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tailscale/prober/prober_test.go

403 lines
10 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
package prober
import (
"context"
"errors"
"fmt"
"strings"
"sync"
"sync/atomic"
"testing"
"time"
"github.com/prometheus/client_golang/prometheus/testutil"
"tailscale.com/tstest"
)
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, FuncProbe(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")
}
}
probe := p.Run("test-spread-probe", probeInterval, nil, FuncProbe(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()
// We need to wait until the main (non-initial) ticker in Probe.loop is
// waiting, or we could race and advance the test clock between when
// the initial delay ticker completes and before the ticker for the
// main loop is created. In this race, we'd first advance the test
// clock, then the ticker would be registered, and the test would fail
// because that ticker would never be fired.
err := tstest.WaitFor(convergenceTimeout, func() error {
clk.Lock()
defer clk.Unlock()
for _, tick := range clk.tickers {
tick.Lock()
stopped, interval := tick.stopped, tick.interval
tick.Unlock()
if stopped {
continue
}
// Test for the main loop, not the initialDelay
if interval == probe.interval {
return nil
}
}
return fmt.Errorf("no ticker with interval %d found", probe.interval)
})
if err != nil {
t.Fatal(err)
}
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, FuncProbe(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)
if c, err := testutil.GatherAndCount(p.metrics, "prober_result"); c != startingProbes || err != nil {
t.Fatalf("expected %d prober_result metrics; got %d (error %s)", startingProbes, c, err)
}
keep := startingProbes / 2
for i := keep; i < startingProbes; i++ {
probes[i].Close()
}
waitActiveProbes(t, p, clk, keep)
clk.Advance(probeInterval)
checkCnt(keep)
if c, err := testutil.GatherAndCount(p.metrics, "prober_result"); c != keep || err != nil {
t.Fatalf("expected %d prober_result metrics; got %d (error %s)", keep, c, err)
}
}
func TestPrometheus(t *testing.T) {
clk := newFakeTime()
p := newForTest(clk.Now, clk.NewTicker).WithMetricNamespace("probe")
var succeed atomic.Bool
p.Run("testprobe", probeInterval, map[string]string{"label": "value"}, FuncProbe(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 {
want := fmt.Sprintf(`
# HELP probe_interval_secs Probe interval in seconds
# TYPE probe_interval_secs gauge
probe_interval_secs{class="",label="value",name="testprobe"} %f
# HELP probe_start_secs Latest probe start time (seconds since epoch)
# TYPE probe_start_secs gauge
probe_start_secs{class="",label="value",name="testprobe"} %d
# HELP probe_end_secs Latest probe end time (seconds since epoch)
# TYPE probe_end_secs gauge
probe_end_secs{class="",label="value",name="testprobe"} %d
# HELP probe_result Latest probe result (1 = success, 0 = failure)
# TYPE probe_result gauge
probe_result{class="",label="value",name="testprobe"} 0
`, probeInterval.Seconds(), epoch.Unix(), epoch.Add(aFewMillis).Unix())
return testutil.GatherAndCompare(p.metrics, strings.NewReader(want),
"probe_interval_secs", "probe_start_secs", "probe_end_secs", "probe_result")
})
if err != nil {
t.Fatal(err)
}
succeed.Store(true)
clk.Advance(probeInterval + halfProbeInterval)
err = tstest.WaitFor(convergenceTimeout, func() error {
start := epoch.Add(probeInterval + halfProbeInterval)
end := start.Add(aFewMillis)
want := fmt.Sprintf(`
# HELP probe_interval_secs Probe interval in seconds
# TYPE probe_interval_secs gauge
probe_interval_secs{class="",label="value",name="testprobe"} %f
# HELP probe_start_secs Latest probe start time (seconds since epoch)
# TYPE probe_start_secs gauge
probe_start_secs{class="",label="value",name="testprobe"} %d
# HELP probe_end_secs Latest probe end time (seconds since epoch)
# TYPE probe_end_secs gauge
probe_end_secs{class="",label="value",name="testprobe"} %d
# HELP probe_latency_millis Latest probe latency (ms)
# TYPE probe_latency_millis gauge
probe_latency_millis{class="",label="value",name="testprobe"} %d
# HELP probe_result Latest probe result (1 = success, 0 = failure)
# TYPE probe_result gauge
probe_result{class="",label="value",name="testprobe"} 1
`, probeInterval.Seconds(), start.Unix(), end.Unix(), aFewMillis.Milliseconds())
return testutil.GatherAndCompare(p.metrics, strings.NewReader(want),
"probe_interval_secs", "probe_start_secs", "probe_end_secs", "probe_latency_millis", "probe_result")
})
if err != nil {
t.Fatal(err)
}
}
func TestOnceMode(t *testing.T) {
clk := newFakeTime()
p := newForTest(clk.Now, clk.NewTicker).WithOnce(true)
p.Run("probe1", probeInterval, nil, FuncProbe(func(context.Context) error { return nil }))
p.Run("probe2", probeInterval, nil, FuncProbe(func(context.Context) error { return fmt.Errorf("error2") }))
p.Run("probe3", probeInterval, nil, FuncProbe(func(context.Context) error {
p.Run("probe4", probeInterval, nil, FuncProbe(func(context.Context) error {
return fmt.Errorf("error4")
}))
return nil
}))
p.Wait()
wantCount := 4
for _, metric := range []string{"prober_result", "prober_end_secs"} {
if c, err := testutil.GatherAndCount(p.metrics, metric); c != wantCount || err != nil {
t.Fatalf("expected %d %s metrics; got %d (error %s)", wantCount, metric, c, 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 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)
}
}