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tailscale/util/singleflight/singleflight_test.go

477 lines
11 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
// Copyright 2013 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 singleflight
import (
"bytes"
"context"
"errors"
"fmt"
"os"
"os/exec"
"runtime"
"runtime/debug"
"strings"
"sync"
"sync/atomic"
"testing"
"time"
)
func TestDo(t *testing.T) {
var g Group[string, any]
v, err, _ := g.Do("key", func() (interface{}, error) {
return "bar", nil
})
if got, want := fmt.Sprintf("%v (%T)", v, v), "bar (string)"; got != want {
t.Errorf("Do = %v; want %v", got, want)
}
if err != nil {
t.Errorf("Do error = %v", err)
}
}
func TestDoErr(t *testing.T) {
var g Group[string, any]
someErr := errors.New("Some error")
v, err, _ := g.Do("key", func() (interface{}, error) {
return nil, someErr
})
if err != someErr {
t.Errorf("Do error = %v; want someErr %v", err, someErr)
}
if v != nil {
t.Errorf("unexpected non-nil value %#v", v)
}
}
func TestDoDupSuppress(t *testing.T) {
var g Group[string, any]
var wg1, wg2 sync.WaitGroup
c := make(chan string, 1)
var calls int32
fn := func() (interface{}, error) {
if atomic.AddInt32(&calls, 1) == 1 {
// First invocation.
wg1.Done()
}
v := <-c
c <- v // pump; make available for any future calls
time.Sleep(10 * time.Millisecond) // let more goroutines enter Do
return v, nil
}
const n = 10
wg1.Add(1)
for range n {
wg1.Add(1)
wg2.Add(1)
go func() {
defer wg2.Done()
wg1.Done()
v, err, _ := g.Do("key", fn)
if err != nil {
t.Errorf("Do error: %v", err)
return
}
if s, _ := v.(string); s != "bar" {
t.Errorf("Do = %T %v; want %q", v, v, "bar")
}
}()
}
wg1.Wait()
// At least one goroutine is in fn now and all of them have at
// least reached the line before the Do.
c <- "bar"
wg2.Wait()
if got := atomic.LoadInt32(&calls); got <= 0 || got >= n {
t.Errorf("number of calls = %d; want over 0 and less than %d", got, n)
}
}
// Test that singleflight behaves correctly after Forget called.
// See https://github.com/golang/go/issues/31420
func TestForget(t *testing.T) {
var g Group[string, any]
var (
firstStarted = make(chan struct{})
unblockFirst = make(chan struct{})
firstFinished = make(chan struct{})
)
go func() {
g.Do("key", func() (i interface{}, e error) {
close(firstStarted)
<-unblockFirst
close(firstFinished)
return
})
}()
<-firstStarted
g.Forget("key")
unblockSecond := make(chan struct{})
secondResult := g.DoChan("key", func() (i interface{}, e error) {
<-unblockSecond
return 2, nil
})
close(unblockFirst)
<-firstFinished
thirdResult := g.DoChan("key", func() (i interface{}, e error) {
return 3, nil
})
close(unblockSecond)
<-secondResult
r := <-thirdResult
if r.Val != 2 {
t.Errorf("We should receive result produced by second call, expected: 2, got %d", r.Val)
}
}
func TestDoChan(t *testing.T) {
var g Group[string, any]
ch := g.DoChan("key", func() (interface{}, error) {
return "bar", nil
})
res := <-ch
v := res.Val
err := res.Err
if got, want := fmt.Sprintf("%v (%T)", v, v), "bar (string)"; got != want {
t.Errorf("Do = %v; want %v", got, want)
}
if err != nil {
t.Errorf("Do error = %v", err)
}
}
// Test singleflight behaves correctly after Do panic.
