CODEWITHSUNDEEP
go
Ganso
Ganso

Reputation: 53

Reset method for bufio.NewScanner?

Is there a way to reset the *Scanner (from bufio.NewScanner) or clear old tokens? Unfortunately "func (b *Reader) Reset(r io.Reader)" does not work with *Scanner.

Update/clarification: I want to resume with the newest data from os.Stdout when "time.Sleep(30 * time.Second)" ends and skip all data that could be read during that 30 seconds.

I am currently using a for loop as dirty workaround:

scanner := bufio.NewScanner(os.Stdout)
for scanner.Scan() {
    fmt.Println(scanner.Text())

    if scanner.Text() == "abc" {
        //do something that takes a little time
        time.Sleep(30 * time.Second)

        // my dirty workaround:
        // skips all old tokens/inputs
        for skip := time.Now(); time.Since(skip).Seconds() < 10; {
            scanner.Scan()
        }
    }
}

Upvotes: 1

Views: 1413

Answers (1)

user13631587
user13631587

Reputation:

Run the long operation in a goroutine. Discard input while the goroutine is running.

scanner := bufio.NewScanner(os.Stdout)
var discard int32
var wg sync.WaitGroup
for scanner.Scan() {
    if atomic.LoadInt32(&discard) != 0 {
        continue
    }

    fmt.Println(scanner.Text())

    if scanner.Text() == "abc" {
        atomic.StoreInt32(&discard, 1)
        wg.Add(1)
        go func() {
            defer wg.Done()
            defer atomic.StoreInt32(&discard, 0)
            //do something that takes a little time
            time.Sleep(30 * time.Second)
        }()
    }
}

wg.Wait() // wait for long process after EOF or error.

Upvotes: 3

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