feat: collect ristretto cache metrics helper

cachex/ristretto.go

@@ -0,0 +1,67 @@
+// Copyright © 2025 Ory Corp
+// SPDX-License-Identifier: Apache-2.0
+
+package cachex
+
+import (
+	"github.com/dgraph-io/ristretto"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+// RistrettoCollector collects Ristretto cache metrics.
+type RistrettoCollector[K ristretto.Key, V any] struct {
+	prefix      string
+	metricsFunc func() *ristretto.Metrics
+}
+
+// NewRistrettoCollector creates a new RistrettoCollector.
+//
+// To use this collector, you need to register it with a Prometheus registry:
+//
+//	func main() {
+//		cache, _ := ristretto.NewCache(&ristretto.Config{
+//			NumCounters: 1e7,
+//			MaxCost:     1 << 30,
+//			BufferItems: 64,
+//		})
+//		collector := NewRistrettoCollector("prefix_", func() *ristretto.Metrics {
+//			return cache.Metrics
+//		})
+//		prometheus.MustRegister(collector)
+//	}
+func NewRistrettoCollector[K ristretto.Key, V any](prefix string, metricsFunc func() *ristretto.Metrics) *RistrettoCollector[K, V] {
+	return &RistrettoCollector[K, V]{
+		prefix:      prefix,
+		metricsFunc: metricsFunc,
+	}
+}
+
+// Describe sends the super-set of all possible descriptors of metrics
+// collected by this Collector.
+func (c *RistrettoCollector[K, V]) Describe(ch chan<- *prometheus.Desc) {
+	ch <- prometheus.NewDesc(c.prefix+"ristretto_hits", "Total number of cache hits", nil, nil)
+	ch <- prometheus.NewDesc(c.prefix+"ristretto_misses", "Total number of cache misses", nil, nil)
+	ch <- prometheus.NewDesc(c.prefix+"ristretto_ratio", "Cache hit ratio", nil, nil)
+	ch <- prometheus.NewDesc(c.prefix+"ristretto_keys_added", "Total number of keys added to the cache", nil, nil)
+	ch <- prometheus.NewDesc(c.prefix+"ristretto_cost_added", "Total cost of keys added to the cache", nil, nil)
+	ch <- prometheus.NewDesc(c.prefix+"ristretto_keys_evicted", "Total number of keys evicted from the cache", nil, nil)
+	ch <- prometheus.NewDesc(c.prefix+"ristretto_cost_evicted", "Total cost of keys evicted from the cache", nil, nil)
+	ch <- prometheus.NewDesc(c.prefix+"ristretto_sets_dropped", "Total number of sets dropped", nil, nil)
+	ch <- prometheus.NewDesc(c.prefix+"ristretto_sets_rejected", "Total number of sets rejected", nil, nil)
+	ch <- prometheus.NewDesc(c.prefix+"ristretto_gets_kept", "Total number of gets kept", nil, nil)
+}
+
+// Collect is called by the Prometheus registry when collecting metrics.
+func (c *RistrettoCollector[K, V]) Collect(ch chan<- prometheus.Metric) {
+	metrics := c.metricsFunc()
+	ch <- prometheus.MustNewConstMetric(prometheus.NewDesc(c.prefix+"ristretto_hits", "Total number of cache hits", nil, nil), prometheus.GaugeValue, float64(metrics.Hits()))
+	ch <- prometheus.MustNewConstMetric(prometheus.NewDesc(c.prefix+"ristretto_misses", "Total number of cache misses", nil, nil), prometheus.GaugeValue, float64(metrics.Misses()))
+	ch <- prometheus.MustNewConstMetric(prometheus.NewDesc(c.prefix+"ristretto_ratio", "Cache hit ratio", nil, nil), prometheus.GaugeValue, metrics.Ratio())
+	ch <- prometheus.MustNewConstMetric(prometheus.NewDesc(c.prefix+"ristretto_keys_added", "Total number of keys added to the cache", nil, nil), prometheus.GaugeValue, float64(metrics.KeysAdded()))
+	ch <- prometheus.MustNewConstMetric(prometheus.NewDesc(c.prefix+"ristretto_cost_added", "Total cost of keys added to the cache", nil, nil), prometheus.GaugeValue, float64(metrics.CostAdded()))
+	ch <- prometheus.MustNewConstMetric(prometheus.NewDesc(c.prefix+"ristretto_keys_evicted", "Total number of keys evicted from the cache", nil, nil), prometheus.GaugeValue, float64(metrics.KeysEvicted()))
+	ch <- prometheus.MustNewConstMetric(prometheus.NewDesc(c.prefix+"ristretto_cost_evicted", "Total cost of keys evicted from the cache", nil, nil), prometheus.GaugeValue, float64(metrics.CostEvicted()))
+	ch <- prometheus.MustNewConstMetric(prometheus.NewDesc(c.prefix+"ristretto_sets_dropped", "Total number of sets dropped", nil, nil), prometheus.GaugeValue, float64(metrics.SetsDropped()))
+	ch <- prometheus.MustNewConstMetric(prometheus.NewDesc(c.prefix+"ristretto_sets_rejected", "Total number of sets rejected", nil, nil), prometheus.GaugeValue, float64(metrics.SetsRejected()))
+	ch <- prometheus.MustNewConstMetric(prometheus.NewDesc(c.prefix+"ristretto_gets_kept", "Total number of gets kept", nil, nil), prometheus.GaugeValue, float64(metrics.GetsKept()))
+}

