[internal/datadog] Fix Datarace in metrics client

internal/datadog/metrics_client.go

@@ -46,6 +46,8 @@ func (m *metricsClient) Gauge(name string, value float64, tags []string, _ float
 	m.gauges[name] = value
 	_, err := m.meter.Float64ObservableGauge(name, metric.WithFloat64Callback(func(_ context.Context, f metric.Float64Observer) error {
 		attr := m.attributeFromTags(tags)
+		m.mutex.Lock()
+		defer m.mutex.Unlock()
 		if v, ok := m.gauges[name]; ok {
 			f.Observe(v, metric.WithAttributeSet(attr))
 		}

internal/datadog/metrics_client_test.go

@@ -4,6 +4,7 @@ package datadog
 
 import (
 	"context"
+	"sync"
 	"testing"
 	"time"
 
@@ -72,6 +73,43 @@ func TestGaugeMultiple(t *testing.T) {
 	metricdatatest.AssertEqual(t, want, got, metricdatatest.IgnoreTimestamp())
 }
 
+func TestGaugeDataRace(t *testing.T) {
+	reader, metricClient, _ := setupMetricClient()
+	var wg sync.WaitGroup
+	wg.Add(2)
+
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	go func() {
+		defer wg.Done()
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			default:
+				err := metricClient.Gauge("test_gauge", 1, []string{"otlp:true"}, 1)
+				assert.NoError(t, err)
+			}
+		}
+	}()
+
+	go func() {
+		defer wg.Done()
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			default:
+				err := reader.Collect(context.Background(), &metricdata.ResourceMetrics{})
+				assert.NoError(t, err)
+			}
+		}
+	}()
+
+	wg.Wait()
+}
+
 func TestCount(t *testing.T) {
 	reader, metricClient, _ := setupMetricClient()