mirror of
https://github.com/golang/net.git
synced 2026-04-01 02:47:08 +09:00
a67aa99698
WithCancel, and WithTimeout to use different concrete types. Update the tests and documentation. This change reduces the size of context structs, reduces the number of allocations (see TestAllocs) and removes unnecessary pointers from the heap, such as the timer field for non-timer contexts. IMPORTANT: I've removed the code in these functions that handles nil Context parameters. Passing a nil parent Context will now cause a panic. LGTM=bcmills R=bcmills, crawshaw CC=adonovan, golang-codereviews, rsc https://golang.org/cl/116400043
537 lines
13 KiB
Go
537 lines
13 KiB
Go
// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package context
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import (
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"fmt"
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"math/rand"
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"runtime"
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"sync"
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"testing"
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"time"
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)
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// otherContext is a Context that's not one of the types defined in context.go.
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// This lets us test code paths that differ based on the underlying type of the
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// Context.
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type otherContext struct {
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Context
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}
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func TestBackground(t *testing.T) {
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c := Background()
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if c == nil {
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t.Fatalf("Background returned nil")
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}
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select {
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case x := <-c.Done():
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t.Errorf("<-c.Done() == %v want nothing (it should block)", x)
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default:
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}
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if s := fmt.Sprint(c); s != "context.Background" {
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t.Errorf(`Background.String = %q want "context.Background"`, s)
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}
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}
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func TestTODO(t *testing.T) {
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c := TODO()
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if c == nil {
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t.Fatalf("TODO returned nil")
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}
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select {
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case x := <-c.Done():
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t.Errorf("<-c.Done() == %v want nothing (it should block)", x)
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default:
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}
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if s := fmt.Sprint(c); s != "context.TODO" {
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t.Errorf(`TODO.String = %q want "context.TODO"`, s)
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}
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}
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func TestWithCancel(t *testing.T) {
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c1, cancel := WithCancel(Background())
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o := otherContext{c1}
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c2, _ := WithCancel(o)
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contexts := []Context{c1, o, c2}
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for i, c := range contexts {
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if d := c.Done(); d == nil {
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t.Errorf("c[%d].Done() == %v want non-nil", i, d)
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}
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if e := c.Err(); e != nil {
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t.Errorf("c[%d].Err() == %v want nil", i, e)
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}
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select {
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case x := <-c.Done():
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t.Errorf("<-c.Done() == %v want nothing (it should block)", x)
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default:
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}
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}
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cancel()
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time.Sleep(100 * time.Millisecond) // let cancellation propagate
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for i, c := range contexts {
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select {
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case <-c.Done():
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default:
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t.Errorf("<-c[%d].Done() blocked, but shouldn't have", i)
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}
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if e := c.Err(); e != Canceled {
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t.Errorf("c[%d].Err() == %v want %v", i, e, Canceled)
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}
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}
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}
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func TestParentFinishesChild(t *testing.T) {
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// Context tree:
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// parent -> cancelChild
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// parent -> valueChild -> timerChild
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parent, cancel := WithCancel(Background())
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cancelChild, stop := WithCancel(parent)
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defer stop()
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valueChild := WithValue(parent, "key", "value")
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timerChild, stop := WithTimeout(valueChild, 10000*time.Hour)
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defer stop()
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select {
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case x := <-parent.Done():
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t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
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case x := <-cancelChild.Done():
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t.Errorf("<-cancelChild.Done() == %v want nothing (it should block)", x)
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case x := <-timerChild.Done():
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t.Errorf("<-timerChild.Done() == %v want nothing (it should block)", x)
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case x := <-valueChild.Done():
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t.Errorf("<-valueChild.Done() == %v want nothing (it should block)", x)
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default:
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}
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// The parent's children should contain the two cancelable children.
