feat(proxyd): change default cache ttl to 2 hours and make it configurable (ethereum-optimism#9645)

Author: felipe-op

proxyd/cache.go

@@ -21,8 +21,6 @@ type Cache interface {
 const (
 	// assuming an average RPCRes size of 3 KB
 	memoryCacheLimit = 4096
-	// Set a large ttl to avoid expirations. However, a ttl must be set for volatile-lru to take effect.
-	redisTTL = 30 * 7 * 24 * time.Hour
 )
 
 type cache struct {
@@ -49,10 +47,11 @@ func (c *cache) Put(ctx context.Context, key string, value string) error {
 type redisCache struct {
 	rdb    *redis.Client
 	prefix string
+	ttl    time.Duration
 }
 
-func newRedisCache(rdb *redis.Client, prefix string) *redisCache {
-	return &redisCache{rdb, prefix}
+func newRedisCache(rdb *redis.Client, prefix string, ttl time.Duration) *redisCache {
+	return &redisCache{rdb, prefix, ttl}
 }
 
 func (c *redisCache) namespaced(key string) string {
@@ -78,7 +77,7 @@ func (c *redisCache) Get(ctx context.Context, key string) (string, error) {
 
 func (c *redisCache) Put(ctx context.Context, key string, value string) error {
 	start := time.Now()
-	err := c.rdb.SetEx(ctx, c.namespaced(key), value, redisTTL).Err()
+	err := c.rdb.SetEx(ctx, c.namespaced(key), value, c.ttl).Err()
 	redisCacheDurationSumm.WithLabelValues("SETEX").Observe(float64(time.Since(start).Milliseconds()))
 
 	if err != nil {

proxyd/config.go

@@ -29,7 +29,8 @@ type ServerConfig struct {
 }
 
 type CacheConfig struct {
-	Enabled bool `toml:"enabled"`
+	Enabled bool         `toml:"enabled"`
+	TTL     TOMLDuration `toml:"ttl"`
 }
 
 type RedisConfig struct {

proxyd/proxyd.go

@@ -235,7 +235,11 @@ func Start(config *Config) (*Server, func(), error) {
 			log.Warn("redis is not configured, using in-memory cache")
 			cache = newMemoryCache()
 		} else {
-			cache = newRedisCache(redisClient, config.Redis.Namespace)
+			ttl := defaultCacheTtl
+			if config.Cache.TTL != 0 {
+				ttl = time.Duration(config.Cache.TTL)
+			}
+			cache = newRedisCache(redisClient, config.Redis.Namespace, ttl)
 		}
 		rpcCache = newRPCCache(newCacheWithCompression(cache))
 	}

proxyd/server.go

@@ -42,6 +42,7 @@ const (
 	defaultWSHandshakeTimeout    = 10 * time.Second
 	defaultWSReadTimeout         = 2 * time.Minute
 	defaultWSWriteTimeout        = 10 * time.Second
+	defaultCacheTtl              = 1 * time.Hour
 	maxRequestBodyLogLen         = 2000
 	defaultMaxUpstreamBatchSize  = 10
 	defaultRateLimitHeader       = "X-Forwarded-For"