blob: 157a3667a64e396c8d78df9954d29d70f39ead7f (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
|
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package sync_test
import (
. "sync"
"sync/atomic"
"runtime"
"testing"
)
type one int
func (o *one) Increment() {
*o++
}
func run(once *Once, o *one, c chan bool) {
once.Do(func() { o.Increment() })
c <- true
}
func TestOnce(t *testing.T) {
o := new(one)
once := new(Once)
c := make(chan bool)
const N = 10
for i := 0; i < N; i++ {
go run(once, o, c)
}
for i := 0; i < N; i++ {
<-c
}
if *o != 1 {
t.Errorf("once failed: %d is not 1", *o)
}
}
func BenchmarkOnce(b *testing.B) {
const CallsPerSched = 1000
procs := runtime.GOMAXPROCS(-1)
N := int32(b.N / CallsPerSched)
var once Once
f := func() {}
c := make(chan bool, procs)
for p := 0; p < procs; p++ {
go func() {
for atomic.AddInt32(&N, -1) >= 0 {
runtime.Gosched()
for g := 0; g < CallsPerSched; g++ {
once.Do(f)
}
}
c <- true
}()
}
for p := 0; p < procs; p++ {
<-c
}
}
|