Initial copy in

target.go

@@ -0,0 +1,70 @@
+package event
+
+import (
+	"math"
+	"math/rand"
+	"time"
+
+	"github.com/go-resty/resty/v2"
+)
+
+type Target struct {
+	client             *resty.Client
+	writePeriodSeconds float64
+	windowSeconds      float64
+	rateClasses        []*rateClass
+	stop               chan bool
+	lastEvent          time.Time
+	events             []*Event
+}
+
+func (target *Target) AddRateClass(grantRate float64, vals ...any) {
+	if len(vals)%2 != 0 {
+		panic(vals)
+	}
+
+	erc := &rateClass{
+		grantRate: grantRate * target.windowSeconds,
+		criteria:  map[string]any{},
+	}
+
+	for i := 0; i < len(vals); i += 2 {
+		erc.criteria[vals[i].(string)] = vals[i+1]
+	}
+
+	target.rateClasses = append(target.rateClasses, erc)
+}
+
+func (target *Target) writeEvent(ev *Event) {
+	now := time.Now()
+	secondsSinceLastEvent := now.Sub(target.lastEvent).Seconds()
+	target.lastEvent = now
+
+	// Example:
+	//   windowSeconds = 100
+	//   secondsSinceLastEvent = 25
+	//   eventRateMultiplier = 0.75
+	eventRateMultiplier := (target.windowSeconds - secondsSinceLastEvent) / target.windowSeconds
+
+	maxProb := 0.0
+
+	for _, erc := range target.rateClasses {
+		if !erc.match(ev) {
+			continue
+		}
+
+		erc.eventRate++
+		erc.eventRate *= eventRateMultiplier
+
+		classProb := erc.grantRate / erc.eventRate
+		maxProb = math.Max(maxProb, classProb)
+	}
+
+	if maxProb <= 0.0 || rand.Float64() > maxProb { //nolint:gosec
+		return
+	}
+
+	ev2 := *ev
+	ev2.SampleRate = int64(math.Max(math.Round(1.0/maxProb), 1.0))
+	target.events = append(target.events, &ev2)
+}