github.com/qiuhoude/go-web@v0.0.0-20220223060959-ab545e78f20d/prepare/18channeluse/or_channel_rec/main.go (about)

     1  package main
     2  
     3  import (
     4  	"fmt"
     5  	"time"
     6  )
     7  
     8  //递归的方式 分而治之的方式，逐步合并channel，最终返回一个channel
     9  func or(channels ...<-chan interface{}) <-chan interface{} {
    10  	// 递归跳出条件
    11  	switch len(channels) {
    12  	case 0:
    13  		return nil
    14  	case 1:
    15  		return channels[0]
    16  	}
    17  
    18  	orDone := make(chan interface{})
    19  	go func() {
    20  		defer close(orDone)
    21  
    22  		switch len(channels) {
    23  		case 2:
    24  			select {
    25  			case <-channels[0]:
    26  			case <-channels[1]:
    27  			}
    28  		default:
    29  			m := len(channels) / 2
    30  			select {
    31  			case <-or(channels[:m]...):
    32  			case <-or(channels[m:]...):
    33  			}
    34  		}
    35  	}()
    36  
    37  	return orDone
    38  }
    39  
    40  func sig(after time.Duration) <-chan interface{} {
    41  	c := make(chan interface{})
    42  	go func() {
    43  		defer close(c)
    44  		time.Sleep(after)
    45  	}()
    46  	return c
    47  }
    48  
    49  func main() {
    50  
    51  	start := time.Now()
    52  
    53  	<-or(
    54  		sig(10*time.Second),
    55  		sig(20*time.Second),
    56  		sig(30*time.Second),
    57  		sig(40*time.Second),
    58  		sig(5*time.Second),
    59  		sig(01*time.Minute),
    60  	)
    61  
    62  	fmt.Printf("done after %v", time.Since(start))
    63  }