// 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.
// +build !go1.7
package context
import (
"fmt"
"math/rand"
"runtime"
"strings"
"sync"
"testing"
"time"
)
// otherContext is a Context that's not one of the types defined in context.go.
// This lets us test code paths that differ based on the underlying type of the
// Context.
type otherContext struct {
Context
}
func TestBackground(t *testing.T) {
c := Background()
if c == nil {
t.Fatalf("Background returned nil")
}
select {
case x := <-c.Done():
t.Errorf("<-c.Done() == %v want nothing (it should block)", x)
default:
}
if got, want := fmt.Sprint(c), "context.Background"; got != want {
t.Errorf("Background().String() = %q want %q", got, want)
}
}
func TestTODO(t *testing.T) {
c := TODO()
if c == nil {
t.Fatalf("TODO returned nil")
}
select {
case x := <-c.Done():
t.Errorf("<-c.Done() == %v want nothing (it should block)", x)
default:
}
if got, want := fmt.Sprint(c), "context.TODO"; got != want {
t.Errorf("TODO().String() = %q want %q", got, want)
}
}
func TestWithCancel(t *testing.T) {
c1, cancel := WithCancel(Background())
if got, want := fmt.Sprint(c1), "context.Background.WithCancel"; got != want {
t.Errorf("c1.String() = %q want %q", got, want)
}
o := otherContext{c1}
c2, _ := WithCancel(o)
contexts := []Context{c1, o, c2}
for i, c := range contexts {
if d := c.Done(); d == nil {
t.Errorf("c[%d].Done() == %v want non-nil", i, d)
}
if e := c.Err(); e != nil {
t.Errorf("c[%d].Err() == %v want nil", i, e)
}
select {
case x := <-c.Done():
t.Errorf("<-c.Done() == %v want nothing (it should block)", x)
default:
}
}
cancel()
time.Sleep(100 * time.Millisecond) // let cancelation propagate
for i, c := range contexts {
select {
case <-c.Done():
default:
t.Errorf("<-c[%d].Done() blocked, but shouldn't have", i)
}
if e := c.Err(); e != Canceled {
t.Errorf("c[%d].Err() == %v want %v", i, e, Canceled)
}
}
}
func TestParentFinishesChild(t *testing.T) {
// Context tree:
// parent -> cancelChild
// parent -> valueChild -> timerChild
parent, cancel := WithCancel(Background())
cancelChild, stop := WithCancel(parent)
defer stop()
valueChild := WithValue(parent, "key", "value")
timerChild, stop := WithTimeout(valueChild, 10000*time.Hour)
defer stop()
select {
case x := <-parent.Done():
t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
case x := <-cancelChild.Done():
t.Errorf("<-cancelChild.Done() == %v want nothing (it should block)", x)
case x := <-timerChild.Done():
t.Errorf("<-timerChild.Done() == %v want nothing (it should block)", x)
case x := <-valueChild.Done():
t.Errorf("<-valueChild.Done() == %v want nothing (it should block)", x)
default:
}
// The parent's children should contain the two cancelable children.
pc := parent.(*cancelCtx)
cc := cancelChild.(*cancelCtx)
tc := timerChild.(*timerCtx)
pc.mu.Lock()
if len(pc.children) != 2 || !pc.children[cc] || !pc.children[tc] {
t.Errorf("bad linkage: pc.children = %v, want %v and %v",
pc.children, cc, tc)
}
pc.mu.Unlock()
if p, ok := parentCancelCtx(cc.Context); !ok || p != pc {
t.Errorf("bad linkage: parentCancelCtx(cancelChild.Context) = %v, %v want %v, true", p, ok, pc)
}
if p, ok := parentCancelCtx(tc.Context); !ok || p != pc {
t.Errorf("bad linkage: parentCancelCtx(timerChild.Context) = %v, %v want %v, true", p, ok, pc)
}
cancel()
pc.mu.Lock()
if len(pc.children) != 0 {
t.Errorf("pc.cancel didn't clear pc.children = %v", pc.children)
}
pc.mu.Unlock()
// parent and children should all be finished.
check := func(ctx Context, name string) {
select {
case <-ctx.Done():
default:
t.Errorf("<-%s.Done() blocked, but shouldn't have", name)
}
if e := ctx.Err(); e != Canceled {
t.Errorf("%s.Err() == %v want %v", name, e, Canceled)
}
}
check(parent, "parent")
check(cancelChild, "cancelChild")
check(valueChild, "valueChild")
check(timerChild, "timerChild")
// WithCancel should return a canceled context on a canceled parent.
