add additional buffer channel

management/server/update_buffer.go

@@ -0,0 +1,74 @@
+package server
+
+import (
+	"context"
+	"sync"
+
+	"github.com/netbirdio/netbird/management/server/telemetry"
+)
+
+type UpdateBuffer struct {
+	mu      sync.Mutex
+	cond    *sync.Cond
+	update  *UpdateMessage
+	closed  bool
+	metrics *telemetry.UpdateChannelMetrics
+}
+
+func NewUpdateBuffer(metrics *telemetry.UpdateChannelMetrics) *UpdateBuffer {
+	ub := &UpdateBuffer{metrics: metrics}
+	ub.cond = sync.NewCond(&ub.mu)
+	return ub
+}
+
+func (b *UpdateBuffer) Push(update *UpdateMessage) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	if b.update == nil || update.Update.NetworkMap.Serial > b.update.Update.NetworkMap.Serial || b.update.Update.NetworkMap.Serial == 0 {
+		b.update = update
+		b.cond.Signal()
+		if b.update == nil {
+			b.metrics.CountBufferPush()
+			return
+		}
+
+		b.metrics.CountBufferOverwrite()
+		return
+	}
+
+	b.metrics.CountBufferIgnore()
+}
+
+func (b *UpdateBuffer) Pop(ctx context.Context) (*UpdateMessage, bool) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	for b.update == nil && !b.closed {
+		waitCh := make(chan struct{})
+		go func() {
+			select {
+			case <-ctx.Done():
+				b.cond.Broadcast()
+			case <-waitCh:
+				// noop
+			}
+		}()
+		b.cond.Wait()
+		close(waitCh)
+	}
+
+	if b.closed {
+		return nil, false
+	}
+	msg := b.update
+	b.update = nil
+	return msg, true
+}
+
+func (b *UpdateBuffer) Close() {
+	b.mu.Lock()
+	b.closed = true
+	b.cond.Broadcast()
+	b.mu.Unlock()
+}