download_mutliple_files.go

func downloadMultipleFiles(urls []string) ([][]byte, error) {
	done := make(chan []byte, len(urls))
	errch := make(chan error, len(urls))
	for _, URL := range urls {
		go func(URL string) {
			b, err := downloadFile(URL)
			if err != nil {
				errch <- err
				done <- nil
				return
			}
			done <- b
			errch <- nil
		}(URL)
	}
	bytesArray := make([][]byte, 0)
	var errStr string
	for i := 0; i < len(urls); i++ {
		bytesArray = append(bytesArray, <-done)
		if err := <-errch; err != nil {
			errStr = errStr + " " + err.Error()
		}
	}
	var err error
	if errStr!=""{
		err = errors.New(errStr)
	}
	return bytesArray, err
}