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pc := parent.(*cancelCtx)
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cc := cancelChild.(*cancelCtx)
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tc := timerChild.(*timerCtx)
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pc.mu.Lock()
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if len(pc.children) != 2 || !pc.children[cc] || !pc.children[tc] {
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t.Errorf("bad linkage: pc.children = %v, want %v and %v",
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pc.children, cc, tc)
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}
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pc.mu.Unlock()
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if p, ok := parentCancelCtx(cc.Context); !ok || p != pc {
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t.Errorf("bad linkage: parentCancelCtx(cancelChild.Context) = %v, %v want %v, true", p, ok, pc)
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}
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if p, ok := parentCancelCtx(tc.Context); !ok || p != pc {
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t.Errorf("bad linkage: parentCancelCtx(timerChild.Context) = %v, %v want %v, true", p, ok, pc)
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}
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cancel()
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pc.mu.Lock()
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if len(pc.children) != 0 {
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t.Errorf("pc.cancel didn't clear pc.children = %v", pc.children)
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}
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pc.mu.Unlock()
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// parent and children should all be finished.
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check := func(ctx Context, name string) {
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select {
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case <-ctx.Done():
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default:
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t.Errorf("<-%s.Done() blocked, but shouldn't have", name)
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}
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if e := ctx.Err(); e != Canceled {
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t.Errorf("%s.Err() == %v want %v", name, e, Canceled)
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}
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}
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check(parent, "parent")
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check(cancelChild, "cancelChild")
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check(valueChild, "valueChild")
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check(timerChild, "timerChild")
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// WithCancel should return a canceled context on a canceled parent.
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precanceledChild := WithValue(parent, "key", "value")
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select {
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case <-precanceledChild.Done():
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default:
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t.Errorf("<-precanceledChild.Done() blocked, but shouldn't have")
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}
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if e := precanceledChild.Err(); e != Canceled {
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t.Errorf("precanceledChild.Err() == %v want %v", e, Canceled)
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}
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}
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func TestChildFinishesFirst(t *testing.T) {
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cancelable, stop := WithCancel(Background())
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defer stop()
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for _, parent := range []Context{Background(), cancelable} {
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child, cancel := WithCancel(parent)
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select {
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case x := <-parent.Done():
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t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
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case x := <-child.Done():
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t.Errorf("<-child.Done() == %v want nothing (it should block)", x)
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default:
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}
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cc := child.(*cancelCtx)
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pc, pcok := parent.(*cancelCtx) // pcok == false when parent == Background()
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if p, ok := parentCancelCtx(cc.Context); ok != pcok || (ok && pc != p) {
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t.Errorf("bad linkage: parentCancelCtx(cc.Context) = %v, %v want %v, %v", p, ok, pc, pcok)
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}
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if pcok {
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pc.mu.Lock()
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if len(pc.children) != 1 || !pc.children[cc] {
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t.Errorf("bad linkage: pc.children = %v, cc = %v", pc.children, cc)
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}
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pc.mu.Unlock()
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}
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cancel()
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if pcok {
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pc.mu.Lock()
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if len(pc.children) != 0 {
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t.Errorf("child's cancel didn't remove self from pc.children = %v", pc.children)
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}
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pc.mu.Unlock()
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}
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// child should be finished.
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select {
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case <-child.Done():
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default:
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t.Errorf("<-child.Done() blocked, but shouldn't have")
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}
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if e := child.Err(); e != Canceled {
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t.Errorf("child.Err() == %v want %v", e, Canceled)
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}
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// parent should not be finished.