configx/provider_watch_test.go

@@ -49,7 +49,7 @@ func assertNoOpenFDs(t require.TestingT, dir, name string) {
 	}
 	var b, be bytes.Buffer
 	// we are only interested in the file descriptors, so we use the `-F f` option
-	c := exec.Command("lsof", "-n", "-F", "f", "--", filepath.Join(dir, name))
+	c := exec.Command("lsof", "-n", "-F", "fc", "--", filepath.Join(dir, name))
 	c.Stdout = &b
 	c.Stderr = &be
 	exitErr := new(exec.ExitError)
@@ -61,13 +61,22 @@ func TestReload(t *testing.T) {
 	setup := func(t *testing.T, dir, name string, c chan<- struct{}, modifiers ...OptionModifier) (*Provider, *logrusx.Logger) {
 		l := logrusx.New("configx", "test")
 		ctx, cancel := context.WithCancel(context.Background())
-		t.Cleanup(cancel)
+		t.Cleanup(func() {
+			close(c)
+			cancel()
+			assertNoOpenFDs(t, dir, name)
+		})
 		modifiers = append(modifiers,
 			WithLogrusWatcher(l),
 			WithLogger(l),
 			AttachWatcher(func(event watcherx.Event, err error) {
-				fmt.Printf("Received event: %+v error: %+v\n", event, err)
-				c <- struct{}{}
+				fmt.Printf("Received event: %+v %T error: %+v\n", event, event, err)
+				select {
+				case <-ctx.Done():
+					return
+				case c <- struct{}{}:
+					return
+				}
 			}),
 			WithContext(ctx),
 		)
@@ -79,12 +88,12 @@ func TestReload(t *testing.T) {
 	t.Run("case=rejects not validating changes", func(t *testing.T) {
 		t.Parallel()
 		dir, name := tmpConfigFile(t, "memory", "bar")
+		assertNoOpenFDs(t, dir, name)
+
 		c := make(chan struct{})
 		p, l := setup(t, dir, name, c)
 		hook := test.NewLocal(l.Entry.Logger)
 
-		assertNoOpenFDs(t, dir, name)
-
 		assert.Equal(t, []*logrus.Entry{}, hook.AllEntries())
 		assert.Equal(t, "memory", p.String("dsn"))
 		assert.Equal(t, "bar", p.String("foo"))
@@ -112,13 +121,12 @@ func TestReload(t *testing.T) {
 	t.Run("case=rejects to update immutable", func(t *testing.T) {
 		t.Parallel()
 		dir, name := tmpConfigFile(t, "memory", "bar")
+
 		c := make(chan struct{})
 		p, l := setup(t, dir, name, c,
 			WithImmutables("dsn"))
 		hook := test.NewLocal(l.Entry.Logger)
 
-		assertNoOpenFDs(t, dir, name)
-
 		assert.Equal(t, []*logrus.Entry{}, hook.AllEntries())
 		assert.Equal(t, "memory", p.String("dsn"))
 		assert.Equal(t, "bar", p.String("foo"))
@@ -133,10 +141,10 @@ func TestReload(t *testing.T) {
 		assert.Equal(t, "bar", p.String("foo"))
 
 		// but it is still watching the files
-		updateConfigFile(t, c, dir, name, "memory", "bar", "baz")
-		assert.Equal(t, "baz", p.String("bar"))
-
-		assertNoOpenFDs(t, dir, name)
+		updateConfigFile(t, c, dir, name, "memory", "foo", "bar")
+		assert.Equal(t, "bar", p.String("bar"))
+		assert.Equal(t, "foo", p.String("bar"))
+		assert.Equal(t, "memory", p.String("dsn"))
 	})
 
 	t.Run("case=allows to update excepted immutable", func(t *testing.T) {