refactor: add functional option to customize lru cache size and expiration

don't expose default values and keep them private.

5 files changed, 31 insertions, 30 deletions

diff --git a/app.go b/app.go
index c62078f7..1cbce369 100644
--- a/app.go
+++ b/app.go
@@ -267,8 +267,6 @@ func (a *theApp) buildHandlerPipeline() (http.Handler, error) {
 	if a.config.RateLimit.SourceIPLimitPerSecond > 0 {
 		rl := ratelimiter.New(
 			lru.New("source_ip",
-				lru.DefaultSourceIPItems,
-				lru.DefaultSourceIPExpirationInterval,
 				lru.WithCachedEntriesMetric(metrics.RateLimitSourceIPCachedEntries),
 				lru.WithCachedRequestsMetric(metrics.RateLimitSourceIPCacheRequests),
 			),
diff --git a/internal/lru/lru.go b/internal/lru/lru.go
index c30573ae..741d9ad2 100644
--- a/internal/lru/lru.go
+++ b/internal/lru/lru.go
@@ -19,8 +19,8 @@ const itemsToPruneDiv = 16
 
 // based on an avg ~4,000 unique IPs per minute
 // https://log.gprd.gitlab.net/app/lens#/edit/f7110d00-2013-11ec-8c8e-ed83b5469915?_g=h@e78830b
-const DefaultSourceIPItems = 5000
-const DefaultSourceIPExpirationInterval = time.Minute
+const defaultSourceIPItems = 5000
+const defaultSourceIPExpirationInterval = time.Minute
 
 // Option function to configure a Cache
 type Option func(*Cache)
@@ -29,21 +29,27 @@ type Option func(*Cache)
 type Cache struct {
 	op                  string
 	duration            time.Duration
+	maxSize             int64
 	cache               *ccache.Cache
 	metricCachedEntries *prometheus.GaugeVec
 	metricCacheRequests *prometheus.CounterVec
 }
 
 // New creates an LRU cache
-func New(op string, maxEntries int64, duration time.Duration, opts ...Option) *Cache {
+func New(op string, opts ...Option) *Cache {
 	c := &Cache{
 		op:       op,
-		duration: duration,
+		duration: defaultSourceIPExpirationInterval,
+		maxSize:  defaultSourceIPItems,
+	}
+
+	for _, opt := range opts {
+		opt(c)
 	}
 
 	configuration := ccache.Configure()
-	configuration.MaxSize(maxEntries)
-	configuration.ItemsToPrune(uint32(maxEntries) / itemsToPruneDiv)
+	configuration.MaxSize(c.maxSize)
+	configuration.ItemsToPrune(uint32(c.maxSize) / itemsToPruneDiv)
 	configuration.GetsPerPromote(getsPerPromote) // if item gets requested frequently promote it
 	configuration.OnDelete(func(*ccache.Item) {
 		if c.metricCachedEntries != nil {
@@ -53,10 +59,6 @@ func New(op string, maxEntries int64, duration time.Duration, opts ...Option) *C
 
 	c.cache = ccache.New(configuration)
 
