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package hostpool
import (
"errors"
"github.com/bmizerany/assert"
"io/ioutil"
"log"
"math/rand"
"os"
"testing"
"time"
)
func TestHostPool(t *testing.T) {
log.SetOutput(ioutil.Discard)
defer log.SetOutput(os.Stdout)
dummyErr := errors.New("Dummy Error")
p := New([]string{"a", "b", "c"})
assert.Equal(t, p.Get().Host(), "a")
assert.Equal(t, p.Get().Host(), "b")
assert.Equal(t, p.Get().Host(), "c")
respA := p.Get()
assert.Equal(t, respA.Host(), "a")
respA.Mark(dummyErr)
respB := p.Get()
respB.Mark(dummyErr)
respC := p.Get()
assert.Equal(t, respC.Host(), "c")
respC.Mark(nil)
// get again, and verify that it's still c
assert.Equal(t, p.Get().Host(), "c")
// now try to mark b as success; should fail because already marked
respB.Mark(nil)
assert.Equal(t, p.Get().Host(), "c") // would be b if it were not dead
// now restore a
respA = &standardHostPoolResponse{host: "a", pool: p}
respA.Mark(nil)
assert.Equal(t, p.Get().Host(), "a")
assert.Equal(t, p.Get().Host(), "c")
// ensure that we get *something* back when all hosts fail
for _, host := range []string{"a", "b", "c"} {
response := &standardHostPoolResponse{host: host, pool: p}
response.Mark(dummyErr)
}
resp := p.Get()
assert.NotEqual(t, resp, nil)
}
type mockTimer struct {
t int // the time it will always return
}
func (t *mockTimer) between(start time.Time, end time.Time) time.Duration {
return time.Duration(t.t) * time.Millisecond
}
func TestEpsilonGreedy(t *testing.T) {
log.SetOutput(ioutil.Discard)
defer log.SetOutput(os.Stdout)
rand.Seed(10)
iterations := 12000
p := NewEpsilonGreedy([]string{"a", "b"}, 0, &LinearEpsilonValueCalculator{}).(*epsilonGreedyHostPool)
timings := make(map[string]int64)
timings["a"] = 200
timings["b"] = 300
hitCounts := make(map[string]int)
hitCounts["a"] = 0
hitCounts["b"] = 0
log.Printf("starting first run (a, b)")
for i := 0; i < iterations; i += 1 {
if i != 0 && i%100 == 0 {
p.performEpsilonGreedyDecay()
}
hostR := p.Get()
host := hostR.Host()
hitCounts[host]++
timing := timings[host]
p.timer = &mockTimer{t: int(timing)}
hostR.Mark(nil)
}
for host := range hitCounts {
log.Printf("host %s hit %d times (%0.2f percent)", host, hitCounts[host], (float64(hitCounts[host])/float64(iterations))*100.0)
}
assert.Equal(t, hitCounts["a"] > hitCounts["b"], true)
hitCounts["a"] = 0
hitCounts["b"] = 0
log.Printf("starting second run (b, a)")
timings["a"] = 500
timings["b"] = 100
for i := 0; i < iterations; i += 1 {
if i != 0 && i%100 == 0 {
p.performEpsilonGreedyDecay()
}
hostR := p.Get()
host := hostR.Host()
hitCounts[host]++
timing := timings[host]
p.timer = &mockTimer{t: int(timing)}
hostR.Mark(nil)
}
for host := range hitCounts {
log.Printf("host %s hit %d times (%0.2f percent)", host, hitCounts[host], (float64(hitCounts[host])/float64(iterations))*100.0)
}
assert.Equal(t, hitCounts["b"] > hitCounts["a"], true)
}
func BenchmarkEpsilonGreedy(b *testing.B) {
b.StopTimer()
// Make up some response times
zipfDist := rand.NewZipf(rand.New(rand.NewSource(0)), 1.1, 5, 5000)
timings := make([]uint64, b.N)
for i := 0; i < b.N; i++ {
timings[i] = zipfDist.Uint64()
}
// Make the hostpool with a few hosts
p := NewEpsilonGreedy([]string{"a", "b"}, 0, &LinearEpsilonValueCalculator{}).(*epsilonGreedyHostPool)
b.StartTimer()
for i := 0; i < b.N; i++ {
if i != 0 && i%100 == 0 {
p.performEpsilonGreedyDecay()
}
hostR := p.Get()
p.timer = &mockTimer{t: int(timings[i])}
hostR.Mark(nil)
}
}
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