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select {
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case x := <-parent.Done():
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t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
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default:
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}
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if e := parent.Err(); e != nil {
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t.Errorf("parent.Err() == %v want nil", e)
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}
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}
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}
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func testDeadline(c Context, wait time.Duration, t *testing.T) {
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select {
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case <-time.After(wait):
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t.Fatalf("context should have timed out")
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case <-c.Done():
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}
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if e := c.Err(); e != DeadlineExceeded {
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t.Errorf("c.Err() == %v want %v", e, DeadlineExceeded)
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}
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}
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func TestDeadline(t *testing.T) {
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c, _ := WithDeadline(Background(), time.Now().Add(100*time.Millisecond))
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testDeadline(c, 200*time.Millisecond, t)
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c, _ = WithDeadline(Background(), time.Now().Add(100*time.Millisecond))
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o := otherContext{c}
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testDeadline(o, 200*time.Millisecond, t)
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c, _ = WithDeadline(Background(), time.Now().Add(100*time.Millisecond))
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o = otherContext{c}
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c, _ = WithDeadline(o, time.Now().Add(300*time.Millisecond))
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testDeadline(c, 200*time.Millisecond, t)
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}
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func TestTimeout(t *testing.T) {
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c, _ := WithTimeout(Background(), 100*time.Millisecond)
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testDeadline(c, 200*time.Millisecond, t)
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c, _ = WithTimeout(Background(), 100*time.Millisecond)
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o := otherContext{c}
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testDeadline(o, 200*time.Millisecond, t)
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c, _ = WithTimeout(Background(), 100*time.Millisecond)
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o = otherContext{c}
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c, _ = WithTimeout(o, 300*time.Millisecond)
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testDeadline(c, 200*time.Millisecond, t)
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}
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func TestCancelledTimeout(t *testing.T) {
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c, _ := WithTimeout(Background(), 200*time.Millisecond)
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o := otherContext{c}
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c, cancel := WithTimeout(o, 400*time.Millisecond)
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cancel()
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time.Sleep(100 * time.Millisecond) // let cancellation propagate
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select {
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case <-c.Done():
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default:
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t.Errorf("<-c.Done() blocked, but shouldn't have")
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}
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if e := c.Err(); e != Canceled {
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t.Errorf("c.Err() == %v want %v", e, Canceled)
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}
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}
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type key1 int
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type key2 int
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var k1 = key1(1)
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var k2 = key2(1) // same int as k1, different type
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var k3 = key2(3) // same type as k2, different int
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func TestValues(t *testing.T) {
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check := func(c Context, nm, v1, v2, v3 string) {
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if v, ok := c.Value(k1).(string); ok == (len(v1) == 0) || v != v1 {
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t.Errorf(`%s.Value(k1).(string) = %q, %t want %q, %t`, nm, v, ok, v1, len(v1) != 0)
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}
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if v, ok := c.Value(k2).(string); ok == (len(v2) == 0) || v != v2 {
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t.Errorf(`%s.Value(k2).(string) = %q, %t want %q, %t`, nm, v, ok, v2, len(v2) != 0)
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}
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if v, ok := c.Value(k3).(string); ok == (len(v3) == 0) || v != v3 {
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t.Errorf(`%s.Value(k3).(string) = %q, %t want %q, %t`, nm, v, ok, v3, len(v3) != 0)
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}
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}
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c0 := Background()
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check(c0, "c0", "", "", "")
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c1 := WithValue(Background(), k1, "c1k1")
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check(c1, "c1", "c1k1", "", "")
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c2 := WithValue(c1, k2, "c2k2")
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check(c2, "c2", "c1k1", "c2k2", "")
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c3 := WithValue(c2, k3, "c3k3")
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check(c3, "c2", "c1k1", "c2k2", "c3k3")
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c4 := WithValue(c3, k1, nil)
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check(c4, "c4", "", "c2k2", "c3k3")
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o0 := otherContext{Background()}
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check(o0, "o0", "", "", "")
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o1 := otherContext{WithValue(Background(), k1, "c1k1")}
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check(o1, "o1", "c1k1", "", "")
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o2 := WithValue(o1, k2, "o2k2")
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check(o2, "o2", "c1k1", "o2k2", "")
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o3 := otherContext{c4}
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check(o3, "o3", "", "c2k2", "c3k3")
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o4 := WithValue(o3, k3, nil)
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check(o4, "o4", "", "c2k2", "")
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}
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func TestAllocs(t *testing.T) {
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bg := Background()
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for _, test := range []struct {
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desc string
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f func()
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limit float64
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gccgoLimit float64
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}{
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{
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desc: "Background()",
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f: func() { Background() },
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limit: 0,
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gccgoLimit: 0,
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},
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{
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desc: fmt.Sprintf("WithValue(bg, %v, nil)", k1),
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f: func() {
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c := WithValue(bg, k1, nil)
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c.Value(k1)
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},
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limit: 1,
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gccgoLimit: 3,
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},
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{
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desc: "WithTimeout(bg, 15*time.Millisecond)",
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f: func() {
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c, _ := WithTimeout(bg, 15*time.Millisecond)
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<-c.Done()
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},
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limit: 8,
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gccgoLimit: 13,
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},
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{
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desc: "WithCancel(bg)",
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f: func() {
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c, cancel := WithCancel(bg)
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cancel()
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<-c.Done()
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},
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limit: 5,
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gccgoLimit: 8,
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},
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{
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desc: "WithTimeout(bg, 100*time.Millisecond)",
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f: func() {
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c, cancel := WithTimeout(bg, 100*time.Millisecond)
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cancel()
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<-c.Done()
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},
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limit: 8,
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gccgoLimit: 25,
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},
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} {
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limit := test.limit
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if runtime.Compiler == "gccgo" {
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// gccgo does not yet do escape analysis.