precanceledChild := WithValue(parent, "key", "value")
select {
case <-precanceledChild.Done():
default:
t.Errorf("<-precanceledChild.Done() blocked, but shouldn't have")
}
if e := precanceledChild.Err(); e != Canceled {
t.Errorf("precanceledChild.Err() == %v want %v", e, Canceled)
}
}
func TestChildFinishesFirst(t *testing.T) {
cancelable, stop := WithCancel(Background())
defer stop()
for _, parent := range []Context{Background(), cancelable} {
child, cancel := WithCancel(parent)
select {
case x := <-parent.Done():
t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
case x := <-child.Done():
t.Errorf("<-child.Done() == %v want nothing (it should block)", x)
default:
}
cc := child.(*cancelCtx)
pc, pcok := parent.(*cancelCtx) // pcok == false when parent == Background()
if p, ok := parentCancelCtx(cc.Context); ok != pcok || (ok && pc != p) {
t.Errorf("bad linkage: parentCancelCtx(cc.Context) = %v, %v want %v, %v", p, ok, pc, pcok)
}
if pcok {
pc.mu.Lock()
if len(pc.children) != 1 || !pc.children[cc] {
t.Errorf("bad linkage: pc.children = %v, cc = %v", pc.children, cc)
}
pc.mu.Unlock()
}
cancel()
if pcok {
pc.mu.Lock()
if len(pc.children) != 0 {
t.Errorf("child's cancel didn't remove self from pc.children = %v", pc.children)
}
pc.mu.Unlock()
}
// child should be finished.
select {
case <-child.Done():
default:
t.Errorf("<-child.Done() blocked, but shouldn't have")
}
if e := child.Err(); e != Canceled {
t.Errorf("child.Err() == %v want %v", e, Canceled)
}
// parent should not be finished.
select {
case x := <-parent.Done():
t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
default:
}
if e := parent.Err(); e != nil {
t.Errorf("parent.Err() == %v want nil", e)
}
}
}
func testDeadline(c Context, wait time.Duration, t *testing.T) {
select {
case <-time.After(wait):
t.Fatalf("context should have timed out")
case <-c.Done():
}
if e := c.Err(); e != DeadlineExceeded {
t.Errorf("c.Err() == %v want %v", e, DeadlineExceeded)
}
}
func TestDeadline(t *testing.T) {
c, _ := WithDeadline(Background(), time.Now().Add(100*time.Millisecond))
if got, prefix := fmt.Sprint(c), "context.Background.WithDeadline("; !strings.HasPrefix(got, prefix) {
t.Errorf("c.String() = %q want prefix %q", got, prefix)
}
testDeadline(c, 200*time.Millisecond, t)
c, _ = WithDeadline(Background(), time.Now().Add(100*time.Millisecond))
o := otherContext{c}
testDeadline(o, 200*time.Millisecond, t)
c, _ = WithDeadline(Background(), time.Now().Add(100*time.Millisecond))
o = otherContext{c}
c, _ = WithDeadline(o, time.Now().Add(300*time.Millisecond))
testDeadline(c, 200*time.Millisecond, t)
}
func TestTimeout(t *testing.T) {
c, _ := WithTimeout(Background(), 100*time.Millisecond)
if got, prefix := fmt.Sprint(c), "context.Background.WithDeadline("; !strings.HasPrefix(got, prefix) {
t.Errorf("c.String() = %q want prefix %q", got, prefix)
}
testDeadline(c, 200*time.Millisecond, t)
c, _ = WithTimeout(Background(), 100*time.Millisecond)
o := otherContext{c}
testDeadline(o, 200*time.Millisecond, t)
c, _ = WithTimeout(Background(), 100*time.Millisecond)
o = otherContext{c}
c, _ = WithTimeout(o, 300*time.Millisecond)
testDeadline(c, 200*time.Millisecond, t)
}
func TestCanceledTimeout(t *testing.T) {
c, _ := WithTimeout(Background(), 200*time.Millisecond)
o := otherContext{c}
