751 lines
17 KiB
Go
751 lines
17 KiB
Go
// Copyright 2009 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 time_test
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import (
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"errors"
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"fmt"
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"runtime"
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"strings"
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"sync"
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"sync/atomic"
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"testing"
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. "time"
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)
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// Go runtime uses different Windows timers for time.Now and sleeping.
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// These can tick at different frequencies and can arrive out of sync.
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// The effect can be seen, for example, as time.Sleep(100ms) is actually
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// shorter then 100ms when measured as difference between time.Now before and
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// after time.Sleep call. This was observed on Windows XP SP3 (windows/386).
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// windowsInaccuracy is to ignore such errors.
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const windowsInaccuracy = 17 * Millisecond
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func TestSleep(t *testing.T) {
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const delay = 100 * Millisecond
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go func() {
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Sleep(delay / 2)
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Interrupt()
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}()
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start := Now()
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Sleep(delay)
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delayadj := delay
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if runtime.GOOS == "windows" {
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delayadj -= windowsInaccuracy
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}
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duration := Now().Sub(start)
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if duration < delayadj {
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t.Fatalf("Sleep(%s) slept for only %s", delay, duration)
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}
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}
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// Test the basic function calling behavior. Correct queueing
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// behavior is tested elsewhere, since After and AfterFunc share
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// the same code.
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func TestAfterFunc(t *testing.T) {
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i := 10
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c := make(chan bool)
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var f func()
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f = func() {
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i--
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if i >= 0 {
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AfterFunc(0, f)
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Sleep(1 * Second)
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} else {
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c <- true
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}
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}
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AfterFunc(0, f)
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<-c
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}
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func TestAfterStress(t *testing.T) {
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stop := uint32(0)
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go func() {
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for atomic.LoadUint32(&stop) == 0 {
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runtime.GC()
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// Yield so that the OS can wake up the timer thread,
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// so that it can generate channel sends for the main goroutine,
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// which will eventually set stop = 1 for us.
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Sleep(Nanosecond)
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}
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}()
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ticker := NewTicker(1)
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for i := 0; i < 100; i++ {
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<-ticker.C
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}
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ticker.Stop()
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atomic.StoreUint32(&stop, 1)
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}
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func benchmark(b *testing.B, bench func(n int)) {
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// Create equal number of garbage timers on each P before starting
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// the benchmark.
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var wg sync.WaitGroup
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garbageAll := make([][]*Timer, runtime.GOMAXPROCS(0))
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for i := range garbageAll {
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wg.Add(1)
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go func(i int) {
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defer wg.Done()
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garbage := make([]*Timer, 1<<15)
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for j := range garbage {
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garbage[j] = AfterFunc(Hour, nil)
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}
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garbageAll[i] = garbage
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}(i)
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}
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wg.Wait()
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b.ResetTimer()
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b.RunParallel(func(pb *testing.PB) {
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for pb.Next() {
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bench(1000)
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}
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})
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b.StopTimer()
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for _, garbage := range garbageAll {
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for _, t := range garbage {
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t.Stop()
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}
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}
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}
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func BenchmarkAfterFunc(b *testing.B) {
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benchmark(b, func(n int) {
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c := make(chan bool)
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var f func()
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f = func() {
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n--
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if n >= 0 {
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AfterFunc(0, f)
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} else {
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c <- true
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}
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}
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AfterFunc(0, f)
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<-c
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})
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}
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func BenchmarkAfter(b *testing.B) {
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benchmark(b, func(n int) {
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for i := 0; i < n; i++ {
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<-After(1)
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}
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})
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}
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func BenchmarkStop(b *testing.B) {
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benchmark(b, func(n int) {
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for i := 0; i < n; i++ {
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NewTimer(1 * Second).Stop()
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}
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})
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}
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func BenchmarkSimultaneousAfterFunc(b *testing.B) {
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benchmark(b, func(n int) {
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var wg sync.WaitGroup
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wg.Add(n)
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for i := 0; i < n; i++ {
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AfterFunc(0, wg.Done)
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}
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wg.Wait()
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})
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}
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func BenchmarkStartStop(b *testing.B) {
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benchmark(b, func(n int) {
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timers := make([]*Timer, n)
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for i := 0; i < n; i++ {
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timers[i] = AfterFunc(Hour, nil)
