Go fan-out task processor

[riking]

type Job interface {
	Process()
	Print()
}

// ===============
// Change this
type HiJob struct {
	name string
}

func (j *HiJob) Process() {
	// do something
}

func (j *HiJob) Print() {
	fmt.Printf("Hi, %s\n", j.name)
}
// ===============

func main() {
	pending := make(chan Job)
	complete := make(chan Job)
	
	var wg sync.WaitGroup

	// Reader
	go func() {
		var line string
		
		for {
			_, err := fmt.Scanln(&line)
			if err != nil {
				break
			}
			pending <- // create Jobs here 
		}
		close(pending)
	}();
	
	// Printer
	go func() {
		for completeJob := range complete {
			completeJob.Print()
		}
	}();
	
	// Workers
	// increase count as needed
	for i := 0; i < 10; i++ {
		go func() {
			for job := range pending {
				job.Process()
				complete <- job
			}
			wg.Done()
		}()
		wg.Add(1)
	}
	
	wg.Wait()
	close(complete)
}

... goddamn it eclipse, did you put in tabs again?

[riking]

Example usage:

type DomainLookupJob struct {
	domain string
	result net.IP
	err error
}

func (j *DomainLookupJob) Process() {
	ips, err := net.LookupIP(j.domain)
	if err == nil {
		for _, ip := range ips {
			j.result = ip
			return
		}
		j.result = nil
		j.err = errors.New("No A or AAAA record found")
	} else {
		j.result = nil
		j.err = err
	}
}


func (j *DomainLookupJob) Print() {
	if j.err != nil {
		fmt.Printf("%s ERROR %s\n", j.domain, j.err)
	} else {
		fmt.Printf("%s %s\n", j.domain, j.result.String())
	}
}

func NewDomainLookupJob(domain string) *DomainLookupJob {
	return &DomainLookupJob{ domain, nil, nil }
}

			pending <- NewDomainLookupJob(line)

cat domains | go run domainlookup.go