func TestRandomNoEndpoints(t *testing.T) {
lb := loadbalancer.NewRandom(static.NewPublisher([]endpoint.Endpoint{}), 123)
_, have := lb.Endpoint()
if want := loadbalancer.ErrNoEndpoints; want != have {
t.Errorf("want %q, have %q", 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(static.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 buildEndpoint(instances []string, factory loadbalancer.Factory, seed int64, logger log.Logger) endpoint.Endpoint {
publisher := static.NewPublisher(instances, factory, logger)
random := loadbalancer.NewRandom(publisher, seed)
return loadbalancer.Retry(10, 10*time.Second, random)
}
func buildEndpoint(tracer opentracing.Tracer, operationName string, instances []string, factory loadbalancer.Factory, seed int64, logger log.Logger) endpoint.Endpoint {
publisher := static.NewPublisher(instances, factory, logger)
random := loadbalancer.NewRandom(publisher, seed)
endpoint := loadbalancer.Retry(10, 10*time.Second, random)
return kitot.TraceClient(tracer, operationName)(endpoint)
}