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}
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for i := 0; i < n; i++ {
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timers[i].Stop()
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}
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})
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}
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func BenchmarkReset(b *testing.B) {
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benchmark(b, func(n int) {
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t := NewTimer(Hour)
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for i := 0; i < n; i++ {
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t.Reset(Hour)
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}
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t.Stop()
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})
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}
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func BenchmarkSleep(b *testing.B) {
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benchmark(b, func(n int) {
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var wg sync.WaitGroup
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wg.Add(n)
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for i := 0; i < n; i++ {
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go func() {
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Sleep(Nanosecond)
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wg.Done()
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}()
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}
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wg.Wait()
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})
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}
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func TestAfter(t *testing.T) {
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const delay = 100 * Millisecond
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start := Now()
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end := <-After(delay)
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delayadj := delay
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if runtime.GOOS == "windows" {
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delayadj -= windowsInaccuracy
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}
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if duration := Now().Sub(start); duration < delayadj {
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t.Fatalf("After(%s) slept for only %d ns", delay, duration)
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}
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if min := start.Add(delayadj); end.Before(min) {
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t.Fatalf("After(%s) expect >= %s, got %s", delay, min, end)
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}
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}
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func TestAfterTick(t *testing.T) {
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const Count = 10
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Delta := 100 * Millisecond
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if testing.Short() {
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Delta = 10 * Millisecond
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}
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t0 := Now()
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for i := 0; i < Count; i++ {
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<-After(Delta)
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}
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t1 := Now()
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d := t1.Sub(t0)
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target := Delta * Count
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if d < target*9/10 {
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t.Fatalf("%d ticks of %s too fast: took %s, expected %s", Count, Delta, d, target)
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}
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if !testing.Short() && d > target*30/10 {
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t.Fatalf("%d ticks of %s too slow: took %s, expected %s", Count, Delta, d, target)
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}
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}
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func TestAfterStop(t *testing.T) {
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// We want to test that we stop a timer before it runs.
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// We also want to test that it didn't run after a longer timer.
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// Since we don't want the test to run for too long, we don't
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// want to use lengthy times. That makes the test inherently flaky.
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// So only report an error if it fails five times in a row.
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var errs []string
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logErrs := func() {
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for _, e := range errs {
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t.Log(e)
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}
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}
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for i := 0; i < 5; i++ {
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AfterFunc(100*Millisecond, func() {})
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t0 := NewTimer(50 * Millisecond)
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c1 := make(chan bool, 1)
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t1 := AfterFunc(150*Millisecond, func() { c1 <- true })
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c2 := After(200 * Millisecond)
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if !t0.Stop() {
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errs = append(errs, "failed to stop event 0")
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continue
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}
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if !t1.Stop() {
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errs = append(errs, "failed to stop event 1")
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continue
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}
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<-c2
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select {
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case <-t0.C:
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errs = append(errs, "event 0 was not stopped")
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continue
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case <-c1:
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errs = append(errs, "event 1 was not stopped")
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continue
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default:
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}
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if t1.Stop() {
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errs = append(errs, "Stop returned true twice")
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continue
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}
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// Test passed, so all done.
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if len(errs) > 0 {
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t.Logf("saw %d errors, ignoring to avoid flakiness", len(errs))
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logErrs()
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}
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return
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}
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t.Errorf("saw %d errors", len(errs))
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logErrs()
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}
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func TestAfterQueuing(t *testing.T) {
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// This test flakes out on some systems,
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// so we'll try it a few times before declaring it a failure.
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const attempts = 5
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err := errors.New("!=nil")
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for i := 0; i < attempts && err != nil; i++ {
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delta := Duration(20+i*50) * Millisecond
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if err = testAfterQueuing(delta); err != nil {
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t.Logf("attempt %v failed: %v", i, err)
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}
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}
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if err != nil {
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t.Fatal(err)
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}
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}
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// For gccgo omit 0 for now because it can take too long to start the
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var slots = []int{5, 3, 6, 6, 6, 1, 1, 2, 7, 9, 4, 8 /*0*/}
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type afterResult struct {
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slot int
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t Time
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}
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func await(slot int, result chan<- afterResult, ac <-chan Time) {
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result <- afterResult{slot, <-ac}
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}
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func testAfterQueuing(delta Duration) error {
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// make the result channel buffered because we don't want
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// to depend on channel queueing semantics that might
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// possibly change in the future.
