[processor/spanmetricsprocessor] Allow set metrics namespace

.chloggen/spanmetricsprocessor_support_set_namespace.yaml

@@ -0,0 +1,17 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: spanmetricsprocessor
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Support set metrics namespace
+
+# One or more tracking issues related to the change
+issues: [18199]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+

processor/spanmetricsprocessor/config.go

@@ -72,6 +72,9 @@ type Config struct {
 
 	// MetricsEmitInterval is the time period between when metrics are flushed or emitted to the configured MetricsExporter.
 	MetricsFlushInterval time.Duration `mapstructure:"metrics_flush_interval"`
+
+	// Namespace defines the namespace for the metrics exported by the spanmetricsprocessor.
+	Namespace string
 }
 
 // GetAggregationTemporality converts the string value given in the config into a AggregationTemporality.

processor/spanmetricsprocessor/processor.go

@@ -46,6 +46,9 @@ const (
 	metricKeySeparator = string(byte(0))
 
 	defaultDimensionsCacheSize = 1000
+
+	metricLatency    = "latency"
+	metricCallsTotal = "calls_total"
 )
 
 var defaultLatencyHistogramBucketsMs = []float64{
@@ -317,11 +320,21 @@ func (p *processorImp) buildMetrics() pmetric.Metrics {
 	return m
 }
 
+// buildMetricName builds a metric name by concatenating the namespace and the metric name with an underscore.
+// If the namespace is not empty, the namespace and metric name will be separated by an underscore.
+// Otherwise, only the metric name will be returned.
+func buildMetricName(namespace, metricName string) string {
+	if namespace != "" {
+		return namespace + "." + metricName
+	}
+	return metricName
+}
+
 // collectLatencyMetrics collects the raw latency metrics, writing the data
 // into the given instrumentation library metrics.
 func (p *processorImp) collectLatencyMetrics(ilm pmetric.ScopeMetrics) {
 	mLatency := ilm.Metrics().AppendEmpty()
-	mLatency.SetName("latency")
+	mLatency.SetName(buildMetricName(p.config.Namespace, metricLatency))
 	mLatency.SetUnit("ms")
 	mLatency.SetEmptyHistogram().SetAggregationTemporality(p.config.GetAggregationTemporality())
 	dps := mLatency.Histogram().DataPoints()
@@ -349,7 +362,7 @@ func (p *processorImp) collectLatencyMetrics(ilm pmetric.ScopeMetrics) {
 // into the given instrumentation library metrics.
 func (p *processorImp) collectCallMetrics(ilm pmetric.ScopeMetrics) {
 	mCalls := ilm.Metrics().AppendEmpty()
-	mCalls.SetName("calls_total")
+	mCalls.SetName(buildMetricName(p.config.Namespace, metricLatency))
 	mCalls.SetEmptySum().SetIsMonotonic(true)
 	mCalls.Sum().SetAggregationTemporality(p.config.GetAggregationTemporality())
 	dps := mCalls.Sum().DataPoints()

processor/spanmetricsprocessor/processor_test.go

@@ -1101,3 +1101,20 @@ func TestConsumeTracesEvictedCacheKey(t *testing.T) {
 	wg.Wait()
 	assert.Empty(t, wantDataPointCounts)
 }
+
+func TestBuildMetricName(t *testing.T) {
+	tests := []struct {
+		namespace  string
+		metricName string
+		expected   string
+	}{
+		{"", "metric", "metric"},
+		{"ns", "metric", "ns_metric"},
+		{"longer_namespace", "metric", "longer_namespace_metric"},
+	}
+
+	for _, test := range tests {
+		actual := buildMetricName(test.namespace, test.metricName)
+		assert.Equal(t, test.expected, actual)
+	}
+}