Method TestThreeSubConnsAffinity

balancer/ringhash/ringhash_test.go:188–329

TestThreeBackendsAffinity covers that there are 3 SubConns, RPCs with the same hash always pick the same SubConn. When the one picked is down, another one will be picked.

(t *testing.T)

// same hash always pick the same SubConn. When the one picked is down, another
// one will be picked.
func (s) TestThreeSubConnsAffinity(t *testing.T) {
	endpoints := []resolver.Endpoint{
		{Addresses: []resolver.Address{{Addr: testBackendAddrStrs[0]}}},
		{Addresses: []resolver.Address{{Addr: testBackendAddrStrs[1]}}},
		{Addresses: []resolver.Address{{Addr: testBackendAddrStrs[2]}}},
	}
	remainingAddrs := map[string]bool{
		testBackendAddrStrs[0]: true,
		testBackendAddrStrs[1]: true,
		testBackendAddrStrs[2]: true,
	}
	cc, _, p0 := setupTest(t, endpoints)
	// This test doesn't update addresses, so this ring will be used by all the
	// pickers.
	ring := p0.(*picker).ring

	firstHash := ring.items[0].hash
	// firstHash+1 will pick the second endpoint from the ring.
	testHash := firstHash + 1
	// The first pick should be queued, and should trigger Connect() on the only
	// SubConn.
	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
	defer cancel()
	if _, err := p0.Pick(balancer.PickInfo{Ctx: iringhash.SetXDSRequestHash(ctx, testHash)}); err != balancer.ErrNoSubConnAvailable {
		t.Fatalf("first pick returned err %v, want %v", err, balancer.ErrNoSubConnAvailable)
	}

	// The picked endpoint should be the second in the ring.
	var subConns [3]*testutils.TestSubConn
	select {
	case <-ctx.Done():
		t.Fatalf("Timed out waiting for SubConn creation.")
	case subConns[1] = <-cc.NewSubConnCh:
	}
	if got, want := subConns[1].Addresses[0].Addr, ring.items[1].hashKey; got != want {
		t.Fatalf("SubConn.Address = %v, want = %v", got, want)
	}
	select {
	case <-subConns[1].ConnectCh:
	case <-time.After(defaultTestTimeout):
		t.Errorf("timeout waiting for Connect() from SubConn %v", subConns[1])
	}
	delete(remainingAddrs, ring.items[1].hashKey)

	// Turn down the subConn in use.
	subConns[1].UpdateState(balancer.SubConnState{ConnectivityState: connectivity.Connecting})
	subConns[1].UpdateState(balancer.SubConnState{ConnectivityState: connectivity.TransientFailure})

	// This should trigger a connection to a new endpoint.
	<-cc.NewPickerCh
	var sc *testutils.TestSubConn
	select {
	case <-ctx.Done():
		t.Fatalf("Timed out waiting for SubConn creation.")
	case sc = <-cc.NewSubConnCh:
	}
	scAddr := sc.Addresses[0].Addr
	if _, ok := remainingAddrs[scAddr]; !ok {