func TestRoundRobin(t *testing.T) {
var (
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 },
}
)
subscriber := sd.FixedSubscriber(endpoints)
balancer := NewRoundRobin(subscriber)
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},
} {
endpoint, err := balancer.Endpoint()
if err != nil {
t.Fatal(err)
}
endpoint(context.Background(), struct{}{})
if have := counts; !reflect.DeepEqual(want, have) {
t.Fatalf("%d: want %v, have %v", i, want, have)
}
}
}
func TestRandom(t *testing.T) {
var (
n = 7
endpoints = make([]endpoint.Endpoint, n)
counts = make([]int, n)
seed = int64(12345)
iterations = 1000000
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 }
}
subscriber := sd.FixedSubscriber(endpoints)
balancer := NewRandom(subscriber, seed)
for i := 0; i < iterations; i++ {
endpoint, _ := balancer.Endpoint()
endpoint(context.Background(), struct{}{})
}
for i, have := range counts {
delta := int(math.Abs(float64(want - have)))
if delta > tolerance {
t.Errorf("%d: want %d, have %d, delta %d > %d tolerance", i, want, have, delta, tolerance)
}
}
}
func TestRoundRobinNoRace(t *testing.T) {
balancer := NewRoundRobin(sd.FixedSubscriber([]endpoint.Endpoint{
endpoint.Nop,
endpoint.Nop,
endpoint.Nop,
endpoint.Nop,
endpoint.Nop,
}))
var (
n = 100
done = make(chan struct{})
wg sync.WaitGroup
count uint64
)
wg.Add(n)
for i := 0; i < n; i++ {
go func() {
defer wg.Done()
for {
select {
case <-done:
return
default:
_, _ = balancer.Endpoint()
atomic.AddUint64(&count, 1)
}
}
}()
}
time.Sleep(time.Second)
close(done)
wg.Wait()
t.Logf("made %d calls", atomic.LoadUint64(&count))
}