Add atomic bool in util (alibaba#80)

* Add atomic bool in util

Author: louyuting

util/atomic.go

@@ -0,0 +1,48 @@
+package util
+
+import "sync/atomic"
+
+func IncrementAndGetInt64(v *int64) int64 {
+	old := int64(0)
+	for {
+		old = atomic.LoadInt64(v)
+		if atomic.CompareAndSwapInt64(v, old, old+1) {
+			break
+		}
+	}
+	return old + 1
+}
+
+type AtomicBool struct {
+	// default 0, means false
+	flag int32
+}
+
+func (b *AtomicBool) CompareAndSet(old, new bool) bool {
+	if old == new {
+		return true
+	}
+	var oldInt, newInt int32
+	if old {
+		oldInt = 1
+	}
+	if new {
+		newInt = 1
+	}
+	return atomic.CompareAndSwapInt32(&(b.flag), oldInt, newInt)
+}
+
+func (b *AtomicBool) Set(value bool) {
+	i := int32(0)
+	if value {
+		i = 1
+	}
+	atomic.StoreInt32(&(b.flag), int32(i))
+}
+
+func (b *AtomicBool) Get() bool {
+	if atomic.LoadInt32(&(b.flag)) != 0 {
+		return true
+	}
+	return false
+}

util/atomic_test.go

@@ -0,0 +1,39 @@
+package util
+
+import (
+	"fmt"
+	"github.com/stretchr/testify/assert"
+	"sync"
+	"testing"
+)
+
+func TestAtomicBool_CompareAndSet(t *testing.T) {
+	b := &AtomicBool{}
+	b.Set(true)
+	ok := b.CompareAndSet(true, false)
+	assert.True(t, ok, "CompareAndSet execute failed.")
+	b.Set(false)
+	ok = b.CompareAndSet(true, false)
+	assert.True(t, !ok, "CompareAndSet execute failed.")
+}
+
+func TestAtomicBool_GetAndSet(t *testing.T) {
+	b := &AtomicBool{}
+	assert.True(t, b.Get() == false, "default value is not false.")
+	b.Set(true)
+	assert.True(t, b.Get() == true, "the value is false, expect true.")
+}
+
+func TestIncrementAndGetInt64(t *testing.T) {
+	n := int64(0)
+	wg := &sync.WaitGroup{}
+	wg.Add(100)
+	for i := 0; i < 100; i++ {
+		go func(g *sync.WaitGroup) {
+			IncrementAndGetInt64(&n)
+			wg.Done()
+		}(wg)
+	}
+	wg.Wait()
+	assert.True(t, n == 100, fmt.Sprintf("current n is %d, expect 100.", n))
+}