cache: Allow setting cache metrics prefix

Custom prefix allows using multiple instances of the cache in an application with unique metrics. Signed-off-by: Sunny <[email protected]>
fluxcd · Nov 7, 2024 · eb427c1 · eb427c1
1 parent 8451ce1
commit eb427c1
Show file tree

Hide file tree

Showing 7 changed files with 30 additions and 14 deletions.
diff --git a/cache/cache.go b/cache/cache.go
@@ -85,7 +85,7 @@ func New[T any](capacity int, opts ...Options) (*Cache[T], error) {
 	}
 
 	if opt.registerer != nil {
-		c.metrics = newCacheMetrics(opt.registerer)
+		c.metrics = newCacheMetrics(opt.metricsPrefix, opt.registerer)
 	}
 
 	C := &Cache[T]{cache: c}

diff --git a/cache/cache_test.go b/cache/cache_test.go
@@ -149,6 +149,7 @@ func Test_Cache_Set(t *testing.T) {
 	reg := prometheus.NewPedanticRegistry()
 	cache, err := New[string](1,
 		WithMetricsRegisterer(reg),
+		WithMetricsPrefix("gotk_"),
 		WithCleanupInterval(10*time.Millisecond))
 	g.Expect(err).ToNot(HaveOccurred())
 
@@ -202,7 +203,7 @@ func Test_Cache_Set(t *testing.T) {
 func Test_Cache_Get(t *testing.T) {
 	g := NewWithT(t)
 	reg := prometheus.NewPedanticRegistry()
-	cache, err := New[string](5, WithMetricsRegisterer(reg))
+	cache, err := New[string](5, WithMetricsRegisterer(reg), WithMetricsPrefix("gotk_"))
 	g.Expect(err).ToNot(HaveOccurred())
 
 	// Reconciling object label values for cache event metric.
@@ -265,6 +266,7 @@ func Test_Cache_Delete(t *testing.T) {
 	reg := prometheus.NewPedanticRegistry()
 	cache, err := New[string](5,
 		WithMetricsRegisterer(reg),
+		WithMetricsPrefix("gotk_"),
 		WithCleanupInterval(1*time.Millisecond))
 	g.Expect(err).ToNot(HaveOccurred())
 

diff --git a/cache/lru.go b/cache/lru.go
@@ -94,7 +94,7 @@ func NewLRU[T any](capacity int, opts ...Options) (*LRU[T], error) {
 	}
 
 	if opt.registerer != nil {
-		lru.metrics = newCacheMetrics(opt.registerer)
+		lru.metrics = newCacheMetrics(opt.metricsPrefix, opt.registerer)
 	}
 
 	return lru, nil

diff --git a/cache/lru_test.go b/cache/lru_test.go
@@ -103,7 +103,8 @@ func Test_LRU_Set(t *testing.T) {
 	g := NewWithT(t)
 	reg := prometheus.NewPedanticRegistry()
 	cache, err := NewLRU[string](1,
-		WithMetricsRegisterer(reg))
+		WithMetricsRegisterer(reg),
+		WithMetricsPrefix("gotk_"))
 	g.Expect(err).ToNot(HaveOccurred())
 
 	// Add an object representing an expiring token
@@ -149,7 +150,8 @@ func Test_LRU_Get(t *testing.T) {
 	g := NewWithT(t)
 	reg := prometheus.NewPedanticRegistry()
 	cache, err := NewLRU[string](5,
-		WithMetricsRegisterer(reg))
+		WithMetricsRegisterer(reg),
+		WithMetricsPrefix("gotk_"))
 	g.Expect(err).ToNot(HaveOccurred())
 
 	// Reconciling object label values for cache event metric.
@@ -209,7 +211,8 @@ func Test_LRU_Delete(t *testing.T) {
 	g := NewWithT(t)
 	reg := prometheus.NewPedanticRegistry()
 	cache, err := NewLRU[string](5,
-		WithMetricsRegisterer(reg))
+		WithMetricsRegisterer(reg),
+		WithMetricsPrefix("gotk_"))
 	g.Expect(err).ToNot(HaveOccurred())
 
 	// Add an object representing an expiring token

diff --git a/cache/metrics.go b/cache/metrics.go
@@ -17,6 +17,8 @@ limitations under the License.
 package cache
 
 import (
+	"fmt"
+
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
 )
@@ -41,32 +43,32 @@ type cacheMetrics struct {
 }
 
 // newcacheMetrics returns a new cacheMetrics.
-func newCacheMetrics(reg prometheus.Registerer) *cacheMetrics {
+func newCacheMetrics(prefix string, reg prometheus.Registerer) *cacheMetrics {
 	labels := []string{"event_type", "kind", "name", "namespace"}
 	return &cacheMetrics{
 		cacheEventsCounter: promauto.With(reg).NewCounterVec(
 			prometheus.CounterOpts{
-				Name: "gotk_cache_events_total",
+				Name: fmt.Sprintf("%scache_events_total", prefix),
 				Help: "Total number of cache retrieval events for a Gitops Toolkit resource reconciliation.",
 			},
 			labels,
 		),
 		cacheItemsGauge: promauto.With(reg).NewGauge(
 			prometheus.GaugeOpts{
-				Name: "gotk_cached_items",
+				Name: fmt.Sprintf("%scached_items", prefix),
 				Help: "Total number of items in the cache.",
 			},
 		),
 		cacheRequestsCounter: promauto.With(reg).NewCounterVec(
 			prometheus.CounterOpts{
-				Name: "gotk_cache_requests_total",
+				Name: fmt.Sprintf("%scache_requests_total", prefix),
 				Help: "Total number of cache requests partioned by success or failure.",
 			},
 			[]string{"status"},
 		),
 		cacheEvictionCounter: promauto.With(reg).NewCounter(
 			prometheus.CounterOpts{
-				Name: "gotk_cache_evictions_total",
+				Name: fmt.Sprintf("%scache_evictions_total", prefix),
 				Help: "Total number of cache evictions.",
 			},
 		),

diff --git a/cache/metrics_test.go b/cache/metrics_test.go
@@ -28,7 +28,7 @@ import (
 func TestCacheMetrics(t *testing.T) {
 	g := NewWithT(t)
 	reg := prometheus.NewPedanticRegistry()
-	m := newCacheMetrics(reg)
+	m := newCacheMetrics("gotk_", reg)
 	g.Expect(m).ToNot(BeNil())
 
 	// CounterVec is a collection of counters and is not exported until it has counters in it.

diff --git a/cache/store.go b/cache/store.go
@@ -44,8 +44,9 @@ type Expirable[T any] interface {
 }
 
 type storeOptions struct {
-	interval   time.Duration
-	registerer prometheus.Registerer
+	interval      time.Duration
+	registerer    prometheus.Registerer
+	metricsPrefix string
 }
 
 // Options is a function that sets the store options.
@@ -66,3 +67,11 @@ func WithMetricsRegisterer(r prometheus.Registerer) Options {
 		return nil
 	}
 }
+
+// WithMetricsPrefix sets the metrics prefix for the cache metrics.
+func WithMetricsPrefix(prefix string) Options {
+	return func(o *storeOptions) error {
+		o.metricsPrefix = prefix
+		return nil
+	}
+}