Go缓冲channel和非缓冲channel的区别说明

package main
import (
 "fmt"
 "time"
)
func loop(ch chan int) {
 for {
  select {
  case i := <-ch:
   fmt.Println("this  value of unbuffer channel", i)
  }
 }
}
func main() {
 ch := make(chan int)
 ch <- 1
 go loop(ch)
 time.Sleep(1 * time.Millisecond)
}

package main
import (
 "fmt"
 "time"
)
func loop(ch chan int) {
 for {
  select {
  case i := <-ch:
   fmt.Println("this  value of unbuffer channel", i)
  }
 }
}
func main() {
 ch := make(chan int,3)
 ch <- 1
 ch <- 2
 ch <- 3
 ch <- 4
 go loop(ch)
 time.Sleep(1 * time.Millisecond)
}

func fanIn(input1, input2 <-chan string) <-chan string {
   c := make(chan string)
   go func() {
       for {
           select {
           case s := <-input1:  c <- s
           case s := <-input2:  c <- s
           }
       }
   }()
   return c
}

func main() {
   g = make(chan int)
   quit = make(chan bool)
   go B()
   for i := 0; i < 3; i++ {
       g <- i
   }
   quit <- true // 没办法等待B的退出只能Sleep
   fmt.Println("Main quit")
}
func B() {
   for {
       select {
       case i := <-g:
           fmt.Println(i + 1)
       case <-quit:
           fmt.Println("B quit")
           return
       }
   }
}
/*
Output:
1
2
3
Main quit
*/

func main() {
   g = make(chan int)
   quit = make(chan chan bool)
   go B()
   for i := 0; i < 5; i++ {
       g <- i
   }
   wait := make(chan bool)
   quit <- wait
   <-wait //这样就可以等待B的退出了
   fmt.Println("Main Quit")
}
func B() {
   for {
       select {
       case i := <-g:
           fmt.Println(i + 1)
       case c := <-quit:
           c <- true
           fmt.Println("B Quit")
           return
       }
   }
}
/* Output
1
2
3
B Quit
Main Quit
*/

func recursiveCall(ctx context.Context, id []byte, initialNodes []*node){
	seen := map[string]*node{} //已见过的节点记录
	request := make(chan *node, 3) //设置请求节点channel
        // 输入初始节点
	go func() {
		for _, n := range initialNodes {
			request <- n
		}
	}()
OUT:
	for {
               //循环直到找到数据
		if data != nil {
		    return
		}
                // 在新的请求，超时和上层取消请求中select
		select {
		case n := <-request:
			go func() {
                                // 发送新的请求
				response := s.sendQuery(ctx, n, MethodFindValue, id)
				select {
				case <-ctx.Done():
				case msg :=<-response:
                                    seen[responseToNode(response)] = n //更新已见过的节点信息
                                                // 加载新的节点
						for _, rn := range LoadNodeInfoFromByte(msg[PayLoadStart:]) {
							mu.Lock()
							_, ok := seen[rn.HexID()]
							mu.Unlock()
                                                        // 见过了，跳过这个节点
							if ok { 
 								continue
							}
							AddNode(rn)
                                                        // 将新的节点送入channel
							request <- rn
						}
					}
				}
			}()
		case <-time.After(500 * time.Millisecond):
			break OUT // break至外层，否则仅仅是跳至loop外
        	case <-ctx.Done():
			break OUT
		}
	}
	return
}