86 lines
1.5 KiB
Go
86 lines
1.5 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 sync_test
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import (
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"runtime"
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. "sync"
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"sync/atomic"
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"testing"
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)
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type one int
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func (o *one) Increment() {
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*o++
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}
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func run(t *testing.T, once *Once, o *one, c chan bool) {
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once.Do(func() { o.Increment() })
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if v := *o; v != 1 {
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t.Errorf("once failed inside run: %d is not 1", v)
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}
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c <- true
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}
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func TestOnce(t *testing.T) {
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o := new(one)
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once := new(Once)
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c := make(chan bool)
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const N = 10
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for i := 0; i < N; i++ {
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go run(t, once, o, c)
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}
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for i := 0; i < N; i++ {
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<-c
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}
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if *o != 1 {
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t.Errorf("once failed outside run: %d is not 1", *o)
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}
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}
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func TestOncePanic(t *testing.T) {
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once := new(Once)
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for i := 0; i < 2; i++ {
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func() {
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defer func() {
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if recover() == nil {
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t.Fatalf("Once.Do() has not panic'ed")
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}
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}()
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once.Do(func() {
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panic("failed")
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})
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}()
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}
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once.Do(func() {})
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once.Do(func() {
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t.Fatalf("Once called twice")
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})
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}
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func BenchmarkOnce(b *testing.B) {
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const CallsPerSched = 1000
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procs := runtime.GOMAXPROCS(-1)
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N := int32(b.N / CallsPerSched)
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var once Once
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f := func() {}
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c := make(chan bool, procs)
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for p := 0; p < procs; p++ {
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go func() {
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for atomic.AddInt32(&N, -1) >= 0 {
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runtime.Gosched()
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for g := 0; g < CallsPerSched; g++ {
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once.Do(f)
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}
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}
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c <- true
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}()
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}
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for p := 0; p < procs; p++ {
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<-c
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}
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}
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