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result := make(chan afterResult, len(slots))
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t0 := Now()
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for _, slot := range slots {
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go await(slot, result, After(Duration(slot)*delta))
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}
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var order []int
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var times []Time
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for range slots {
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r := <-result
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order = append(order, r.slot)
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times = append(times, r.t)
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}
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for i := range order {
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if i > 0 && order[i] < order[i-1] {
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return fmt.Errorf("After calls returned out of order: %v", order)
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}
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}
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for i, t := range times {
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dt := t.Sub(t0)
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target := Duration(order[i]) * delta
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if dt < target-delta/2 || dt > target+delta*10 {
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return fmt.Errorf("After(%s) arrived at %s, expected [%s,%s]", target, dt, target-delta/2, target+delta*10)
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}
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}
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return nil
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}
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func TestTimerStopStress(t *testing.T) {
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if testing.Short() {
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return
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}
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for i := 0; i < 100; i++ {
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go func(i int) {
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timer := AfterFunc(2*Second, func() {
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t.Errorf("timer %d was not stopped", i)
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})
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Sleep(1 * Second)
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timer.Stop()
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}(i)
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}
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Sleep(3 * Second)
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}
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func TestSleepZeroDeadlock(t *testing.T) {
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// Sleep(0) used to hang, the sequence of events was as follows.
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// Sleep(0) sets G's status to Gwaiting, but then immediately returns leaving the status.
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// Then the goroutine calls e.g. new and falls down into the scheduler due to pending GC.
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// After the GC nobody wakes up the goroutine from Gwaiting status.
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defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(4))
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c := make(chan bool)
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go func() {
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for i := 0; i < 100; i++ {
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runtime.GC()
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}
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c <- true
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}()
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for i := 0; i < 100; i++ {
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Sleep(0)
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tmp := make(chan bool, 1)
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tmp <- true
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<-tmp
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}
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<-c
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}
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func testReset(d Duration) error {
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t0 := NewTimer(2 * d)
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Sleep(d)
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if !t0.Reset(3 * d) {
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return errors.New("resetting unfired timer returned false")
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}
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Sleep(2 * d)
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select {
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case <-t0.C:
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return errors.New("timer fired early")
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default:
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}
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Sleep(2 * d)
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select {
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case <-t0.C:
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default:
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return errors.New("reset timer did not fire")
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}
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if t0.Reset(50 * Millisecond) {
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return errors.New("resetting expired timer returned true")
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}
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return nil
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}
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func TestReset(t *testing.T) {
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// We try to run this test with increasingly larger multiples
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// until one works so slow, loaded hardware isn't as flaky,
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// but without slowing down fast machines unnecessarily.
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const unit = 25 * Millisecond
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tries := []Duration{
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1 * unit,
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3 * unit,
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7 * unit,
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15 * unit,
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}
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var err error
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for _, d := range tries {
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err = testReset(d)
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if err == nil {
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t.Logf("passed using duration %v", d)
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return
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}
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}
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t.Error(err)
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}
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// Test that sleeping (via Sleep or Timer) for an interval so large it
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// overflows does not result in a short sleep duration. Nor does it interfere
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// with execution of other timers. If it does, timers in this or subsequent
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// tests may not fire.
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func TestOverflowSleep(t *testing.T) {
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const big = Duration(int64(1<<63 - 1))
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go func() {
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Sleep(big)
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// On failure, this may return after the test has completed, so
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// we need to panic instead.
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panic("big sleep returned")
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}()
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select {
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case <-After(big):
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t.Fatalf("big timeout fired")
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case <-After(25 * Millisecond):
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// OK
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}
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const neg = Duration(-1 << 63)
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Sleep(neg) // Returns immediately.
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select {
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case <-After(neg):
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// OK
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case <-After(1 * Second):
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t.Fatalf("negative timeout didn't fire")
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}
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}
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// Test that a panic while deleting a timer does not leave
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// the timers mutex held, deadlocking a ticker.Stop in a defer.
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func TestIssue5745(t *testing.T) {
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ticker := NewTicker(Hour)
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defer func() {
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// would deadlock here before the fix due to
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// lock taken before the segfault.
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ticker.Stop()
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if r := recover(); r == nil {
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t.Error("Expected panic, but none happened.")
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}
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}()
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// cause a panic due to a segfault
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var timer *Timer
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timer.Stop()
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t.Error("Should be unreachable.")
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}
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func TestOverflowPeriodRuntimeTimer(t *testing.T) {
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// This may hang forever if timers are broken. See comment near
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// the end of CheckRuntimeTimerOverflow in internal_test.go.
