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tailscale/prober/prober_test.go

408 lines
9.1 KiB
Go

// Copyright (c) 2022 Tailscale Inc & 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 prober
import (
"bytes"
"context"
"encoding/json"
"errors"
"fmt"
"strings"
"sync"
"sync/atomic"
"testing"
"time"
"github.com/google/go-cmp/cmp"
"tailscale.com/tstest"
"tailscale.com/tsweb"
)
const (
probeInterval = 8 * time.Second // So expvars that are integer numbers of seconds change
halfProbeInterval = probeInterval / 2
quarterProbeInterval = probeInterval / 4
convergenceTimeout = time.Second
convergenceSleep = time.Millisecond
aFewMillis = 20 * time.Millisecond
)
var epoch = time.Unix(0, 0)
func TestProberTiming(t *testing.T) {
clk := newFakeTime()
p := newForTest(clk.Now, clk.NewTicker)
invoked := make(chan struct{}, 1)
notCalled := func() {
t.Helper()
select {
case <-invoked:
t.Fatal("probe was invoked earlier than expected")
default:
}
}
called := func() {
t.Helper()
select {
case <-invoked:
case <-time.After(2 * time.Second):
t.Fatal("probe wasn't invoked as expected")
}
}
p.Run("test-probe", probeInterval, nil, func(context.Context) error {
invoked <- struct{}{}
return nil
})
waitActiveProbes(t, p, clk, 1)
called()
notCalled()
clk.Advance(probeInterval + halfProbeInterval)
called()
notCalled()
clk.Advance(quarterProbeInterval)
notCalled()
clk.Advance(probeInterval)
called()
notCalled()
}
func TestProberTimingSpread(t *testing.T) {
clk := newFakeTime()
p := newForTest(clk.Now, clk.NewTicker).WithSpread(true)
invoked := make(chan struct{}, 1)
notCalled := func() {
t.Helper()
select {
case <-invoked:
t.Fatal("probe was invoked earlier than expected")
default:
}
}
called := func() {
t.Helper()
select {
case <-invoked:
case <-time.After(2 * time.Second):
t.Fatal("probe wasn't invoked as expected")
}
}
p.Run("test-spread-probe", probeInterval, nil, func(context.Context) error {
invoked <- struct{}{}
return nil
})
waitActiveProbes(t, p, clk, 1)
notCalled()
// Name of the probe (test-spread-probe) has been chosen to ensure that
// the initial delay is smaller than half of the probe interval.
clk.Advance(halfProbeInterval)
called()
notCalled()
clk.Advance(quarterProbeInterval)
notCalled()
clk.Advance(probeInterval)
called()
notCalled()
}
func TestProberRun(t *testing.T) {
clk := newFakeTime()
p := newForTest(clk.Now, clk.NewTicker)
var (
mu sync.Mutex
cnt int
)
const startingProbes = 100
var probes []*Probe
for i := 0; i < startingProbes; i++ {
probes = append(probes, p.Run(fmt.Sprintf("probe%d", i), probeInterval, nil, func(context.Context) error {
mu.Lock()
defer mu.Unlock()
cnt++
return nil
}))
}
checkCnt := func(want int) {
t.Helper()
err := tstest.WaitFor(convergenceTimeout, func() error {
mu.Lock()
defer mu.Unlock()
if cnt == want {
cnt = 0
return nil
}
return fmt.Errorf("wrong number of probe counter increments, got %d want %d", cnt, want)
})
if err != nil {
t.Fatal(err)
}
}
waitActiveProbes(t, p, clk, startingProbes)
checkCnt(startingProbes)
clk.Advance(probeInterval + halfProbeInterval)
checkCnt(startingProbes)
keep := startingProbes / 2
for i := keep; i < startingProbes; i++ {
probes[i].Close()
}
waitActiveProbes(t, p, clk, keep)
clk.Advance(probeInterval)
checkCnt(keep)
}
func TestExpvar(t *testing.T) {
clk := newFakeTime()
p := newForTest(clk.Now, clk.NewTicker)
var succeed atomic.Bool
p.Run("probe", probeInterval, map[string]string{"label": "value"}, func(context.Context) error {
clk.Advance(aFewMillis)
if succeed.Load() {
return nil
}
return errors.New("failing, as instructed by test")
})
waitActiveProbes(t, p, clk, 1)
check := func(name string, want probeInfo) {
t.Helper()
err := tstest.WaitFor(convergenceTimeout, func() error {
vars := probeExpvar(t, p)
if got, want := len(vars), 1; got != want {
return fmt.Errorf("wrong probe count in expvar, got %d want %d", got, want)
}
for k, v := range vars {
if k != name {
return fmt.Errorf("wrong probe name in expvar, got %q want %q", k, name)
}
if diff := cmp.Diff(v, &want); diff != "" {
return fmt.Errorf("wrong probe stats (-got+want):\n%s", diff)
}
}
return nil
})
if err != nil {
t.Fatal(err)
}
}
check("probe", probeInfo{
Labels: map[string]string{"label": "value"},
Start: epoch,
End: epoch.Add(aFewMillis),
Latency: aFewMillis.String(),
Result: false,
})
succeed.Store(true)
clk.Advance(probeInterval + halfProbeInterval)