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// TOOD(iant): Remove this when gccgo does do escape analysis.
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limit = test.gccgoLimit
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}
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if n := testing.AllocsPerRun(100, test.f); n > limit {
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t.Errorf("%s allocs = %f want %d", test.desc, n, int(limit))
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}
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}
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}
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func TestSimultaneousCancels(t *testing.T) {
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root, cancel := WithCancel(Background())
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m := map[Context]CancelFunc{root: cancel}
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q := []Context{root}
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// Create a tree of contexts.
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for len(q) != 0 && len(m) < 100 {
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parent := q[0]
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q = q[1:]
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for i := 0; i < 4; i++ {
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ctx, cancel := WithCancel(parent)
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m[ctx] = cancel
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q = append(q, ctx)
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}
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}
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// Start all the cancels in a random order.
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var wg sync.WaitGroup
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wg.Add(len(m))
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for _, cancel := range m {
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go func(cancel CancelFunc) {
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cancel()
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wg.Done()
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}(cancel)
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}
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// Wait on all the contexts in a random order.
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for ctx := range m {
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select {
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case <-ctx.Done():
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case <-time.After(1 * time.Second):
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buf := make([]byte, 10<<10)
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n := runtime.Stack(buf, true)
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t.Fatalf("timed out waiting for <-ctx.Done(); stacks:\n%s", buf[:n])
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}
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}
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// Wait for all the cancel functions to return.
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done := make(chan struct{})
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go func() {
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wg.Wait()
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close(done)
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}()
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select {
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case <-done:
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case <-time.After(1 * time.Second):
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buf := make([]byte, 10<<10)
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n := runtime.Stack(buf, true)
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t.Fatalf("timed out waiting for cancel functions; stacks:\n%s", buf[:n])
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}
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}
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func TestInterlockedCancels(t *testing.T) {
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parent, cancelParent := WithCancel(Background())
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child, cancelChild := WithCancel(parent)
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go func() {
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parent.Done()
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cancelChild()
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}()
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cancelParent()
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select {
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case <-child.Done():
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case <-time.After(1 * time.Second):
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buf := make([]byte, 10<<10)
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n := runtime.Stack(buf, true)
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t.Fatalf("timed out waiting for child.Done(); stacks:\n%s", buf[:n])
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}
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}
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func TestLayersCancel(t *testing.T) {
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testLayers(t, time.Now().UnixNano(), false)
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}
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func TestLayersTimeout(t *testing.T) {
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testLayers(t, time.Now().UnixNano(), true)
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}
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func testLayers(t *testing.T, seed int64, testTimeout bool) {
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rand.Seed(seed)
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errorf := func(format string, a ...interface{}) {
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t.Errorf(fmt.Sprintf("seed=%d: %s", seed, format), a...)
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}
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const (
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timeout = 200 * time.Millisecond
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minLayers = 30
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)
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type value int
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var (
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vals []*value
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cancels []CancelFunc
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numTimers int
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ctx = Background()
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)
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for i := 0; i < minLayers || numTimers == 0 || len(cancels) == 0 || len(vals) == 0; i++ {
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switch rand.Intn(3) {
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case 0:
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v := new(value)
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t.Logf("WithValue(%p, %p)", v, v)
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ctx = WithValue(ctx, v, v)
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vals = append(vals, v)
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case 1:
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var cancel CancelFunc
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t.Logf("WithCancel")
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ctx, cancel = WithCancel(ctx)
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cancels = append(cancels, cancel)
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case 2:
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var cancel CancelFunc
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t.Logf("WithTimeout")
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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:
|
|
}
|
|
checkValues("before cancel")
|
|
if testTimeout {
|
|
select {
|
|
case <-ctx.Done():
|
|
case <-time.After(timeout + timeout/10):
|
|
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")
|
|
}
|
|
}
|