 	}
 
 	rc := &redisCounter{
@@ -54,10 +57,10 @@ func NewRedisLimitCounter(cfg *Config) (*redisCounter, error) {
 	if cfg.Client == nil {
 		maxIdle, maxActive := cfg.MaxIdle, cfg.MaxActive
 		if maxIdle < 1 {
-			maxIdle = 20
+			maxIdle = 5
 		}
 		if maxActive < 1 {
-			maxActive = 50
+			maxActive = 10
 		}
 
 		rc.client = redis.NewClient(&redis.Options{
@@ -107,13 +110,8 @@ func (c *redisCounter) IncrementBy(key string, currentWindow time.Time, amount i
 			return c.fallbackCounter.IncrementBy(key, currentWindow, amount)
 		}
 		defer func() {
-			if err != nil {
-				// On redis network error, fallback to local in-memory counter.
-				var netErr net.Error
-				if errors.As(err, &netErr) || errors.Is(err, redis.ErrClosed) {
-					c.fallback()
-					err = c.fallbackCounter.IncrementBy(key, currentWindow, amount)
-				}
+			if c.shouldFallback(err) {
+				err = c.fallbackCounter.IncrementBy(key, currentWindow, amount)
 			}
 		}()
 	}
@@ -147,13 +145,8 @@ func (c *redisCounter) Get(key string, currentWindow, previousWindow time.Time)
 			return c.fallbackCounter.Get(key, currentWindow, previousWindow)
 		}
 		defer func() {
-			if err != nil {
-				// On redis network error, fallback to local in-memory counter.
-				var netErr net.Error
-				if errors.As(err, &netErr) || errors.Is(err, redis.ErrClosed) {
-					c.fallback()
-					curr, prev, err = c.fallbackCounter.Get(key, currentWindow, previousWindow)
-				}
+			if c.shouldFallback(err) {
+				curr, prev, err = c.fallbackCounter.Get(key, currentWindow, previousWindow)
 			}
 		}()
 	}
@@ -189,25 +182,34 @@ func (c *redisCounter) IsFallbackActivated() bool {
 	return c.fallbackActivated.Load()
 }
 
-func (c *redisCounter) fallback() {
-	// Activate the in-memory counter fallback, unless activated by some other goroutine.
-	fallbackAlreadyActivated := c.fallbackActivated.Swap(true)
-	if fallbackAlreadyActivated {
-		return
+func (c *redisCounter) Close() error {
+	return c.client.Close()
+}
+
+func (c *redisCounter) shouldFallback(err error) bool {
+	if err == nil {
+		return false
+	}
+
+	// Activate the local in-memory counter fallback, unless activated by some other goroutine.
+	alreadyActivated := c.fallbackActivated.Swap(true)
+	if !alreadyActivated {
+		go c.reconnect()
 	}
 
-	go c.reconnect()
+	return true
 }
 
 func (c *redisCounter) reconnect() {
 	// Try to re-connect to redis every 200ms.
 	for {
+		time.Sleep(200 * time.Millisecond)
+
 		err := c.client.Ping(context.Background()).Err()
 		if err == nil {
 			c.fallbackActivated.Store(false)
 			return
 		}
-		time.Sleep(200 * time.Millisecond)
 	}
 }
 

httprateredis_test.go

@@ -15,8 +15,8 @@ func TestRedisCounter(t *testing.T) {
 	limitCounter, err := httprateredis.NewRedisLimitCounter(&httprateredis.Config{
 		Host:             "localhost",
 		Port:             6379,
-		MaxIdle:          100,
-		MaxActive:        200,
+		MaxIdle:          0,
+		MaxActive:        2,
 		DBIndex:          0,
 		ClientName:       "httprateredis_test",
 		PrefixKey:        fmt.Sprintf("httprate:test:%v", rand.Int31n(100000)), // Unique Redis key for each test
@@ -26,6 +26,7 @@ func TestRedisCounter(t *testing.T) {
 	if err != nil {
 		t.Fatalf("redis not available: %v", err)
 	}
+	defer limitCounter.Close()
 
 	limitCounter.Config(1000, time.Minute)
 
@@ -156,23 +157,28 @@ func TestRedisCounter(t *testing.T) {
 
 func BenchmarkLocalCounter(b *testing.B) {
 	limitCounter, err := httprateredis.NewRedisLimitCounter(&httprateredis.Config{
-		Host:       "localhost",
-		Port:       6379,
-		MaxIdle:    500,
-		MaxActive:  500,
-		DBIndex:    0,
-		ClientName: "httprateredis_test",
-		PrefixKey:  fmt.Sprintf("httprate:test:%v", rand.Int31n(100000)), // Unique key for each test
+		Host:             "localhost",
+		Port:             6379,
+		DBIndex:          0,
+		ClientName:       "httprateredis_test",
+		PrefixKey:        fmt.Sprintf("httprate:test:%v", rand.Int31n(100000)), // Unique key for each test
+		MaxActive:        10,
+		MaxIdle:          0,
+		FallbackDisabled: true,
+		FallbackTimeout:  5 * time.Second,
 	})
 	if err != nil {
 		b.Fatalf("redis not available: %v", err)
 	}
+	defer limitCounter.Close()
 
 	limitCounter.Config(1000, time.Minute)
 
 	currentWindow := time.Now().UTC().Truncate(time.Minute)
 	previousWindow := currentWindow.Add(-time.Minute)
 
+	concurrentRequests := 100
+
 	b.ResetTimer()
 
 	for i := 0; i < b.N; i++ {
@@ -182,14 +188,14 @@ func BenchmarkLocalCounter(b *testing.B) {
 			previousWindow.Add(time.Duration(i) * time.Minute)
 
 			wg := sync.WaitGroup{}
-			wg.Add(1000)
-			for i := 0; i < 1000; i++ {
+			wg.Add(concurrentRequests)
+			for i := 0; i < concurrentRequests; i++ {
 				// Simulate concurrent requests with different rate-limit keys.
 				go func(i int) {
 					defer wg.Done()
 
 					_, _, _ = limitCounter.Get(fmt.Sprintf("key:%v", i), currentWindow, previousWindow)
-					_ = limitCounter.IncrementBy(fmt.Sprintf("key:%v", i), currentWindow, rand.Intn(100))
+					_ = limitCounter.IncrementBy(fmt.Sprintf("key:%v", i), currentWindow, rand.Intn(20))
 				}(i)
 			}
 			wg.Wait()