c, cancel := WithTimeout(o, 400*time.Millisecond)
cancel()
time.Sleep(100 * time.Millisecond) // let cancelation propagate
select {
case <-c.Done():
default:
t.Errorf("<-c.Done() blocked, but shouldn't have")
}
if e := c.Err(); e != Canceled {
t.Errorf("c.Err() == %v want %v", e, Canceled)
}
}
type key1 int
type key2 int
var k1 = key1(1)
var k2 = key2(1) // same int as k1, different type
var k3 = key2(3) // same type as k2, different int
func TestValues(t *testing.T) {
check := func(c Context, nm, v1, v2, v3 string) {
if v, ok := c.Value(k1).(string); ok == (len(v1) == 0) || v != v1 {
t.Errorf(`%s.Value(k1).(string) = %q, %t want %q, %t`, nm, v, ok, v1, len(v1) != 0)
}
if v, ok := c.Value(k2).(string); ok == (len(v2) == 0) || v != v2 {
t.Errorf(`%s.Value(k2).(string) = %q, %t want %q, %t`, nm, v, ok, v2, len(v2) != 0)
}
if v, ok := c.Value(k3).(string); ok == (len(v3) == 0) || v != v3 {
t.Errorf(`%s.Value(k3).(string) = %q, %t want %q, %t`, nm, v, ok, v3, len(v3) != 0)
}
}
c0 := Background()
check(c0, "c0", "", "", "")
c1 := WithValue(Background(), k1, "c1k1")
check(c1, "c1", "c1k1", "", "")
if got, want := fmt.Sprint(c1), `context.Background.WithValue(1, "c1k1")`; got != want {
t.Errorf("c.String() = %q want %q", got, want)
}
c2 := WithValue(c1, k2, "c2k2")
check(c2, "c2", "c1k1", "c2k2", "")
c3 := WithValue(c2, k3, "c3k3")
check(c3, "c2", "c1k1", "c2k2", "c3k3")
c4 := WithValue(c3, k1, nil)
check(c4, "c4", "", "c2k2", "c3k3")
o0 := otherContext{Background()}
check(o0, "o0", "", "", "")
o1 := otherContext{WithValue(Background(), k1, "c1k1")}
check(o1, "o1", "c1k1", "", "")
o2 := WithValue(o1, k2, "o2k2")
check(o2, "o2", "c1k1", "o2k2", "")
o3 := otherContext{c4}
check(o3, "o3", "", "c2k2", "c3k3")
o4 := WithValue(o3, k3, nil)
check(o4, "o4", "", "c2k2", "")
}
func TestAllocs(t *testing.T) {
bg := Background()
for _, test := range []struct {
desc string
f func()
limit float64
gccgoLimit float64
}{
{
desc: "Background()",
f: func() { Background() },
limit: 0,
gccgoLimit: 0,
},
{
desc: fmt.Sprintf("WithValue(bg, %v, nil)", k1),
f: func() {
c := WithValue(bg, k1, nil)
c.Value(k1)
},
limit: 3,
gccgoLimit: 3,
},
{
desc: "WithTimeout(bg, 15*time.Millisecond)",
f: func() {
c, _ := WithTimeout(bg, 15*time.Millisecond)
<-c.Done()
},
limit: 8,
gccgoLimit: 16,
},
{
desc: "WithCancel(bg)",
f: func() {
c, cancel := WithCancel(bg)
cancel()
<-c.Done()
},
limit: 5,
gccgoLimit: 8,
},
{
desc: "WithTimeout(bg, 100*time.Millisecond)",
f: func() {
c, cancel := WithTimeout(bg, 100*time.Millisecond)
cancel()
<-c.Done()
},
limit: 8,
gccgoLimit: 25,
},
} {
limit := test.limit
if runtime.Compiler == "gccgo" {
// gccgo does not yet do escape analysis.
// TODO(iant): Remove this when gccgo does do escape analysis.
limit = test.gccgoLimit
}
if n := testing.AllocsPerRun(100, test.f); n > limit {
t.Errorf("%s allocs = %f want %d", test.desc, n, int(limit))
}
}
}
func TestSimultaneousCancels(t *testing.T) {
root, cancel := WithCancel(Background())
m := map[Context]CancelFunc{root: cancel}
q := []Context{root}
// Create a tree of contexts.
for len(q) != 0 && len(m) < 100 {
parent := q[0]
q = q[1:]
for i := 0; i < 4; i++ {
ctx, cancel := WithCancel(parent)
m[ctx] = cancel
q = append(q, ctx)
}
}
// Start all the cancels in a random order.