// See https://github.com/golang/go/issues/41133
func TestPanicDo(t *testing.T) {
var g Group[string, any]
fn := func() (interface{}, error) {
panic("invalid memory address or nil pointer dereference")
}
const n = 5
waited := int32(n)
panicCount := int32(0)
done := make(chan struct{})
for range n {
go func() {
defer func() {
if err := recover(); err != nil {
t.Logf("Got panic: %v\n%s", err, debug.Stack())
atomic.AddInt32(&panicCount, 1)
}
if atomic.AddInt32(&waited, -1) == 0 {
close(done)
}
}()
g.Do("key", fn)
}()
}
select {
case <-done:
if panicCount != n {
t.Errorf("Expect %d panic, but got %d", n, panicCount)
}
case <-time.After(time.Second):
t.Fatalf("Do hangs")
}
}
func TestGoexitDo(t *testing.T) {
var g Group[string, any]
fn := func() (interface{}, error) {
runtime.Goexit()
return nil, nil
}
const n = 5
waited := int32(n)
done := make(chan struct{})
for range n {
go func() {
var err error
defer func() {
if err != nil {
t.Errorf("Error should be nil, but got: %v", err)
}
if atomic.AddInt32(&waited, -1) == 0 {
close(done)
}
}()
_, err, _ = g.Do("key", fn)
}()
}
select {
case <-done:
case <-time.After(time.Second):
t.Fatalf("Do hangs")
}
}
func TestPanicDoChan(t *testing.T) {
if runtime.GOOS == "js" {
t.Skipf("js does not support exec")
}
if os.Getenv("TEST_PANIC_DOCHAN") != "" {
defer func() {
recover()
}()
g := new(Group[string, any])
ch := g.DoChan("", func() (interface{}, error) {
panic("Panicking in DoChan")
})
<-ch
t.Fatalf("DoChan unexpectedly returned")
}
t.Parallel()
cmd := exec.Command(os.Args[0], "-test.run="+t.Name(), "-test.v")
cmd.Env = append(os.Environ(), "TEST_PANIC_DOCHAN=1")
out := new(bytes.Buffer)
cmd.Stdout = out
cmd.Stderr = out
if err := cmd.Start(); err != nil {
t.Fatal(err)
}
err := cmd.Wait()
t.Logf("%s:\n%s", strings.Join(cmd.Args, " "), out)
if err == nil {
t.Errorf("Test subprocess passed; want a crash due to panic in DoChan")
}
if bytes.Contains(out.Bytes(), []byte("DoChan unexpectedly")) {
t.Errorf("Test subprocess failed with an unexpected failure mode.")
}
if !bytes.Contains(out.Bytes(), []byte("Panicking in DoChan")) {
t.Errorf("Test subprocess failed, but the crash isn't caused by panicking in DoChan")
}
}
func TestPanicDoSharedByDoChan(t *testing.T) {
if runtime.GOOS == "js" {
t.Skipf("js does not support exec")
}
if os.Getenv("TEST_PANIC_DOCHAN") != "" {
blocked := make(chan struct{})
unblock := make(chan struct{})
g := new(Group[string, any])
go func() {
defer func() {
recover()
}()
g.Do("", func() (interface{}, error) {
close(blocked)
<-unblock
panic("Panicking in Do")
})
}()
<-blocked
ch := g.DoChan("", func() (interface{}, error) {
panic("DoChan unexpectedly executed callback")
})
close(unblock)
<-ch
t.Fatalf("DoChan unexpectedly returned")
}
t.Parallel()
cmd := exec.Command(os.Args[0], "-test.run="+t.Name(), "-test.v")
cmd.Env = append(os.Environ(), "TEST_PANIC_DOCHAN=1")
out := new(bytes.Buffer)
cmd.Stdout = out
cmd.Stderr = out
if err := cmd.Start(); err != nil {
t.Fatal(err)
}
err := cmd.Wait()
t.Logf("%s:\n%s", strings.Join(cmd.Args, " "), out)
if err == nil {
t.Errorf("Test subprocess passed; want a crash due to panic in Do shared by DoChan")
}
if bytes.Contains(out.Bytes(), []byte("DoChan unexpectedly")) {
t.Errorf("Test subprocess failed with an unexpected failure mode.")
