[receiver/windowsperfcounters] fix: Drop metrics with empty datapoints.

.chloggen/windowsperfcounters-empty-datapoints.yaml

@@ -0,0 +1,6 @@
+change_type: bug_fix
+component: windowsperfcountersreceiver
+note: Metric definitions with no matching performance counter are no longer included as metrics with zero datapoints in the scrape output.
+issues: [4972]
+subtext:
+change_logs: [user]

receiver/windowsperfcountersreceiver/testdata/scraper/metric_not_scraped.yaml

@@ -0,0 +1,14 @@
+resourceMetrics:
+  - resource: {}
+    scopeMetrics:
+      - metrics:
+          - description: percentage of time CPU is idle.
+            gauge:
+              dataPoints:
+                - asDouble: 0
+                  timeUnixNano: "1646857199239674900"
+            name: cpu.idle
+            unit: '%'
+        # Should not be present in the scrape output.
+        # - name: no.counter
+        scope: {}

receiver/windowsperfcountersreceiver/testdata/scraper/no_metric_def.yaml

@@ -7,4 +7,5 @@ resourceMetrics:
                 - asInt: "25089622016"
                   timeUnixNano: "1647459021285009300"
             name: \Memory\Committed Bytes
+            unit: '1'
         scope: {}

receiver/windowsperfcountersreceiver/testdata/scraper/standard.yaml

@@ -11,48 +11,6 @@ resourceMetrics:
                       value:
                         stringValue: "0"
                   timeUnixNano: "1646857199239674900"
-                - asDouble: 0
-                  attributes:
-                    - key: instance
-                      value:
-                        stringValue: "1"
-                  timeUnixNano: "1646857199239674900"
-                - asDouble: 0
-                  attributes:
-                    - key: instance
-                      value:
-                        stringValue: "2"
-                  timeUnixNano: "1646857199239674900"
-                - asDouble: 0
-                  attributes:
-                    - key: instance
-                      value:
-                        stringValue: "3"
-                  timeUnixNano: "1646857199239674900"
-                - asDouble: 0
-                  attributes:
-                    - key: instance
-                      value:
-                        stringValue: "4"
-                  timeUnixNano: "1646857199239674900"
-                - asDouble: 0
-                  attributes:
-                    - key: instance
-                      value:
-                        stringValue: "5"
-                  timeUnixNano: "1646857199239674900"
-                - asDouble: 0
-                  attributes:
-                    - key: instance
-                      value:
-                        stringValue: "6"
-                  timeUnixNano: "1646857199239674900"
-                - asDouble: 0
-                  attributes:
-                    - key: instance
-                      value:
-                        stringValue: "7"
-                  timeUnixNano: "1646857199239674900"
             name: cpu.idle
             unit: '%'
           - description: number of bytes committed to memory
@@ -71,12 +29,6 @@ resourceMetrics:
                       value:
                         stringValue: "1"
                   timeUnixNano: "1646857199239674900"
-                - asDouble: 0
-                  attributes:
-                    - key: instance
-                      value:
-                        stringValue: "2"
-                  timeUnixNano: "1646857199239674900"
             name: processor.time
             unit: '%'
         scope: {}

receiver/windowsperfcountersreceiver/testdata/scraper/sum_metric.yaml

@@ -6,6 +6,7 @@ resourceMetrics:
             name: bytes.committed
             sum:
               aggregationTemporality: 2
+              isMonotonic: true
               dataPoints:
                 - asDouble: 1.94461696e+10
                   timeUnixNano: "1646862225775600200"

receiver/windowsperfcountersreceiver/windowsperfcounters_scraper.go

@@ -157,9 +157,24 @@ func (s *scraper) scrape(context.Context) (pmetric.Metrics, error) {
 			initializeMetricDps(metric, now, val, watcher.MetricRep.Attributes)
 		}
 	}
+
+	// Drop metrics with no datapoints. This happens when configured counters don't exist on the host.
+	// This may result in a Metrics message with no metrics if all counters are missing.
+	metricSlice.RemoveIf(func(m pmetric.Metric) bool {
+		switch m.Type() {
+		case pmetric.MetricTypeGauge:
+			return m.Gauge().DataPoints().Len() == 0
+		case pmetric.MetricTypeSum:
+			return m.Sum().DataPoints().Len() == 0
+		default:
+			return false
+		}
+	})
+
 	if scrapeFailures != 0 && scrapeFailures != len(s.watchers) {
 		errs = scrapererror.NewPartialScrapeError(errs, scrapeFailures)
 	}
+
 	return md, errs
 }
 

