Additional metrics and bug fixes

examples/prometheus/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"net/http"
@@ -31,7 +32,7 @@ func main() {
 		panic(err)
 	}
 
-	rdb := cache.NewCache(redisClient)
+	rdb := cache.New(redisClient)
 
 	if err := prometheus.InstrumentMetrics(rdb); err != nil {
 		panic(err)
@@ -63,6 +64,27 @@ func main() {
 			return
 		}
 	}))
+	http.Handle("/mget", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+
+		type request struct {
+			Keys []string `json:"keys"`
+		}
+
+		var req request
+		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+			w.WriteHeader(http.StatusBadRequest)
+			return
+		}
+
+		res, err := cache.MGet[string](r.Context(), rdb, req.Keys...)
+		if err != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			return
+		}
+
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(res)
+	}))
 
 	http.ListenAndServe(":8080", nil)
 }

prometheus/config.go

@@ -4,21 +4,26 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 )
 
-var defaultBuckets = prometheus.ExponentialBuckets(0.005, 2, 8)
+var (
+	defaultBuckets         = prometheus.ExponentialBuckets(0.005, 2, 8)
+	defaultMgetKeysBuckets = []float64{50, 100, 200, 500, 1000, 2000, 4000, 8000, 16000}
+)
 
 type config struct {
-	namespace    string
-	subSystem    string
-	globalLabels map[string]string
-	buckets      []float64
+	namespace       string
+	subSystem       string
+	globalLabels    map[string]string
+	buckets         []float64
+	mgetKeysBuckets []float64
 }
 
 func newConfig() *config {
 	return &config{
-		namespace:    "redis",
-		subSystem:    "cache",
-		globalLabels: make(map[string]string),
-		buckets:      defaultBuckets,
+		namespace:       "redis",
+		subSystem:       "cache",
+		globalLabels:    make(map[string]string),
+		buckets:         defaultBuckets,
+		mgetKeysBuckets: defaultMgetKeysBuckets,
 	}
 }
 
@@ -51,3 +56,11 @@ func WithBuckets(buckets []float64) Option {
 		c.buckets = buckets
 	}
 }
+
+// WithMGETKeysBuckets overrides the default buckets used for the Prometheus
+// histogram that tracks the number of keys requested in MGET commands
+func WithMGETKeysBuckets(buckets []float64) Option {
+	return func(c *config) {
+		c.mgetKeysBuckets = buckets
+	}
+}

prometheus/prometheus.go

@@ -250,14 +250,23 @@ func InstrumentClientMetrics(rdb redis.UniversalClient, opts ...Option) error {
 		Help:        "Number of operations cancelled in flight",
 		ConstLabels: conf.globalLabels,
 	}, []string{"operation"})
+	mgetKeys := prometheus.NewHistogram(prometheus.HistogramOpts{
+		Namespace:   conf.namespace,
+		Subsystem:   conf.subSystem,
+		Name:        "mget_keys_requested",
+		Help:        "Count of keys requested in MGET operations",
+		ConstLabels: conf.globalLabels,
+		Buckets:     conf.mgetKeysBuckets,
+	})
 
 	err := multierr.Combine(
 		prometheus.Register(processTime),
 		prometheus.Register(dialTime),
 		prometheus.Register(hits),
 		prometheus.Register(misses),
 		prometheus.Register(errs),
-		prometheus.Register(cancels))
+		prometheus.Register(cancels),
+		prometheus.Register(mgetKeys))
 	if err != nil {
 		return fmt.Errorf("failed to register prometheus collectors: %w", err)
 	}
@@ -269,6 +278,7 @@ func InstrumentClientMetrics(rdb redis.UniversalClient, opts ...Option) error {
 		misses:      misses,
 		errors:      errs,
 		cancels:     cancels,
+		mgetKeys:    mgetKeys,
 	}
 	rdb.AddHook(hook)
 
@@ -301,6 +311,7 @@ type clientMetricsHook struct {
 	misses      prometheus.Counter
 	errors      *prometheus.CounterVec
 	cancels     *prometheus.CounterVec
+	mgetKeys    prometheus.Histogram
 }
 
 func (c *clientMetricsHook) DialHook(next redis.DialHook) redis.DialHook {
@@ -335,15 +346,22 @@ func (c *clientMetricsHook) ProcessHook(next redis.ProcessHook) redis.ProcessHoo
 
 		c.processTime.WithLabelValues(cmd.Name()).Observe(dur)
 
-		if strings.ToLower(cmd.Name()) == "get" {
+		switch strings.ToLower(cmd.Name()) {
+		case "get":
 			if strCmd, ok := cmd.(*redis.StringCmd); ok {
 				if errors.Is(strCmd.Err(), redis.Nil) || (strCmd.Val() == "" && strCmd.Err() == nil) {
 					c.misses.Inc()
+					break
 				}
 				if strCmd.Err() == nil {
 					c.hits.Inc()
 				}
 			}
+		case "mget":
+			if mgetCmd, ok := cmd.(*redis.SliceCmd); ok {
+				keysRequested := len(mgetCmd.Args()) - 1
+				c.mgetKeys.Observe(float64(keysRequested))
+			}
 		}
 
 		if errors.Is(err, context.Canceled) {

version.go

@@ -2,5 +2,5 @@ package cache
 
 // Version returns the current version of redis-cache.
 func Version() string {
-	return "1.5.0"
+	return "1.5.1"
 }