}
if !bytes.Contains(out.Bytes(), []byte("Panicking in Do")) {
t.Errorf("Test subprocess failed, but the crash isn't caused by panicking in Do")
}
}
func TestDoChanContext(t *testing.T) {
t.Run("Basic", func(t *testing.T) {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
var g Group[string, int]
ch := g.DoChanContext(ctx, "key", func(_ context.Context) (int, error) {
return 1, nil
})
ret := <-ch
assertOKResult(t, ret, 1)
})
t.Run("DoesNotPropagateValues", func(t *testing.T) {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
key := new(int)
const value = "hello world"
ctx = context.WithValue(ctx, key, value)
var g Group[string, int]
ch := g.DoChanContext(ctx, "foobar", func(ctx context.Context) (int, error) {
if _, ok := ctx.Value(key).(string); ok {
t.Error("expected no value, but was present in context")
}
return 1, nil
})
ret := <-ch
assertOKResult(t, ret, 1)
})
t.Run("NoCancelWhenWaiters", func(t *testing.T) {
testCtx, testCancel := context.WithTimeout(context.Background(), 10*time.Second)
defer testCancel()
trigger := make(chan struct{})
ctx1, cancel1 := context.WithCancel(context.Background())
defer cancel1()
ctx2, cancel2 := context.WithCancel(context.Background())
defer cancel2()
fn := func(ctx context.Context) (int, error) {
select {
case <-ctx.Done():
return 0, ctx.Err()
case <-trigger:
return 1234, nil
}
}
// Create two waiters, then cancel the first before we trigger
// the function to return a value. This shouldn't result in a
// context canceled error.
var g Group[string, int]
ch1 := g.DoChanContext(ctx1, "key", fn)
ch2 := g.DoChanContext(ctx2, "key", fn)
cancel1()
// The first channel, now that it's canceled, should return a
// context canceled error.
select {
case res := <-ch1:
if !errors.Is(res.Err, context.Canceled) {
t.Errorf("unexpected error; got %v, want context.Canceled", res.Err)
}
case <-testCtx.Done():
t.Fatal("test timed out")
}
// Actually return
close(trigger)
res := <-ch2
assertOKResult(t, res, 1234)
})
t.Run("AllCancel", func(t *testing.T) {
for _, n := range []int{1, 2, 10, 20} {
t.Run(fmt.Sprintf("NumWaiters=%d", n), func(t *testing.T) {
testCtx, testCancel := context.WithTimeout(context.Background(), 10*time.Second)
defer testCancel()
trigger := make(chan struct{})
defer close(trigger)
fn := func(ctx context.Context) (int, error) {
select {
case <-ctx.Done():
return 0, ctx.Err()
case <-trigger:
t.Error("unexpected trigger; want all callers to cancel")
return 0, errors.New("unexpected trigger")
}
}
// Launch N goroutines that all wait on the same key.
var (
g Group[string, int]
chs []<-chan Result[int]
cancels []context.CancelFunc
)
for i := range n {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
cancels = append(cancels, cancel)
ch := g.DoChanContext(ctx, "key", fn)
chs = append(chs, ch)
// Every third goroutine should cancel
// immediately, which better tests the
// cancel logic.
if i%3 == 0 {
cancel()
}
}
// Now that everything is waiting, cancel all the contexts.
for _, cancel := range cancels {
cancel()
}
// Wait for a result from each channel. They
// should all return an error showing a context
// cancel.
for _, ch := range chs {
select {
case res := <-ch:
if !errors.Is(res.Err, context.Canceled) {
t.Errorf("unexpected error; got %v, want context.Canceled", res.Err)
}
case <-testCtx.Done():
t.Fatal("test timed out")
}
}
})
}
})
}
func assertOKResult[V comparable](t testing.TB, res Result[V], want V) {
if res.Err != nil {
t.Fatalf("unexpected error: %v", res.Err)
}
if res.Val != want {
t.Fatalf("unexpected value; got %v, want %v", res.Val, want)
}
}