How to listen to fifo wait for a fifo file's output in golang

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I'll run a command that will push output to a FIFO file in the file system.

In bash, I can write timeout 3000 cat server_fifo>server.url to wait until either the fifo was pushed an output, or it reaches the 3000 timeout.

I wonder how we can do this in golang, i.e. keep waiting for the output of an fifo file, and set a timeout for this wait.

Per matishsiao's gist script here, I know we can do

    file, err := os.OpenFile(urlFileName, os.O_CREATE, os.ModeNamedPipe)
    if err != nil {
        log.Fatal("Open named pipe file error:", err)
    }

    reader := bufio.NewReader(file)

    for {
        _, err := reader.ReadBytes('\n')
        if err == nil {
            fmt.Println("cockroach server started")
            break
        }
    }

But in this case, how to add a time out to the for loop?

go
1 Answers

This is a simple boilerplate you can use:

finished := make(chan bool)
go func() {
    /*
     * Place your code here
     */
    finished <- true
}()
select {
case <-time.After(timeout):
    fmt.Println("Timed out")
case <-finished:
    fmt.Println("Successfully executed")
}

Assign time.Second*3 or any Duration to the timeout variable.

EDIT: Adding example function with callback:

func timeoutMyFunc(timeout time.Duration, myFunc func()) bool {
    finished := make(chan bool)
    go func() {
        myFunc()
        finished <- true
    }()
    select {
    case <-time.After(timeout):
        return false
    case <-finished:
        return true
    }
}

func main() {
    success := timeoutMyFunc(3*time.Second, func() {
        /*
         * Place your code here
         */
    })
}
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