updated counter to counter vec, added counter vec tests

Author: pranavmishradatabricks

internal/cortex/frontend/transport/handler.go

@@ -62,7 +62,7 @@ type Handler struct {
 	querySeconds *prometheus.CounterVec
 	querySeries  *prometheus.CounterVec
 	queryBytes   *prometheus.CounterVec
-	cachedHits   prometheus.Counter
+	cachedHits   *prometheus.CounterVec
 	activeUsers  *util.ActiveUsersCleanupService
 }
 
@@ -108,10 +108,10 @@ func NewHandler(cfg HandlerConfig, roundTripper http.RoundTripper, log log.Logge
 		_ = h.activeUsers.StartAsync(context.Background())
 	}
 
-	h.cachedHits = promauto.With(reg).NewCounter(prometheus.CounterOpts{
+	h.cachedHits = promauto.With(reg).NewCounterVec(prometheus.CounterOpts{
 		Name: "cached_failed_queries_count",
 		Help: "Total number of queries that hit the failed query cache.",
-	})
+	}, []string{"total"})
 
 	return h
 }
@@ -148,7 +148,7 @@ func (f *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		if cached {
 			w.WriteHeader(http.StatusForbidden)
 			level.Info(util_log.WithContext(r.Context(), f.log)).Log(message)
-			f.cachedHits.Inc()
+			f.cachedHits.WithLabelValues("total").Inc()
 			return
 		}
 	}

internal/cortex/frontend/transport/utils/utils_test.go

@@ -8,6 +8,10 @@ import (
 	"errors"
 	"net/url"
 	"testing"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+	"github.com/prometheus/client_golang/prometheus/testutil"
 )
 
 func TestNewFailedQueryCache(t *testing.T) {
@@ -195,3 +199,29 @@ func TestQueryHitCache(t *testing.T) {
 		})
 	}
 }
+
+func TestCacheCounterVec(t *testing.T) {
+	reg := prometheus.NewRegistry()
+	cachedHits := promauto.With(reg).NewCounterVec(prometheus.CounterOpts{
+		Name: "cached_failed_queries_count",
+		Help: "Total number of queries that hit the failed query cache.",
+	}, []string{"total"})
+
+	cachedHits.WithLabelValues("total").Inc()
+	expectedValue := 1.0
+	value := testutil.ToFloat64(cachedHits.WithLabelValues("total"))
+	if value != expectedValue {
+		t.Errorf("expected %v, got %v", expectedValue, value)
+	}
+	cachedHits.WithLabelValues("total").Inc()
+	expectedValue = 2.0
+	value = testutil.ToFloat64(cachedHits.WithLabelValues("total"))
+	if value != expectedValue {
+		t.Errorf("expected %v, got %v", expectedValue, value)
+	}
+	expectedValue = 0.0
+	value = testutil.ToFloat64(cachedHits.WithLabelValues("incorrect_label"))
+	if value != expectedValue {
+		t.Errorf("expected %v, got %v", expectedValue, value)
+	}
+}