go language from the beginning of the example Example27. timeout handling

Timeout  for a connection to an external resource, or some other program in terms of the time it takes to perform the operation is very important. Thanks to the channel and  selectachieve operation timeout in Go is simple and elegant.

Example:

main Package 

Import  " FMT " 
Import  " Time " 



FUNC main () { 
    c1: = the make (Chan String)


     // In our example, if we execute an external call, and 2 back through the passage c1 seconds after its execution result. 
    FUNC Go () { 
        time.sleep (time.Second * 2 ) 
        C1 <- " One " 
    } ()

     // this is implemented using a select operation timeout. res: = <- c1 wait for the results, <- Time.After 1 wait timeout value after the second transmission.
    // Since select the default handler is ready to receive the first operation, if the operation exceeds the allowable 1 second, it will timeout case. 
    {SELECT 
    Case RES: = <- C1: 
        fmt.Println (RES) 
    Case<- time.After(time.Second * 1):
        fmt.Println("timeout 1")    
    }

    c2 := make(chan string)
    go func(){
        time.Sleep(time.Second * 2)
        c2 <- "two"
    }()
    
    select{
    case res := <-c2:
        fmt.Println(res)
    case <- time.After(time.Second * 3):
        fmt.Println("timeount 2")
    }

}

Result:

$ go run example.go

    timeout 1
    two

 Run the program, first time out of the show running operation, and then successfully received.

Use this  select timeout mode, the results need to pass the channel. This is a good way for the general case, because other important feature is based on channel and Go select 's.