WireGuard inbound: Reduce memory held by idle UDP flows (#6856)

https://github.com/XTLS/Xray-core/pull/6856#issuecomment-5870639238

proxy/wireguard/queue_bench_test.go

@@ -0,0 +1,80 @@
+package wireguard
+
+import (
+	"runtime"
+	"testing"
+)
+
+const benchBatch = 64
+
+// Raw cost of queueing and draining a small burst, as one flow's reader does.
+func BenchmarkQueueBurstChan(b *testing.B) {
+	ch := make(chan *packet, udpQueueLimit)
+	p := &packet{}
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		for j := 0; j < benchBatch; j++ {
+			ch <- p
+		}
+		for j := 0; j < benchBatch; j++ {
+			<-ch
+		}
+	}
+}
+
+func BenchmarkQueueBurstPacketQueue(b *testing.B) {
+	q := newPacketQueue(udpQueueLimit)
+	p := &packet{}
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		for j := 0; j < benchBatch; j++ {
+			q.push(p)
+		}
+		for j := 0; j < benchBatch; j++ {
+			q.pop()
+		}
+	}
+}
+
+// Producer and consumer on different goroutines; the producer yields when the
+// queue is full instead of spinning, like a blocking channel send would.
+func BenchmarkQueueStreamChan(b *testing.B) {
+	ch := make(chan *packet, udpQueueLimit)
+	p := &packet{}
+	done := make(chan struct{})
+	go func() {
+		for range ch {
+		}
+		close(done)
+	}()
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		ch <- p
+	}
+	close(ch)
+	<-done
+}
+
+func BenchmarkQueueStreamPacketQueue(b *testing.B) {
+	q := newPacketQueue(udpQueueLimit)
+	p := &packet{}
+	done := make(chan struct{})
+	go func() {
+		for {
+			if _, ok := q.pop(); !ok {
+				break
+			}
+		}
+		close(done)
+	}()
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		for !q.push(p) {
+			runtime.Gosched()
+		}
+	}
+	q.close()
+	<-done
+}