From 996819084081c1bf3cc3f9486b570e3112ff3d30 Mon Sep 17 00:00:00 2001
From: nynicg <nynicg@outlook.com>
Date: Fri, 10 May 2019 14:57:25 +0800
Subject: [PATCH] barrier pattern

---
 concurrency/n_barrier/main.go | 141 +++++++++++++---------------------
 1 file changed, 52 insertions(+), 89 deletions(-)

diff --git a/concurrency/n_barrier/main.go b/concurrency/n_barrier/main.go
index 2957fa5..984e1f7 100644
--- a/concurrency/n_barrier/main.go
+++ b/concurrency/n_barrier/main.go
@@ -6,40 +6,69 @@ import (
 )
 
 type IBarrier interface {
+	// error for timeout if need
 	Await() error
 }
 
-type Barrier struct {
-	cond *sync.Cond
-	gos uint
-	curgos uint
+
+// once
+type ChanBarrier struct {
+	gos int
+	curGos int
+	ch chan struct{}
+	m sync.Mutex
 }
 
-func NewBarrier(syncGos uint)*Barrier{
-	if syncGos < 1{
-		panic("min 1")
-	}
-	l := &sync.Mutex{}
-	c := sync.NewCond(l)
-	return &Barrier{
-		cond:c,
-		gos:syncGos,
+func NewChanBarrier(gos int)*ChanBarrier{
+	return &ChanBarrier{
+		gos:gos,
+		ch:make(chan struct{}),
 	}
 }
 
-func (b *Barrier)Await() error{
-	b.cond.L.Lock()
-	defer b.cond.L.Unlock()
-	b.curgos++
-	if b.gos != b.curgos{
-		b.cond.Wait()
+func (c *ChanBarrier) Await() error {
+	c.m.Lock()
+	if c.curGos++;c.gos != c.curGos{
+		c.m.Unlock()
+		<- c.ch
 	}else{
-		b.curgos = 0
-		b.cond.Broadcast()
+		c.m.Unlock()
+		close(c.ch)
 	}
 	return nil
 }
 
+//type Barrier struct {
+//	cond *sync.Cond
+//	gos uint
+//	curgos uint
+//}
+//
+//func NewBarrier(syncGos uint)*Barrier{
+//	if syncGos < 1{
+//		panic("min 1")
+//	}
+//	l := &sync.Mutex{}
+//	c := sync.NewCond(l)
+//	return &Barrier{
+//		cond:c,
+//		gos:syncGos,
+//	}
+//}
+//
+//func (b *Barrier)Await() error{
+//	b.cond.L.Lock()
+//	defer b.cond.L.Unlock()
+//	b.curgos++
+//	if b.gos != b.curgos{
+//		b.cond.Wait()
+//	}else{
+//		b.curgos = 0
+//		b.cond.Broadcast()
+//	}
+//	return nil
+//}
+
 
 
 func main(){
@@ -47,7 +76,8 @@ func main(){
 	wg := &sync.WaitGroup{}
 	gos := 10
 	wg.Add(gos)
-	b = NewBarrier(uint(gos))
+	//b = NewBarrier(uint(gos))
+	b = NewChanBarrier(gos)
 	for i:=0;i<gos ;i++ {
 		go func() {
 			log.Println("await")
@@ -59,72 +89,5 @@ func main(){
 		}()
 	}
 	wg.Wait()
-
-	//b = NewTimeoutBarrier(time.Second ,2)
-	//wg.Add(2)
-	//
-	//go func() {
-	//	log.Println("await 1")
-	//	if err := b.Await();err != nil{
-	//		log.Println(err)
-	//	}
-	//	log.Println("pass 1")
-	//	wg.Done()
-	//}()
-	//go func() {
-	//	log.Println("await 2")
-	//	// 导致前一个await超时
-	//	time.Sleep(time.Second*4)
-	//	if err := b.Await();err != nil{
-	//		log.Println(err)
-	//	}
-	//	log.Println("pass 2")
-	//	wg.Done()
-	//}()
-	//wg.Wait()
 }
 
-//// only use once
-//type TimeoutBarrier struct {
-//	ch chan struct{}
-//	t time.Duration
-//	gos uint
-//	arrgos uint
-//	togos int
-//	m sync.Mutex
-//}
-//
-//func NewTimeoutBarrier(t time.Duration ,syncgos uint)*TimeoutBarrier{
-//	if t == 0{
-//		t = math.MaxInt64
-//	}
-//	if syncgos < 1{
-//		panic("min goroutine num = 1")
-//	}
-//	return &TimeoutBarrier{
-//		ch:make(chan struct{}),
-//		t:t,
-//		gos:syncgos,
-//	}
-//}
-//
-//func (b *TimeoutBarrier)Await() (err error){
-//	b.m.Lock()
-//	b.arrgos++
-//	if b.arrgos != b.gos{
-//		b.m.Unlock()
-//		select {
-//		case <- b.ch:
-//		case <- time.After(b.t):
-//			b.togos++
-//			err = errors.New("time out")
-//		}
-//	}else{
-//		for i:=0;i<int(b.gos)-1-b.togos;i++{
-//			b.ch <- struct{}{}
-//		}
-//		close(b.ch)
-//		b.m.Unlock()
-//	}
-//	return err
-//}