error handling inside goroutines

This commit is contained in:
Sebastian Hugentobler 2019-05-28 12:30:32 +02:00
parent 2a88e5c900
commit 25eef75018

View File

@ -41,6 +41,10 @@ func DownloadBook(outDir string, size string, id string, logger Logger) error {
semaphore := make(chan struct{}, MAX_DOWNLOADS) semaphore := make(chan struct{}, MAX_DOWNLOADS)
logger.Info.Println("downloading pages...") logger.Info.Println("downloading pages...")
ec := make(chan error)
finished := make(chan bool, 1)
for index, pageUrl := range pageUrls { for index, pageUrl := range pageUrls {
wg.Add(1) wg.Add(1)
@ -52,18 +56,31 @@ func DownloadBook(outDir string, size string, id string, logger Logger) error {
<-semaphore <-semaphore
}() }()
downloadUrl, err:= getSizeLink(pageUrl, size) downloadUrl, err := getSizeLink(pageUrl, size)
if err != nil { if err != nil {
//return err ec <- err
} }
filename := fmt.Sprintf("%06d.jpg", index) filename := fmt.Sprintf("%06d.jpg", index)
downloadToFile(filename, dir, downloadUrl) err = downloadToFile(filename, dir, downloadUrl)
if err != nil {
ec <- err
}
}(index, pageUrl) }(index, pageUrl)
} }
go func() {
wg.Wait() wg.Wait()
close(finished)
}()
select {
case <-finished:
case err := <-ec:
if err != nil {
return err
}
}
err = os.MkdirAll(outDir, os.ModePerm) err = os.MkdirAll(outDir, os.ModePerm)
if err != nil { if err != nil {
@ -77,7 +94,7 @@ func DownloadBook(outDir string, size string, id string, logger Logger) error {
} }
// Find the download link for a page of a specific size. // Find the download link for a page of a specific size.
func getSizeLink(pageUrl string , size string) (string, error) { func getSizeLink(pageUrl string, size string) (string, error) {
doc, err := fetchDocument(pageUrl) doc, err := fetchDocument(pageUrl)
if err != nil { if err != nil {
return "", err return "", err