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CheckRuntimeTimerPeriodOverflow()
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}
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func checkZeroPanicString(t *testing.T) {
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e := recover()
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s, _ := e.(string)
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if want := "called on uninitialized Timer"; !strings.Contains(s, want) {
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t.Errorf("panic = %v; want substring %q", e, want)
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}
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}
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func TestZeroTimerResetPanics(t *testing.T) {
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defer checkZeroPanicString(t)
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var tr Timer
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tr.Reset(1)
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}
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func TestZeroTimerStopPanics(t *testing.T) {
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defer checkZeroPanicString(t)
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var tr Timer
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tr.Stop()
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}
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// Test that zero duration timers aren't missed by the scheduler. Regression test for issue 44868.
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func TestZeroTimer(t *testing.T) {
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if testing.Short() {
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t.Skip("-short")
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}
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for i := 0; i < 1000000; i++ {
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s := Now()
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ti := NewTimer(0)
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<-ti.C
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if diff := Since(s); diff > 2*Second {
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t.Errorf("Expected time to get value from Timer channel in less than 2 sec, took %v", diff)
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}
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}
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}
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// Test that rapidly moving a timer earlier doesn't cause it to get dropped.
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// Issue 47329.
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func TestTimerModifiedEarlier(t *testing.T) {
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past := Until(Unix(0, 0))
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count := 1000
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fail := 0
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for i := 0; i < count; i++ {
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timer := NewTimer(Hour)
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for j := 0; j < 10; j++ {
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if !timer.Stop() {
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<-timer.C
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}
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timer.Reset(past)
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}
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deadline := NewTimer(10 * Second)
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defer deadline.Stop()
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now := Now()
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select {
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case <-timer.C:
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if since := Since(now); since > 8*Second {
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t.Errorf("timer took too long (%v)", since)
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fail++
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}
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case <-deadline.C:
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t.Error("deadline expired")
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}
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}
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if fail > 0 {
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t.Errorf("%d failures", fail)
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}
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}
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// Benchmark timer latency when the thread that creates the timer is busy with
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// other work and the timers must be serviced by other threads.
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// https://golang.org/issue/38860
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func BenchmarkParallelTimerLatency(b *testing.B) {
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gmp := runtime.GOMAXPROCS(0)
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if gmp < 2 || runtime.NumCPU() < gmp {
|
|
b.Skip("skipping with GOMAXPROCS < 2 or NumCPU < GOMAXPROCS")
|
|
}
|
|
|
|
// allocate memory now to avoid GC interference later.
|
|
timerCount := gmp - 1
|
|
stats := make([]struct {
|
|
sum float64
|
|
max Duration
|
|
count int64
|
|
_ [5]int64 // cache line padding
|
|
}, timerCount)
|
|
|
|
// Ensure the time to start new threads to service timers will not pollute
|
|
// the results.
|
|
warmupScheduler(gmp)
|
|
|
|
// Note that other than the AfterFunc calls this benchmark is measuring it
|
|
// avoids using any other timers. In particular, the main goroutine uses
|
|
// doWork to spin for some durations because up through Go 1.15 if all
|
|
// threads are idle sysmon could leave deep sleep when we wake.
|
|
|
|
// Ensure sysmon is in deep sleep.
|
|
doWork(30 * Millisecond)
|
|
|
|
b.ResetTimer()
|
|
|
|
const delay = Millisecond
|
|
var wg sync.WaitGroup
|
|
var count int32
|
|
for i := 0; i < b.N; i++ {
|
|
wg.Add(timerCount)
|
|
atomic.StoreInt32(&count, 0)
|
|
for j := 0; j < timerCount; j++ {
|
|
j := j
|
|
expectedWakeup := Now().Add(delay)
|
|
AfterFunc(delay, func() {
|
|
late := Since(expectedWakeup)
|
|
if late < 0 {
|
|
late = 0
|
|
}
|
|
stats[j].count++
|
|
stats[j].sum += float64(late.Nanoseconds())
|
|
if late > stats[j].max {
|
|
stats[j].max = late
|
|
}
|
|
atomic.AddInt32(&count, 1)
|
|
for atomic.LoadInt32(&count) < int32(timerCount) {
|
|
// spin until all timers fired
|
|
}
|
|
wg.Done()
|
|
})
|
|
}
|
|
|
|
for atomic.LoadInt32(&count) < int32(timerCount) {
|
|
// spin until all timers fired
|
|
}
|
|
wg.Wait()
|
|
|
|
// Spin for a bit to let the other scheduler threads go idle before the
|
|
// next round.
