feat(data-plane): implement phase3c gateway

gateway/telemetry.go

@@ -0,0 +1,67 @@
+package gateway
+
+import (
+	"context"
+	"sync/atomic"
+	"time"
+)
+
+type Metrics struct {
+	ActiveSessions   atomic.Int64
+	AdmissionRejects atomic.Uint64
+	MediaDrops       atomic.Uint64
+	ProviderErrors   atomic.Uint64
+	InputRejected    atomic.Uint64
+}
+
+type MetricsSnapshot struct {
+	ActiveSessions   int64
+	AdmissionRejects uint64
+	MediaDrops       uint64
+	ProviderErrors   uint64
+	InputRejected    uint64
+}
+
+func (m *Metrics) Snapshot() MetricsSnapshot {
+	return MetricsSnapshot{
+		ActiveSessions:   m.ActiveSessions.Load(),
+		AdmissionRejects: m.AdmissionRejects.Load(),
+		MediaDrops:       m.MediaDrops.Load(),
+		ProviderErrors:   m.ProviderErrors.Load(),
+		InputRejected:    m.InputRejected.Load(),
+	}
+}
+
+type Pacer struct {
+	bytesPerSecond int64
+	last           time.Time
+}
+
+func NewPacer(kbps int64) *Pacer {
+	if kbps < 1 {
+		return &Pacer{}
+	}
+	return &Pacer{bytesPerSecond: kbps * 1000 / 8}
+}
+
+func (p *Pacer) Wait(ctx context.Context, bytes int) error {
+	if p.bytesPerSecond < 1 || bytes < 1 {
+		return nil
+	}
+	now := time.Now()
+	if p.last.IsZero() || now.After(p.last) {
+		p.last = now
+	}
+	delay := time.Duration(float64(bytes) / float64(p.bytesPerSecond) * float64(time.Second))
+	p.last = p.last.Add(delay)
+	if wait := time.Until(p.last); wait > 0 {
+		timer := time.NewTimer(wait)
+		defer timer.Stop()
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		case <-timer.C:
+		}
+	}
+	return nil
+}