From f41768955d8626453264d9c5d8a42c9ed298f845 Mon Sep 17 00:00:00 2001
From: nynicg <nynicg@outlook.com>
Date: Mon, 6 May 2019 16:00:16 +0800
Subject: [PATCH] barrier pattern

---
 README.md                     |   2 +-
 concurrency/n_barrier/main.go | 130 ++++++++++++++++++++++++++++++++++
 2 files changed, 131 insertions(+), 1 deletion(-)
 create mode 100644 concurrency/n_barrier/main.go

diff --git a/README.md b/README.md
index f1f0347..903e12b 100644
--- a/README.md
+++ b/README.md
@@ -61,7 +61,7 @@ A curated collection of idiomatic design & application patterns for Go language.
 
 | Pattern | Description | Status |
 |:-------:|:----------- |:------:|
-| [N-Barrier](/concurrency/barrier.md) | Prevents a process from proceeding until all N processes reach to the barrier | ✘ |
+| [N-Barrier](/concurrency/barrier/main.go) | Prevents a process from proceeding until all N processes reach to the barrier | ✔ |
 | [Bounded Parallelism](/concurrency/bounded_parallelism.md) | Completes large number of independent tasks with resource limits | ✔ |
 | [Broadcast](/concurrency/broadcast.md) | Transfers a message to all recipients simultaneously | ✘ |
 | [Coroutines](/concurrency/coroutine.md) | Subroutines that allow suspending and resuming execution at certain locations | ✘ |
diff --git a/concurrency/n_barrier/main.go b/concurrency/n_barrier/main.go
new file mode 100644
index 0000000..2957fa5
--- /dev/null
+++ b/concurrency/n_barrier/main.go
@@ -0,0 +1,130 @@
+package main
+
+import (
+	"log"
+	"sync"
+)
+
+type IBarrier interface {
+	Await() error
+}
+
+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(){
+	var b IBarrier
+	wg := &sync.WaitGroup{}
+	gos := 10
+	wg.Add(gos)
+	b = NewBarrier(uint(gos))
+	for i:=0;i<gos ;i++ {
+		go func() {
+			log.Println("await")
+			if err := b.Await();err != nil{
+				log.Println(err)
+			}
+			log.Println("pass")
+			wg.Done()
+		}()
+	}
+	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
+//}