Add valuecounter aggregator plugin (#3523)

plugins/aggregators/valuecounter/valuecounter.go

@@ -0,0 +1,108 @@
+package valuecounter
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/plugins/aggregators"
+)
+
+type aggregate struct {
+	name       string
+	tags       map[string]string
+	fieldCount map[string]int
+}
+
+// ValueCounter an aggregation plugin
+type ValueCounter struct {
+	cache  map[uint64]aggregate
+	Fields []string
+}
+
+// NewValueCounter create a new aggregation plugin which counts the occurances
+// of fields and emits the count.
+func NewValueCounter() telegraf.Aggregator {
+	vc := &ValueCounter{}
+	vc.Reset()
+	return vc
+}
+
+var sampleConfig = `
+  ## General Aggregator Arguments:
+  ## The period on which to flush & clear the aggregator.
+  period = "30s"
+  ## If true, the original metric will be dropped by the
+  ## aggregator and will not get sent to the output plugins.
+  drop_original = false
+  ## The fields for which the values will be counted
+  fields = []
+`
+
+// SampleConfig generates a sample config for the ValueCounter plugin
+func (vc *ValueCounter) SampleConfig() string {
+	return sampleConfig
+}
+
+// Description returns the description of the ValueCounter plugin
+func (vc *ValueCounter) Description() string {
+	return "Count the occurance of values in fields."
+}
+
+// Add is run on every metric which passes the plugin
+func (vc *ValueCounter) Add(in telegraf.Metric) {
+	id := in.HashID()
+
+	// Check if the cache already has an entry for this metric, if not create it
+	if _, ok := vc.cache[id]; !ok {
+		a := aggregate{
+			name:       in.Name(),
+			tags:       in.Tags(),
+			fieldCount: make(map[string]int),
+		}
+		vc.cache[id] = a
+	}
+
+	// Check if this metric has fields which we need to count, if so increment
+	// the count.
+	for fk, fv := range in.Fields() {
+		for _, cf := range vc.Fields {
+			if fk == cf {
+				// Do not process float types to prevent memory from blowing up
+				switch fv.(type) {
+				default:
+					log.Printf("I! Valuecounter: Unsupported field type. " +
+						"Must be an int, string or bool. Ignoring.")
+					continue
+				case uint64, int64, string, bool:
+				}
+				fn := fmt.Sprintf("%v_%v", fk, fv)
+				vc.cache[id].fieldCount[fn]++
+			}
+		}
+	}
+}
+
+// Push emits the counters
+func (vc *ValueCounter) Push(acc telegraf.Accumulator) {
+	for _, agg := range vc.cache {
+		fields := map[string]interface{}{}
+
+		for field, count := range agg.fieldCount {
+			fields[field] = count
+		}
+
+		acc.AddFields(agg.name, fields, agg.tags)
+	}
+}
+
+// Reset the cache, executed after each push
+func (vc *ValueCounter) Reset() {
+	vc.cache = make(map[uint64]aggregate)
+}
+
+func init() {
+	aggregators.Add("valuecounter", func() telegraf.Aggregator {
+		return NewValueCounter()
+	})
+}