0design.txt

Parallelism design.

var numParallel = 20
var tokens = make(chan struct{}, numParallel)
var results = make(chan *ResponseInfo)

var wg sync.WaitGroup


go func() {
    for query := loopOverFile(BatchFile) {
        wg.Add(1)
	tokens <- struct{}{}                     // acquire token
        go func(query string) {
            defer wg.Done()
	    results <- runQuery(query)
            <- tokens                            // release token
        }(query)
    }
    wg.Wait()
    close(results)
}()


for r := range(results) {
    printResponse(r)
}

#############

fun runQuery() {
    responses := make(chan *ResponseInfo)

    for _, server := range serverList {
    	r := &ResponseInfo()
	go sendDNSquery(server, responses)
    }
    for i := 0; i < len(serverList); i++ {
    	r1 = <-responses
	if responseOK(r1) {
	   break
	}
    }
    return r1
}