receiver/windowsperfcountersreceiver/windowsperfcounters_scraper_test.go

@@ -118,7 +118,7 @@ func Test_WindowsPerfCounterScraper(t *testing.T) {
 					"bytes.committed": {
 						Description: "number of bytes committed to memory",
 						Unit:        "By",
-						Sum:         SumMetric{},
+						Sum:         SumMetric{Aggregation: "cumulative", Monotonic: true},
 					},
 				},
 				PerfCounters: []ObjectConfig{
@@ -156,6 +156,28 @@ func Test_WindowsPerfCounterScraper(t *testing.T) {
 			startMessage: "some performance counters could not be initialized",
 			startErr:     "failed to create perf counter with path \\Invalid Object\\Invalid Counter: The specified object was not found on the computer.\r\n",
 		},
+		{
+			name: "MetricDefinedButNoScrapedValue",
+			cfg: &Config{
+				MetricMetaData: map[string]MetricConfig{
+					"cpu.idle": {
+						Description: "percentage of time CPU is idle.",
+						Unit:        "%",
+						Gauge:       GaugeMetric{},
+					},
+					"no.counter": {
+						Description: "there is no counter or data for this metric",
+						Unit:        "By",
+						Gauge:       GaugeMetric{},
+					},
+				},
+				PerfCounters: []ObjectConfig{
+					{Object: "Processor", Instances: []string{"_Total"}, Counters: []CounterConfig{{Name: "% Idle Time", MetricRep: MetricRep{Name: "cpu.idle"}}}},
+				},
+				ControllerConfig: scraperhelper.ControllerConfig{CollectionInterval: time.Minute, InitialDelay: time.Second},
+			},
+			expectedMetricPath: filepath.Join("testdata", "scraper", "metric_not_scraped.yaml"),
+		},
 	}
 
 	for _, test := range testCases {
@@ -192,8 +214,16 @@ func Test_WindowsPerfCounterScraper(t *testing.T) {
 			expectedMetrics, err := golden.ReadMetrics(test.expectedMetricPath)
 			require.NoError(t, err)
 
-			// TODO: Metrics comparison is failing, not verifying the result until that is fixed.
-			_ = pmetrictest.CompareMetrics(expectedMetrics, actualMetrics, pmetrictest.IgnoreMetricValues())
+			require.NoError(t, pmetrictest.CompareMetrics(expectedMetrics, actualMetrics,
+				// Scraping test host means static values, timestamps and instance counts are unreliable. ScopeMetrics order is also unpredictable.
+				// The check only takes the first instance of multi-instance counters and assumes that the other instances would be included.
+				pmetrictest.IgnoreSubsequentDataPoints("cpu.idle"),
+				pmetrictest.IgnoreSubsequentDataPoints("processor.time"),
+				pmetrictest.IgnoreScopeMetricsOrder(),
+				pmetrictest.IgnoreResourceMetricsOrder(),
+				pmetrictest.IgnoreMetricValues(),
+				pmetrictest.IgnoreTimestamp(),
+			))
 		})
 	}
 }
@@ -473,18 +503,28 @@ func TestScrape(t *testing.T) {
 			metrics.Sort(func(a, b pmetric.Metric) bool {
 				return a.Name() < b.Name()
 			})
+
+			assert.Equal(t, len(test.mockPerfCounters)-len(expectedErrors), metrics.Len())
+
 			curMetricsNum := 0
 			for _, pc := range test.cfg.PerfCounters {
 
 				for counterIdx, counterCfg := range pc.Counters {
+					counterValues := test.mockPerfCounters[counterIdx].counterValues
+					scrapeErr := test.mockPerfCounters[counterIdx].scrapeErr
+
+					if scrapeErr != nil {
+						require.Empty(t, counterValues, "Invalid test case. Scrape error and counter values simultaneously.")
+						continue // no data for this counter.
+					}
+
 					metric := metrics.At(curMetricsNum)
 					assert.Equal(t, counterCfg.MetricRep.Name, metric.Name())
 					metricData := test.cfg.MetricMetaData[counterCfg.MetricRep.Name]
 					assert.Equal(t, metricData.Description, metric.Description())
 					assert.Equal(t, metricData.Unit, metric.Unit())
 					dps := metric.Gauge().DataPoints()
 
-					counterValues := test.mockPerfCounters[counterIdx].counterValues
 					assert.Equal(t, len(counterValues), dps.Len())
 					for dpIdx, val := range counterValues {
 						assert.Equal(t, val.Value, dps.At(dpIdx).DoubleValue())