fix: data race in chunk client hedging tests (#15466)

Author: na--

pkg/storage/chunk/client/hedging/hedging.go

@@ -64,12 +64,6 @@ func (cfg *Config) RegisterFlagsWithPrefix(prefix string, f *flag.FlagSet) {
 	f.IntVar(&cfg.MaxPerSecond, prefix+"hedge-max-per-second", 5, "The maximum of hedge requests allowed per seconds.")
 }
 
-// Client returns a hedged http client.
-// The client transport will be mutated to use the hedged roundtripper.
-func (cfg *Config) Client(client *http.Client) (*http.Client, error) {
-	return cfg.ClientWithRegisterer(client, prometheus.DefaultRegisterer)
-}
-
 // ClientWithRegisterer returns a hedged http client with instrumentation registered to the provided registerer.
 // The client transport will be mutated to use the hedged roundtripper.
 func (cfg *Config) ClientWithRegisterer(client *http.Client, reg prometheus.Registerer) (*http.Client, error) {

pkg/storage/chunk/client/hedging/hedging_test.go

@@ -18,37 +18,39 @@ func (fn RoundTripperFunc) RoundTrip(req *http.Request) (*http.Response, error)
 	return fn(req)
 }
 
-func resetMetrics() {
+func resetMetrics() *prometheus.Registry {
+	//TODO: clean up this massive hack...
 	reg := prometheus.NewRegistry()
 	prometheus.DefaultRegisterer = reg
 	prometheus.DefaultGatherer = reg
 	initMetrics()
+	return reg
 }
 
 func TestHedging(t *testing.T) {
-	resetMetrics()
+	reg := resetMetrics()
 	cfg := &Config{
 		At:           time.Duration(1),
 		UpTo:         3,
 		MaxPerSecond: 1000,
 	}
 	count := atomic.NewInt32(0)
-	client, err := cfg.Client(&http.Client{
+	client, err := cfg.ClientWithRegisterer(&http.Client{
 		Transport: RoundTripperFunc(func(_ *http.Request) (*http.Response, error) {
 			count.Inc()
 			time.Sleep(200 * time.Millisecond)
 			return &http.Response{
 				StatusCode: http.StatusOK,
 			}, nil
 		}),
-	})
+	}, reg)
 	if err != nil {
 		t.Fatal(err)
 	}
 	_, _ = client.Get("http://example.com")
 
 	require.Equal(t, int32(3), count.Load())
-	require.NoError(t, testutil.GatherAndCompare(prometheus.DefaultGatherer,
+	require.NoError(t, testutil.GatherAndCompare(reg,
 		strings.NewReader(`
 # HELP hedged_requests_rate_limited_total The total number of hedged requests rejected via rate limiting.
 # TYPE hedged_requests_rate_limited_total counter
@@ -61,29 +63,29 @@ hedged_requests_total 2
 }
 
 func TestHedgingRateLimit(t *testing.T) {
-	resetMetrics()
+	reg := resetMetrics()
 	cfg := &Config{
 		At:           time.Duration(1),
 		UpTo:         20,
 		MaxPerSecond: 1,
 	}
 	count := atomic.NewInt32(0)
-	client, err := cfg.Client(&http.Client{
+	client, err := cfg.ClientWithRegisterer(&http.Client{
 		Transport: RoundTripperFunc(func(_ *http.Request) (*http.Response, error) {
 			count.Inc()
 			time.Sleep(200 * time.Millisecond)
 			return &http.Response{
 				StatusCode: http.StatusOK,
 			}, nil
 		}),
-	})
+	}, reg)
 	if err != nil {
 		t.Fatal(err)
 	}
 	_, _ = client.Get("http://example.com")
 
 	require.Equal(t, int32(2), count.Load())
-	require.NoError(t, testutil.GatherAndCompare(prometheus.DefaultGatherer,
+	require.NoError(t, testutil.GatherAndCompare(reg,
 		strings.NewReader(`
 # HELP hedged_requests_rate_limited_total The total number of hedged requests rejected via rate limiting.
 # TYPE hedged_requests_rate_limited_total counter