var wg sync.WaitGroup
wg.Add(len(m))
for _, cancel := range m {
go func(cancel CancelFunc) {
cancel()
wg.Done()
}(cancel)
}
// Wait on all the contexts in a random order.
for ctx := range m {
select {
case <-ctx.Done():
case <-time.After(1 * time.Second):
buf := make([]byte, 10<<10)
n := runtime.Stack(buf, true)
t.Fatalf("timed out waiting for <-ctx.Done(); stacks:\n%s", buf[:n])
}
}
// Wait for all the cancel functions to return.
done := make(chan struct{})
go func() {
wg.Wait()
close(done)
}()
select {
case <-done:
case <-time.After(1 * time.Second):
buf := make([]byte, 10<<10)
n := runtime.Stack(buf, true)
t.Fatalf("timed out waiting for cancel functions; stacks:\n%s", buf[:n])
}
}
func TestInterlockedCancels(t *testing.T) {
parent, cancelParent := WithCancel(Background())
child, cancelChild := WithCancel(parent)
go func() {
parent.Done()
cancelChild()
}()
cancelParent()
select {
case <-child.Done():
case <-time.After(1 * time.Second):
buf := make([]byte, 10<<10)
n := runtime.Stack(buf, true)
t.Fatalf("timed out waiting for child.Done(); stacks:\n%s", buf[:n])
}
}
func TestLayersCancel(t *testing.T) {
testLayers(t, time.Now().UnixNano(), false)
}
func TestLayersTimeout(t *testing.T) {
testLayers(t, time.Now().UnixNano(), true)
}
func testLayers(t *testing.T, seed int64, testTimeout bool) {
rand.Seed(seed)
errorf := func(format string, a ...interface{}) {
t.Errorf(fmt.Sprintf("seed=%d: %s", seed, format), a...)
}
const (
timeout = 200 * time.Millisecond
minLayers = 30
)
type value int
var (
vals []*value
cancels []CancelFunc
numTimers int
ctx = Background()
)
for i := 0; i < minLayers || numTimers == 0 || len(cancels) == 0 || len(vals) == 0; i++ {
switch rand.Intn(3) {
case 0:
v := new(value)
ctx = WithValue(ctx, v, v)
vals = append(vals, v)
case 1:
var cancel CancelFunc
ctx, cancel = WithCancel(ctx)
cancels = append(cancels, cancel)
case 2:
var cancel CancelFunc
ctx, cancel = WithTimeout(ctx, timeout)
cancels = append(cancels, cancel)
numTimers++
}
}
checkValues := func(when string) {
for _, key := range vals {
if val := ctx.Value(key).(*value); key != val {
errorf("%s: ctx.Value(%p) = %p want %p", when, key, val, key)
}
}
}
select {
case <-ctx.Done():
errorf("ctx should not be canceled yet")
default:
}
if s, prefix := fmt.Sprint(ctx), "context.Background."; !strings.HasPrefix(s, prefix) {
t.Errorf("ctx.String() = %q want prefix %q", s, prefix)
}
t.Log(ctx)
checkValues("before cancel")
if testTimeout {
select {
case <-ctx.Done():
case <-time.After(timeout + 100*time.Millisecond):
errorf("ctx should have timed out")
}
checkValues("after timeout")
} else {
cancel := cancels[rand.Intn(len(cancels))]
cancel()
select {
case <-ctx.Done():
default:
errorf("ctx should be canceled")
}
checkValues("after cancel")
}
}
func TestCancelRemoves(t *testing.T) {
checkChildren := func(when string, ctx Context, want int) {
if got := len(ctx.(*cancelCtx).children); got != want {
t.Errorf("%s: context has %d children, want %d", when, got, want)
}
}
ctx, _ := WithCancel(Background())
checkChildren("after creation", ctx, 0)
_, cancel := WithCancel(ctx)
checkChildren("with WithCancel child ", ctx, 1)
cancel()
checkChildren("after cancelling WithCancel child", ctx, 0)
ctx, _ = WithCancel(Background())
checkChildren("after creation", ctx, 0)
_, cancel = WithTimeout(ctx, 60*time.Minute)
checkChildren("with WithTimeout child ", ctx, 1)
cancel()
checkChildren("after cancelling WithTimeout child", ctx, 0)
}