libgo/go/sync/once_test.go

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