func TestRandomNoEndpoints(t *testing.T) {
lb := loadbalancer.NewRandom(fixed.NewPublisher([]endpoint.Endpoint{}), 123)
_, have := lb.Endpoint()
if want := loadbalancer.ErrNoEndpoints; want != have {
t.Errorf("want %q, have %q", want, have)
}
}
func TestRoundRobinDistribution(t *testing.T) {
var (
ctx = context.Background()
counts = []int{0, 0, 0}
endpoints = []endpoint.Endpoint{
func(context.Context, interface{}) (interface{}, error) { counts[0]++; return struct{}{}, nil },
func(context.Context, interface{}) (interface{}, error) { counts[1]++; return struct{}{}, nil },
func(context.Context, interface{}) (interface{}, error) { counts[2]++; return struct{}{}, nil },
}
)
lb := loadbalancer.NewRoundRobin(fixed.NewPublisher(endpoints))
for i, want := range [][]int{
{1, 0, 0},
{1, 1, 0},
{1, 1, 1},
{2, 1, 1},
{2, 2, 1},
{2, 2, 2},
{3, 2, 2},
} {
e, err := lb.Endpoint()
if err != nil {
t.Fatal(err)
}
e(ctx, struct{}{})
if have := counts; !reflect.DeepEqual(want, have) {
t.Fatalf("%d: want %v, have %v", i, want, have)
}
}
}
func TestRandomDistribution(t *testing.T) {
var (
n = 3
endpoints = make([]endpoint.Endpoint, n)
counts = make([]int, n)
seed = int64(123)
ctx = context.Background()
iterations = 100000
want = iterations / n
tolerance = want / 100 // 1%
)
for i := 0; i < n; i++ {
i0 := i
endpoints[i] = func(context.Context, interface{}) (interface{}, error) { counts[i0]++; return struct{}{}, nil }
}
lb := loadbalancer.NewRandom(fixed.NewPublisher(endpoints), seed)
for i := 0; i < iterations; i++ {
e, err := lb.Endpoint()
if err != nil {
t.Fatal(err)
}
e(ctx, struct{}{})
}
for i, have := range counts {
if math.Abs(float64(want-have)) > float64(tolerance) {
t.Errorf("%d: want %d, have %d", i, want, have)
}
}
}
func TestRetryMaxTotalFail(t *testing.T) {
var (
endpoints = []endpoint.Endpoint{} // no endpoints
p = fixed.NewPublisher(endpoints)
lb = loadbalancer.NewRoundRobin(p)
retry = loadbalancer.Retry(999, time.Second, lb) // lots of retries
ctx = context.Background()
)
if _, err := retry(ctx, struct{}{}); err == nil {
t.Errorf("expected error, got none") // should fail
}
}
// NewPublisher returns a static endpoint Publisher.
func NewPublisher(instances []string, factory loadbalancer.Factory, logger log.Logger) Publisher {
logger = log.NewContext(logger).With("component", "Fixed Publisher")
endpoints := []endpoint.Endpoint{}
for _, instance := range instances {
e, err := factory(instance)
if err != nil {
_ = logger.Log("instance", instance, "err", err)
continue
}
endpoints = append(endpoints, e)
}
return Publisher{fixed.NewPublisher(endpoints)}
}
func TestFixed(t *testing.T) {
var (
e1 = func(context.Context, interface{}) (interface{}, error) { return struct{}{}, nil }
e2 = func(context.Context, interface{}) (interface{}, error) { return struct{}{}, nil }
endpoints = []endpoint.Endpoint{e1, e2}
)
p := fixed.NewPublisher(endpoints)
have, err := p.Endpoints()
if err != nil {
t.Fatal(err)
}
if want := endpoints; !reflect.DeepEqual(want, have) {
t.Fatalf("want %#+v, have %#+v", want, have)
}
}
func TestRetryMaxSuccess(t *testing.T) {
var (
endpoints = []endpoint.Endpoint{
func(context.Context, interface{}) (interface{}, error) { return nil, errors.New("error one") },
func(context.Context, interface{}) (interface{}, error) { return nil, errors.New("error two") },
func(context.Context, interface{}) (interface{}, error) { return struct{}{}, nil /* OK */ },
}
retries = len(endpoints) // exactly enough retries
p = fixed.NewPublisher(endpoints)
lb = loadbalancer.NewRoundRobin(p)
ctx = context.Background()
)
if _, err := loadbalancer.Retry(retries, time.Second, lb)(ctx, struct{}{}); err != nil {
t.Error(err)
}
}
func TestRetryMaxPartialFail(t *testing.T) {
var (
endpoints = []endpoint.Endpoint{
func(context.Context, interface{}) (interface{}, error) { return nil, errors.New("error one") },
func(context.Context, interface{}) (interface{}, error) { return nil, errors.New("error two") },
func(context.Context, interface{}) (interface{}, error) { return struct{}{}, nil /* OK */ },
}
retries = len(endpoints) - 1 // not quite enough retries
p = fixed.NewPublisher(endpoints)
lb = loadbalancer.NewRoundRobin(p)
ctx = context.Background()
)
if _, err := loadbalancer.Retry(retries, time.Second, lb)(ctx, struct{}{}); err == nil {
t.Errorf("expected error, got none")
}
}
func TestFixedReplace(t *testing.T) {
p := fixed.NewPublisher([]endpoint.Endpoint{
func(context.Context, interface{}) (interface{}, error) { return struct{}{}, nil },
})
have, err := p.Endpoints()
if err != nil {
t.Fatal(err)
}
if want, have := 1, len(have); want != have {
t.Fatalf("want %d, have %d", want, have)
}
p.Replace([]endpoint.Endpoint{})
have, err = p.Endpoints()
if err != nil {
t.Fatal(err)
}
if want, have := 0, len(have); want != have {
t.Fatalf("want %d, have %d", want, have)
}
}
func TestRetryTimeout(t *testing.T) {
var (
step = make(chan struct{})
e = func(context.Context, interface{}) (interface{}, error) { <-step; return struct{}{}, nil }
timeout = time.Millisecond
retry = loadbalancer.Retry(999, timeout, loadbalancer.NewRoundRobin(fixed.NewPublisher([]endpoint.Endpoint{e})))
errs = make(chan error, 1)
invoke = func() { _, err := retry(context.Background(), struct{}{}); errs <- err }
)
go func() { step <- struct{}{} }() // queue up a flush of the endpoint
invoke() // invoke the endpoint and trigger the flush
if err := <-errs; err != nil { // that should succeed
t.Error(err)
}
go func() { time.Sleep(10 * timeout); step <- struct{}{} }() // a delayed flush
invoke() // invoke the endpoint
if err := <-errs; err != context.DeadlineExceeded { // that should not succeed
t.Errorf("wanted %v, got none", context.DeadlineExceeded)
}
}