If filterprocessor filters all data, stop further processing (#1500)

processor/README.md

@@ -135,6 +135,8 @@ are checked before the `exclude` properties.
 
 ```yaml
 filter:
+  # metrics indicates this processor applies to metrics
+  metrics:
     # include and/or exclude can be specified. However, the include properties
     # are always checked before the exclude properties.
     {include, exclude}:
@@ -149,7 +151,7 @@ filter:
 
       # metric_names specify an array of items to match the metric name against.
       # This is a required field.
-      metric_name: [<item1>, ..., <itemN>]
+      metric_names: [<item1>, ..., <itemN>]
 ```
 
 #### Match Configuration

processor/filterprocessor/filter_processor.go

@@ -22,6 +22,7 @@ import (
 	"go.opentelemetry.io/collector/consumer/pdata"
 	"go.opentelemetry.io/collector/consumer/pdatautil"
 	"go.opentelemetry.io/collector/internal/processor/filtermetric"
+	"go.opentelemetry.io/collector/processor/processorhelper"
 )
 
 type filterMetricProcessor struct {
@@ -62,9 +63,10 @@ func createMatcher(mp *filtermetric.MatchProperties) (*filtermetric.Matcher, err
 	return &matcher, nil
 }
 
-// ProcessMetrics filters the given spans based off the filterMetricProcessor's filters.
+// ProcessMetrics filters the given metrics based off the filterMetricProcessor's filters.
 func (fmp *filterMetricProcessor) ProcessMetrics(_ context.Context, md pdata.Metrics) (pdata.Metrics, error) {
 	mds := pdatautil.MetricsToMetricsData(md)
+	foundMetricToKeep := false
 	for i := range mds {
 		if len(mds[i].Metrics) == 0 {
 			continue
@@ -72,11 +74,16 @@ func (fmp *filterMetricProcessor) ProcessMetrics(_ context.Context, md pdata.Met
 		keep := make([]*metricspb.Metric, 0, len(mds[i].Metrics))
 		for _, m := range mds[i].Metrics {
 			if fmp.shouldKeepMetric(m) {
+				foundMetricToKeep = true
 				keep = append(keep, m)
 			}
 		}
 		mds[i].Metrics = keep
 	}
+
+	if !foundMetricToKeep {
+		return md, processorhelper.ErrSkipProcessingData
+	}
 	return pdatautil.MetricsFromMetricsData(mds), nil
 }
 

processor/filterprocessor/filter_processor_test.go

@@ -32,11 +32,12 @@ import (
 )
 
 type metricNameTest struct {
-	name  string
-	inc   *filtermetric.MatchProperties
-	exc   *filtermetric.MatchProperties
-	inMN  [][]*metricspb.Metric // input Metric batches
-	outMN [][]string            // output Metric names
+	name               string
+	inc                *filtermetric.MatchProperties
+	exc                *filtermetric.MatchProperties
+	inMN               [][]*metricspb.Metric // input Metric batches
+	outMN              [][]string            // output Metric names
+	allMetricsFiltered bool
 }
 
 var (
@@ -169,8 +170,8 @@ var (
 					MatchType: filterset.Strict,
 				},
 			},
-			inMN:  [][]*metricspb.Metric{metricsWithName(inMetricNames)},
-			outMN: [][]string{{}},
+			inMN:               [][]*metricspb.Metric{metricsWithName(inMetricNames)},
+			allMetricsFiltered: true,
 		},
 		{
 			name: "emptyFilterExclude",
@@ -220,8 +221,13 @@ func TestFilterMetricProcessor(t *testing.T) {
 				context.Background(),
 				pdatautil.MetricsFromMetricsData(mds))
 			assert.Nil(t, cErr)
-
 			got := next.AllMetrics()
+
+			if test.allMetricsFiltered {
+				require.Equal(t, 0, len(got))
+				return
+			}
+
 			require.Equal(t, 1, len(got))
 			gotMD := pdatautil.MetricsToMetricsData(got[0])
 			require.Equal(t, len(test.outMN), len(gotMD))

processor/processorhelper/processor.go

@@ -26,6 +26,11 @@ import (
 	"go.opentelemetry.io/collector/obsreport"
 )
 
+// ErrSkipProcessingData is a sentinel value to indicate when traces or metrics should intentionally be dropped
+// from further processing in the pipeline because the data is determined to be irrelevant. A processor can return this error
+// to stop further processing without propagating an error back up the pipeline to logs.
+var ErrSkipProcessingData = errors.New("sentinel error to skip processing data from the remainder of the pipeline")
+
 // Start specifies the function invoked when the processor is being started.
 type Start func(context.Context, component.Host) error
 
@@ -172,6 +177,9 @@ func (mp *metricsProcessor) ConsumeMetrics(ctx context.Context, md pdata.Metrics
 	var err error
 	md, err = mp.processor.ProcessMetrics(processorCtx, md)
 	if err != nil {
+		if err == ErrSkipProcessingData {
+			return nil
+		}
 		return err
 	}
 	return mp.nextConsumer.ConsumeMetrics(ctx, md)

processor/processorhelper/processor_test.go

@@ -129,6 +129,12 @@ func TestNewMetricsExporter_ProcessMetricsError(t *testing.T) {
 	assert.Equal(t, want, me.ConsumeMetrics(context.Background(), pdatautil.MetricsFromInternalMetrics(testdata.GenerateMetricDataEmpty())))
 }
 
+func TestNewMetricsExporter_ProcessMetricsErrSkipProcessingData(t *testing.T) {
+	me, err := NewMetricsProcessor(testCfg, exportertest.NewNopMetricsExporter(), newTestMProcessor(ErrSkipProcessingData))
+	require.NoError(t, err)
+	assert.Equal(t, nil, me.ConsumeMetrics(context.Background(), pdatautil.MetricsFromInternalMetrics(testdata.GenerateMetricDataEmpty())))
+}
+
 func TestNewLogsExporter(t *testing.T) {
 	me, err := NewLogsProcessor(testCfg, exportertest.NewNopLogsExporter(), newTestLProcessor(nil))
 	require.NoError(t, err)