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

     1  package main
     2  
     3  import (
     4  	"fmt"
     5  	"time"
     6  )
     7  
     8  // refer to https://github.com/kat-co/concurrency-in-go-src/blob/master/concurrency-patterns-in-go/the-or-channel/fig-or-channel.go
     9  func or(channels ...<-chan interface{}) <-chan interface{} {
    10  	switch len(channels) {
    11  	case 0:
    12  		return nil
    13  	case 1:
    14  		return channels[0]
    15  	}
    16  	// 分治思想, 两个channel合成1个
    17  	orDone := make(chan interface{})
    18  	go func() {
    19  		defer close(orDone)
    20  
    21  		switch len(channels) {
    22  		case 2:
    23  			select {
    24  			case <-channels[0]:
    25  			case <-channels[1]:
    26  			}
    27  		default: //>=3
    28  			select {
    29  			case <-channels[0]:
    30  			case <-channels[1]:
    31  			case <-channels[2]:
    32  			case <-or(append(channels[3:], orDone)...):
    33  			}
    34  		}
    35  	}()
    36  	return orDone
    37  }
    38  
    39  func sig(after time.Duration) <-chan interface{} {
    40  	c := make(chan interface{})
    41  	go func() {
    42  		defer close(c)
    43  		time.Sleep(after)
    44  	}()
    45  	return c
    46  }
    47  
    48  func main() {
    49  
    50  	start := time.Now()
    51  
    52  	<-or(
    53  		sig(20*time.Second),
    54  		sig(30*time.Second),
    55  		sig(5*time.Second),
    56  		sig(40*time.Second),
    57  		sig(50*time.Second),
    58  		sig(01*time.Minute),
    59  		sig(3*time.Second),
    60  	)
    61  
    62  	fmt.Printf("done after %v", time.Since(start))
    63  }