feat: aggregator histogram add expiration (#10520)

plugins/aggregators/histogram/histogram.go

@@ -3,8 +3,10 @@ package histogram
 import (
 	"sort"
 	"strconv"
+	"time"
 
 	"github.com/influxdata/telegraf"
+	telegrafConfig "github.com/influxdata/telegraf/config"
 	"github.com/influxdata/telegraf/plugins/aggregators"
 )
 
@@ -22,9 +24,10 @@ const bucketNegInf = "-Inf"
 
 // HistogramAggregator is aggregator with histogram configs and particular histograms for defined metrics
 type HistogramAggregator struct {
-	Configs      []config `toml:"config"`
-	ResetBuckets bool     `toml:"reset"`
-	Cumulative   bool     `toml:"cumulative"`
+	Configs            []config                `toml:"config"`
+	ResetBuckets       bool                    `toml:"reset"`
+	Cumulative         bool                    `toml:"cumulative"`
+	ExpirationInterval telegrafConfig.Duration `toml:"expiration_interval"`
 
 	buckets bucketsByMetrics
 	cache   map[uint64]metricHistogramCollection
@@ -51,6 +54,7 @@ type metricHistogramCollection struct {
 	histogramCollection map[string]counts
 	name                string
 	tags                map[string]string
+	expireTime          time.Time
 }
 
 // counts is the number of hits in the bucket
@@ -63,6 +67,8 @@ type groupedByCountFields struct {
 	fieldsWithCount map[string]int64
 }
 
+var timeNow = time.Now
+
 // NewHistogramAggregator creates new histogram aggregator
 func NewHistogramAggregator() *HistogramAggregator {
 	h := &HistogramAggregator{
@@ -90,6 +96,10 @@ var sampleConfig = `
   ## Defaults to true.
   cumulative = true
 
+  ## Expiration interval for each histogram. The histogram will be expired if 
+  ## there are no changes in any buckets for this time interval. 0 == no expiration.
+  # expiration_interval = "0m"
+
   ## Example config that aggregates all fields of the metric.
   # [[aggregators.histogram.config]]
   #   ## Right borders of buckets (with +Inf implicitly added).
@@ -119,6 +129,8 @@ func (h *HistogramAggregator) Description() string {
 
 // Add adds new hit to the buckets
 func (h *HistogramAggregator) Add(in telegraf.Metric) {
+	addTime := timeNow()
+
 	bucketsByField := make(map[string][]float64)
 	for field := range in.Fields() {
 		buckets := h.getBuckets(in.Name(), field)
@@ -151,6 +163,9 @@ func (h *HistogramAggregator) Add(in telegraf.Metric) {
 				index := sort.SearchFloat64s(buckets, value)
 				agr.histogramCollection[field][index]++
 			}
+			if h.ExpirationInterval != 0 {
+				agr.expireTime = addTime.Add(time.Duration(h.ExpirationInterval))
+			}
 		}
 	}
 
@@ -160,8 +175,13 @@ func (h *HistogramAggregator) Add(in telegraf.Metric) {
 // Push returns histogram values for metrics
 func (h *HistogramAggregator) Push(acc telegraf.Accumulator) {
 	metricsWithGroupedFields := []groupedByCountFields{}
+	now := timeNow()
 
-	for _, aggregate := range h.cache {
+	for id, aggregate := range h.cache {
+		if h.ExpirationInterval != 0 && now.After(aggregate.expireTime) {
+			delete(h.cache, id)
+			continue
+		}
 		for field, counts := range aggregate.histogramCollection {
 			h.groupFieldsByBuckets(&metricsWithGroupedFields, aggregate.name, field, copyTags(aggregate.tags), counts)
 		}

plugins/aggregators/histogram/histogram_test.go

@@ -8,6 +8,7 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"github.com/influxdata/telegraf"
+	telegrafConfig "github.com/influxdata/telegraf/config"
 	"github.com/influxdata/telegraf/metric"
 	"github.com/influxdata/telegraf/testutil"
 )
@@ -17,10 +18,15 @@ type tags map[string]string
 
 // NewTestHistogram creates new test histogram aggregation with specified config
 func NewTestHistogram(cfg []config, reset bool, cumulative bool) telegraf.Aggregator {
+	return NewTestHistogramWithExpirationInterval(cfg, reset, cumulative, 0)
+}
+
+func NewTestHistogramWithExpirationInterval(cfg []config, reset bool, cumulative bool, expirationInterval telegrafConfig.Duration) telegraf.Aggregator {
 	htm := NewHistogramAggregator()
 	htm.Configs = cfg
 	htm.ResetBuckets = reset
 	htm.Cumulative = cumulative
+	htm.ExpirationInterval = expirationInterval
 
 	return htm
 }
@@ -244,6 +250,37 @@ func TestWrongBucketsOrder(t *testing.T) {
 	histogram.Add(firstMetric2)
 }
 
+// TestHistogram tests two metrics getting added and metric expiration
+func TestHistogramMetricExpiration(t *testing.T) {
+	currentTime := time.Unix(10, 0)
+	timeNow = func() time.Time {
+		return currentTime
+	}
+	defer func() {
+		timeNow = time.Now
+	}()
+
+	var cfg []config
+	cfg = append(cfg, config{Metric: "first_metric_name", Fields: []string{"a"}, Buckets: []float64{0.0, 10.0, 20.0, 30.0, 40.0}})
+	cfg = append(cfg, config{Metric: "second_metric_name", Buckets: []float64{0.0, 4.0, 10.0, 23.0, 30.0}})
+	histogram := NewTestHistogramWithExpirationInterval(cfg, false, true, telegrafConfig.Duration(30))
+
+	acc := &testutil.Accumulator{}
+
+	histogram.Add(firstMetric1)
+	currentTime = time.Unix(41, 0)
+	histogram.Add(secondMetric)
+	histogram.Push(acc)
+
+	require.Len(t, acc.Metrics, 6, "Incorrect number of metrics")
+	assertContainsTaggedField(t, acc, "second_metric_name", fields{"a_bucket": int64(0), "ignoreme_bucket": int64(0), "andme_bucket": int64(0)}, tags{bucketRightTag: "0"})
+	assertContainsTaggedField(t, acc, "second_metric_name", fields{"a_bucket": int64(0), "ignoreme_bucket": int64(0), "andme_bucket": int64(0)}, tags{bucketRightTag: "4"})
+	assertContainsTaggedField(t, acc, "second_metric_name", fields{"a_bucket": int64(0), "ignoreme_bucket": int64(0), "andme_bucket": int64(0)}, tags{bucketRightTag: "10"})
+	assertContainsTaggedField(t, acc, "second_metric_name", fields{"a_bucket": int64(0), "ignoreme_bucket": int64(0), "andme_bucket": int64(0)}, tags{bucketRightTag: "23"})
+	assertContainsTaggedField(t, acc, "second_metric_name", fields{"a_bucket": int64(0), "ignoreme_bucket": int64(0), "andme_bucket": int64(0)}, tags{bucketRightTag: "30"})
+	assertContainsTaggedField(t, acc, "second_metric_name", fields{"a_bucket": int64(1), "ignoreme_bucket": int64(0), "andme_bucket": int64(0)}, tags{bucketRightTag: bucketPosInf})
+}
+
 // assertContainsTaggedField is help functions to test histogram data
 func assertContainsTaggedField(t *testing.T, acc *testutil.Accumulator, metricName string, fields map[string]interface{}, tags map[string]string) {
 	acc.Lock()