-	for _, opt := range opts {
-		opt(c)
-	}
-
 	return c
 }
 
@@ -103,3 +105,15 @@ func WithCachedRequestsMetric(m *prometheus.CounterVec) Option {
 		c.metricCacheRequests = m
 	}
 }
+
+func WithSourceIPExpirationInterval(t time.Duration) Option {
+	return func(c *Cache) {
+		c.duration = t
+	}
+}
+
+func WithSourceIPItems(i int64) Option {
+	return func(c *Cache) {
+		c.maxSize = i
+	}
+}
diff --git a/internal/ratelimiter/middleware_test.go b/internal/ratelimiter/middleware_test.go
index 132b24b9..6560956c 100644
--- a/internal/ratelimiter/middleware_test.go
+++ b/internal/ratelimiter/middleware_test.go
@@ -29,10 +29,7 @@ func TestSourceIPLimiterWithDifferentLimits(t *testing.T) {
 	for tn, tc := range sharedTestCases {
 		t.Run(tn, func(t *testing.T) {
 			rl := New(
-				lru.New("source_ip",
-					lru.DefaultSourceIPItems,
-					lru.DefaultSourceIPExpirationInterval,
-				),
+				lru.New("source_ip"),
 				WithNow(mockNow),
 				WithSourceIPLimitPerSecond(tc.sourceIPLimit),
 				WithSourceIPBurstSize(tc.sourceIPBurstSize),
@@ -89,8 +86,6 @@ func TestSourceIPLimiterDenyRequestsAfterBurst(t *testing.T) {
 		t.Run(tn, func(t *testing.T) {
 			rl := New(
 				lru.New("source_ip",
-					lru.DefaultSourceIPItems,
-					lru.DefaultSourceIPExpirationInterval,
 					lru.WithCachedEntriesMetric(cachedEntries),
 					lru.WithCachedRequestsMetric(cacheReqs),
 				),
diff --git a/internal/ratelimiter/ratelimiter_test.go b/internal/ratelimiter/ratelimiter_test.go
index 5fb9ef2b..a85663af 100644
--- a/internal/ratelimiter/ratelimiter_test.go
+++ b/internal/ratelimiter/ratelimiter_test.go
@@ -53,10 +53,7 @@ func TestSourceIPAllowed(t *testing.T) {
 	for tn, tc := range sharedTestCases {
 		t.Run(tn, func(t *testing.T) {
 			rl := New(
-				lru.New("source_ip",
-					lru.DefaultSourceIPItems,
-					lru.DefaultSourceIPExpirationInterval,
-				),
+				lru.New("source_ip"),
 				WithNow(mockNow),
 				WithSourceIPLimitPerSecond(tc.sourceIPLimit),
 				WithSourceIPBurstSize(tc.sourceIPBurstSize),
@@ -80,10 +77,7 @@ func TestSingleRateLimiterWithMultipleSourceIPs(t *testing.T) {
 	rate := 10 * time.Millisecond
 
 	rl := New(
-		lru.New("source_ip",
-			lru.DefaultSourceIPItems,
-			lru.DefaultSourceIPExpirationInterval,
-		),
+		lru.New("source_ip"),
 		WithSourceIPLimitPerSecond(float64(1/rate)),
 		WithSourceIPBurstSize(1),
 	)
diff --git a/internal/vfs/zip/vfs.go b/internal/vfs/zip/vfs.go
index 67fe94dc..24d32163 100644
--- a/internal/vfs/zip/vfs.go
+++ b/internal/vfs/zip/vfs.go
@@ -86,15 +86,15 @@ func New(cfg *config.ZipServing) vfs.VFS {
 	// TODO: To be removed with https://gitlab.com/gitlab-org/gitlab-pages/-/issues/480
 	zipVFS.dataOffsetCache = lru.New(
 		"data-offset",
-		defaultDataOffsetItems,
-		defaultDataOffsetExpirationInterval,
+		lru.WithSourceIPItems(defaultDataOffsetItems),
+		lru.WithSourceIPExpirationInterval(defaultDataOffsetExpirationInterval),
 		lru.WithCachedEntriesMetric(metrics.ZipCachedEntries),
 		lru.WithCachedRequestsMetric(metrics.ZipCacheRequests),
 	)
 	zipVFS.readlinkCache = lru.New(
 		"readlink",
-		defaultReadlinkItems,
-		defaultReadlinkExpirationInterval,
+		lru.WithSourceIPItems(defaultReadlinkItems),
+		lru.WithSourceIPExpirationInterval(defaultReadlinkExpirationInterval),
 		lru.WithCachedEntriesMetric(metrics.ZipCachedEntries),
 		lru.WithCachedRequestsMetric(metrics.ZipCacheRequests),
 	)