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    async fetching of urls using goroutines and channels
  
        
  
    
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  | package main | |
| import ( | |
| "fmt" | |
| "net/http" | |
| "time" | |
| ) | |
| var urls = []string{ | |
| "https://splice.com/", | |
| "https://golang.org/", | |
| "https://matt.aimonetti.net/", | |
| } | |
| type HttpResponse struct { | |
| url string | |
| response *http.Response | |
| err error | |
| } | |
| func asyncHttpGets(urls []string) []*HttpResponse { | |
| ch := make(chan *HttpResponse, len(urls)) // buffered | |
| responses := []*HttpResponse{} | |
| for _, url := range urls { | |
| go func(url string) { | |
| fmt.Printf("Fetching %s \n", url) | |
| resp, err := http.Get(url) | |
| if err == nil { | |
| resp.Body.Close() | |
| } | |
| ch <- &HttpResponse{url, resp, err} | |
| }(url) | |
| } | |
| for { | |
| select { | |
| case r := <-ch: | |
| fmt.Printf("%s was fetched\n", r.url) | |
| responses = append(responses, r) | |
| if len(responses) == len(urls) { | |
| return responses | |
| } | |
| case <-time.After(50 * time.Millisecond): | |
| fmt.Printf(".") | |
| } | |
| } | |
| return responses | |
| } | |
| func main() { | |
| results := asyncHttpGets(urls) | |
| for _, result := range results { | |
| if result.err != nil { | |
| fmt.Printf("%s error: %v\n", result.url, | |
| result.err) | |
| continue | |
| } | |
| fmt.Printf("%s status: %s\n", result.url, | |
| result.response.Status) | |
| } | |
| } | 
  
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