|
|
doWork(Millisecond)
|
|
}
|
|
var total float64
|
|
var samples float64
|
|
max := Duration(0)
|
|
for _, s := range stats {
|
|
if s.max > max {
|
|
max = s.max
|
|
}
|
|
total += s.sum
|
|
samples += float64(s.count)
|
|
}
|
|
b.ReportMetric(0, "ns/op")
|
|
b.ReportMetric(total/samples, "avg-late-ns")
|
|
b.ReportMetric(float64(max.Nanoseconds()), "max-late-ns")
|
|
}
|
|
|
|
// Benchmark timer latency with staggered wakeup times and varying CPU bound
|
|
// workloads. https://golang.org/issue/38860
|
|
func BenchmarkStaggeredTickerLatency(b *testing.B) {
|
|
gmp := runtime.GOMAXPROCS(0)
|
|
if gmp < 2 || runtime.NumCPU() < gmp {
|
|
b.Skip("skipping with GOMAXPROCS < 2 or NumCPU < GOMAXPROCS")
|
|
}
|
|
|
|
const delay = 3 * Millisecond
|
|
|
|
for _, dur := range []Duration{300 * Microsecond, 2 * Millisecond} {
|
|
b.Run(fmt.Sprintf("work-dur=%s", dur), func(b *testing.B) {
|
|
for tickersPerP := 1; tickersPerP < int(delay/dur)+1; tickersPerP++ {
|
|
tickerCount := gmp * tickersPerP
|
|
b.Run(fmt.Sprintf("tickers-per-P=%d", tickersPerP), func(b *testing.B) {
|
|
// allocate memory now to avoid GC interference later.
|
|
stats := make([]struct {
|
|
sum float64
|
|
max Duration
|
|
count int64
|
|
_ [5]int64 // cache line padding
|
|
}, tickerCount)
|
|
|
|
// Ensure the time to start new threads to service timers
|
|
// will not pollute the results.
|
|
warmupScheduler(gmp)
|
|
|
|
b.ResetTimer()
|
|
|
|
var wg sync.WaitGroup
|
|
wg.Add(tickerCount)
|
|
for j := 0; j < tickerCount; j++ {
|
|
j := j
|
|
doWork(delay / Duration(gmp))
|
|
expectedWakeup := Now().Add(delay)
|
|
ticker := NewTicker(delay)
|
|
go func(c int, ticker *Ticker, firstWake Time) {
|
|
defer ticker.Stop()
|
|
|
|
for ; c > 0; c-- {
|
|
<-ticker.C
|
|
late := Since(expectedWakeup)
|
|
if late < 0 {
|
|
late = 0
|
|
}
|
|
stats[j].count++
|
|
stats[j].sum += float64(late.Nanoseconds())
|
|
if late > stats[j].max {
|
|
stats[j].max = late
|
|
}
|
|
expectedWakeup = expectedWakeup.Add(delay)
|
|
doWork(dur)
|
|
}
|
|
wg.Done()
|
|
}(b.N, ticker, expectedWakeup)
|
|
}
|
|
wg.Wait()
|
|
|
|
var total float64
|
|
var samples float64
|
|
max := Duration(0)
|
|
for _, s := range stats {
|
|
if s.max > max {
|
|
max = s.max
|
|
}
|
|
total += s.sum
|
|
samples += float64(s.count)
|
|
}
|
|
b.ReportMetric(0, "ns/op")
|
|
b.ReportMetric(total/samples, "avg-late-ns")
|
|
b.ReportMetric(float64(max.Nanoseconds()), "max-late-ns")
|
|
})
|
|
}
|
|
})
|
|
}
|
|
}
|
|
|
|
// warmupScheduler ensures the scheduler has at least targetThreadCount threads
|
|
// in its thread pool.
|
|
func warmupScheduler(targetThreadCount int) {
|
|
var wg sync.WaitGroup
|
|
var count int32
|
|
for i := 0; i < targetThreadCount; i++ {
|
|
wg.Add(1)
|
|
go func() {
|
|
atomic.AddInt32(&count, 1)
|
|
for atomic.LoadInt32(&count) < int32(targetThreadCount) {
|
|
// spin until all threads started
|
|
}
|
|
|
|
// spin a bit more to ensure they are all running on separate CPUs.
|
|
doWork(Millisecond)
|
|
wg.Done()
|
|
}()
|
|
}
|
|
wg.Wait()
|
|
}
|
|
|
|
func doWork(dur Duration) {
|
|
start := Now()
|
|
for Since(start) < dur {
|
|
}
|
|
}
|