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// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package net
import (
"testing"
)
func checkDistribution(t *testing.T, data []*SRV, margin float64) {
sum := 0
for _, srv := range data {
sum += int(srv.Weight)
}
results := make(map[string]int)
count := 10000
for j := 0; j < count; j++ {
d := make([]*SRV, len(data))
copy(d, data)
byPriorityWeight(d).shuffleByWeight()
key := d[0].Target
results[key] = results[key] + 1
}
actual := results[data[0].Target]
expected := float64(count) * float64(data[0].Weight) / float64(sum)
diff := float64(actual) - expected
t.Logf("actual: %v diff: %v e: %v m: %v", actual, diff, expected, margin)
if diff < 0 {
diff = -diff
}
if diff > (expected * margin) {
t.Errorf("missed target weight: expected %v, %v", expected, actual)
}
}
func testUniformity(t *testing.T, size int, margin float64) {
data := make([]*SRV, size)
for i := 0; i < size; i++ {
data[i] = &SRV{Target: string('a' + rune(i)), Weight: 1}
}
checkDistribution(t, data, margin)
}
func TestDNSSRVUniformity(t *testing.T) {
testUniformity(t, 2, 0.05)
testUniformity(t, 3, 0.10)
testUniformity(t, 10, 0.20)
testWeighting(t, 0.05)
}
func testWeighting(t *testing.T, margin float64) {
data := []*SRV{
{Target: "a", Weight: 60},
{Target: "b", Weight: 30},
{Target: "c", Weight: 10},
}
checkDistribution(t, data, margin)
}
func TestWeighting(t *testing.T) {
testWeighting(t, 0.05)
}
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