func BasicCrawler(baseUrl string, maxDepth int, GoThere func(string) bool) map[string]string {
// URL result map with data
resUrls := make(map[string]string)
// Downloader url feedback channel
chUrl := make(chan queue.UrlItem)
// Downloader finish response channel
chResp := make(chan RespItem)
defer func() {
close(chUrl)
close(chResp)
}()
q := queue.UrlQueue{}
// Push base url to queue
q.Push(baseUrl, 0)
// running coroutine count
running := 0
// Main loop for concurrent crawler
for {
// Queue empty, and no running routine, exit
if q.Size == 0 && running == 0 {
break
}
if q.Size > 0 {
if running < THREAD_NUMBER {
ui, err := q.Pop()
if err != nil {
continue
}
_, visited := resUrls[ui.Url]
if visited {
continue
}
resUrls[ui.Url] = "OK"
go crawl(ui, chUrl, chResp)
running++
//fmt.Println("running: ", running)
}
}
select {
case url := <-chUrl:
if url.Depth < maxDepth && GoThere(url.Url) {
q.Push(url.Url, url.Depth)
}
case ri := <-chResp:
resUrls[ri.Url] = ri.RespBody
running--
default:
continue
}
}
return resUrls
}
func main() {
q := queue.UrlQueue{}
for i := 1; i < 10; i++ {
q.Push(fmt.Sprintf("URL: %d", i), i)
}
for {
a, err := q.Pop()
if err != nil {
fmt.Println("Queue cleared.")
break
}
fmt.Println(a.Url, a.Depth, q.Size)
}
}