Or-Channel

• 使用场景：
  当你需要同时监测多个信号时，只要接收到其中任一个信号，就认为信号接收成功，需要进行下一步处理

• 代码：

  func or(channels ...<-chan interface{}) <-chan interface{} {
      switch len(channels) {
      case 0:
          return nil
      case 1:
          return channels[0]
      }
      orDone := make(chan interface{})
      go func() {
          defer close(orDone)
          switch len(channels) {
          case 2:
              select {
              case <-channels[0]:
              case <-channels[1]:
              }
          default:
              select {
              case <-channels[0]:
              case <-channels[1]:
              case <-channels[2]:
              case <-or(append(channels[3:], orDone)...):
              }
          }
      }()
      return orDone
  }
  

• 测试：

  func TestOr(t *testing.T) {
      st := time.Now()
      r := rand.New(rand.NewSource(time.Now().Unix()))
      <-or(
          randSig(r),
          randSig(r),
          randSig(r),
          randSig(r),
          randSig(r),
      )
      fmt.Printf("closed after %v!\n", time.Since(st))
  }
  
  func randSig(r *rand.Rand) <-chan interface{} {
      ch := make(chan interface{})
      go func() {
          defer close(ch)
          sec := time.Duration(r.Int63n(10)+3) * time.Second
          fmt.Printf("closing after %v!\n", sec)
          time.Sleep(sec)
      }()
      return ch
  }
  

  结果：

  closing after 4s!
  closing after 10s!
  closing after 3s!
  closing after 9s!
  closing after 11s!
  closed after 3.001062582s!