st := epoch.Add(probeInterval + halfProbeInterval + aFewMillis)
check("probe", probeInfo{
Labels: map[string]string{"label": "value"},
Start: st,
End: st.Add(aFewMillis),
Latency: aFewMillis.String(),
Result: true,
})
}
func TestPrometheus(t *testing.T) {
clk := newFakeTime()
p := newForTest(clk.Now, clk.NewTicker)
var succeed atomic.Bool
p.Run("testprobe", probeInterval, map[string]string{"label": "value"}, func(context.Context) error {
clk.Advance(aFewMillis)
if succeed.Load() {
return nil
}
return errors.New("failing, as instructed by test")
})
waitActiveProbes(t, p, clk, 1)
err := tstest.WaitFor(convergenceTimeout, func() error {
var b bytes.Buffer
p.Expvar().(tsweb.PrometheusVar).WritePrometheus(&b, "probe")
want := strings.TrimSpace(fmt.Sprintf(`
probe_interval_secs{name="testprobe",label="value"} %f
probe_start_secs{name="testprobe",label="value"} %d
probe_end_secs{name="testprobe",label="value"} %d
probe_latency_millis{name="testprobe",label="value"} %d
probe_result{name="testprobe",label="value"} 0
`, probeInterval.Seconds(), epoch.Unix(), epoch.Add(aFewMillis).Unix(), aFewMillis.Milliseconds()))
if diff := cmp.Diff(strings.TrimSpace(b.String()), want); diff != "" {
return fmt.Errorf("wrong probe stats (-got+want):\n%s", diff)
}
return nil
})
if err != nil {
t.Fatal(err)
}
succeed.Store(true)
clk.Advance(probeInterval + halfProbeInterval)
err = tstest.WaitFor(convergenceTimeout, func() error {
var b bytes.Buffer
p.Expvar().(tsweb.PrometheusVar).WritePrometheus(&b, "probe")
start := epoch.Add(probeInterval + halfProbeInterval)
end := start.Add(aFewMillis)
want := strings.TrimSpace(fmt.Sprintf(`
probe_interval_secs{name="testprobe",label="value"} %f
probe_start_secs{name="testprobe",label="value"} %d
probe_end_secs{name="testprobe",label="value"} %d
probe_latency_millis{name="testprobe",label="value"} %d
probe_result{name="testprobe",label="value"} 1
`, probeInterval.Seconds(), start.Unix(), end.Unix(), aFewMillis.Milliseconds()))
if diff := cmp.Diff(strings.TrimSpace(b.String()), want); diff != "" {
return fmt.Errorf("wrong probe stats (-got+want):\n%s", diff)
}
return nil
})
if err != nil {
t.Fatal(err)
}
}
type fakeTicker struct {
ch chan time.Time
interval time.Duration
sync.Mutex
next time.Time
stopped bool
}
func (t *fakeTicker) Chan() <-chan time.Time {
return t.ch
}
func (t *fakeTicker) Stop() {
t.Lock()
defer t.Unlock()
t.stopped = true
}
func (t *fakeTicker) fire(now time.Time) {
t.Lock()
defer t.Unlock()
// Slight deviation from the stdlib ticker: time.Ticker will
// adjust t.next to make up for missed ticks, whereas we tick on a
// fixed interval regardless of receiver behavior. In our case
// this is fine, since we're using the ticker as a wakeup
// mechanism and not a precise timekeeping system.
select {
case t.ch <- now:
default:
}
for now.After(t.next) {
t.next = t.next.Add(t.interval)
}
}
type fakeTime struct {
sync.Mutex
*sync.Cond
curTime time.Time
tickers []*fakeTicker
}
func newFakeTime() *fakeTime {
ret := &fakeTime{
curTime: epoch,
}
ret.Cond = &sync.Cond{L: &ret.Mutex}
return ret
}
func (t *fakeTime) Now() time.Time {
t.Lock()
defer t.Unlock()
ret := t.curTime
return ret
}
func (t *fakeTime) NewTicker(d time.Duration) ticker {
t.Lock()
defer t.Unlock()
ret := &fakeTicker{
ch: make(chan time.Time, 1),
interval: d,
next: t.curTime.Add(d),
}
t.tickers = append(t.tickers, ret)
t.Cond.Broadcast()
return ret
}
func (t *fakeTime) Advance(d time.Duration) {
t.Lock()
defer t.Unlock()
t.curTime = t.curTime.Add(d)
for _, tick := range t.tickers {
if t.curTime.After(tick.next) {
tick.fire(t.curTime)
}
}
}
func (t *fakeTime) activeTickers() (count int) {
t.Lock()
defer t.Unlock()
for _, tick := range t.tickers {
if !tick.stopped {
count += 1
}
}
return
}
func probeExpvar(t *testing.T, p *Prober) map[string]*probeInfo {
t.Helper()
s := p.Expvar().String()
ret := map[string]*probeInfo{}
if err := json.Unmarshal([]byte(s), &ret); err != nil {
t.Fatalf("expvar json decode failed: %v", err)
}
return ret
}
func waitActiveProbes(t *testing.T, p *Prober, clk *fakeTime, want int) {
t.Helper()
err := tstest.WaitFor(convergenceTimeout, func() error {
if got := p.activeProbes(); got != want {
return fmt.Errorf("installed probe count is %d, want %d", got, want)
}
if got := clk.activeTickers(); got != want {
return fmt.Errorf("active ticker count is %d, want %d", got, want)
}
return nil
})
if err != nil {
t.Fatal(err)
}
}