Remove metric recreation when filtering (#4767)

internal/models/running_output.go

@@ -7,7 +7,6 @@ import (
 
 	"github.com/influxdata/telegraf"
 	"github.com/influxdata/telegraf/internal/buffer"
-	"github.com/influxdata/telegraf/metric"
 	"github.com/influxdata/telegraf/selfstat"
 )
 
@@ -42,6 +41,12 @@ type RunningOutput struct {
 	writeMutex sync.Mutex
 }
 
+// OutputConfig containing name and filter
+type OutputConfig struct {
+	Name   string
+	Filter Filter
+}
+
 func NewRunningOutput(
 	name string,
 	output telegraf.Output,
@@ -95,36 +100,25 @@ func NewRunningOutput(
 
 // AddMetric adds a metric to the output. This function can also write cached
 // points if FlushBufferWhenFull is true.
-func (ro *RunningOutput) AddMetric(m telegraf.Metric) {
-
-	if m == nil {
+func (ro *RunningOutput) AddMetric(metric telegraf.Metric) {
+	if ok := ro.Config.Filter.Select(metric); !ok {
+		ro.MetricsFiltered.Incr(1)
 		return
 	}
-	// Filter any tagexclude/taginclude parameters before adding metric
-	if ro.Config.Filter.IsActive() {
-		// In order to filter out tags, we need to create a new metric, since
-		// metrics are immutable once created.
-		name := m.Name()
-		tags := m.Tags()
-		fields := m.Fields()
-		t := m.Time()
-		tp := m.Type()
-		if ok := ro.Config.Filter.Apply(name, fields, tags); !ok {
-			ro.MetricsFiltered.Incr(1)
-			return
-		}
-		// error is not possible if creating from another metric, so ignore.
-		m, _ = metric.New(name, tags, fields, t, tp)
+
+	ro.Config.Filter.Modify(metric)
+	if len(metric.FieldList()) == 0 {
+		return
 	}
 
 	if output, ok := ro.Output.(telegraf.AggregatingOutput); ok {
 		ro.aggMutex.Lock()
-		output.Add(m)
+		output.Add(metric)
 		ro.aggMutex.Unlock()
 		return
 	}
 
-	ro.metrics.Add(m)
+	ro.metrics.Add(metric)
 	if ro.metrics.Len() == ro.MetricBatchSize {
 		batch := ro.metrics.Batch(ro.MetricBatchSize)
 		err := ro.write(batch)
@@ -206,9 +200,3 @@ func (ro *RunningOutput) write(metrics []telegraf.Metric) error {
 	}
 	return err
 }
-
-// OutputConfig containing name and filter
-type OutputConfig struct {
-	Name   string
-	Filter Filter
-}