Function TestMaxAgeFIFORotation

plugin/pkg/proxy/persistent_test.go:277–315

TestMaxAgeFIFORotation verifies that connections in a FIFO pool are closed by max_age even when continuously rotated (which refreshes their used timestamps). Regression test for Scale up: new upstream pods should receive traffic after existing connections exceed max_age, regardless of request rate.

(t *testing.T)

// Regression test for Scale up: new upstream pods should receive traffic after
// existing connections exceed max_age, regardless of request rate.
func TestMaxAgeFIFORotation(t *testing.T) {
	s := dnstest.NewServer(func(w dns.ResponseWriter, r *dns.Msg) {
		ret := new(dns.Msg)
		ret.SetReply(r)
		w.WriteMsg(ret)
	})
	defer s.Close()

	tr := newTransport("TestMaxAgeFIFORotation", s.Addr)
	tr.SetExpire(10 * time.Second)       // long idle-timeout: FIFO rotation keeps connections alive
	tr.SetMaxAge(100 * time.Millisecond) // max-age: connections must be closed by creation age
	tr.Start()
	defer tr.Stop()

	// Inject 3 connections old by creation time but with fresh used timestamps,
	// simulating active FIFO rotation where idle-timeout never triggers.
	tr.mu.Lock()
	for range 3 {
		c, err := dns.DialTimeout("udp", tr.addr, maxDialTimeout)
		if err != nil {
			tr.mu.Unlock()
			t.Fatalf("Failed to dial: %v", err)
		}
		tr.conns[typeUDP] = append(tr.conns[typeUDP], &persistConn{
			c:       c,
			created: time.Now().Add(-200 * time.Millisecond), // exceeds max-age
			used:    time.Now(),                              // fresh: idle-timeout would pass
		})
	}
	tr.mu.Unlock()

	// All 3 connections must be rejected by max_age despite fresh used timestamps.
	for i := range 3 {
		_, cached, _ := tr.Dial("udp")
		if cached {
			t.Errorf("Dial %d: connection should be closed by max_age (FIFO rotation must not prevent max-age expiry)", i+1)
		}
	}
}

func BenchmarkYield(b *testing.B) {
	s := dnstest.NewServer(func(w dns.ResponseWriter, r *dns.Msg) {