有条件的例程/通道

Question

I would like to make the statistics routine conditional so that it only runs on certain cases otherwise it will waste cycles half the time. Right now I have one go routine act as a producer to feed the two consumer routines via buffered channels. Is there a way I can make it so the statistics routine is conditional or is there a better pattern I should follow? Thanks in advance for any and all help!

func main() {
    options()
    go produce(readCSV(loc))
    go process()
    go statistics() // only on flag
    <-done
}

func produce(entries [][]string) {
    regex, err := regexp.Compile(reg)
    if err != nil {
        log.Error(reg + ", is not a valid regular expression")
    } else {
        for _, each := range entries {
            if regex.MatchString(each[col]) {
                matches <- each
                stats <- each // only on flag
            }
        }
    }
    done <- true
}

func process() {
    for {
        match := <-matches
        if len(match) != 0 {
            // PROCESS
        }
    }
}

func statistics() {
    for {
        stat := <-stats
        if len(stat) != 0 {
            // STATISTICS
        }
    }
}

Answer 1

There is nothing wrong with making this conditional:

var stats chan []string  // Don't initialize stats.

func main() {
    options()
    go produce(readCSV(loc))
    go process()
    if flag {
        stats = make(chan []string, 1024)
        go statistics() // only on flag
    }
    <-done
}

func produce(entries [][]string) {
    regex, err := regexp.Compile(reg)
    if err != nil {
        log.Error(reg + ", is not a valid regular expression")
    } else {
        for _, each := range entries {
            if regex.MatchString(each[col]) {
                matches <- each
                if stats != nil {
                    stats <- each // only on flag
                }
            }
        }
    }
    close(done)
}

func process() {
    for {
        select {
        case match := <-matches:
            if len(match) != 0 {
              // PROCESS
            }
        case <-done:
            return
        }
    }
}

func statistics() {
    for {
        select {
        case stat := <-stats:
            if len(stat) != 0 {
                // STATISTICS
            }
        case <-done:
            return
        }
    }
}