最近公司工作有点多，Golang的select进阶就这样被拖沓啦，今天坚持把时间挤一挤，把吹的牛皮补上。

前一篇文章《Golang并发模型：轻松入门select》介绍了select的作用和它的基本用法，这次介绍它的3个进阶特性。

nilfor-selectselect{}
nil
casenilcaseselectselectcasecasenil
func combine(inCh1, inCh2 <-chan int) <-chan int {
    // 输出通道
    out := make(chan int)

    // 启动协程合并数据
    go func() {
        defer close(out)
        for {
            select {
            case x, open := <-inCh1:
                if !open {
                    inCh1 = nil
                    continue
                }
                out<-x
            case x, open := <-inCh2:
                if !open {
                    inCh2 = nil
                    continue
                }
                out<-x
            }

            // 当ch1和ch2都关闭是才退出
            if inCh1 == nil && inCh2 == nil {
                break
            }
        }
    }()

    return out
}

如何跳出for-select

breakselectfor-selectconsumeinChinChfor-select
func consume(inCh <-chan int) {
    i := 0
    for {
        fmt.Printf("for: %d\n", i)
        select {
        case x, open := <-inCh:
            if !open {
                break
            }
            fmt.Printf("read: %d\n", x)
        }
        i++
    }

    fmt.Println("combine-routine exit")
}

运行结果：

➜ go run x.go
for: 0
read: 0
for: 1
read: 1
for: 2
read: 2
for: 3
gen exit
for: 4
for: 5
for: 6
for: 7
for: 8
... // never stop
breakfor-select
casereturndeferselectforbreakcombinegoto
select{}
select{}
ch := make(chan int)
<-ch
select{}mainmain

select应用场景

select
select

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